std.Io.Threaded: fix incorrect alignment of trailing data in closure#25868

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std.Io.Threaded: fix incorrect alignment of trailing data in closure #25868

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72590e4
std.Io.Threaded: fix incorrect alignment of trailing data in closure
Techatrix Nov 10, 2025
f90001d
std.Io: fix calls on functions that return an array type
Techatrix Nov 9, 2025
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14 changes: 7 additions & 7 deletions lib/std/Io.zig
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -990,15 +990,15 @@ pub fn Future(Result: type) type {
/// Idempotent. Not threadsafe.
pub fn cancel(f: *@This(), io: Io) Result {
const any_future = f.any_future orelse return f.result;
io.vtable.cancel(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
io.vtable.cancel(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
f.any_future = null;
return f.result;
}

/// Idempotent. Not threadsafe.
pub fn await(f: *@This(), io: Io) Result {
const any_future = f.any_future orelse return f.result;
io.vtable.await(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
io.vtable.await(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
f.any_future = null;
return f.result;
}
Expand DownExpand Up@@ -1034,7 +1034,7 @@ pub const Group = struct {
@call(.auto, function, args_casted.*);
}
};
io.vtable.groupAsync(io.userdata, g, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
io.vtable.groupAsync(io.userdata, g, @ptrCast(&args), .of(Args), TypeErased.start);
}

/// Blocks until all tasks of the group finish. During this time,
Expand DownExpand Up@@ -1111,7 +1111,7 @@ pub fn Select(comptime U: type) type {
}
};
_ = @atomicRmw(usize, &s.outstanding, .Add, 1, .monotonic);
s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast(&args), .of(Args), TypeErased.start);
}

/// Blocks until another task of the select finishes.
Expand DownExpand Up@@ -1539,9 +1539,9 @@ pub fn async(
var future: Future(Result) = undefined;
future.any_future = io.vtable.async(
io.userdata,
@ptrCast((&future.result)[0..1]),
@ptrCast(&future.result),
.of(Result),
@ptrCast((&args)[0..1]),
@ptrCast(&args),
.of(Args),
TypeErased.start,
);
Expand DownExpand Up@@ -1580,7 +1580,7 @@ pub fn concurrent(
io.userdata,
@sizeOf(Result),
.of(Result),
@ptrCast((&args)[0..1]),
@ptrCast(&args),
.of(Args),
TypeErased.start,
);
Expand Down
52 changes: 31 additions & 21 deletions lib/std/Io/Threaded.zig
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -388,7 +388,8 @@ const AsyncClosure = struct {
reset_event: ResetEvent,
select_condition: ?*ResetEvent,
context_alignment: std.mem.Alignment,
result_offset: usize,
result_alignment: std.mem.Alignment,
result_offset_before_padding: usize,

const done_reset_event: *ResetEvent = @ptrFromInt(@alignOf(ResetEvent));

Expand DownExpand Up@@ -420,12 +421,12 @@ const AsyncClosure = struct {

fn resultPointer(ac: *AsyncClosure) [*]u8 {
const base: [*]u8 = @ptrCast(ac);
return base + ac.result_offset;
return @ptrFromInt(ac.result_alignment.forward(@intFromPtr(base + ac.result_offset_before_padding)));
}

fn contextPointer(ac: *AsyncClosure) [*]u8 {
const base: [*]u8 = @ptrCast(ac);
return base + ac.context_alignment.forward(@sizeOf(AsyncClosure));
return @ptrFromInt(ac.context_alignment.forward(@intFromPtr(base + @sizeOf(AsyncClosure))));
}

fn waitAndFree(ac: *AsyncClosure, gpa: Allocator, result: []u8) void {
Expand All@@ -436,7 +437,9 @@ const AsyncClosure = struct {

fn free(ac: *AsyncClosure, gpa: Allocator, result_len: usize) void {
const base: [*]align(@alignOf(AsyncClosure)) u8 = @ptrCast(ac);
gpa.free(base[0 .. ac.result_offset + result_len]);
const result_offset_with_padding = ac.result_alignment.forward(ac.result_offset_before_padding);
const allocated_size = result_offset_with_padding + result_len;
gpa.free(base[0..allocated_size]);
}
};

Expand All@@ -460,13 +463,16 @@ fn async(
};
};
const gpa = t.allocator;
const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
const result_offset = result_alignment.forward(context_offset + context.len);
const n = result_offset + result.len;
const ac: *AsyncClosure = @ptrCast(@alignCast(gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch {
const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
const result_offset_before_padding = context_offset_with_padding + context.len;
const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
const allocated_size = result_offset_with_padding + result.len;
const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch {
start(context.ptr, result.ptr);
return null;
}));
};
const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

ac.* = .{
.closure = .{
Expand All@@ -476,7 +482,8 @@ fn async(
},
.func = start,
.context_alignment = context_alignment,
.result_offset = result_offset,
.result_alignment = result_alignment,
.result_offset_before_padding = result_offset_before_padding,
.reset_event = .unset,
.select_condition = null,
};
Expand DownExpand Up@@ -531,10 +538,12 @@ fn concurrent(
const t: *Threaded = @ptrCast(@alignCast(userdata));
const cpu_count = t.cpu_count catch 1;
const gpa = t.allocator;
const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
const result_offset = result_alignment.forward(context_offset + context.len);
const n = result_offset + result_len;
const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch
const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
const result_offset_before_padding = context_offset_with_padding + context.len;
const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
const allocated_size = result_offset_with_padding + result_len;
const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch
return error.ConcurrencyUnavailable;
const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

Expand All@@ -546,7 +555,8 @@ fn concurrent(
},
.func = start,
.context_alignment = context_alignment,
.result_offset = result_offset,
.result_alignment = result_alignment,
.result_offset_before_padding = result_offset_before_padding,
.reset_event = .unset,
.select_condition = null,
};
Expand DownExpand Up@@ -580,6 +590,8 @@ fn concurrent(
return @ptrCast(ac);
}

/// Trailing data:
/// 1. context
const GroupClosure = struct {
closure: Closure,
t: *Threaded,
Expand DownExpand Up@@ -621,17 +633,15 @@ const GroupClosure = struct {
gpa.free(base[0..contextEnd(gc.context_alignment, gc.context_len)]);
}

fn contextOffset(context_alignment: std.mem.Alignment) usize {
return context_alignment.forward(@sizeOf(GroupClosure));
}

fn contextEnd(context_alignment: std.mem.Alignment, context_len: usize) usize {
return contextOffset(context_alignment) + context_len;
const context_offset_before_padding = @alignOf(GroupClosure) + @sizeOf(GroupClosure);
const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
return context_offset_with_padding + context_len;
}

fn contextPointer(gc: *GroupClosure) [*]u8 {
const base: [*]u8 = @ptrCast(gc);
return base + contextOffset(gc.context_alignment);
return @ptrFromInt(gc.context_alignment.forward(@intFromPtr(base + @sizeOf(GroupClosure))));
}

const sync_is_waiting: usize = 1 << 0;
Expand Down
66 changes: 66 additions & 0 deletions lib/std/Io/Threaded/test.zig
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -56,3 +56,69 @@ test "concurrent vs concurrent prevents deadlock via oversubscription" {
getter.await(io);
putter.await(io);
}

fn paramWithExtraAlignment(param: Align64) void {
assert(param.data == 3);
}

fn returnValueWithExtraAlignment() Align64 {
return .{ .data = 5 };
}

const Align64 = struct {
data: u8 align(64),
};

test "async closure where result or context has extra alignment" {
// A fixed buffer allocator is used instead of `std.testing.allocator` to
// not get memory that has better alignment than requested.
var buffer: [1024]u8 align(64) = undefined;
var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

var threaded: std.Io.Threaded = .init(fba.allocator());
defer threaded.deinit();
const io = threaded.io();

