introduce operating system version ranges as part of the target; self-host native dynamic linker detection and native glibc version detection by andrewrk · Pull Request #4550 · ziglang/zig

andrewrk · 2020-02-25T07:19:40Z

Commit Details

introduce std.zig.CrossTarget which is distinct from std.Target. std.zig.CrossTarget wraps std.Target so that it can be annotated as "the native target" or an explicitly specified target.
std.Target.Os is moved to std.Target.Os.Tag. The former is now a struct which has the tag as well as version range information.
std.elf gains some more ELF header constants.
std.Target.parse gains the ability to parse operating system version ranges as well as glibc version.
Added std.Target.isGnuLibC().
self-hosted dynamic linker detection and glibc version detection. This also adds the improved logic using /usr/bin/env rather than invoking the system C compiler to find the dynamic linker when zig is statically linked. Related: zig fails to detect musl as the native C ABI on alpine linux #2084
Note: this /usr/bin/env code is work-in-progress.
-target-glibc CLI option is removed in favor of the new -target syntax. Example: -target x86_64-linux-gnu.2.27

closes#1907

What this means for Zig programmers

comptime code will have access to exactly which version(s) of an OS are being targeted.

Updated syntax for -target to take into account OS version ranges:

# still valid. default version range
-target x86_64-windows-msvc
# minimum windows version: XP
# maximum windows version: 10
-target x86_64-windows.xp...win10-msvc
# minimum windows version: 7
# maximum windows version: latest
-target x86_64-windows.win7-msvc
# linux example
-target aarch64-linux.3.16...5.3.1-musl
# specifying glibc version
-target mipsel-linux.4.10-gnu.2.1

Here's what it will look like to populate a std.Target:

- tc.target = tests.Target{- .Cross = .{- .cpu = Target.Cpu.baseline(.x86_64),- .os = Target.Os.defaultVersionRange(.linux),- .abi = .gnu,- },+ tc.target = std.zig.CrossTarget{+ .cpu_arch = .x86_64,+ .os_tag = .linux,+ .abi = .gnu,

Code that used Target.parse need not be updated.

Checking for the OS when doing conditional compilation:

Option 1: easy, might get deprecated in the future:

--- a/lib/std/build/run.zig+++ b/lib/std/build/run.zig@@ -82,7 +82,7 @@ pub const RunStep = struct {
var key: []const u8 = undefined;
var prev_path: ?[]const u8 = undefined;
- if (builtin.os == .windows) {+ if (builtin.os.tag == .windows) {
key = "Path";
prev_path = env_map.get(key);
if (prev_path == null) {

Option 2, more verbose, less likely to be deprecated in the future:

--- a/test/stage1/behavior/byteswap.zig+++ b/test/stage1/behavior/byteswap.zig@@ -1,6 +1,5 @@
const std = @import("std");
const expect = std.testing.expect;
-const builtin = @import("builtin");
test "@byteSwap integers" {
const ByteSwapIntTest = struct {
@@ -41,10 +40,10 @@ test "@byteSwap integers" {
test "@byteSwap vectors" {
// https://github.com/ziglang/zig/issues/3563
- if (builtin.os == .dragonfly) return error.SkipZigTest;+ if (std.Target.current.os.tag == .dragonfly) return error.SkipZigTest;
// https://github.com/ziglang/zig/issues/3317
- if (builtin.arch == .mipsel) return error.SkipZigTest;+ if (std.Target.current.cpu.arch == .mipsel) return error.SkipZigTest;
const ByteSwapVectorTest = struct {
fn run() void {

Checklist:

Follow-up Items

Take advantage of this feature and merge std: implement sendfile on linux #4131!

andrewrk · 2020-02-26T06:47:36Z

In this branch Zig supports a more fine-grained sense of what is native and what is
not. Some examples:

# This is now allowed:
-target native
# Different OS but native CPU, default Windows C ABI:
-target native-windows
# This could be useful for example when running in Wine.
# Different CPU but native OS, native C ABI.
-target x86_64-native -mcpu=skylake
# Different C ABI but otherwise native target:
-target native-native-musl
-target native-native-gnu
# Different glibc version but otherwise native target:
-target native-native-gnu.2.25
# Different OS minimum version, but otherwise native target:
-target native-native.xp

Lots of breaking changes to related std lib APIs.
Calls to getOs() will need to be changed to getOsTag().
Calls to getArch() will need to be changed to getCpuArch().

Usage of Target.Cross and Target.Native need to be updated to use
CrossTarget API.

std.build.Builder.standardTargetOptions is changed to accept its
parameters as a struct with default values. It now has the ability to
specify a whitelist of targets allowed, as well as the default target.
Rather than two different ways of collecting the target, it's now always
a string that is validated, and prints helpful diagnostics for invalid
targets. This feature should now be actually useful, and contributions
welcome to further improve the user experience.

std.build.LibExeObjStep.setTheTarget is removed.
std.build.LibExeObjStep.setTarget is updated to take a CrossTarget
parameter.

std.build.LibExeObjStep.setTargetGLibC is removed. glibc versions are
handled in the CrossTarget API and can be specified with the -target
triple.

std.builtin.Version gains a format method.

daurnimator · 2020-02-28T04:00:11Z

+
+ pub const LinuxVersionRange = struct {
+ range: Version.Range,
+ glibc: Version,


Shouldn't this field only be present for glibc targets?

