My WORKSPACE file contains this code snippet:

new_local_repository(
    name = "boost",
    build_file = "//bazel/third_party:boost.BUILD",
    path = "C:/msys64/mingw64/include"
)

bazel/third_party:boost.BUILD looks like that:

cc_library(
    name = "boost",
    includes = ["."],
    visibility = ["//visibility:public"]
)

Building the main target, that depends on boost, works perfectly fine.

Now let’s remove “include” from the path attribute in the WORKSPACE file and add it to the includes attribute in bazel/third_party:boost.BUILD:

WORKSPACE:

new_local_repository(
    name = "boost",
    build_file = "//bazel/third_party:boost.BUILD",
    path = "C:/msys64/mingw64"
)

bazel/third_party:boost.BUILD:

cc_library(
    name = "boost",
    includes = ["include"],
    visibility = ["//visibility:public"]
)

Building the main target now suddenly produces this error:

ERROR: C:/users/vschaerl/projects/testbazel/testbazel/src/BUILD:1:10: Compiling src/main.cpp failed: (Exit 1): g++ failed: error executing CppCompile command (from target //src:main) C:msys64mingw64bing++ -MD -MF bazel-out/x64_windows-fastbuild/bin/src/_objs/main/main.d -frandom-seed=bazel-out/x64_windows-fastbuild/bin/src/_objs/main/main.o -iquote . -iquote ... (remaining 25 arguments skipped)
In file included from C:/msys64/mingw64/include/c++/13.2.0/ext/string_conversions.h:43,
                 from C:/msys64/mingw64/include/c++/13.2.0/bits/basic_string.h:4097,
                 from C:/msys64/mingw64/include/c++/13.2.0/string:54,
                 from C:/msys64/mingw64/include/c++/13.2.0/bits/locale_classes.h:40,
                 from C:/msys64/mingw64/include/c++/13.2.0/bits/ios_base.h:41,
                 from C:/msys64/mingw64/include/c++/13.2.0/streambuf:43,
                 from C:/msys64/mingw64/include/c++/13.2.0/bits/streambuf_iterator.h:35,
                 from C:/msys64/mingw64/include/c++/13.2.0/iterator:66,
                 from external/boost/include/boost/array.hpp:44,
                 from src/main.cpp:1:
C:/msys64/mingw64/include/c++/13.2.0/cstdlib:79:15: fatal error: stdlib.h: No such file or directory
   79 | #include_next <stdlib.h>
      |               ^~~~~~~~~~
compilation terminated.
Target //src:main failed to build

Why? Shouln’t it behave just the same? I only moved “include” from path to includes…

By the way, I’m on Windows and defined a custom MinGW toolchain for Bazel according to this tutorial: https://github.com/EhabHelaly/bazel_mingw_toolchain

And there are three stdlib.h files in C:msys64mingw64include:

• in C:msys64mingw64include
• in C:msys64mingw64includec++13.2.0
• in C:msys64mingw64includec++13.2.0tr1

Thanks a lot.

EDIT/ADDITIONAL INFORMATION:

This is the compiler command line generated by Bazel before moving “include” from path to includes, when everything works fine (I separated the compiler options by lines for better readability):

C:msys64mingw64bing++
-MD
-MF bazel-out/x64_windows-fastbuild/bin/src/_objs/main/main.d
-frandom-seed=bazel-out/x64_windows-fastbuild/bin/src/_objs/main/main.o
-iquote .
-iquote bazel-out/x64_windows-fastbuild/bin
-iquote external/boost
-iquote bazel-out/x64_windows-fastbuild/bin/external/boost
-iquote external/bazel_tools
-iquote bazel-out/x64_windows-fastbuild/bin/external/bazel_tools
-isystem external/boost
-isystem bazel-out/x64_windows-fastbuild/bin/external/boost
-c src/main.cpp
-o bazel-out/x64_windows-fastbuild/bin/src/_objs/main/main.o

This is the compiler command line after moving “include” from path to includes, which produces said error:

C:msys64mingw64bing++
-MD 
-MF bazel-out/x64_windows-fastbuild/bin/src/_objs/main/main.d
-frandom-seed=bazel-out/x64_windows-fastbuild/bin/src/_objs/main/main.o
-iquote .
-iquote bazel-out/x64_windows-fastbuild/bin
-iquote external/boost
-iquote bazel-out/x64_windows-fastbuild/bin/external/boost
-iquote external/bazel_tools
-iquote bazel-out/x64_windows-fastbuild/bin/external/bazel_tools
-isystem external/boost/include
-isystem bazel-out/x64_windows-fastbuild/bin/external/boost/include
-c src/main.cpp
-o bazel-out/x64_windows-fastbuild/bin/src/_objs/main/main.o

I think the problem lies in -iquote external/boost not changing. Before, external/boost points to C:msys64mingw64include, which is the correct path, but after, it points to C:msys64mingw64, which is not correct. Why does Bazel not change the path in the -iquote compiler option?

EDIT 2:

echo | gcc -Wp,-v -x c++ - -fsyntax-only, which according to /a/19839946/18226035 shows the default GCC include directories, prints this:

ignoring nonexistent directory "C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/13.2.0/../../../../x86_64-w64-mingw32/include"
ignoring duplicate directory "C:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/13.2.0/../../../../include/c++/13.2.0"
ignoring duplicate directory "C:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/13.2.0/../../../../include/c++/13.2.0/x86_64-w64-mingw32"
ignoring duplicate directory "C:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/13.2.0/../../../../include/c++/13.2.0/backward"
ignoring duplicate directory "C:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/13.2.0/include"
ignoring nonexistent directory "D:/a/msys64/mingw64/include"
ignoring nonexistent directory "/mingw64/include"
ignoring duplicate directory "C:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/13.2.0/include-fixed"
ignoring nonexistent directory "C:/msys64/mingw64/lib/gcc/../../lib/gcc/x86_64-w64-mingw32/13.2.0/../../../../x86_64-w64-mingw32/include"
ignoring nonexistent directory "D:/a/msys64/mingw64/include"
#include "..." search starts here:
#include <...> search starts here:
 C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/13.2.0/../../../../include/c++/13.2.0
 C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/13.2.0/../../../../include/c++/13.2.0/x86_64-w64-mingw32
 C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/13.2.0/../../../../include/c++/13.2.0/backward
 C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/13.2.0/include
 C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/13.2.0/../../../../include
 C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/13.2.0/include-fixed
End of search list.