{
var future = io.async(paramWithExtraAlignment, .{.{ .data = 3 }});
future.await(io);
}

{
var future = io.async(returnValueWithExtraAlignment, .{});
const result = future.await(io);
try std.testing.expectEqual(5, result.data);
}
}

test "group closure where context has extra alignment" {
// A fixed buffer allocator is used instead of `std.testing.allocator` to
// not get memory that has better alignment than requested.
var buffer: [1024]u8 align(64) = undefined;
var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

var threaded: std.Io.Threaded = .init(fba.allocator());
defer threaded.deinit();
const io = threaded.io();

var group: std.Io.Group = .init;
defer group.cancel(io);

group.async(io, paramWithExtraAlignment, .{.{ .data = 3 }});
}

fn returnArray() [32]u8 {
return @splat(5);
}

test "async on function with array parameter or return type" {
var threaded: std.Io.Threaded = .init(std.testing.allocator);
defer threaded.deinit();
const io = threaded.io();

var future = io.async(returnArray, .{});
const result = future.await(io);
for (result) |actual| {
try std.testing.expectEqual(5, actual);
}
}
Loading
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
 blocks\n(function() {\n function addCopyButtons() {\n document.querySelectorAll('pre code').forEach(function(codeBlock) {\n if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;\n codeBlock.parentElement.setAttribute('data-copy-added', 'true');\n \n var btn = document.createElement('button');\n btn.textContent = 'Copy';\n btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';\n btn.onmouseover = function() { this.style.opacity = '1'; };\n btn.onmouseout = function() { this.style.opacity = '0.7'; };\n btn.onclick = function() {\n navigator.clipboard.writeText(codeBlock.textContent).then(function() {\n btn.textContent = 'Copied!';\n setTimeout(function() { btn.textContent = 'Copy'; }, 1500);\n });\n };\n codeBlock.parentElement.style.position = 'relative';\n codeBlock.parentElement.appendChild(btn);\n });\n }\n \n addCopyButtons();\n \n // Re-run on dynamic content\n var observer = new MutationObserver(addCopyButtons);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Add Copy Buttons to Code Blocks");
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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std.Io.Threaded: fix incorrect alignment of trailing data in closure#25868

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std.Io.Threaded: fix incorrect alignment of trailing data in closure
#25868
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72590e4

std.Io.Threaded: fix incorrect alignment of trailing data in closure


Techatrix Nov 10, 2025
f90001d

std.Io: fix calls on functions that return an array type


Techatrix Nov 9, 2025

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14 changes: 7 additions & 7 deletions
lib/std/Io.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -990,15 +990,15 @@ pub fn Future(Result: type) type {
 /// Idempotent. Not threadsafe.
 pub fn cancel(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.cancel(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.cancel(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }

 /// Idempotent. Not threadsafe.
 pub fn await(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.await(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.await(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }
Expand DownExpand Up@@ -1034,7 +1034,7 @@ pub const Group = struct {
 @call(.auto, function, args_casted.*);
 }
 };
 io.vtable.groupAsync(io.userdata, g, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 io.vtable.groupAsync(io.userdata, g, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until all tasks of the group finish. During this time,
Expand DownExpand Up@@ -1111,7 +1111,7 @@ pub fn Select(comptime U: type) type {
 }
 };
 _ = @atomicRmw(usize, &s.outstanding, .Add, 1, .monotonic);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until another task of the select finishes.
Expand DownExpand Up@@ -1539,9 +1539,9 @@ pub fn async(
 var future: Future(Result) = undefined;
 future.any_future = io.vtable.async(
 io.userdata,
 @ptrCast((&future.result)[0..1]),
 @ptrCast(&future.result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand DownExpand Up@@ -1580,7 +1580,7 @@ pub fn concurrent(
 io.userdata,
 @sizeOf(Result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand Down

52 changes: 31 additions & 21 deletions
lib/std/Io/Threaded.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -388,7 +388,8 @@ const AsyncClosure = struct {
 reset_event: ResetEvent,
 select_condition: ?*ResetEvent,
 context_alignment: std.mem.Alignment,
 result_offset: usize,
 result_alignment: std.mem.Alignment,
 result_offset_before_padding: usize,

 const done_reset_event: *ResetEvent = @ptrFromInt(@alignOf(ResetEvent));

Expand DownExpand Up@@ -420,12 +421,12 @@ const AsyncClosure = struct {

 fn resultPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.result_offset;
 return @ptrFromInt(ac.result_alignment.forward(@intFromPtr(base + ac.result_offset_before_padding)));
 }

 fn contextPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.context_alignment.forward(@sizeOf(AsyncClosure));
 return @ptrFromInt(ac.context_alignment.forward(@intFromPtr(base + @sizeOf(AsyncClosure))));
 }

 fn waitAndFree(ac: *AsyncClosure, gpa: Allocator, result: []u8) void {
Expand All@@ -436,7 +437,9 @@ const AsyncClosure = struct {

 fn free(ac: *AsyncClosure, gpa: Allocator, result_len: usize) void {
 const base: [*]align(@alignOf(AsyncClosure)) u8 = @ptrCast(ac);
 gpa.free(base[0 .. ac.result_offset + result_len]);
 const result_offset_with_padding = ac.result_alignment.forward(ac.result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 gpa.free(base[0..allocated_size]);
 }
};

Expand All@@ -460,13 +463,16 @@ fn async(
 };
 };
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result.len;
 const ac: *AsyncClosure = @ptrCast(@alignCast(gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch {
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result.len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch {
 start(context.ptr, result.ptr);
 return null;
 }));
 };
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

 ac.* = .{
 .closure = .{
Expand All@@ -476,7 +482,8 @@ fn async(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -531,10 +538,12 @@ fn concurrent(
 const t: *Threaded = @ptrCast(@alignCast(userdata));
 const cpu_count = t.cpu_count catch 1;
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch
 return error.ConcurrencyUnavailable;
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

Expand All@@ -546,7 +555,8 @@ fn concurrent(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -580,6 +590,8 @@ fn concurrent(
 return @ptrCast(ac);
}

