diff --git a/CMakeLists.txt b/CMakeLists.txt index c31f14ef11..424689f89f 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -33,8 +33,16 @@ include(FetchContent) include(FindPkgConfig) include(AvifExternalProjectUtils) +option(AVIF_ENABLE_NODISCARD "Add [[nodiscard]] to some functions. CMake must be at least 3.21 to request C23." OFF) + # Set C99 as the default -set(CMAKE_C_STANDARD 99) +if(AVIF_ENABLE_NODISCARD AND CMAKE_VERSION VERSION_GREATER_EQUAL 3.21.0) + # [[nodiscard]] requires C23. The supported value 23 for CMAKE_C_STANDARD + # was added in CMake version 3.21. + set(CMAKE_C_STANDARD 23) +else() + set(CMAKE_C_STANDARD 99) +endif() # SOVERSION scheme: MAJOR.MINOR.PATCH # If there was an incompatible interface change: @@ -52,7 +60,6 @@ set(LIBRARY_SOVERSION ${LIBRARY_VERSION_MAJOR}) option(BUILD_SHARED_LIBS "Build shared avif library" ON) option(AVIF_ENABLE_WERROR "Treat all compiler warnings as errors" OFF) -option(AVIF_ENABLE_NODISCARD "Add [[nodiscard]] to some functions. CMake must be at least 3.21 to force C23" OFF) option(AVIF_ENABLE_EXPERIMENTAL_YCGCO_R "Enable experimental YCgCo-R matrix code" OFF) option(AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP @@ -334,22 +341,6 @@ endif() target_link_libraries(avif_obj PRIVATE avif_enable_warnings) -if(AVIF_ENABLE_NODISCARD) - if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.21.0) - set(CMAKE_C_STANDARD 23) - set_property(TARGET avif_obj PROPERTY C_STANDARD 23) - else() - unset(CMAKE_C_STANDARD) - set_property(TARGET avif_obj PROPERTY C_STANDARD) - if(CMAKE_C_COMPILER_ID MATCHES "Clang" OR CMAKE_C_COMPILER_ID MATCHES "GNU") - target_compile_options(avif_obj PUBLIC $:-std=gnu2x>>) - elseif(CMAKE_C_COMPILER_ID MATCHES "MSVC") - target_compile_options(avif_obj PUBLIC $:/std:clatest>>) - endif() - endif() - target_compile_definitions(avif_obj PUBLIC $) -endif() - if(AVIF_ENABLE_COVERAGE) if(CMAKE_C_COMPILER_ID MATCHES "Clang" OR CMAKE_C_COMPILER_ID MATCHES "GNU") message(STATUS "libavif: Enabling coverage for Clang") @@ -592,6 +583,7 @@ if(AVIF_LIB_USE_CXX OR (AVIF_BUILD_APPS AND AVIF_ENABLE_EXPERIMENTAL_GAIN_MAP) O ) enable_language(CXX) if(AVIF_ENABLE_NODISCARD) + # [[nodiscard]] requires C++17. set(CMAKE_CXX_STANDARD 17) else() set(CMAKE_CXX_STANDARD 14) diff --git a/include/avif/avif.h b/include/avif/avif.h index 25e16f6639..91b719d138 100644 --- a/include/avif/avif.h +++ b/include/avif/avif.h @@ -48,8 +48,7 @@ extern "C" { #define AVIF_API #endif // defined(AVIF_DLL) -#if defined(AVIF_ENABLE_NODISCARD) || (defined(__cplusplus) && __cplusplus >= 201703L) || \ - (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) +#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L) #define AVIF_NODISCARD [[nodiscard]] #else // Starting with 3.9, clang allows defining the warn_unused_result attribute for enums.