zig cc -target x86_64-windows.win7-gnu stopped working

[markus-oberhumer]

Zig Version

zig-linux-x86_64-0.12.0-dev.2334+aef1da163

Steps to Reproduce and Observed Behavior

At https://github.com/upx/upx-test-build-with-zig we are continuously testing building UPX for 104 different build targets, and it seems that recently zig cc -target x86_64-windows.win7-gnu stopped working

Possible cause: recent upgrade from msvcrt to ucrt

# create a simple main() file
echo 'int main() { return 0; }' > x.c

# works
./zig-linux-x86_64-0.12.0-dev.2285+b80cad248/zig cc -target x86_64-windows.win7-gnu x.c

# FAILS
./zig-linux-x86_64-0.12.0-dev.2334+aef1da163/zig cc -target x86_64-windows.win7-gnu x.c

zig-linux-x86_64-0.12.0-dev.2334+aef1da163/lib/libc/mingw/libsrc/dloadhelper.c:31:3: error: unknown type name 'PDELAYLOAD_FAILURE_DLL_CALLBACK'
   31 |                 PDELAYLOAD_FAILURE_DLL_CALLBACK FailureDllHook,
      |                 ^
zig-linux-x86_64-0.12.0-dev.2334+aef1da163/lib/libc/mingw/libsrc/dloadhelper.c:52:66: error: use of undeclared identifier '__pfnDliFailureHook2'
   52 |         return ResolveDelayLoadedAPI(&__ImageBase, DelayloadDescriptor, __pfnDliFailureHook2, DelayLoadFailureHook, ThunkAddress, 0);
      |                                                                         ^
2 errors generated.

Expected Behavior

No error.

[rootbeer]

Reproduced. Fails for windows.win7 and earlier (e.g., windows.xp) targets, but passes for later Windows targets (e.g., windows.win8).

lib/libc/mingw/libsrc/dloadhelper.c includes delayloadhandler.h (which has the missing definition), but that file hides the required definition behind a version check:

#if NTDDI_VERSION >= NTDDI_WIN8

(I'm guessing this is the source of the inconsistency, but haven't verified.)

The changelog in #16109 explicitly calls out the "New libdloadhelper.a, like libdelayimp.a but using Windows 8 and later APIs.", so the bug is probably that Zig is including dloadhelper.c when building the CRT for older targets.

zig/src/mingw.zig includes dloadhelper.c in its mingwex_generic_src list, which is, AFAICT the list of files to unilaterally compile into the CRTFile.mingwex_lib CRT target.

I'm guessing that mingw.zig should somehow know to skip this file for older Windows targets. Or the dloadhelper.c itself should hide symbols when targeting older targets.

[markus-oberhumer]

Somewhat related, I think ucrt requires at least Windows 7, so the older targets (windows.xp , windows.vista etc) probably should issue some warning or error.

[ypsvlq]

I think the correct approach is to always build the CRT with the latest version, then _WIN32_WINNT should be defined only when including the headers to restrict what declarations are visible (see the upstream Makefile).

UCRT is supported on XP and above.

[mikdusan]

This regresses -target x86_64-windows-msvc -lc to no longer define _WIN32_WINNT. Note .msvc ABI, because .isMinGW() specifically applies to only .gnu ABI.

caveat: I'm not sure, is -msvc still a supported/desired thing? Because it doesn't show up in the output of zig targets in the libc: section.

[sskras]

caveat: I'm not sure, is -msvc still a supported/desired thing? Because it doesn't show up in the output of zig targets in the libc: section.

@mikdusan, since -target x86_64-windows-msvc is currently mentioned in the CI script, line 98:

zig/ci/x86_64-windows-release.ps1

Lines 90 to 100 in 1e0739f

	Write-Output "Build x86_64-windows-msvc behavior tests using the C backend..."
	& "stage3-release\bin\zig.exe" test `
	..\test\behavior.zig `
	--zig-lib-dir "$ZIG_LIB_DIR" `
	-ofmt=c `
	-femit-bin="test-x86_64-windows-msvc.c" `
	--test-no-exec `
	-target x86_64-windows-msvc `
	-lc
	CheckLastExitCode

... I guess it's still a thing.

Did you ever file/find another issue about that?