/// Trailing data:
/// 1. context
const GroupClosure = struct {
 closure: Closure,
 t: *Threaded,
Expand DownExpand Up@@ -621,17 +633,15 @@ const GroupClosure = struct {
 gpa.free(base[0..contextEnd(gc.context_alignment, gc.context_len)]);
 }

 fn contextOffset(context_alignment: std.mem.Alignment) usize {
 return context_alignment.forward(@sizeOf(GroupClosure));
 }

 fn contextEnd(context_alignment: std.mem.Alignment, context_len: usize) usize {
 return contextOffset(context_alignment) + context_len;
 const context_offset_before_padding = @alignOf(GroupClosure) + @sizeOf(GroupClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 return context_offset_with_padding + context_len;
 }

 fn contextPointer(gc: *GroupClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(gc);
 return base + contextOffset(gc.context_alignment);
 return @ptrFromInt(gc.context_alignment.forward(@intFromPtr(base + @sizeOf(GroupClosure))));
 }

 const sync_is_waiting: usize = 1 << 0;
Expand Down

66 changes: 66 additions & 0 deletions
lib/std/Io/Threaded/test.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -56,3 +56,69 @@ test "concurrent vs concurrent prevents deadlock via oversubscription" {
 getter.await(io);
 putter.await(io);
}

fn paramWithExtraAlignment(param: Align64) void {
 assert(param.data == 3);
}

fn returnValueWithExtraAlignment() Align64 {
 return .{ .data = 5 };
}

const Align64 = struct {
 data: u8 align(64),
};

test "async closure where result or context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 {
 var future = io.async(paramWithExtraAlignment, .{.{ .data = 3 }});
 future.await(io);
 }

 {
 var future = io.async(returnValueWithExtraAlignment, .{});
 const result = future.await(io);
 try std.testing.expectEqual(5, result.data);
 }
}

test "group closure where context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 var group: std.Io.Group = .init;
 defer group.cancel(io);

 group.async(io, paramWithExtraAlignment, .{.{ .data = 3 }});
}

fn returnArray() [32]u8 {
 return @splat(5);
}

test "async on function with array parameter or return type" {
 var threaded: std.Io.Threaded = .init(std.testing.allocator);
 defer threaded.deinit();
 const io = threaded.io();

 var future = io.async(returnArray, .{});
 const result = future.await(io);
 for (result) |actual| {
 try std.testing.expectEqual(5, actual);
 }
}
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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std.Io.Threaded: fix incorrect alignment of trailing data in closure#25868

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std.Io.Threaded: fix incorrect alignment of trailing data in closure
#25868
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72590e4

std.Io.Threaded: fix incorrect alignment of trailing data in closure


Techatrix Nov 10, 2025
f90001d

std.Io: fix calls on functions that return an array type


Techatrix Nov 9, 2025

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14 changes: 7 additions & 7 deletions
lib/std/Io.zig

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -990,15 +990,15 @@ pub fn Future(Result: type) type {
 /// Idempotent. Not threadsafe.
 pub fn cancel(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.cancel(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.cancel(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }

 /// Idempotent. Not threadsafe.
 pub fn await(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.await(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.await(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }
Expand DownExpand Up@@ -1034,7 +1034,7 @@ pub const Group = struct {
 @call(.auto, function, args_casted.*);
 }
 };
 io.vtable.groupAsync(io.userdata, g, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 io.vtable.groupAsync(io.userdata, g, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until all tasks of the group finish. During this time,
Expand DownExpand Up@@ -1111,7 +1111,7 @@ pub fn Select(comptime U: type) type {
 }
 };
 _ = @atomicRmw(usize, &s.outstanding, .Add, 1, .monotonic);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until another task of the select finishes.
Expand DownExpand Up@@ -1539,9 +1539,9 @@ pub fn async(
 var future: Future(Result) = undefined;
 future.any_future = io.vtable.async(
 io.userdata,
 @ptrCast((&future.result)[0..1]),
 @ptrCast(&future.result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand DownExpand Up@@ -1580,7 +1580,7 @@ pub fn concurrent(
 io.userdata,
 @sizeOf(Result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand Down

52 changes: 31 additions & 21 deletions
lib/std/Io/Threaded.zig

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -388,7 +388,8 @@ const AsyncClosure = struct {
 reset_event: ResetEvent,
 select_condition: ?*ResetEvent,
 context_alignment: std.mem.Alignment,
 result_offset: usize,
 result_alignment: std.mem.Alignment,
 result_offset_before_padding: usize,

 const done_reset_event: *ResetEvent = @ptrFromInt(@alignOf(ResetEvent));

Expand DownExpand Up@@ -420,12 +421,12 @@ const AsyncClosure = struct {

 fn resultPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.result_offset;
 return @ptrFromInt(ac.result_alignment.forward(@intFromPtr(base + ac.result_offset_before_padding)));
 }

 fn contextPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.context_alignment.forward(@sizeOf(AsyncClosure));
 return @ptrFromInt(ac.context_alignment.forward(@intFromPtr(base + @sizeOf(AsyncClosure))));
 }

 fn waitAndFree(ac: *AsyncClosure, gpa: Allocator, result: []u8) void {
Expand All@@ -436,7 +437,9 @@ const AsyncClosure = struct {

 fn free(ac: *AsyncClosure, gpa: Allocator, result_len: usize) void {
 const base: [*]align(@alignOf(AsyncClosure)) u8 = @ptrCast(ac);
 gpa.free(base[0 .. ac.result_offset + result_len]);
 const result_offset_with_padding = ac.result_alignment.forward(ac.result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 gpa.free(base[0..allocated_size]);
 }
};

Expand All@@ -460,13 +463,16 @@ fn async(
 };
 };
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result.len;
 const ac: *AsyncClosure = @ptrCast(@alignCast(gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch {
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result.len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch {
 start(context.ptr, result.ptr);
 return null;
 }));
 };
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

 ac.* = .{
 .closure = .{
Expand All@@ -476,7 +482,8 @@ fn async(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -531,10 +538,12 @@ fn concurrent(
 const t: *Threaded = @ptrCast(@alignCast(userdata));
 const cpu_count = t.cpu_count catch 1;
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch
 return error.ConcurrencyUnavailable;
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

Expand All@@ -546,7 +555,8 @@ fn concurrent(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -580,6 +590,8 @@ fn concurrent(
 return @ptrCast(ac);
}

/// Trailing data:
/// 1. context
const GroupClosure = struct {
 closure: Closure,
 t: *Threaded,
Expand DownExpand Up@@ -621,17 +633,15 @@ const GroupClosure = struct {
 gpa.free(base[0..contextEnd(gc.context_alignment, gc.context_len)]);
 }

 fn contextOffset(context_alignment: std.mem.Alignment) usize {
 return context_alignment.forward(@sizeOf(GroupClosure));
 }

 fn contextEnd(context_alignment: std.mem.Alignment, context_len: usize) usize {
 return contextOffset(context_alignment) + context_len;
 const context_offset_before_padding = @alignOf(GroupClosure) + @sizeOf(GroupClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 return context_offset_with_padding + context_len;
 }

 fn contextPointer(gc: *GroupClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(gc);
 return base + contextOffset(gc.context_alignment);
 return @ptrFromInt(gc.context_alignment.forward(@intFromPtr(base + @sizeOf(GroupClosure))));
 }

 const sync_is_waiting: usize = 1 << 0;
Expand Down

66 changes: 66 additions & 0 deletions
lib/std/Io/Threaded/test.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -56,3 +56,69 @@ test "concurrent vs concurrent prevents deadlock via oversubscription" {
 getter.await(io);
 putter.await(io);
}

fn paramWithExtraAlignment(param: Align64) void {
 assert(param.data == 3);
}

fn returnValueWithExtraAlignment() Align64 {
 return .{ .data = 5 };
}

const Align64 = struct {
 data: u8 align(64),
};

test "async closure where result or context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 {
 var future = io.async(paramWithExtraAlignment, .{.{ .data = 3 }});
 future.await(io);
 }

