CMake isn't using configured compiler

[bryceschober]

Trying to use non-default gcc-7 on Ubuntu 14.04, it uses the default instead and fails with an error:

$ conan create -s compiler.version=7.3 .. cpputest/test
Exporting package recipe
CppUTest/master@cpputest/test: A new conanfile.py version was exported
CppUTest/master@cpputest/test: Folder: /home/bschober/.conan/data/CppUTest/master/cpputest/test/export
Configuration:
[settings]
os=Linux
os_build=Linux
arch=x86_64
arch_build=x86_64
compiler=gcc
compiler.version=7.3
compiler.libcxx=libstdc++
build_type=Release
[options]
[build_requires]
[env]

...

CppUTest/master@cpputest/test: Copying sources to build folder
CppUTest/master@cpputest/test: Generator txt created conanbuildinfo.txt
CppUTest/master@cpputest/test: Calling build()
-- The C compiler identification is GNU 4.8.5
-- The CXX compiler identification is GNU 4.8.5
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works

...

-------------------------------------------------------
CppUTest Version 3.8

Current compiler options:
    CC:                                 /usr/bin/cc
    CXX:                                /usr/bin/c++

...

CppUTest/master@cpputest/test (test package): Generator cmake created conanbuildinfo.cmake
CppUTest/master@cpputest/test (test package): Generator txt created conanbuildinfo.txt
CppUTest/master@cpputest/test (test package): Generated conaninfo.txt
CppUTest/master@cpputest/test (test package): Running build()
-- The CXX compiler identification is GNU 4.8.5
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Conan: called by CMake conan helper
-- Conan: Compiler GCC>=5, checking major version 7.3
-- Conan: Checking correct version: 4.8
CMake Error at build/f903b28b40a2bcdd4a89871fc41d46a21bbd9fa9/conanbuildinfo.cmake:352 (message):
  Incorrect 'gcc' version 'compiler.version=7.3' is not the one detected by
  CMake: 'GNU=4.8'
Call Stack (most recent call first):
  build/f903b28b40a2bcdd4a89871fc41d46a21bbd9fa9/conanbuildinfo.cmake:404 (conan_error_compiler_version)
  build/f903b28b40a2bcdd4a89871fc41d46a21bbd9fa9/conanbuildinfo.cmake:480 (check_compiler_version)
  build/f903b28b40a2bcdd4a89871fc41d46a21bbd9fa9/conanbuildinfo.cmake:117 (conan_check_compiler)
  CMakeLists.txt:5 (conan_basic_setup)

-- Configuring incomplete, errors occurred!

So it looks like the cmake integration didn't pick up the correct compiler version from the conan configuration, and it just used the system-default gcc.

[bryceschober]

@offa Can you reproduce this problem with a non-default compiler specification? Any help you can offer on this would be awesome.

[offa]

Yes, I can reproduce it using clang:

conan create -s compiler=clang -s compiler.libcxx=libstdc++11 -s compiler.version=7.0 . cpputest/test

Conan picks up clang:

Configuration:
[settings]
…
compiler=clang
build_type=Release
compiler.libcxx=libstdc++11
compiler.version=7.0
…

But Cmake compiles with GCC.

[bryceschober]

If you have the cmake skills and any free time, it'd be awesome if you could help.

[offa]

@bryceschober There's related issue: conan-io/conan#199

Update:

As mentioned there, the compiler should be set using -e CC=... -e CXX=.... And this worked for me:

conan create -e CC=clang -e CXX=clang++ . cpputest/test

In your case: -e CC=gcc-7 -e CXX=g++-7

Update:

At least until the package test is executed …
I then get a compiler mismatch error: Canan has Gcc and Cmake has Clang set. Probably this is where profiles become handy.

[offa]

Combining the -s and -e options together works:

conan create -e CC=clang -e CXX=clang++ -s compiler=clang -s compiler.libcxx=libstdc++11 -s compiler.version=7.0 . cpputest/test

[bryceschober]

Yep. Looks like the docs I should have RTF'd were here: https://docs.conan.io/en/latest/reference/profiles.html#examples

[bryceschober]

I suppose a pointer in the README is probably in order here, since CppUTest users are likely to have more than one compiler installed and want to select one.