Allow project options to be used in creation of a conan package.

[lambtonr]

Stumbled across this problem when using project options to build a library, that library could no longer be built via a conan recipe.

i have wrapped part of the conan.cmake to test if we are been built via conan and allow conan to define the build settings, rather than call ''conan_cmake_autodetect``

you can find my test project library and recipe that shows the problem (currently calling my fork of project options) reverting back to current release should show the following issue.

gcc conan create ./all 0.0.1@lambtonr/testing

[ 50%] Building CXX object CMakeFiles/example.dir/example.cpp.o
[100%] Linking CXX executable bin/example
[100%] Built target example
HelloWorld/0.0.1@lambtonr/testing (test package): Running test()
Hello World! Release!

clang conan create ./all 0.0.1@lambtonr/testing

[ 50%] Building CXX object CMakeFiles/example.dir/example.cpp.o
[100%] Linking CXX executable bin/example
CMakeFiles/example.dir/example.cpp.o: In function `main':
example.cpp:(.text+0xd): undefined reference to `ConanLibrary::HelloWorld()'

This is caused by the fact conan_cmake_autodetect will use different setting to conan GCC default profile matches that of conan_cmake_autodetect where as clangs defaults differ causing the issue.

Configuration: (conan profile show default)
[settings]
arch=x86_64
arch_build=x86_64
build_type=Release
compiler=clang
compiler.libcxx=libstdc++
compiler.version=13
os=Linux
os_build=Linux
[options]
[build_requires]
[env]

....

Configuration: (conan_cmake_autodetect)
[settings]
arch=x86_64
arch_build=x86_64
build_type=Release
compiler=clang
compiler.cppstd=11
compiler.libcxx=libstdc++11
compiler.version=13
os=Linux
os_build=Linux
[options]
[build_requires]
[env]
CC=
CXX=/usr/bin/clang++

[aminya]

@ddalcino Could you review this?

[aminya]

The MacOS failure seems to be caused by llvm 14.0.0.

ld: warning: dylib (/Users/runner/hostedtoolcache/llvm/14.0.0/x64/lib/libc++.dylib) was built for newer macOS version (11.6) than being linked (11.0)
ld: warning: dylib (/Users/runner/hostedtoolcache/llvm/14.0.0/x64/lib/libunwind.dylib) was built for newer macOS version (11.6) than being linked (11.0)
ld: warning: dylib (/Users/runner/hostedtoolcache/llvm/14.0.0/x64/lib/libunwind.dylib) was built for newer macOS version (11.6) than being linked (11.0)
ThinLTO: CMakeFiles/main.dir/Release/src/main/main.cpp.o0: error: Invalid record
LLVM ERROR: Can't load module, abort.
clang-14: error: unable to execute command: Abort trap: 6
clang-14: error: linker command failed due to signal (use -v to see invocation)

[aminya]

Thanks for fixing this!