Add compilation and running test for C++20 to GCC and Clang (nonstd-l…

…ite-project issue 64)

martinmoene/nonstd-lite-project#64

Also, use toplevel unit_name and enable_testing().

test/CMakeLists.txt

@@ -1,4 +1,4 @@
-# Copyright 2020 by Martin Moene
+# Copyright 2020-2022 by Martin Moene
 #
 # https://github.com/martinmoene/bit-lite
 #
@@ -11,10 +11,11 @@ endif()
 
 project( test LANGUAGES CXX )
 
-set( unit_name "bit" )
+# unit_name provided by toplevel CMakeLists.txt [set( unit_name "xxx" )]
 set( PACKAGE   ${unit_name}-lite )
 set( PROGRAM   ${unit_name}-lite )
 set( SOURCES   ${unit_name}-main.t.cpp ${unit_name}.t.cpp )
+set( TWEAKD    "." )
 
 message( STATUS "Subproject '${PROJECT_NAME}', programs '${PROGRAM}-*'")
 
@@ -69,6 +70,9 @@ elseif( CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang|AppleClang" )
         if( NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 7.1.0 )
             set( HAS_CPP17_FLAG TRUE )
         endif()
+        if( NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 10.0.0 )
+            set( HAS_CPP20_FLAG TRUE )
+        endif()
 
     # AppleClang: available -std flags depends on version
     elseif( CMAKE_CXX_COMPILER_ID MATCHES "AppleClang" )
@@ -83,6 +87,9 @@ elseif( CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang|AppleClang" )
         if( NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.2.0 )
             set( HAS_CPP17_FLAG TRUE )
         endif()
+        # if( NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS x.x.x )
+        #     set( HAS_CPP20_FLAG TRUE )
+        # endif()
 
     # Clang: available -std flags depends on version
     elseif( CMAKE_CXX_COMPILER_ID MATCHES "Clang" )
@@ -97,6 +104,9 @@ elseif( CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang|AppleClang" )
         if( NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.0.0 )
             set( HAS_CPP17_FLAG TRUE )
         endif()
+        if( NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 10.0.0 )
+            set( HAS_CPP20_FLAG TRUE )
+        endif()
     endif()
 
 elseif( CMAKE_CXX_COMPILER_ID MATCHES "Intel" )
@@ -125,6 +135,7 @@ function( make_target target std )
 
     add_executable            ( ${target} ${SOURCES} )
     target_include_directories( ${target} SYSTEM  PRIVATE lest )
+    target_include_directories( ${target} PRIVATE ${TWEAKD} )
     target_link_libraries     ( ${target} PRIVATE ${PACKAGE} )
     target_compile_options    ( ${target} PRIVATE ${OPTIONS} )
     target_compile_definitions( ${target} PRIVATE ${DEFINITIONS} )
@@ -172,6 +183,10 @@ else()
         enable_msvs_guideline_checker( ${PROGRAM}-cpp17.t )
     endif()
 
+    if( HAS_CPP20_FLAG )
+        make_target( ${PROGRAM}-cpp20.t 20 )
+    endif()
+
     if( HAS_CPPLATEST_FLAG )
         make_target( ${PROGRAM}-cpplatest.t latest )
     endif()
@@ -197,8 +212,6 @@ endif()
 
 # configure unit tests via CTest:
 
-enable_testing()
-
 if( HAS_STD_FLAGS )
     # unconditionally add C++98 variant for MSVC:
     add_test(     NAME test-cpp98     COMMAND ${PROGRAM}-cpp98.t )
@@ -212,6 +225,9 @@ if( HAS_STD_FLAGS )
     if( HAS_CPP17_FLAG )
         add_test( NAME test-cpp17     COMMAND ${PROGRAM}-cpp17.t )
     endif()
+    if( HAS_CPP20_FLAG )
+        add_test( NAME test-cpp20     COMMAND ${PROGRAM}-cpp20.t )
+    endif()
     if( HAS_CPPLATEST_FLAG )
         add_test( NAME test-cpplatest COMMAND ${PROGRAM}-cpplatest.t )
     endif()