Importing `pal.h` causes undeclared identifier because of order of macro definitions

[tonybaloney]

Description

I have some code which uses the .NET 6 JIT and I'm updating it too .NET 7. It needs to import <windows.h> and <pal.h> but I'm getting an error on cross-compile/universal2 builds in clang-c++:

 In file included from /Users/anthonyshaw/CLionProjects/pyjion/src/pyjion/codemodel.h:43:
      In file included from /Users/anthonyshaw/CLionProjects/pyjion/CoreCLR/src/coreclr/pal/inc/rt/windows.h:12:
      In file included from /Users/anthonyshaw/CLionProjects/pyjion/CoreCLR/src/coreclr/pal/inc/rt/palrt.h:136:
      /Users/anthonyshaw/CLionProjects/pyjion/CoreCLR/src/coreclr/pal/inc/pal.h:3546:1: error: use of undeclared identifier 'g_arm64_atomics_present'
      Define_InterlockMethod(
      ^
      /Users/anthonyshaw/CLionProjects/pyjion/CoreCLR/src/coreclr/pal/inc/pal.h:3501:9: note: expanded from macro 'Define_InterlockMethod'
          if (g_arm64_atomics_present)                                \
              ^
      /Users/anthonyshaw/CLionProjects/pyjion/CoreCLR/src/coreclr/pal/inc/pal.h:3553:1: error: use of undeclared identifier 'g_arm64_atomics_present'
      Define_InterlockMethod(
      ^
      /Users/anthonyshaw/CLionProjects/pyjion/CoreCLR/src/coreclr/pal/inc/pal.h:3501:9: note: expanded from macro 'Define_InterlockMethod'
          if (g_arm64_atomics_present)                                \

Looking at the source code, the macro HOST_ARM64 is defined beneath the check on line 77 for it, so the global is never defined, which means imports of this header fail.

The header is required to use clrlibjit.xxx directly.

Reproduction Steps

Expected behavior

Actual behavior

Regression?

Yes, worked on .NET 6

Known Workarounds

No response

Configuration

No response

Other information

No response

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[tonybaloney]

This is for the v7.0.0 tag

runtime/src/coreclr/pal/inc/pal.h

Lines 77 to 81 in d099f07

	#if defined(HOST_ARM64)
	// Flag to check if atomics feature is available on
	// the machine
	extern bool g_arm64_atomics_present;
	#endif

[am11]

If you cherry-pick 536f34d on release/7.0, does it fix the error?

[akorchev]

I tried cherry-picking that commit on release/7.0 and ended up with different errors. I am building on Mac m1.

src/coreclr/pal/inc/pal.h:2517:2: error: Unknown architecture for defining CONTEXT.
#error Unknown architecture for defining CONTEXT.

[tonybaloney]

@akorchev I ended up targeting d099f07 as that was ABI compatible with the release 7.0.0 binaries.

Also added a workaround by predefining some macros before importing windows.h https://github.com/tonybaloney/Pyjion/blob/6694a01570bce1f55fc7a7cf972d196fb33714dd/src/pyjion/crossplat.h

[akorchev]

Thanks! I ended up doing something similar - defining HOST_ARM64 in the CMake configuration:

add_compile_definitions(HOST_ARM64)