Cannot specify a non default C/C++ compiler in CMake under MinGW64 / MSYS

Question

From Mingw-w64, CMake cannot find the non-default compiler I specified on the command line.

This is the pre-build output:

MINGW64 /C/projects/TEST
$ cmake -G "MSYS Makefiles" -D CMAKE_C_COMPILER=/mingw64/bin/gcc -D CMAKE_CXX_COMPILER=/mingw64/bin/g++ ../Test-LineHandler
Sub-project name: Test
-- The C compiler identification is GNU 10.2.0
-- The CXX compiler identification is GNU 10.2.0
CMake Error at CMakeLists.txt:16 (project):
  The CMAKE_C_COMPILER:

    C:/msys64/mingw64/bin/gcc

  is not a full path to an existing compiler tool.

  Tell CMake where to find the compiler by setting either the environment
  variable "CC" or the CMake cache entry CMAKE_C_COMPILER to the full path to
  the compiler, or to the compiler name if it is in the PATH.


CMake Error at CMakeLists.txt:16 (project):
  The CMAKE_CXX_COMPILER:

    C:/msys64/mingw64/bin/g++

  is not a full path to an existing compiler tool.

  Tell CMake where to find the compiler by setting either the environment
  variable "CXX" or the CMake cache entry CMAKE_CXX_COMPILER to the full path
  to the compiler, or to the compiler name if it is in the PATH.


-- Configuring incomplete, errors occurred!
See also "C:/projects/TEST/CMakeFiles/CMakeOutput.log".

However, both gcc and g++ exist:

$ ls -l C:/msys64/mingw64/bin/gcc
-rwxr-xr-x 1 RFT RFT 2218766 Dec 10 00:50 C:/msys64/mingw64/bin/gcc

$ ls -l C:/msys64/mingw64/bin/g++
-rwxr-xr-x 1 RFT RFT 2221326 Dec 10 00:50 C:/msys64/mingw64/bin/g++

$ ls -l /mingw64/bin/gcc
-rwxr-xr-x 1 RFT RFT 2218766 Dec 10 00:50 /mingw64/bin/gcc

$ ls -l /mingw64/bin/g++
-rwxr-xr-x 1 RFT RFT 2221326 Dec 10 00:50 /mingw64/bin/g++

This is the generated CMakeOutput.log file:

$ more ./CMakeFiles/CMakeOutput.log
The system is: Windows - 10.0.19041 - AMD64
Compiling the C compiler identification source file "CMakeCCompilerId.c" succeeded.
Compiler: C:/msys64/mingw64/bin/gcc
Build flags:
Id flags:

The output was:
0


Compilation of the C compiler identification source "CMakeCCompilerId.c" produced "a.exe"

The C compiler identification is GNU, found in "C:/projects/TEST/CMakeFiles/3.19.3/CompilerIdC/a.exe"

Compiling the CXX compiler identification source file "CMakeCXXCompilerId.cpp" succeeded.
Compiler: C:/msys64/mingw64/bin/g++
Build flags:
Id flags:

The output was:
0


Compilation of the CXX compiler identification source "CMakeCXXCompilerId.cpp" produced "a.exe"

The CXX compiler identification is GNU, found in "C:/projects/TEST/CMakeFiles/3.19.3/CompilerIdCXX/a.exe"

Am I specifying the non default compiler correctly on the command line?

Answer 1

The exact error is: C:/msys64/mingw64/bin/gcc is not a full path to an existing compiler tool.

Which is correct as the full path is C:/msys64/mingw64/bin/gcc.exe.

So just include the .exe extension of the compiler specified.