Weird bug around handling `-v` flag in `zig cc -target`

[tesuji]

Zig Version

0.14.0-dev.2540+f857bf72e

Steps to Reproduce and Observed Behavior

1. Download the required zig version
2. Run zig cc -target x86_64-linux-gnu.2.35 with:

-v
# or
-xc -E -v -

4. Confirm that zig fails with either zig: error: version '.2.35' in target triple 'x86_64-unknown-linux-gnu.2.35' is invalid or UnknownApplicationBinaryInterface.

Also reproducible on discord: https://discord.com/channels/605571803288698900/1319191118163873812/1319191118163873812

Expected Behavior

zig cc -target x86_64-linux-gnu.2.35 -v should succeed.
Other build systems like meson or cmake validates availability of a C compiler by running cc -xc -E -v -.
If zig cc -v fails, the build system will fail.

[Cloudef]

To clarify:

zig cc -target x86_64-linux-gnu2.35.0 -v # works
zig cc -target x86_64-linux-gnu.2.35.0 -v # does not work
zig cc -target x86_64-linux-gnu2.35.0 -xc -E -v - # does not work
zig cc -target x86_64-linux-gnu.2.35.0 -xc -E -v - # works

[alexrp]

zig cc -target x86_64-linux-gnu-2.35.0 -v should succeed.

Why should it succeed when you've given an invalid target string?

[tesuji]

Edit: I updated the top post to reflect the changes.

Why should it succeed when you've given an invalid target string?

The doc about choosing glibc version is unclear. I tried: gnu.ver, or gnu-ver, or gnu-ver.0 but all fails.
The related link I found is from Andrew.

andy@ark ~/tmp> zig build-exe rand.zig -lc -target native-native-gnu.2.25

Anyway I still got the error using the same syntax that Andrew mentioned in the post for zig on the master branch,
meanwhile zig 0.13 succeeds.

> ~/zig/0.14.0-dev.2540+f857bf72e/files/zig cc -target x86_64-linux-gnu.2.35 -v
zig: error: version '.2.35' in target triple 'x86_64-unknown-linux-gnu.2.35' is invalid
clang version 19.1.0 (https://github.com/ziglang/zig-bootstrap 46b9e66db90230fe62404b27b85a378ccf2c82c2)
Target: x86_64-unknown-linux-gnu.2.35
Thread model: posix
InstalledDir: /home/lzutao/zig/0.14.0-dev.2540+f857bf72e/files
Found candidate GCC installation: /usr/lib/gcc-cross/i686-linux-gnu/14
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/12
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/13
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/14
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/14
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
> ~/zig/0.13.0/files/zig cc -target x86_64-linux-gnu.2.35 -v
clang version 18.1.6 (https://github.com/ziglang/zig-bootstrap 98bc6bf4fc4009888d33941daf6b600d20a42a56)
Target: x86_64-unknown-linux-gnu.2.35
... [redacted ..]

[alexrp]

Ok, I see. That error is coming from Clang. LLVM/Clang indeed do not support a version string on the ABI component in general. I'm not sure why Clang is even seeing the Zig target string, though; normally, we process it into a form that LLVM/Clang understand.

[chouquette]

Hello,

I'm having a similar issue: same error, but also happens when doing something akin to zig cc -target x86_64-linux-gnu.2.17 foo.so -o foo.so.X (FWIW, this happens when building python through bazel & hermetic_cc_toolchain`)

I'd love to help fix this, but could definitely use some pointers as to where to look, since I'm very new to the zig codebase

[andrewrk]

zig/src/codegen/llvm.zig

Lines 283 to 297 in 6c3cbb0

	switch (target.os.versionRange()) {
	.none,
	.semver,
	.windows,
	=> {},
	inline .hurd, .linux => |ver| if (target.abi.isGnu()) {
	try llvm_triple.writer().print("{d}.{d}.{d}", .{
	ver.glibc.major,
	ver.glibc.minor,
	ver.glibc.patch,
	});
	} else if (@TypeOf(ver) == std.Target.Os.LinuxVersionRange and target.abi.isAndroid()) {
	try llvm_triple.writer().print("{d}", .{ver.android});
	},
	}

this is the llvm triple. it's incorrect to put the zig os version range there.

why did you make it do that?

[ofek]

why did you make it do that?

Who are you asking?

[andrewrk]

@alexrp, but I don't think that's the issue. It's probably the passthrough mechanism being triggered.

[alexrp]

this is the llvm triple. it's incorrect to put the zig os version range there.

why did you make it do that?

LLVM's target triple parser is mostly a bunch of "starts with" checks, so in general, you can put whatever you want after a valid identifier. More to the point, though:

• https://github.com/llvm/llvm-project/blob/872e4a33884b56384ca1ac92aed135bb0d9cc280/llvm/lib/TargetParser/Triple.cpp#L1413-L1425
• https://github.com/llvm/llvm-project/blob/872e4a33884b56384ca1ac92aed135bb0d9cc280/llvm/lib/TargetParser/Triple.cpp#L1386-L1388

Which means that my comment above is just incorrect, and for some reason I posted it after I wrote this code in the LLVM backend. I have no idea what past me was thinking.

At any rate, the error happens because Clang for some reasons sees x86_64-unknown-linux-gnu.2.35 when it should see x86_64-unknown-linux-gnu2.35 (no dot to separate identifier and version).