build(Linux): use compiler-selected libgcov for coverage (#5597)

packaging/linux/Arch/PKGBUILD

@@ -191,7 +191,9 @@ check() {
       export CXX="g++${_gcc_env_suffix}"
 
       cd "${srcdir}/build/tests"
-      ./test_sunshine --gtest_color=yes --gtest_output=xml:test_results.xml
+      # Do not silently upload misleading coverage if the gcov runtime cannot
+      # write profile data, such as when its version differs from the compiler.
+      GCOV_EXIT_AT_ERROR=1 ./test_sunshine --gtest_color=yes --gtest_output=xml:test_results.xml
 
       # Generate coverage report
       # Run gcovr from the build directory (where all .gcda/.gcno files are)

tests/CMakeLists.txt

@@ -34,42 +34,23 @@ else()
     set(CMAKE_C_FLAGS "-fprofile-arcs -ftest-coverage -ggdb -O0")
 endif()
 
-# Find the correct libgcov library path matching the gcc compiler version
-# This ensures the test executable links against the same libgcov version used during compilation
-if(UNIX AND NOT APPLE)
-    # Get the gcc compiler version
+# Link the libgcov that belongs to the selected compiler. Asking GCC directly
+# avoids selecting another installed GCC version through platform-specific
+# library directory names (for example, the GCC required by CUDA on Arch Linux).
+if(UNIX AND NOT APPLE AND CMAKE_C_COMPILER_ID STREQUAL "GNU")
     execute_process(
-        COMMAND ${CMAKE_C_COMPILER} -dumpversion
-        OUTPUT_VARIABLE GCC_VERSION
+        COMMAND ${CMAKE_C_COMPILER} -print-file-name=libgcov.a
+        OUTPUT_VARIABLE LIBGCOV_LIBRARY
         OUTPUT_STRIP_TRAILING_WHITESPACE
+        RESULT_VARIABLE LIBGCOV_RESULT
     )
 
-    # Extract major version
-    string(REGEX MATCH "^[0-9]+" GCC_MAJOR_VERSION "${GCC_VERSION}")
-
-    # Search for the gcc library directory matching this version
-    file(GLOB GCC_LIB_DIRS "/usr/lib/gcc/*/*${GCC_MAJOR_VERSION}.*")
-
-    if(GCC_LIB_DIRS)
-        list(GET GCC_LIB_DIRS 0 GCC_LIB_DIR)
-        message(STATUS "Found GCC library directory: ${GCC_LIB_DIR}")
-
-        # Look for libgcov.a in the gcc library directory
-        find_library(LIBGCOV_LIBRARY
-            NAMES gcov
-            PATHS ${GCC_LIB_DIR}
-            NO_DEFAULT_PATH
-        )
-
-        if(LIBGCOV_LIBRARY)
-            message(STATUS "Found libgcov: ${LIBGCOV_LIBRARY}")
-            # Store this to link against later
-            set(GCOV_LINK_LIBRARY ${LIBGCOV_LIBRARY})
-        else()
-            message(WARNING "Could not find libgcov in ${GCC_LIB_DIR}")
-        endif()
+    if(LIBGCOV_RESULT EQUAL 0 AND EXISTS "${LIBGCOV_LIBRARY}")
+        message(STATUS "Found libgcov: ${LIBGCOV_LIBRARY}")
+        set(GCOV_LINK_LIBRARY "${LIBGCOV_LIBRARY}")
     else()
-        message(WARNING "Could not find GCC library directory for version ${GCC_VERSION}")
+        message(WARNING "Could not find libgcov for ${CMAKE_C_COMPILER}")
+        unset(GCOV_LINK_LIBRARY)
     endif()
 endif()