 {
 var future = io.async(returnValueWithExtraAlignment, .{});
 const result = future.await(io);
 try std.testing.expectEqual(5, result.data);
 }
}

test "group closure where context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 var group: std.Io.Group = .init;
 defer group.cancel(io);

 group.async(io, paramWithExtraAlignment, .{.{ .data = 3 }});
}

fn returnArray() [32]u8 {
 return @splat(5);
}

test "async on function with array parameter or return type" {
 var threaded: std.Io.Threaded = .init(std.testing.allocator);
 defer threaded.deinit();
 const io = threaded.io();

 var future = io.async(returnArray, .{});
 const result = future.await(io);
 for (result) |actual| {
 try std.testing.expectEqual(5, actual);
 }
}
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if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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std.Io.Threaded: fix incorrect alignment of trailing data in closure#25868

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Techatrix
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from

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std.Io.Threaded: fix incorrect alignment of trailing data in closure
#25868
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72590e4

std.Io.Threaded: fix incorrect alignment of trailing data in closure


Techatrix Nov 10, 2025
f90001d

std.Io: fix calls on functions that return an array type


Techatrix Nov 9, 2025

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14 changes: 7 additions & 7 deletions
lib/std/Io.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -990,15 +990,15 @@ pub fn Future(Result: type) type {
 /// Idempotent. Not threadsafe.
 pub fn cancel(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.cancel(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.cancel(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }

 /// Idempotent. Not threadsafe.
 pub fn await(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.await(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.await(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }
Expand DownExpand Up@@ -1034,7 +1034,7 @@ pub const Group = struct {
 @call(.auto, function, args_casted.*);
 }
 };
 io.vtable.groupAsync(io.userdata, g, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 io.vtable.groupAsync(io.userdata, g, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until all tasks of the group finish. During this time,
Expand DownExpand Up@@ -1111,7 +1111,7 @@ pub fn Select(comptime U: type) type {
 }
 };
 _ = @atomicRmw(usize, &s.outstanding, .Add, 1, .monotonic);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until another task of the select finishes.
Expand DownExpand Up@@ -1539,9 +1539,9 @@ pub fn async(
 var future: Future(Result) = undefined;
 future.any_future = io.vtable.async(
 io.userdata,
 @ptrCast((&future.result)[0..1]),
 @ptrCast(&future.result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand DownExpand Up@@ -1580,7 +1580,7 @@ pub fn concurrent(
 io.userdata,
 @sizeOf(Result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand Down

52 changes: 31 additions & 21 deletions
lib/std/Io/Threaded.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -388,7 +388,8 @@ const AsyncClosure = struct {
 reset_event: ResetEvent,
 select_condition: ?*ResetEvent,
 context_alignment: std.mem.Alignment,
 result_offset: usize,
 result_alignment: std.mem.Alignment,
 result_offset_before_padding: usize,

 const done_reset_event: *ResetEvent = @ptrFromInt(@alignOf(ResetEvent));

Expand DownExpand Up@@ -420,12 +421,12 @@ const AsyncClosure = struct {

 fn resultPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.result_offset;
 return @ptrFromInt(ac.result_alignment.forward(@intFromPtr(base + ac.result_offset_before_padding)));
 }

 fn contextPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.context_alignment.forward(@sizeOf(AsyncClosure));
 return @ptrFromInt(ac.context_alignment.forward(@intFromPtr(base + @sizeOf(AsyncClosure))));
 }

 fn waitAndFree(ac: *AsyncClosure, gpa: Allocator, result: []u8) void {
Expand All@@ -436,7 +437,9 @@ const AsyncClosure = struct {

 fn free(ac: *AsyncClosure, gpa: Allocator, result_len: usize) void {
 const base: [*]align(@alignOf(AsyncClosure)) u8 = @ptrCast(ac);
 gpa.free(base[0 .. ac.result_offset + result_len]);
 const result_offset_with_padding = ac.result_alignment.forward(ac.result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 gpa.free(base[0..allocated_size]);
 }
};

Expand All@@ -460,13 +463,16 @@ fn async(
 };
 };
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result.len;
 const ac: *AsyncClosure = @ptrCast(@alignCast(gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch {
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result.len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch {
 start(context.ptr, result.ptr);
 return null;
 }));
 };
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

 ac.* = .{
 .closure = .{
Expand All@@ -476,7 +482,8 @@ fn async(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -531,10 +538,12 @@ fn concurrent(
 const t: *Threaded = @ptrCast(@alignCast(userdata));
 const cpu_count = t.cpu_count catch 1;
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch
 return error.ConcurrencyUnavailable;
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

Expand All@@ -546,7 +555,8 @@ fn concurrent(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -580,6 +590,8 @@ fn concurrent(
 return @ptrCast(ac);
}

/// Trailing data:
/// 1. context
const GroupClosure = struct {
 closure: Closure,
 t: *Threaded,
Expand DownExpand Up@@ -621,17 +633,15 @@ const GroupClosure = struct {
 gpa.free(base[0..contextEnd(gc.context_alignment, gc.context_len)]);
 }

 fn contextOffset(context_alignment: std.mem.Alignment) usize {
 return context_alignment.forward(@sizeOf(GroupClosure));
 }

 fn contextEnd(context_alignment: std.mem.Alignment, context_len: usize) usize {
 return contextOffset(context_alignment) + context_len;
 const context_offset_before_padding = @alignOf(GroupClosure) + @sizeOf(GroupClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 return context_offset_with_padding + context_len;
 }

 fn contextPointer(gc: *GroupClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(gc);
 return base + contextOffset(gc.context_alignment);
 return @ptrFromInt(gc.context_alignment.forward(@intFromPtr(base + @sizeOf(GroupClosure))));
 }

 const sync_is_waiting: usize = 1 << 0;
Expand Down

66 changes: 66 additions & 0 deletions
lib/std/Io/Threaded/test.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -56,3 +56,69 @@ test "concurrent vs concurrent prevents deadlock via oversubscription" {
 getter.await(io);
 putter.await(io);
}

fn paramWithExtraAlignment(param: Align64) void {
 assert(param.data == 3);
}

fn returnValueWithExtraAlignment() Align64 {
 return .{ .data = 5 };
}

const Align64 = struct {
 data: u8 align(64),
};

test "async closure where result or context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 {
 var future = io.async(paramWithExtraAlignment, .{.{ .data = 3 }});
 future.await(io);
 }