That's correct, the field is only valid for glibc targets and is otherwise undefined

Rather than undefined should it be an optional with null? Or union(enum) { Musl, Glibc: Version }

* re-introduce `std.build.Target` which is distinct from `std.Target`. `std.build.Target` wraps `std.Target` so that it can be annotated as "the native target" or an explicitly specified target. * `std.Target.Os` is moved to `std.Target.Os.Tag`. The former is now a struct which has the tag as well as version range information. * `std.elf` gains some more ELF header constants. * `std.Target.parse` gains the ability to parse operating system version ranges as well as glibc version. * Added `std.Target.isGnuLibC()`. * self-hosted dynamic linker detection and glibc version detection. This also adds the improved logic using `/usr/bin/env` rather than invoking the system C compiler to find the dynamic linker when zig is statically linked. Related: #2084 Note: this `/usr/bin/env` code is work-in-progress. * `-target-glibc` CLI option is removed in favor of the new `-target` syntax. Example: `-target x86_64-linux-gnu.2.27` closes#1907

and glibc_detect_native_version

Zig now supports a more fine-grained sense of what is native and what is not. Some examples: This is now allowed: -target native Different OS but native CPU, default Windows C ABI: -target native-windows This could be useful for example when running in Wine. Different CPU but native OS, native C ABI. -target x86_64-native -mcpu=skylake Different C ABI but otherwise native target: -target native-native-musl -target native-native-gnu Lots of breaking changes to related std lib APIs. Calls to getOs() will need to be changed to getOsTag(). Calls to getArch() will need to be changed to getCpuArch(). Usage of Target.Cross and Target.Native need to be updated to use CrossTarget API. `std.build.Builder.standardTargetOptions` is changed to accept its parameters as a struct with default values. It now has the ability to specify a whitelist of targets allowed, as well as the default target. Rather than two different ways of collecting the target, it's now always a string that is validated, and prints helpful diagnostics for invalid targets. This feature should now be actually useful, and contributions welcome to further improve the user experience. `std.build.LibExeObjStep.setTheTarget` is removed. `std.build.LibExeObjStep.setTarget` is updated to take a CrossTarget parameter. `std.build.LibExeObjStep.setTargetGLibC` is removed. glibc versions are handled in the CrossTarget API and can be specified with the `-target` triple. `std.builtin.Version` gains a `format` method.

The bug is #2154

* `std.Target.getStandardDynamicLinkerPath` => `std.Target.standardDynamicLinkerPath` * it now takes a pointer to fixed size array rather than an allocator * `std.zig.system.NativeTargetInfo.detect` now supports reading PT_INTERP from /usr/bin/env

now it is integrated with zig's target OS range.

andrewrk · 2020-02-28T20:09:37Z

Blocking on #4578

It now takes a std.zig.CrossTarget parameter, and only resolves native things, leaving explicitly overridden things alone.

andrewrk changed the title ~~introduce operating system version ranges as part of the target~~introduce operating system version ranges as part of the target; self-host native dynamic linker detection and native glibc version detectionFeb 25, 2020

andrewrk force-pushed the os-version-ranges branch 2 times, most recently from fde3a8f to 6d008f1Compare February 27, 2020 16:53

daurnimator reviewed Feb 28, 2020
View reviewed changes

andrewrk force-pushed the os-version-ranges branch from 35b1e75 to 4b49247Compare February 28, 2020 07:38

andrewrk added 24 commits February 28, 2020 14:51

restructuring std.Target for OS version ranges, pass 1
fba39ff

stage1: remove get_self_libc_path
d4f375c
and glibc_detect_native_version

update std lib to new Target API
87b9e74

improve debug info for optionals
c8669a4

fix target parsing
cf233ba

fix standardTargetOptions and improve init-exe to use it
cebcacd

improve the "external executor" detection logic
0912484

fix not setting the dynamic linker path when cross compiling
622b5b6

clean up CrossTarget.getExternalExecutor
34d2700

mips: implement Target.getStandardDynamicLinkerPath
7927764

fix incorrect builtin import code for windows
2387f48

fix builder.findProgram test
6226726

fix __stack_chk_guard emitted even when not linking libc
36aa3c8

compiler-rt: inline at call site to workaround a bug
bafa895
The bug is #2154

WASI has no dynamic linker
2536e4c

update tests to new Target API
3c3316d

update docgen to new Target API
70bf887

don't error out for targets with unknown standard dynamic linker path
f89a184

update docs to latest Target API
662b5f7

std.zig.system.NativeTargetInfo.detect: almost no Allocator
fd006c1

complete the native target detection based on /usr/bin/env
3683ba8

andrewrk added 4 commits February 28, 2020 14:51

stage1: make get_native_target go through self-hosted
d45ea4d

remove special darwin os version min handling
ef24f2d
now it is integrated with zig's target OS range.

implement native OS version detection for linux
07f5211

dynamic_linker becomes a field of std.zig.CrossTarget
500dde3

fix compiler crash when comptime parsing targets
578dc16

andrewrk force-pushed the os-version-ranges branch from 7c6ba97 to 578dc16Compare February 28, 2020 21:12

andrewrk added 8 commits February 28, 2020 17:23

improve std.zig.system.NativeTargetInfo.detect
8691d3c
It now takes a std.zig.CrossTarget parameter, and only resolves native things, leaving explicitly overridden things alone.

fix handling of CrossTarget.cpu_model
aa13f33

CrossTarget.cpu_model: communicate intent precisely
4591236

don't choose native ld path when os is non native
7e3bb00

update test to newer API
4bc893c

fix CrossTarget.isNative, setGnuLibCVersion, zigTriple
e683eee

std.Target.Os.WindowsVersion: non-exhaustive enum
1aef0be

fix crash when building docgen
3cba603

andrewrk merged commit 7617610 into masterFeb 29, 2020

andrewrk deleted the os-version-ranges branch February 29, 2020 06:57

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introduce operating system version ranges as part of the target; self-host native dynamic linker detection and native glibc version detection - #4550

introduce operating system version ranges as part of the target; self-host native dynamic linker detection and native glibc version detection#4550
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Commit Details

What this means for Zig programmers

Checklist:

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