Fix Clang detection

[michalbiesek]

• use CMAKE_CXX_COMPILER_VERSION/CMAKE_CXX_COMPILER_ID for
  setting compiler conditions
• fixes Clang detection does not work if there is no clang (but e.g. clang-9) #1090

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This change is 

[igchor]

Reviewed 2 of 2 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @michalbiesek)

[codecov]

Codecov Report

Merging #1102 (1e6a675) into master (1db710e) will decrease coverage by 0.07%.
The diff coverage is n/a.

❗ Current head 1e6a675 differs from pull request most recent head 7e916ad. Consider uploading reports for the commit 7e916ad to get more accurate results

@@            Coverage Diff             @@
##           master    #1102      +/-   ##
==========================================
- Coverage   94.39%   94.31%   -0.08%     
==========================================
  Files          51       51              
  Lines        5193     5193              
==========================================
- Hits         4902     4898       -4     
- Misses        291      295       +4     

Flag	Coverage Δ
tests_clang_debug_cpp17	93.85% <ø> (-0.03%)	⬇️
tests_gcc_debug	91.82% <ø> (-0.11%)	⬇️

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Impacted Files	Coverage Δ
...libpmemobj++/detail/enumerable_thread_specific.hpp	98.91% <0.00%> (-1.09%)	⬇️
include/libpmemobj++/transaction.hpp	79.83% <0.00%> (-0.81%)	⬇️
...ude/libpmemobj++/container/concurrent_hash_map.hpp	94.20% <0.00%> (-0.32%)	⬇️

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[lukaszstolarczuk]

this looks good! thanks for this change

Reviewable status: all files reviewed, 3 unresolved discussions (waiting on @michalbiesek)

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CMakeLists.txt, line 157 at r1 (raw file):

endif()

# Find Clang

with this approach, we don't even need this status printing, I believe.

The current compiler is checked at the beginning of the CMake execution, e.g.:

-- The CXX compiler identification is Clang 9.0.1
-- Check for working CXX compiler: /usr/bin/clang++-9
-- Check for working CXX compiler: /usr/bin/clang++-9 -- works

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tests/ctest_helpers.cmake, line 142 at r1 (raw file):

function(build_test_atomic name)
	build_test(${name} ${ARGN})
	if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")

what about CMAKE_C_COMPILER_ID ?

we have some check in/tests/CMakeLists.txt file for GNU, and we check both variables...

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tests/ctest_helpers.cmake, line 142 at r1 (raw file):

function(build_test_atomic name)
	build_test(${name} ${ARGN})
	if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang")

how about MATCHES instead of STREQUAL...?

[michalbiesek]

Reviewable status: 0 of 2 files reviewed, 1 unresolved discussion (waiting on @igchor and @lukaszstolarczuk)

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CMakeLists.txt, line 157 at r1 (raw file):

Previously, lukaszstolarczuk (Łukasz Stolarczuk) wrote…

with this approach, we don't even need this status printing, I believe.

The current compiler is checked at the beginning of the CMake execution, e.g.:

-- The CXX compiler identification is Clang 9.0.1
-- Check for working CXX compiler: /usr/bin/clang++-9
-- Check for working CXX compiler: /usr/bin/clang++-9 -- works

Done (removed)

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tests/ctest_helpers.cmake, line 142 at r1 (raw file):

Previously, lukaszstolarczuk (Łukasz Stolarczuk) wrote…

how about MATCHES instead of STREQUAL...?

Done.

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tests/ctest_helpers.cmake, line 142 at r1 (raw file):

Previously, lukaszstolarczuk (Łukasz Stolarczuk) wrote…

what about CMAKE_C_COMPILER_ID ?

we have some check in/tests/CMakeLists.txt file for GNU, and we check both variables...

Done - out of curiosity can you give me the use case where you set the "C compiler" and for the CPP as a different one e.g. Clang for C and GCC for C++

[lukaszstolarczuk]

Reviewed 2 of 2 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @michalbiesek)

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tests/ctest_helpers.cmake, line 142 at r1 (raw file):

Previously, michalbiesek wrote…

Done - out of curiosity can you give me the use case where you set the "C compiler" and for the CPP as a different one e.g. Clang for C and GCC for C++

yeah, there's probably none, that's why it was more of an open question (rather than a blocking issue). Thx for updating