 {
 var future = io.async(returnValueWithExtraAlignment, .{});
 const result = future.await(io);
 try std.testing.expectEqual(5, result.data);
 }
}

test "group closure where context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 var group: std.Io.Group = .init;
 defer group.cancel(io);

 group.async(io, paramWithExtraAlignment, .{.{ .data = 3 }});
}

fn returnArray() [32]u8 {
 return @splat(5);
}

test "async on function with array parameter or return type" {
 var threaded: std.Io.Threaded = .init(std.testing.allocator);
 defer threaded.deinit();
 const io = threaded.io();

 var future = io.async(returnArray, .{});
 const result = future.await(io);
 for (result) |actual| {
 try std.testing.expectEqual(5, actual);
 }
}
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

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std.Io.Threaded: fix incorrect alignment of trailing data in closure#25868

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std.Io.Threaded: fix incorrect alignment of trailing data in closure
#25868
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72590e4

std.Io.Threaded: fix incorrect alignment of trailing data in closure


Techatrix Nov 10, 2025
f90001d

std.Io: fix calls on functions that return an array type


Techatrix Nov 9, 2025

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14 changes: 7 additions & 7 deletions
lib/std/Io.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -990,15 +990,15 @@ pub fn Future(Result: type) type {
 /// Idempotent. Not threadsafe.
 pub fn cancel(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.cancel(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.cancel(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }

 /// Idempotent. Not threadsafe.
 pub fn await(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.await(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.await(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }
Expand DownExpand Up@@ -1034,7 +1034,7 @@ pub const Group = struct {
 @call(.auto, function, args_casted.*);
 }
 };
 io.vtable.groupAsync(io.userdata, g, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 io.vtable.groupAsync(io.userdata, g, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until all tasks of the group finish. During this time,
Expand DownExpand Up@@ -1111,7 +1111,7 @@ pub fn Select(comptime U: type) type {
 }
 };
 _ = @atomicRmw(usize, &s.outstanding, .Add, 1, .monotonic);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until another task of the select finishes.
Expand DownExpand Up@@ -1539,9 +1539,9 @@ pub fn async(
 var future: Future(Result) = undefined;
 future.any_future = io.vtable.async(
 io.userdata,
 @ptrCast((&future.result)[0..1]),
 @ptrCast(&future.result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand DownExpand Up@@ -1580,7 +1580,7 @@ pub fn concurrent(
 io.userdata,
 @sizeOf(Result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand Down

52 changes: 31 additions & 21 deletions
lib/std/Io/Threaded.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -388,7 +388,8 @@ const AsyncClosure = struct {
 reset_event: ResetEvent,
 select_condition: ?*ResetEvent,
 context_alignment: std.mem.Alignment,
 result_offset: usize,
 result_alignment: std.mem.Alignment,
 result_offset_before_padding: usize,

 const done_reset_event: *ResetEvent = @ptrFromInt(@alignOf(ResetEvent));

Expand DownExpand Up@@ -420,12 +421,12 @@ const AsyncClosure = struct {

 fn resultPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.result_offset;
 return @ptrFromInt(ac.result_alignment.forward(@intFromPtr(base + ac.result_offset_before_padding)));
 }

 fn contextPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.context_alignment.forward(@sizeOf(AsyncClosure));
 return @ptrFromInt(ac.context_alignment.forward(@intFromPtr(base + @sizeOf(AsyncClosure))));
 }

 fn waitAndFree(ac: *AsyncClosure, gpa: Allocator, result: []u8) void {
Expand All@@ -436,7 +437,9 @@ const AsyncClosure = struct {

 fn free(ac: *AsyncClosure, gpa: Allocator, result_len: usize) void {
 const base: [*]align(@alignOf(AsyncClosure)) u8 = @ptrCast(ac);
 gpa.free(base[0 .. ac.result_offset + result_len]);
 const result_offset_with_padding = ac.result_alignment.forward(ac.result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 gpa.free(base[0..allocated_size]);
 }
};

Expand All@@ -460,13 +463,16 @@ fn async(
 };
 };
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result.len;
 const ac: *AsyncClosure = @ptrCast(@alignCast(gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch {
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result.len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch {
 start(context.ptr, result.ptr);
 return null;
 }));
 };
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

 ac.* = .{
 .closure = .{
Expand All@@ -476,7 +482,8 @@ fn async(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -531,10 +538,12 @@ fn concurrent(
 const t: *Threaded = @ptrCast(@alignCast(userdata));
 const cpu_count = t.cpu_count catch 1;
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch
 return error.ConcurrencyUnavailable;
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

Expand All@@ -546,7 +555,8 @@ fn concurrent(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -580,6 +590,8 @@ fn concurrent(
 return @ptrCast(ac);
}

/// Trailing data:
/// 1. context
const GroupClosure = struct {
 closure: Closure,
 t: *Threaded,
Expand DownExpand Up@@ -621,17 +633,15 @@ const GroupClosure = struct {
 gpa.free(base[0..contextEnd(gc.context_alignment, gc.context_len)]);
 }

 fn contextOffset(context_alignment: std.mem.Alignment) usize {
 return context_alignment.forward(@sizeOf(GroupClosure));
 }

 fn contextEnd(context_alignment: std.mem.Alignment, context_len: usize) usize {
 return contextOffset(context_alignment) + context_len;
 const context_offset_before_padding = @alignOf(GroupClosure) + @sizeOf(GroupClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 return context_offset_with_padding + context_len;
 }

 fn contextPointer(gc: *GroupClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(gc);
 return base + contextOffset(gc.context_alignment);
 return @ptrFromInt(gc.context_alignment.forward(@intFromPtr(base + @sizeOf(GroupClosure))));
 }

 const sync_is_waiting: usize = 1 << 0;
Expand Down

66 changes: 66 additions & 0 deletions
lib/std/Io/Threaded/test.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -56,3 +56,69 @@ test "concurrent vs concurrent prevents deadlock via oversubscription" {
 getter.await(io);
 putter.await(io);
}

fn paramWithExtraAlignment(param: Align64) void {
 assert(param.data == 3);
}

fn returnValueWithExtraAlignment() Align64 {
 return .{ .data = 5 };
}

const Align64 = struct {
 data: u8 align(64),
};

test "async closure where result or context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 {
 var future = io.async(paramWithExtraAlignment, .{.{ .data = 3 }});
 future.await(io);
 }

 {
 var future = io.async(returnValueWithExtraAlignment, .{});
 const result = future.await(io);
 try std.testing.expectEqual(5, result.data);
 }
}

test "group closure where context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 var group: std.Io.Group = .init;
 defer group.cancel(io);

 group.async(io, paramWithExtraAlignment, .{.{ .data = 3 }});
}

fn returnArray() [32]u8 {
 return @splat(5);
}

test "async on function with array parameter or return type" {
 var threaded: std.Io.Threaded = .init(std.testing.allocator);
 defer threaded.deinit();
 const io = threaded.io();

 var future = io.async(returnArray, .{});
 const result = future.await(io);
 for (result) |actual| {
 try std.testing.expectEqual(5, actual);
 }
}
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
std.Io.Threaded: fix incorrect alignment of trailing data in closure#25868

