Add COVERAGE cmake flag for clang.

This only works with clang/llvm. Coveralls support needs to be added later.

CMakeLists.txt

@@ -89,6 +89,12 @@ if(NOT MSVC)
     add_flag("-Werror")
   endif()
 
+  option(COVERAGE "Track code coverage" OFF)
+  if(COVERAGE)
+    add_flag("-fprofile-instr-generate")
+    add_flag("-fcoverage-mapping")
+  endif()
+
   option(DEBUG "Enable assertions and other debugging facilities" OFF)
   if(DEBUG)
     set(MIN_LOGGER_LEVEL DEBUG)
@@ -457,6 +463,7 @@ function(auto_test target)
     if(NOT ARGV1 STREQUAL "DONT_RUN")
       add_test(NAME ${target} COMMAND ${CROSSCOMPILING_EMULATOR} auto_${target}_test)
       set_tests_properties(${target} PROPERTIES TIMEOUT "${TEST_TIMEOUT_SECONDS}")
+      set_property(TEST ${target} PROPERTY ENVIRONMENT "LLVM_PROFILE_FILE=${target}.profraw")
     endif()
   endif()
 endfunction()

cmake/CompileGTest.cmake

@@ -54,5 +54,6 @@ function(unit_test subdir target)
     target_link_modules(unit_${target}_test toxcore gtest)
     set_target_properties(unit_${target}_test PROPERTIES COMPILE_FLAGS "${TEST_CXX_FLAGS}")
     add_test(NAME ${target} COMMAND ${CROSSCOMPILING_EMULATOR} unit_${target}_test)
+    set_property(TEST ${target} PROPERTY ENVIRONMENT "LLVM_PROFILE_FILE=${target}.profraw")
   endif()
 endfunction()