zig fails to build from source: error: use of unknown builtin '__builtin_inff16'

[andrewrk]

current master branch: 8a3aeba

andy@Andrews-MBP build-release % cmake .. -DCMAKE_PREFIX_PATH=$HOME/local/llvm19-assert -GNinja -DZIG_NO_LIB=ON -DCMAKE_BUILD_TYPE=Release
andy@Andrews-MBP build-release % ninja install
[16/20] Building C object CMakeFiles/zig2.dir/compiler_rt.c.o
FAILED: CMakeFiles/zig2.dir/compiler_rt.c.o
/Library/Developer/CommandLineTools/usr/bin/cc -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -I/Users/andy/dev/zig/stage1 -I/Users/andy/local/llvm19-assert/include -O3 -DNDEBUG -arch arm64 -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX13.3.sdk -std=c99 -O0 -fno-stack-protector -MD -MT CMakeFiles/zig2.dir/compiler_rt.c.o -MF CMakeFiles/zig2.dir/compiler_rt.c.o.d -o CMakeFiles/zig2.dir/compiler_rt.c.o -c /Users/andy/dev/zig/build-release/compiler_rt.c
/Users/andy/dev/zig/build-release/compiler_rt.c:17580:10: error: use of unknown builtin '__builtin_inff16' [-Wimplicit-function-declaration]
  return zig_make_special_f16(, inf, , UINT16_C(0x7c00));
         ^
/Users/andy/dev/zig/stage1/zig.h:3180:59: note: expanded from macro 'zig_make_special_f16'
#define  zig_make_special_f16(sign, name, arg, repr) sign zig_make_f16 (__builtin_##name, )(arg)
                                                          ^
/Users/andy/dev/zig/stage1/zig.h:3207:32: note: expanded from macro 'zig_make_f16'
#define zig_make_f16(fp, repr) fp##f16
                               ^
<scratch space>:389:1: note: expanded from here
__builtin_inff16
^

[alexrp]

llvm/llvm-project@52818fd97f0f2

What are your Xcode and Apple Clang versions?

[alexrp]

Actually, I think I caused this: d19e191

When I made that commit, I was not aware of 176940b, which is probably the issue you're hitting again. Will see if there's a way to salvage my commit; otherwise I'll revert.

[andrewrk]

Confirmed the fix, thanks!