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 Closed

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std.Io.Threaded: fix incorrect alignment of trailing data in closure
#25868
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72590e4

std.Io.Threaded: fix incorrect alignment of trailing data in closure


Techatrix Nov 10, 2025
f90001d

std.Io: fix calls on functions that return an array type


Techatrix Nov 9, 2025

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14 changes: 7 additions & 7 deletions
lib/std/Io.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -990,15 +990,15 @@ pub fn Future(Result: type) type {
 /// Idempotent. Not threadsafe.
 pub fn cancel(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.cancel(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.cancel(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }

 /// Idempotent. Not threadsafe.
 pub fn await(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.await(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.await(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }
Expand DownExpand Up@@ -1034,7 +1034,7 @@ pub const Group = struct {
 @call(.auto, function, args_casted.*);
 }
 };
 io.vtable.groupAsync(io.userdata, g, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 io.vtable.groupAsync(io.userdata, g, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until all tasks of the group finish. During this time,
Expand DownExpand Up@@ -1111,7 +1111,7 @@ pub fn Select(comptime U: type) type {
 }
 };
 _ = @atomicRmw(usize, &s.outstanding, .Add, 1, .monotonic);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until another task of the select finishes.
Expand DownExpand Up@@ -1539,9 +1539,9 @@ pub fn async(
 var future: Future(Result) = undefined;
 future.any_future = io.vtable.async(
 io.userdata,
 @ptrCast((&future.result)[0..1]),
 @ptrCast(&future.result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand DownExpand Up@@ -1580,7 +1580,7 @@ pub fn concurrent(
 io.userdata,
 @sizeOf(Result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand Down

52 changes: 31 additions & 21 deletions
lib/std/Io/Threaded.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -388,7 +388,8 @@ const AsyncClosure = struct {
 reset_event: ResetEvent,
 select_condition: ?*ResetEvent,
 context_alignment: std.mem.Alignment,
 result_offset: usize,
 result_alignment: std.mem.Alignment,
 result_offset_before_padding: usize,

 const done_reset_event: *ResetEvent = @ptrFromInt(@alignOf(ResetEvent));

Expand DownExpand Up@@ -420,12 +421,12 @@ const AsyncClosure = struct {

 fn resultPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.result_offset;
 return @ptrFromInt(ac.result_alignment.forward(@intFromPtr(base + ac.result_offset_before_padding)));
 }

 fn contextPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.context_alignment.forward(@sizeOf(AsyncClosure));
 return @ptrFromInt(ac.context_alignment.forward(@intFromPtr(base + @sizeOf(AsyncClosure))));
 }

 fn waitAndFree(ac: *AsyncClosure, gpa: Allocator, result: []u8) void {
Expand All@@ -436,7 +437,9 @@ const AsyncClosure = struct {

 fn free(ac: *AsyncClosure, gpa: Allocator, result_len: usize) void {
 const base: [*]align(@alignOf(AsyncClosure)) u8 = @ptrCast(ac);
 gpa.free(base[0 .. ac.result_offset + result_len]);
 const result_offset_with_padding = ac.result_alignment.forward(ac.result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 gpa.free(base[0..allocated_size]);
 }
};

Expand All@@ -460,13 +463,16 @@ fn async(
 };
 };
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result.len;
 const ac: *AsyncClosure = @ptrCast(@alignCast(gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch {
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result.len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch {
 start(context.ptr, result.ptr);
 return null;
 }));
 };
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

 ac.* = .{
 .closure = .{
Expand All@@ -476,7 +482,8 @@ fn async(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -531,10 +538,12 @@ fn concurrent(
 const t: *Threaded = @ptrCast(@alignCast(userdata));
 const cpu_count = t.cpu_count catch 1;
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch
 return error.ConcurrencyUnavailable;
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

Expand All@@ -546,7 +555,8 @@ fn concurrent(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -580,6 +590,8 @@ fn concurrent(
 return @ptrCast(ac);
}

/// Trailing data:
/// 1. context
const GroupClosure = struct {
 closure: Closure,
 t: *Threaded,
Expand DownExpand Up@@ -621,17 +633,15 @@ const GroupClosure = struct {
 gpa.free(base[0..contextEnd(gc.context_alignment, gc.context_len)]);
 }

 fn contextOffset(context_alignment: std.mem.Alignment) usize {
 return context_alignment.forward(@sizeOf(GroupClosure));
 }

 fn contextEnd(context_alignment: std.mem.Alignment, context_len: usize) usize {
 return contextOffset(context_alignment) + context_len;
 const context_offset_before_padding = @alignOf(GroupClosure) + @sizeOf(GroupClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 return context_offset_with_padding + context_len;
 }

 fn contextPointer(gc: *GroupClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(gc);
 return base + contextOffset(gc.context_alignment);
 return @ptrFromInt(gc.context_alignment.forward(@intFromPtr(base + @sizeOf(GroupClosure))));
 }

 const sync_is_waiting: usize = 1 << 0;
Expand Down

66 changes: 66 additions & 0 deletions
lib/std/Io/Threaded/test.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -56,3 +56,69 @@ test "concurrent vs concurrent prevents deadlock via oversubscription" {
 getter.await(io);
 putter.await(io);
}

fn paramWithExtraAlignment(param: Align64) void {
 assert(param.data == 3);
}

fn returnValueWithExtraAlignment() Align64 {
 return .{ .data = 5 };
}

const Align64 = struct {
 data: u8 align(64),
};

test "async closure where result or context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 {
 var future = io.async(paramWithExtraAlignment, .{.{ .data = 3 }});
 future.await(io);
 }

 {
 var future = io.async(returnValueWithExtraAlignment, .{});
 const result = future.await(io);
 try std.testing.expectEqual(5, result.data);
 }
}

test "group closure where context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 var group: std.Io.Group = .init;
 defer group.cancel(io);

 group.async(io, paramWithExtraAlignment, .{.{ .data = 3 }});
}

fn returnArray() [32]u8 {
 return @splat(5);
}

test "async on function with array parameter or return type" {
 var threaded: std.Io.Threaded = .init(std.testing.allocator);
 defer threaded.deinit();
 const io = threaded.io();

 var future = io.async(returnArray, .{});
 const result = future.await(io);
 for (result) |actual| {
 try std.testing.expectEqual(5, actual);
 }
}
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, 'i');
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std.Io.Threaded: fix incorrect alignment of trailing data in closure#25868

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std.Io.Threaded: fix incorrect alignment of trailing data in closure
#25868
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72590e4

std.Io.Threaded: fix incorrect alignment of trailing data in closure


Techatrix Nov 10, 2025
f90001d

std.Io: fix calls on functions that return an array type


Techatrix Nov 9, 2025

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14 changes: 7 additions & 7 deletions
lib/std/Io.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -990,15 +990,15 @@ pub fn Future(Result: type) type {
 /// Idempotent. Not threadsafe.
 pub fn cancel(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.cancel(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.cancel(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }

