[cfe-dev] Header Search Paths with MinGW

[Fernando Pelliccioni]

Hi,

I found a problem and I am writing to propose a solution, I would like to
know what you think.
I am working on Win32 with MinGW (GCC 4.4)

I quote an extract of the InitHeaderSearch class (
/tools/clang/lib/Frontend/InitHeaderSearch.cpp )

//----------------------------------------------------------------------------------------------------

void InitHeaderSearch::AddMinGWCPlusPlusIncludePaths(llvm::StringRef Base,
                                                     llvm::StringRef Arch,
                                                     llvm::StringRef
Version) {

  AddPath(Base + "/" + Arch + "/" + Version + "/include",
          System, true, false, false);
  AddPath(Base + "/" + Arch + "/" + Version + "/include/c++",
          System, true, false, false);
  AddPath(Base + "/" + Arch + "/" + Version + "/include/c++/backward",
          System, true, false, false);
}

void InitHeaderSearch::AddDefaultCPlusPlusIncludePaths(const llvm::Triple
&triple) {
//...
  case llvm::Triple::MinGW64:
    // Try gcc 4.4.0
    AddMinGWCPlusPlusIncludePaths("c:/MinGW/lib/gcc", "mingw64", "4.4.0");
    // Try gcc 4.3.0
    AddMinGWCPlusPlusIncludePaths("c:/MinGW/lib/gcc", "mingw64", "4.3.0");
    // Fall through.
  case llvm::Triple::MinGW32:
    // Try gcc 4.4.0
    AddMinGWCPlusPlusIncludePaths("c:/MinGW/lib/gcc", "mingw32", "4.4.0");
    // Try gcc 4.3.0
    AddMinGWCPlusPlusIncludePaths("c:/MinGW/lib/gcc", "mingw32", "4.3.0");
    break;
//...
}

//----------------------------------------------------------------------------------------------------

For example, in this line ...

    AddMinGWCPlusPlusIncludePaths("c:/MinGW/lib/gcc", "mingw32", "4.4.0");

... "mingw32" corresponds to the parameter "Arch" of function
"AddMinGWCPlusPlusIncludePaths". It is harcoded!


In GCC, if I want to know what is the Header Seach Path, I can run ...

    > g++ -v -c xxx.cpp

        ...
        #include "..." search starts here:
        #include <...> search starts here:
         c:\mingw\bin\../lib/gcc/mingw32/4.4.0/include/c++
         c:\mingw\bin\../lib/gcc/mingw32/4.4.0/include/c++/mingw32
         c:\mingw\bin\../lib/gcc/mingw32/4.4.0/include/c++/backward
         c:\mingw\bin\../lib/gcc/mingw32/4.4.0/../../../../include
         c:\mingw\bin\../lib/gcc/mingw32/4.4.0/include
         c:\mingw\bin\../lib/gcc/mingw32/4.4.0/include-fixed
         c:\mingw\bin\../lib/gcc/mingw32/4.4.0/../../../../mingw32/include
        End of search list.
        ...


I tried another implementation of MinGW (GCC 4.6) in which I got X.

         c:\mingw\bin\../lib/gcc/i686-pc-mingw32/4.6.0/include/c++

 c:\mingw\bin\../lib/gcc/i686-pc-mingw32/4.6.0/include/c++/i686-pc-mingw32
         c:\mingw\bin\../lib/gcc/i686-pc-mingw32/4.6.0/include/c++/backward
         c:\mingw\bin\../lib/gcc/i686-pc-mingw32/4.6.0/../../../../include
         c:\mingw\bin\../lib/gcc/i686-pc-mingw32/4.6.0/include
         c:\mingw\bin\../lib/gcc/i686-pc-mingw32/4.6.0/include-fixed

 c:\mingw\bin\../lib/gcc/i686-pc-mingw32/4.6.0/../../../../i686-pc-mingw32/include


The problem is in the "Arch" parameter, in one implementation I have
"mingw32" and in the other "i686-pc-mingw32"

How I can know which parameter to use?

The answer is...

    > g++ -dumpmachine
    mingw32

or in the second MinGW implementation...

    > g++ -dumpmachine
    i686-pc-mingw32


To fix this, I propose to add a new preprocessor #define on "config.h" and
"llvm-config.h", like the following...

    #define LLVM_MINGW_DUMPMACHINE "mingw32"

LLVM_MINGW_DUMPMACHINE is fed in the CMake configuration phase, and can be
used in the InitHeaderSearch class as follows...

    AddMinGWCPlusPlusIncludePaths("c:/MinGW/lib/gcc",
llvm::StringRef(LLVM_MINGW_DUMPMACHINE), "4.4.0");


The files involved are:

/cmake/config-ix.cmake
/cmake/modules/GetTargetTriple.cmake
/include/llvm/Config/config.h.cmake
/include/llvm/Config/llvm-config.h.cmake
/include/llvm/Config/config.h.in
/include/llvm/Config/llvm-config.h.in
/tools/clang/lib/Frontend/InitHeaderSearch.cpp



I want to know what do you think about this solution. If you approve, I will
send the patches.

The next step is to avoid the hardcoding of "c:/MinGW/lib/gcc"...


Thanks and Regards.
Fernando Pelliccioni.
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