Bazel build is broken on MacOS / Clang 19.1.7

[phaedon]

Steps to repro:

git clone https://github.com/emscripten-core/emsdk.git
cd emsdk/bazel
echo "7.6.0" > .bazelversion
bazel build hello-world/...

Errors:

ERROR: /Users/phaedon/git/emsdk/bazel/hello-world/BUILD:9:10: Compiling hello-world/hello-world-simd.cc failed: (Exit 1): cc_wrapper.sh failed: error executing CppCompile command (from target //hello-world:hello-world-simd) external/bazel_tools~cc_configure_extension~local_config_cc/cc_wrapper.sh -U_FORTIFY_SOURCE -fstack-protector -Wall -Wthread-safety -Wself-assign -Wunused-but-set-parameter -Wno-free-nonheap-object ... (remaining 29 arguments skipped)

Use --sandbox_debug to see verbose messages from the sandbox and retain the sandbox build root for debugging
In file included from hello-world/hello-world-simd.cc:1:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:932:10: error: use of undeclared identifier '__builtin_wasm_any_true_v128'
  932 |   return __builtin_wasm_any_true_v128((__i8x16)__a);
      |          ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:938:18: error: use of undeclared identifier '__builtin_wasm_bitselect'
  938 |   return (v128_t)__builtin_wasm_bitselect((__i32x4)__a, (__i32x4)__b,
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:943:18: error: use of undeclared identifier '__builtin_wasm_abs_i8x16'
  943 |   return (v128_t)__builtin_wasm_abs_i8x16((__i8x16)__a);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:951:10: error: use of undeclared identifier '__builtin_wasm_all_true_i8x16'
  951 |   return __builtin_wasm_all_true_i8x16((__i8x16)__a);
      |          ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:955:10: error: use of undeclared identifier '__builtin_wasm_bitmask_i8x16'
  955 |   return __builtin_wasm_bitmask_i8x16((__i8x16)__a);
      |          ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:959:18: error: use of undeclared identifier '__builtin_wasm_popcnt_i8x16'
  959 |   return (v128_t)__builtin_wasm_popcnt_i8x16((__i8x16)__a);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:984:18: error: use of undeclared identifier '__builtin_wasm_add_sat_s_i8x16'
  984 |   return (v128_t)__builtin_wasm_add_sat_s_i8x16((__i8x16)__a, (__i8x16)__b);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:989:18: error: use of undeclared identifier '__builtin_wasm_add_sat_u_i8x16'
  989 |   return (v128_t)__builtin_wasm_add_sat_u_i8x16((__u8x16)__a, (__u8x16)__b);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:999:18: error: use of undeclared identifier '__builtin_wasm_sub_sat_s_i8x16'
  999 |   return (v128_t)__builtin_wasm_sub_sat_s_i8x16((__i8x16)__a, (__i8x16)__b);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:1004:18: error: use of undeclared identifier '__builtin_wasm_sub_sat_u_i8x16'
 1004 |   return (v128_t)__builtin_wasm_sub_sat_u_i8x16((__u8x16)__a, (__u8x16)__b);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:1009:18: error: use of undeclared identifier '__builtin_wasm_min_s_i8x16'
 1009 |   return (v128_t)__builtin_wasm_min_s_i8x16((__i8x16)__a, (__i8x16)__b);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:1014:18: error: use of undeclared identifier '__builtin_wasm_min_u_i8x16'
 1014 |   return (v128_t)__builtin_wasm_min_u_i8x16((__u8x16)__a, (__u8x16)__b);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:1019:18: error: use of undeclared identifier '__builtin_wasm_max_s_i8x16'
 1019 |   return (v128_t)__builtin_wasm_max_s_i8x16((__i8x16)__a, (__i8x16)__b);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:1024:18: error: use of undeclared identifier '__builtin_wasm_max_u_i8x16'
 1024 |   return (v128_t)__builtin_wasm_max_u_i8x16((__u8x16)__a, (__u8x16)__b);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:1029:18: error: use of undeclared identifier '__builtin_wasm_avgr_u_i8x16'
 1029 |   return (v128_t)__builtin_wasm_avgr_u_i8x16((__u8x16)__a, (__u8x16)__b);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:1033:18: error: use of undeclared identifier '__builtin_wasm_abs_i16x8'
 1033 |   return (v128_t)__builtin_wasm_abs_i16x8((__i16x8)__a);
      |                  ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:1041:10: error: use of undeclared identifier '__builtin_wasm_all_true_i16x8'
 1041 |   return __builtin_wasm_all_true_i16x8((__i16x8)__a);
      |          ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:1045:10: error: use of undeclared identifier '__builtin_wasm_bitmask_i16x8'
 1045 |   return __builtin_wasm_bitmask_i16x8((__i16x8)__a);
      |          ^
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include/wasm_simd128.h:1070:18: error: use of undeclared identifier '__builtin_wasm_add_sat_s_i16x8'
 1070 |   return (v128_t)__builtin_wasm_add_sat_s_i16x8((__i16x8)__a, (__i16x8)__b);
      |                  ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

[phaedon]

Verifying that this also fails on Ubuntu/GCC:

ERROR: /home/fjsinis/github/emsdk/bazel/hello-world/BUILD:9:10: Compiling hello-world/hello-world-simd.cc failed: (Exit 1): gcc failed: error executing CppCompile command (from target //hello-world:hello-world-simd) /usr/bin/gcc -U_FORTIFY_SOURCE -fstack-protector -Wall -Wunused-but-set-parameter -Wno-free-nonheap-object -fno-omit-frame-pointer '-std=c++14' -MD -MF ... (remaining 24 arguments skipped)

Use --sandbox_debug to see verbose messages from the sandbox and retain the sandbox build root for debugging
hello-world/hello-world-simd.cc:1:10: fatal error: wasm_simd128.h: No such file or directory
    1 | #include <wasm_simd128.h>
      |          ^~~~~~~~~~~~~~~~
compilation terminated.

[sbc100]

It looks like you are trying to build stuff with the host macOS toolchain somehow. At least the location of failing header file suggest a local clang 16 (/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/lib/clang/16/include).

emsdk is a cross compiler so the host toolchains and headers should never be used. So something must not be configured correctly here.

Can you try just building the wasm_cc_binaries targets? e.g.bazel build //hello-world:hello-world-wasm

I don't think the default cc_binary targets in bazel/hello-world/BUILD are supposed to be buildable except with the emscripten toolchain. I think in the past they could be built with --config=wasm.. but I'm not sure that works these days? @walkingeyerobot ?