Cmake doesn't recognize MSVC compiler

Question

It's the first time I encounter this error.

I am trying to clone openvr and get the hello opengl sample running, following their instructions:

cd samples
mkdir build
cd build
cmake .. -G "Visual Studio 14 2015 Win64" -DCMAKE_PREFIX_PATH=C:/Qt/5.6/msvc2013_64/lib/cmake

I get:

$ cmake .. -G "Visual Studio 14 2015 Win64" -DCMAKE_PREFIX_PATH=C:/Qt/5.6/msvc20                                                                       13_64/lib/cmake
-- The C compiler identification is MSVC 19.0.24215.1
-- The CXX compiler identification is MSVC 19.0.24215.1
-- Check for working C compiler using: Visual Studio 14 2015 Win64
-- Check for working C compiler using: Visual Studio 14 2015 Win64 -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler using: Visual Studio 14 2015 Win64
-- Check for working CXX compiler using: Visual Studio 14 2015 Win64 -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Compilation set for 64bits architectures.
CMake Warning at CMakeLists.txt:40 (message):
  SDL x64 runtime binaries not provided on Windows.


CMake Error at CMakeLists.txt:98 (message):
  Unsupported compiler.


-- Configuring incomplete, errors occurred!
See also "C:/Users/GBarbieri/Documents/Visual Studio 2015/Projects/openvr/sample                                                                       s/build/CMakeFiles/CMakeOutput.log".

If I go to check line 98:

if(   (${CMAKE_CXX_COMPILER_ID} MATCHES "GNU")
   OR (${CMAKE_CXX_COMPILER_ID} MATCHES "Clang"))
  # Better to use the prebuilt GNU preprocessor define __GNUC__,
  # kept for legacy reason with the sample code.
  add_definitions(-DGNUC)

  set(CMAKE_CXX_FLAGS         "${CMAKE_CXX_FLAGS} -std=c++11 -include ${SHARED_SRC_DIR}/compat.h")
  set(CMAKE_CXX_FLAGS_DEBUG   "${CMAKE_CXX_FLAGS_DEBUG} -Wall -Wextra -pedantic -g")
  set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O2")

  # Handles x86 compilation support on x64 arch.
  if(${PLATFORM} MATCHES 32)
    set(CMAKE_CXX_FLAGS        "${CMAKE_CXX_FLAGS} -m32")
    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -m32")
  endif()
elseif(${CMAKE_CXX_COMPILER_ID} MATCHES "MSVC")
  set(CMAKE_CXX_FLAGS         "${CMAKE_CXX_FLAGS} /Za")
  set(CMAKE_CXX_FLAGS_DEBUG   "${CMAKE_CXX_FLAGS_DEBUG} /w2 /DEBUG")
  set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} /MP /INCREMENTAL:NO")
else()
  message(FATAL_ERROR "Unsupported compiler. ")    // line 98
endif()

It seems it couldn't match "MSVC".. let me do a try, let me add before this snippet of code:

message("${CMAKE_CXX_COMPILER_ID}")
if(${CMAKE_CXX_COMPILER_ID} MATCHES "MSVC")
    message("match")
else()
    message("!match")
endif()

And then it returns:

MSVC
!match
CMake Error at CMakeLists.txt:104 (message):
  Unsupported compiler.

What?

Can you spot what is wrong, guys?

Ballesteros

Shouldn't it be just: if(MSVC) ? – Stratify

Have you tried this? if(CMAKE_CXX_COMPILER_ID MATCHES "MSVC") – Stratify

That works.. I'll modify the CMakeList.txt – Ballesteros

Do you have cmake version > 3.1 ? – Underquote

cmake version 3.3.2 – Ballesteros

However it worked, I am now dealing with the qt – Ballesteros

Answer 1

Ok, as I've tried in the comment, the right answer is to use:

if(CMAKE_CXX_COMPILER_ID MATCHES "MSVC")

instead of

if(${CMAKE_CXX_COMPILER_ID} MATCHES "MSVC")

Stratify

If you are interested in the details why the first works and the second is not working see What's the CMake syntax to set and use variables?. The funny part is, I used exactly this MSVC example there to demonstrate the problem with variable naming resolution. – Fitzhugh