cmake: new option to enable compilations with coverage flags

Note that this will only work with gcc and clang.

CMakeLists.txt

@@ -64,6 +64,7 @@ mark_as_advanced(
 )
 
 option( BUILD_WITH_CCACHE             "Use ccache to speed up compilations"                   OFF )
+option( BUILD_WITH_COVERAGE           "Add compiler flags to generate coverage stats"         OFF )
 
 if ( EXIV2_ENABLE_WEBREADY )
     set ( EXIV2_ENABLE_CURL ON )

cmake/compilerFlags.cmake

@@ -19,6 +19,15 @@ if ( MINGW OR UNIX ) # MINGW, Linux, APPLE, CYGWIN
     endif()
 
     if (COMPILER_IS_GCC OR COMPILER_IS_CLANG)
+
+        if(BUILD_WITH_COVERAGE)
+            set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g ")
+            set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O0")
+            set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fprofile-arcs")
+            set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ftest-coverage")
+            set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} --coverage")
+        endif()
+
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wcast-align -Wpointer-arith -Wformat-security -Wmissing-format-attribute -Woverloaded-virtual -W")
 
         if ( CYGWIN OR (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER 5.0))

cmake/printSummary.cmake

@@ -63,6 +63,7 @@ OptionOutput( "Building samples:                   " EXIV2_BUILD_SAMPLES
 OptionOutput( "Building PO files:                  " EXIV2_BUILD_PO                  )
 OptionOutput( "Building unit tests:                " EXIV2_BUILD_UNIT_TESTS          )
 OptionOutput( "Building doc:                       " EXIV2_BUILD_DOC                 )
+OptionOutput( "Building with coverage flags:       " BUILD_WITH_COVERAGE             )
 OptionOutput( "Using ccache:                       " BUILD_WITH_CCACHE               )