[C++ Modules] XMake references the very module being built within its own command

[remi6397]

Xmake Version

v2.6.4+dev.0fcbe01

Operating System Version and Architecture

macOS 12.2.1

Describe Bug

The following pattern causes XMake to seize up by referencing a module in its own compilation command as -fmodule-file=:

• Module b imports module importable
• Module a imports both importable and b

Test case: https://gist.github.com/ab56fbaad6045fa5f1434253efe5e4bb.git

Expected Behavior

-fmodule-file=build/.gens/rules/modules/cache/a.pcm is not passed as a parameter.

Project Configuration

No response

Additional Information and Error Logs

Details

❯ git clone https://gist.github.com/ab56fbaad6045fa5f1434253efe5e4bb.git test
❯ cd !$
❯ xmake f -c --toolchain=llvm --sdk=/usr/local/llvm14 --ar=/usr/local/llvm14/bin/llvm-ar --mode=debug --cxxflags='-g -O0' -vD -y
checking for platform ... macosx
checking for architecture ... x86_64
checking for Xcode directory ... /Applications/Xcode.app
checking for SDK version of Xcode for macosx (x86_64) ... 12.1
configure
{
    mode = debug
    network = public
    xcode = /Applications/Xcode.app
    theme = default
    plat = macosx
    cxxflags = -g -O0
    ar = /usr/local/llvm14/bin/llvm-ar
    arch = x86_64
    proxy_pac = pac.lua
    pkg_searchdirs = /Users/redacted/Downloads
    kind = static
    clean = true
    host = macosx
    sdk = /usr/local/llvm14
    ndk_stdcxx = true
    buildir = build
    toolchain = llvm
    ccache = true
}
warning: cannot match target(abc).add_files("*.cpp") at ./xmake.lua:5
❯ xmake -rv
checking for clang ... /usr/local/llvm14/bin/clang
checking for the c++ compiler (cxx) ... clang
checking for /usr/local/llvm14/bin/clang ... ok
checking for flags (-fPIC) ... ok
checking for flags (-fmodules) ... ok
generating.moduledeps b.mpp
generating.moduledeps a.mpp
generating.moduledeps importable.mpp
checking for flags (-std=c++20) ... ok
checking for ccache ... no
[ 16%]: compiling.debug importable.mpp
/usr/local/llvm14/bin/clang -c -Qunused-arguments -m64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk -fPIC -g -O0 -std=c++20 -fmodules -fimplicit-modules -fimplicit-module-maps -fprebuilt-module-path=build/.gens/rules/modules/cache --precompile -x c++-module -fmodules-cache-path=build/.gens/rules/modules/cache -o build/.gens/rules/modules/cache/importable.pcm importable.mpp
checking for flags (-MMD -MF) ... ok
[ 16%]: compiling.debug importable.mpp
/usr/local/llvm14/bin/clang -c -Qunused-arguments -m64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk -fPIC -g -O0 -std=c++20 -fmodules -fimplicit-modules -fimplicit-module-maps -fprebuilt-module-path=build/.gens/rules/modules/cache --precompile -x c++-module -fmodules-cache-path=build/.gens/rules/modules/cache -o build/.gens/rules/modules/cache/importable.pcm importable.mpp
checking for flags (-fdiagnostics-color=always) ... ok
/usr/local/llvm14/bin/clang -c -Qunused-arguments -m64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk -fPIC -g -O0 -std=c++20 -fmodules -fmodules-cache-path=build/.gens/rules/modules/cache -fimplicit-modules -fimplicit-module-maps -fprebuilt-module-path=build/.gens/rules/modules/cache -o build/.objs/abc/macosx/x86_64/debug/importable.mpp.o build/.gens/rules/modules/cache/importable.pcm