 /// Idempotent. Not threadsafe.
 pub fn await(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.await(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.await(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }
Expand DownExpand Up@@ -1034,7 +1034,7 @@ pub const Group = struct {
 @call(.auto, function, args_casted.*);
 }
 };
 io.vtable.groupAsync(io.userdata, g, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 io.vtable.groupAsync(io.userdata, g, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until all tasks of the group finish. During this time,
Expand DownExpand Up@@ -1111,7 +1111,7 @@ pub fn Select(comptime U: type) type {
 }
 };
 _ = @atomicRmw(usize, &s.outstanding, .Add, 1, .monotonic);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until another task of the select finishes.
Expand DownExpand Up@@ -1539,9 +1539,9 @@ pub fn async(
 var future: Future(Result) = undefined;
 future.any_future = io.vtable.async(
 io.userdata,
 @ptrCast((&future.result)[0..1]),
 @ptrCast(&future.result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand DownExpand Up@@ -1580,7 +1580,7 @@ pub fn concurrent(
 io.userdata,
 @sizeOf(Result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand Down

52 changes: 31 additions & 21 deletions
lib/std/Io/Threaded.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -388,7 +388,8 @@ const AsyncClosure = struct {
 reset_event: ResetEvent,
 select_condition: ?*ResetEvent,
 context_alignment: std.mem.Alignment,
 result_offset: usize,
 result_alignment: std.mem.Alignment,
 result_offset_before_padding: usize,

 const done_reset_event: *ResetEvent = @ptrFromInt(@alignOf(ResetEvent));

Expand DownExpand Up@@ -420,12 +421,12 @@ const AsyncClosure = struct {

 fn resultPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.result_offset;
 return @ptrFromInt(ac.result_alignment.forward(@intFromPtr(base + ac.result_offset_before_padding)));
 }

 fn contextPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.context_alignment.forward(@sizeOf(AsyncClosure));
 return @ptrFromInt(ac.context_alignment.forward(@intFromPtr(base + @sizeOf(AsyncClosure))));
 }

 fn waitAndFree(ac: *AsyncClosure, gpa: Allocator, result: []u8) void {
Expand All@@ -436,7 +437,9 @@ const AsyncClosure = struct {

 fn free(ac: *AsyncClosure, gpa: Allocator, result_len: usize) void {
 const base: [*]align(@alignOf(AsyncClosure)) u8 = @ptrCast(ac);
 gpa.free(base[0 .. ac.result_offset + result_len]);
 const result_offset_with_padding = ac.result_alignment.forward(ac.result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 gpa.free(base[0..allocated_size]);
 }
};

Expand All@@ -460,13 +463,16 @@ fn async(
 };
 };
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result.len;
 const ac: *AsyncClosure = @ptrCast(@alignCast(gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch {
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result.len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch {
 start(context.ptr, result.ptr);
 return null;
 }));
 };
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

 ac.* = .{
 .closure = .{
Expand All@@ -476,7 +482,8 @@ fn async(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -531,10 +538,12 @@ fn concurrent(
 const t: *Threaded = @ptrCast(@alignCast(userdata));
 const cpu_count = t.cpu_count catch 1;
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch
 return error.ConcurrencyUnavailable;
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

Expand All@@ -546,7 +555,8 @@ fn concurrent(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -580,6 +590,8 @@ fn concurrent(
 return @ptrCast(ac);
}

/// Trailing data:
/// 1. context
const GroupClosure = struct {
 closure: Closure,
 t: *Threaded,
Expand DownExpand Up@@ -621,17 +633,15 @@ const GroupClosure = struct {
 gpa.free(base[0..contextEnd(gc.context_alignment, gc.context_len)]);
 }

 fn contextOffset(context_alignment: std.mem.Alignment) usize {
 return context_alignment.forward(@sizeOf(GroupClosure));
 }

 fn contextEnd(context_alignment: std.mem.Alignment, context_len: usize) usize {
 return contextOffset(context_alignment) + context_len;
 const context_offset_before_padding = @alignOf(GroupClosure) + @sizeOf(GroupClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 return context_offset_with_padding + context_len;
 }

 fn contextPointer(gc: *GroupClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(gc);
 return base + contextOffset(gc.context_alignment);
 return @ptrFromInt(gc.context_alignment.forward(@intFromPtr(base + @sizeOf(GroupClosure))));
 }

 const sync_is_waiting: usize = 1 << 0;
Expand Down

66 changes: 66 additions & 0 deletions
lib/std/Io/Threaded/test.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -56,3 +56,69 @@ test "concurrent vs concurrent prevents deadlock via oversubscription" {
 getter.await(io);
 putter.await(io);
}

fn paramWithExtraAlignment(param: Align64) void {
 assert(param.data == 3);
}

fn returnValueWithExtraAlignment() Align64 {
 return .{ .data = 5 };
}

const Align64 = struct {
 data: u8 align(64),
};

test "async closure where result or context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 {
 var future = io.async(paramWithExtraAlignment, .{.{ .data = 3 }});
 future.await(io);
 }

 {
 var future = io.async(returnValueWithExtraAlignment, .{});
 const result = future.await(io);
 try std.testing.expectEqual(5, result.data);
 }
}

test "group closure where context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 var group: std.Io.Group = .init;
 defer group.cancel(io);

 group.async(io, paramWithExtraAlignment, .{.{ .data = 3 }});
}

fn returnArray() [32]u8 {
 return @splat(5);
}

test "async on function with array parameter or return type" {
 var threaded: std.Io.Threaded = .init(std.testing.allocator);
 defer threaded.deinit();
 const io = threaded.io();

 var future = io.async(returnArray, .{});
 const result = future.await(io);
 for (result) |actual| {
 try std.testing.expectEqual(5, actual);
 }
}
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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std.Io.Threaded: fix incorrect alignment of trailing data in closure#25868

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std.Io.Threaded: fix incorrect alignment of trailing data in closure
#25868
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72590e4

std.Io.Threaded: fix incorrect alignment of trailing data in closure


Techatrix Nov 10, 2025
f90001d

std.Io: fix calls on functions that return an array type


Techatrix Nov 9, 2025

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14 changes: 7 additions & 7 deletions
lib/std/Io.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -990,15 +990,15 @@ pub fn Future(Result: type) type {
 /// Idempotent. Not threadsafe.
 pub fn cancel(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.cancel(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.cancel(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }

 /// Idempotent. Not threadsafe.
 pub fn await(f: *@This(), io: Io) Result {
 const any_future = f.any_future orelse return f.result;
 io.vtable.await(io.userdata, any_future, @ptrCast((&f.result)[0..1]), .of(Result));
 io.vtable.await(io.userdata, any_future, @ptrCast(&f.result), .of(Result));
 f.any_future = null;
 return f.result;
 }
Expand DownExpand Up@@ -1034,7 +1034,7 @@ pub const Group = struct {
 @call(.auto, function, args_casted.*);
 }
 };
 io.vtable.groupAsync(io.userdata, g, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 io.vtable.groupAsync(io.userdata, g, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until all tasks of the group finish. During this time,
Expand DownExpand Up@@ -1111,7 +1111,7 @@ pub fn Select(comptime U: type) type {
 }
 };
 _ = @atomicRmw(usize, &s.outstanding, .Add, 1, .monotonic);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast((&args)[0..1]), .of(Args), TypeErased.start);
 s.io.vtable.groupAsync(s.io.userdata, &s.group, @ptrCast(&args), .of(Args), TypeErased.start);
 }

