From 39be8a9d191410ad7dfe4ec033d7e91f55a71cf6 Mon Sep 17 00:00:00 2001 From: Brad King Date: Mon, 11 Sep 2017 14:55:36 -0400 Subject: MSVC: Avoid unnecessary C++ feature detection steps Since commit v3.9.0-rc1~17^2~4 (Compilers: Port to use default cmake_record_lang_compile_features macros, 2017-05-10) we run full per-language-standard feature detection for MSVC. This is not necessary because the base mode for MSVC has all features we define except for the meta-features for C++14 and above. Override the default C++ feature detection macro for MSVC to run detection only once as before. Fixes: #17274 --- Modules/Compiler/MSVC-CXX.cmake | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/Modules/Compiler/MSVC-CXX.cmake b/Modules/Compiler/MSVC-CXX.cmake index 3a63e3f..789fff5 100644 --- a/Modules/Compiler/MSVC-CXX.cmake +++ b/Modules/Compiler/MSVC-CXX.cmake @@ -24,6 +24,16 @@ if ((CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 19.0.24215.1 AND endif() __compiler_check_default_language_standard(CXX 19.0 14) + + # All features that we define are available in the base mode, except + # for meta-features for C++14 and above. Override the default macro + # to avoid doing unnecessary work. + macro(cmake_record_cxx_compile_features) + list(APPEND CMAKE_CXX17_COMPILE_FEATURES cxx_std_17) + list(APPEND CMAKE_CXX14_COMPILE_FEATURES cxx_std_14) + list(APPEND CMAKE_CXX98_COMPILE_FEATURES cxx_std_11) # no flag needed for 11 + _record_compiler_features_cxx(98) + endmacro() elseif (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 16.0) # MSVC has no specific options to set language standards, but set them as # empty strings anyways so the feature test infrastructure can at least check @@ -39,4 +49,18 @@ elseif (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 16.0) # There is no meaningful default for this set(CMAKE_CXX_STANDARD_DEFAULT "") + + # There are no compiler modes so we only need to test features once. + # Override the default macro for this special case. Pretend that + # all language standards are available so that at least compilation + # can be attempted. + macro(cmake_record_cxx_compile_features) + list(APPEND CMAKE_CXX_COMPILE_FEATURES + cxx_std_98 + cxx_std_11 + cxx_std_14 + cxx_std_17 + ) + _record_compiler_features(CXX "" CMAKE_CXX_COMPILE_FEATURES) + endmacro() endif() -- cgit v0.12