/usr/local/llvm14/bin/clang -c -Qunused-arguments -m64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk -fPIC -g -O0 -std=c++20 -fmodules -fmodules-cache-path=build/.gens/rules/modules/cache -fimplicit-modules -fimplicit-module-maps -fprebuilt-module-path=build/.gens/rules/modules/cache -o build/.objs/abc/macosx/x86_64/debug/importable.mpp.o build/.gens/rules/modules/cache/importable.pcm
[ 50%]: compiling.debug b.mpp
/usr/local/llvm14/bin/clang -c -Qunused-arguments -m64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk -fPIC -g -O0 -std=c++20 -fmodules -fimplicit-modules -fimplicit-module-maps -fprebuilt-module-path=build/.gens/rules/modules/cache --precompile -x c++-module -fmodules-cache-path=build/.gens/rules/modules/cache -o build/.gens/rules/modules/cache/b.pcm b.mpp
[ 50%]: compiling.debug b.mpp
/usr/local/llvm14/bin/clang -c -Qunused-arguments -m64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk -fPIC -g -O0 -std=c++20 -fmodules -fimplicit-modules -fimplicit-module-maps -fprebuilt-module-path=build/.gens/rules/modules/cache --precompile -x c++-module -fmodules-cache-path=build/.gens/rules/modules/cache -o build/.gens/rules/modules/cache/b.pcm b.mpp
/usr/local/llvm14/bin/clang -c -Qunused-arguments -m64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk -fPIC -g -O0 -std=c++20 -fmodules -fmodules-cache-path=build/.gens/rules/modules/cache -fimplicit-modules -fimplicit-module-maps -fprebuilt-module-path=build/.gens/rules/modules/cache -o build/.objs/abc/macosx/x86_64/debug/b.mpp.o build/.gens/rules/modules/cache/b.pcm
/usr/local/llvm14/bin/clang -c -Qunused-arguments -m64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk -fPIC -g -O0 -std=c++20 -fmodules -fmodules-cache-path=build/.gens/rules/modules/cache -fimplicit-modules -fimplicit-module-maps -fprebuilt-module-path=build/.gens/rules/modules/cache -o build/.objs/abc/macosx/x86_64/debug/b.mpp.o build/.gens/rules/modules/cache/b.pcm
[ 83%]: compiling.debug a.mpp
/usr/local/llvm14/bin/clang -c -Qunused-arguments -m64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.1.sdk -fPIC -g -O0 -std=c++20 -fmodule-file=build/.gens/rules/modules/cache/b.pcm -fmodule-file=build/.gens/rules/modules/cache/a.pcm -fmodule-file=build/.gens/rules/modules/cache/importable.pcm -fmodules -fimplicit-modules -fimplicit-module-maps -fprebuilt-module-path=build/.gens/rules/modules/cache --precompile -x c++-module -fmodules-cache-path=build/.gens/rules/modules/cache -o build/.gens/rules/modules/cache/a.pcm a.mpp
error: fatal error: module file 'build/.gens/rules/modules/cache/a.pcm' not found: module file not found
1 error generated.

[waruqi]

This is a more complex issue, caused by the current imperfect support for building dependency graphs, which causes problems when #parent > 1. At the moment I haven't had time to deal with it and perhaps the dependency graph needs to be improved, which will take some time to refactor it.

xmake/xmake/rules/c++/modules/build_modules/clang.lua

Lines 134 to 136 in 06b374d

	for _, parent in ipairs(moduledep.parents) do
	batchjobs:add(moduledep.job, parent.job)
	end

{ 
  importable = { 
    name = "importable",
    file = "importable.mpp",
    parents = { 
      { &1
        name = "a",
        deps = { 
          "importable",
          "b" 
        },
        file = "a.mpp" 
      },
      { &2
        parents = { 
          *1 
        },
        name = "b",
        deps = { 
          "importable" 
        },
        file = "b.mpp" 
      } 
    } 
  },
  a = *1,
  b = *2 
}

[waruqi]

I have fixed it, you can try this patch. #2237

xmake update -s dev