stdin is NotOpenForReading when you run `zig build run`

[doongjohn]

Zig Version

0.10.0-dev.3315+1a16b7214

Steps to Reproduce

// main.zig
const std = @import("std");
const stdout = std.io.getStdOut().writer();
const stdin = std.io.getStdIn().reader();

pub fn main() !void {
 var general_purpose_allocator = std.heap.GeneralPurposeAllocator(.{}){};
 const galloc = general_purpose_allocator.allocator();
 defer _ = general_purpose_allocator.deinit();

 const input = try stdin.readUntilDelimiterAlloc(galloc, '\n', 1000);
 defer galloc.free(input);
 _ = try stdout.print("input = {s}\n", .{input});
}

// build.zig
const std = @import("std");

pub fn build(b: *std.build.Builder) void {
 // Standard target options allows the person running `zig build` to choose
 // what target to build for. Here we do not override the defaults, which
 // means any target is allowed, and the default is native. Other options
 // for restricting supported target set are available.
 const target = b.standardTargetOptions(.{});

 // Standard release options allow the person running `zig build` to select
 // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
 const mode = b.standardReleaseOptions();

 const exe = b.addExecutable("app", "src/main.zig");
 exe.setTarget(target);
 exe.setBuildMode(mode);
 exe.install();

 const run_cmd = exe.run();
 run_cmd.step.dependOn(b.getInstallStep());
 if (b.args) |args| {
 run_cmd.addArgs(args);
 }

 const run_step = b.step("run", "Run the app");
 run_step.dependOn(&run_cmd.step);

 const exe_tests = b.addTest("src/main.zig");
 exe_tests.setTarget(target);
 exe_tests.setBuildMode(mode);

 const test_step = b.step("test", "Run unit tests");
 test_step.dependOn(&exe_tests.step);
}

zig build run

Expected Behavior

should be able to read from stdin

Actual Behavior

~/projects/exp/zig
❯ zig build run
error: NotOpenForReading
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/os.zig:650:22: 0x228fd5 in std.os.read (app)
 .BADF => return error.NotOpenForReading, // Can be a race condition.
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/fs/file.zig:975:13: 0x228e31 in std.fs.file.File.read (app)
 return os.read(self.handle, buffer);
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/io/reader.zig:26:13: 0x22ca1f in std.io.reader.Reader(std.fs.file.File,std.os.ReadError,std.fs.file.File.read)
.read (app)
 return readFn(self.context, buffer);
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/io/reader.zig:232:30: 0x22c930 in std.io.reader.Reader(std.fs.file.File,std.os.ReadError,std.fs.file.File.read
).readByte (app)
 const amt_read = try self.read(result[0..]);
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/io/reader.zig:114:32: 0x22c811 in std.io.reader.Reader(std.fs.file.File,std.os.ReadError,std.fs.file.File.read
).readUntilDelimiterArrayList (app)
 var byte: u8 = try self.readByte();
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/io/reader.zig:136:13: 0x22c562 in std.io.reader.Reader(std.fs.file.File,std.os.ReadError,std.fs.file.File.read
).readUntilDelimiterAlloc (app)
 try self.readUntilDelimiterArrayList(&array_list, delimiter, max_size);
 ^
/home/username/projects/exp/zig/src/main.zig:10:19: 0x22a1a3 in main (app)
 const input = try stdin.readUntilDelimiterAlloc(galloc, '\n', 1000);
 ^
The following command exited with error code 1 (expected 0):
cd /home/username/projects/exp/zig && /home/username/projects/exp/zig/zig-out/bin/app
error: UnexpectedExitCode
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/os.zig:2749:19: 0x2a168b in std.os.mkdiratZ (build)
 .EXIST => return error.PathAlreadyExists,
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/os.zig:2709:9: 0x2a1573 in std.os.mkdirat (build)
 return mkdiratZ(dir_fd, &sub_dir_path_c, mode);
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/fs.zig:1332:9: 0x2a1466 in std.fs.Dir.makeDir (build)
 try os.mkdirat(self.fd, sub_path, default_new_dir_mode);
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/os.zig:1680:23: 0x28afdd in std.os.openatZ (build)
 .NOENT => return error.FileNotFound,
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/fs.zig:1081:13: 0x276e4c in std.fs.Dir.openFileZ (build)
 try os.openatZ(self.fd, sub_path, os_flags, 0);
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/fs.zig:1008:9: 0x274c61 in std.fs.Dir.openFile (build)
 return self.openFileZ(&path_c, flags);
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/os.zig:2754:19: 0x2a1702 in std.os.mkdiratZ (build)
 .NOENT => return error.FileNotFound,
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/os.zig:2709:9: 0x2a1573 in std.os.mkdirat (build)
 return mkdiratZ(dir_fd, &sub_dir_path_c, mode);
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/fs.zig:1332:9: 0x2a1466 in std.fs.Dir.makeDir (build)
 try os.mkdirat(self.fd, sub_path, default_new_dir_mode);
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/build/RunStep.zig:277:17: 0x2dc687 in std.build.RunStep.runCommand (build)
 return error.UnexpectedExitCode;
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/build/RunStep.zig:183:5: 0x2ccad6 in std.build.RunStep.make (build)
 try runCommand(
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/build.zig:3648:9: 0x2a1b9e in std.build.Step.make (build)
 try self.makeFn(self);
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/build.zig:508:9: 0x2a0fec in std.build.Builder.makeOneStep (build)
 try s.make();
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/build.zig:502:17: 0x2a0f98 in std.build.Builder.makeOneStep (build)
 return err;
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/std/build.zig:463:13: 0x2974c1 in std.build.Builder.make (build)
 try self.makeOneStep(s);
 ^
/home/username/zig/0.10.0-dev.3315+1a16b7214/files/lib/build_runner.zig:213:21: 0x2911b5 in main (build)
 else => return err,
 ^
error: the following build command failed with exit code 1:
/home/username/projects/exp/zig/zig-cache/o/f68e9a1804c76861e552af4fc326bcdf/build /home/username/zig/0.10.0-dev.3315+1a16b7214/files/zig /home/username/projects/exp/z
ig /home/username/projects/exp/zig/zig-cache /home/username/.cache/zig run

this error only happens when build.zig is being compiled when you execute zig build run
so if you run zig build run again this error does not occur

[Vexu]

Can't reproduce, what OS are you on?

[doongjohn]

I'm using WSL2 (Void linux)

[doongjohn]

This issue no longer occurs in the latest version 0.11.0-dev.201+3c3def6ac