 /// Blocks until another task of the select finishes.
Expand DownExpand Up@@ -1539,9 +1539,9 @@ pub fn async(
 var future: Future(Result) = undefined;
 future.any_future = io.vtable.async(
 io.userdata,
 @ptrCast((&future.result)[0..1]),
 @ptrCast(&future.result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand DownExpand Up@@ -1580,7 +1580,7 @@ pub fn concurrent(
 io.userdata,
 @sizeOf(Result),
 .of(Result),
 @ptrCast((&args)[0..1]),
 @ptrCast(&args),
 .of(Args),
 TypeErased.start,
 );
Expand Down

52 changes: 31 additions & 21 deletions
lib/std/Io/Threaded.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -388,7 +388,8 @@ const AsyncClosure = struct {
 reset_event: ResetEvent,
 select_condition: ?*ResetEvent,
 context_alignment: std.mem.Alignment,
 result_offset: usize,
 result_alignment: std.mem.Alignment,
 result_offset_before_padding: usize,

 const done_reset_event: *ResetEvent = @ptrFromInt(@alignOf(ResetEvent));

Expand DownExpand Up@@ -420,12 +421,12 @@ const AsyncClosure = struct {

 fn resultPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.result_offset;
 return @ptrFromInt(ac.result_alignment.forward(@intFromPtr(base + ac.result_offset_before_padding)));
 }

 fn contextPointer(ac: *AsyncClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(ac);
 return base + ac.context_alignment.forward(@sizeOf(AsyncClosure));
 return @ptrFromInt(ac.context_alignment.forward(@intFromPtr(base + @sizeOf(AsyncClosure))));
 }

 fn waitAndFree(ac: *AsyncClosure, gpa: Allocator, result: []u8) void {
Expand All@@ -436,7 +437,9 @@ const AsyncClosure = struct {

 fn free(ac: *AsyncClosure, gpa: Allocator, result_len: usize) void {
 const base: [*]align(@alignOf(AsyncClosure)) u8 = @ptrCast(ac);
 gpa.free(base[0 .. ac.result_offset + result_len]);
 const result_offset_with_padding = ac.result_alignment.forward(ac.result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 gpa.free(base[0..allocated_size]);
 }
};

Expand All@@ -460,13 +463,16 @@ fn async(
 };
 };
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result.len;
 const ac: *AsyncClosure = @ptrCast(@alignCast(gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch {
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result.len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch {
 start(context.ptr, result.ptr);
 return null;
 }));
 };
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

 ac.* = .{
 .closure = .{
Expand All@@ -476,7 +482,8 @@ fn async(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -531,10 +538,12 @@ fn concurrent(
 const t: *Threaded = @ptrCast(@alignCast(userdata));
 const cpu_count = t.cpu_count catch 1;
 const gpa = t.allocator;
 const context_offset = context_alignment.forward(@sizeOf(AsyncClosure));
 const result_offset = result_alignment.forward(context_offset + context.len);
 const n = result_offset + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), n) catch
 const context_offset_before_padding = @alignOf(AsyncClosure) + @sizeOf(AsyncClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 const result_offset_before_padding = context_offset_with_padding + context.len;
 const result_offset_with_padding = result_alignment.forward(result_offset_before_padding);
 const allocated_size = result_offset_with_padding + result_len;
 const ac_bytes = gpa.alignedAlloc(u8, .of(AsyncClosure), allocated_size) catch
 return error.ConcurrencyUnavailable;
 const ac: *AsyncClosure = @ptrCast(@alignCast(ac_bytes));

Expand All@@ -546,7 +555,8 @@ fn concurrent(
 },
 .func = start,
 .context_alignment = context_alignment,
 .result_offset = result_offset,
 .result_alignment = result_alignment,
 .result_offset_before_padding = result_offset_before_padding,
 .reset_event = .unset,
 .select_condition = null,
 };
Expand DownExpand Up@@ -580,6 +590,8 @@ fn concurrent(
 return @ptrCast(ac);
}

/// Trailing data:
/// 1. context
const GroupClosure = struct {
 closure: Closure,
 t: *Threaded,
Expand DownExpand Up@@ -621,17 +633,15 @@ const GroupClosure = struct {
 gpa.free(base[0..contextEnd(gc.context_alignment, gc.context_len)]);
 }

 fn contextOffset(context_alignment: std.mem.Alignment) usize {
 return context_alignment.forward(@sizeOf(GroupClosure));
 }

 fn contextEnd(context_alignment: std.mem.Alignment, context_len: usize) usize {
 return contextOffset(context_alignment) + context_len;
 const context_offset_before_padding = @alignOf(GroupClosure) + @sizeOf(GroupClosure);
 const context_offset_with_padding = context_alignment.forward(context_offset_before_padding);
 return context_offset_with_padding + context_len;
 }

 fn contextPointer(gc: *GroupClosure) [*]u8 {
 const base: [*]u8 = @ptrCast(gc);
 return base + contextOffset(gc.context_alignment);
 return @ptrFromInt(gc.context_alignment.forward(@intFromPtr(base + @sizeOf(GroupClosure))));
 }

 const sync_is_waiting: usize = 1 << 0;
Expand Down

66 changes: 66 additions & 0 deletions
lib/std/Io/Threaded/test.zig

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -56,3 +56,69 @@ test "concurrent vs concurrent prevents deadlock via oversubscription" {
 getter.await(io);
 putter.await(io);
}

fn paramWithExtraAlignment(param: Align64) void {
 assert(param.data == 3);
}

fn returnValueWithExtraAlignment() Align64 {
 return .{ .data = 5 };
}

const Align64 = struct {
 data: u8 align(64),
};

test "async closure where result or context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 {
 var future = io.async(paramWithExtraAlignment, .{.{ .data = 3 }});
 future.await(io);
 }

 {
 var future = io.async(returnValueWithExtraAlignment, .{});
 const result = future.await(io);
 try std.testing.expectEqual(5, result.data);
 }
}

test "group closure where context has extra alignment" {
 // A fixed buffer allocator is used instead of `std.testing.allocator` to
 // not get memory that has better alignment than requested.
 var buffer: [1024]u8 align(64) = undefined;
 var fba: std.heap.FixedBufferAllocator = .init(buffer[1..]);

 var threaded: std.Io.Threaded = .init(fba.allocator());
 defer threaded.deinit();
 const io = threaded.io();

 var group: std.Io.Group = .init;
 defer group.cancel(io);

 group.async(io, paramWithExtraAlignment, .{.{ .data = 3 }});
}

fn returnArray() [32]u8 {
 return @splat(5);
}

test "async on function with array parameter or return type" {
 var threaded: std.Io.Threaded = .init(std.testing.allocator);
 defer threaded.deinit();
 const io = threaded.io();

 var future = io.async(returnArray, .{});
 const result = future.await(io);
 for (result) |actual| {
 try std.testing.expectEqual(5, actual);
 }
}
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