Revert "Remove some try_compile CMake checks for compiler flags (llvm#92953)"

This reverts commit 4feae05.

Author: Endilll

clang/CMakeLists.txt

@@ -350,7 +350,10 @@ if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -pedantic -Wno-long-long")
   endif ()
 
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-nested-anon-types" )
+  check_cxx_compiler_flag("-Werror -Wnested-anon-types" CXX_SUPPORTS_NO_NESTED_ANON_TYPES_FLAG)
+  if( CXX_SUPPORTS_NO_NESTED_ANON_TYPES_FLAG )
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-nested-anon-types" )
+  endif()
 endif ()
 
 # Determine HOST_LINK_VERSION on Darwin.

clang/tools/scan-build-py/tests/functional/exec/CMakeLists.txt

@@ -2,7 +2,11 @@ project(exec C)
 
 cmake_minimum_required(VERSION 3.20.0)
 
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
+include(CheckCCompilerFlag)
+check_c_compiler_flag("-std=c99" C99_SUPPORTED)
+if (C99_SUPPORTED)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
+endif()
 
 include(CheckFunctionExists)
 include(CheckSymbolExists)

lldb/cmake/modules/LLDBConfig.cmake

@@ -187,18 +187,24 @@ include_directories("${CMAKE_CURRENT_BINARY_DIR}/../clang/include")
 # form -W<foo>, and if supported, add the corresponding -Wno-<foo> option.
 
 # Disable GCC warnings
-append("-Wno-deprecated-declarations" CMAKE_CXX_FLAGS)
-append("-Wno-unknown-pragmas" CMAKE_CXX_FLAGS)
-append("-Wno-strict-aliasing" CMAKE_CXX_FLAGS)
+check_cxx_compiler_flag("-Wdeprecated-declarations" CXX_SUPPORTS_DEPRECATED_DECLARATIONS)
+append_if(CXX_SUPPORTS_DEPRECATED_DECLARATIONS "-Wno-deprecated-declarations" CMAKE_CXX_FLAGS)
+
+check_cxx_compiler_flag("-Wunknown-pragmas" CXX_SUPPORTS_UNKNOWN_PRAGMAS)
+append_if(CXX_SUPPORTS_UNKNOWN_PRAGMAS "-Wno-unknown-pragmas" CMAKE_CXX_FLAGS)
+
+check_cxx_compiler_flag("-Wstrict-aliasing" CXX_SUPPORTS_STRICT_ALIASING)
+append_if(CXX_SUPPORTS_STRICT_ALIASING "-Wno-strict-aliasing" CMAKE_CXX_FLAGS)
 
 check_cxx_compiler_flag("-Wstringop-truncation" CXX_SUPPORTS_STRINGOP_TRUNCATION)
 append_if(CXX_SUPPORTS_STRINGOP_TRUNCATION "-Wno-stringop-truncation" CMAKE_CXX_FLAGS)
 
 # Disable Clang warnings
-if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  append("-Wno-deprecated-register" CMAKE_CXX_FLAGS)
-  append("-Wno-vla-extension" CMAKE_CXX_FLAGS)
-endif()
+check_cxx_compiler_flag("-Wdeprecated-register" CXX_SUPPORTS_DEPRECATED_REGISTER)
+append_if(CXX_SUPPORTS_DEPRECATED_REGISTER "-Wno-deprecated-register" CMAKE_CXX_FLAGS)
+
+check_cxx_compiler_flag("-Wvla-extension" CXX_SUPPORTS_VLA_EXTENSION)
+append_if(CXX_SUPPORTS_VLA_EXTENSION "-Wno-vla-extension" CMAKE_CXX_FLAGS)
 
 # Disable MSVC warnings
 if( MSVC )

llvm/cmake/config-ix.cmake

@@ -426,18 +426,15 @@ if( LLVM_ENABLE_PIC )
   set(ENABLE_PIC 1)
 else()
   set(ENABLE_PIC 0)
-  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -fno-pie")
+  check_cxx_compiler_flag("-fno-pie" SUPPORTS_NO_PIE_FLAG)
+  if(SUPPORTS_NO_PIE_FLAG)
+    set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -fno-pie")
+  endif()
 endif()
 
-set(SUPPORTS_VARIADIC_MACROS_FLAG 0)
-if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
-  set(SUPPORTS_VARIADIC_MACROS_FLAG 1)
-endif()
-if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  set(SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG 1)
-else()
-  set(SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG 0)
-endif()
+check_cxx_compiler_flag("-Wvariadic-macros" SUPPORTS_VARIADIC_MACROS_FLAG)
+check_cxx_compiler_flag("-Wgnu-zero-variadic-macro-arguments"
+                        SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG)
 
 set(USE_NO_MAYBE_UNINITIALIZED 0)
 set(USE_NO_UNINITIALIZED 0)
@@ -447,9 +444,11 @@ set(USE_NO_UNINITIALIZED 0)
 if (CMAKE_COMPILER_IS_GNUCXX)
   # Disable all -Wuninitialized warning for old GCC versions.
   if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS 12.0)
-    set(USE_NO_UNINITIALIZED 1)
+    check_cxx_compiler_flag("-Wuninitialized" HAS_UNINITIALIZED)
+    set(USE_NO_UNINITIALIZED ${HAS_UNINITIALIZED})
   else()
-    set(USE_NO_MAYBE_UNINITIALIZED 1)
+    check_cxx_compiler_flag("-Wmaybe-uninitialized" HAS_MAYBE_UNINITIALIZED)
+    set(USE_NO_MAYBE_UNINITIALIZED ${HAS_MAYBE_UNINITIALIZED})
   endif()
 endif()
 

llvm/cmake/modules/AddLLVM.cmake

@@ -276,11 +276,11 @@ if (NOT DEFINED LLVM_LINKER_DETECTED AND NOT WIN32)
 
   if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
     include(CheckLinkerFlag)
-    # Linkers that support Darwin allow a setting to internalize all symbol exports,
+    # Linkers that support Darwin allow a setting to internalize all symbol exports, 
     # aiding in reducing binary size and often is applicable for executables.
     check_linker_flag(C "-Wl,-no_exported_symbols" LLVM_LINKER_SUPPORTS_NO_EXPORTED_SYMBOLS)
-
-    if (NOT LLVM_USE_LINKER)
+    
+    if (NOT LLVM_USE_LINKER) 
       # Apple's linker complains about duplicate libraries, which CMake likes to do
       # to support ELF platforms. To silence that warning, we can use
       # -no_warn_duplicate_libraries, but only in versions of the linker that
@@ -289,8 +289,8 @@ if (NOT DEFINED LLVM_LINKER_DETECTED AND NOT WIN32)
     else()
       set(LLVM_LINKER_SUPPORTS_NO_WARN_DUPLICATE_LIBRARIES OFF CACHE INTERNAL "")
     endif()
-
-  else()
+  
+  else() 
     set(LLVM_LINKER_SUPPORTS_NO_EXPORTED_SYMBOLS OFF CACHE INTERNAL "")
   endif()
 endif()
@@ -1069,7 +1069,7 @@ macro(add_llvm_executable name)
     add_llvm_symbol_exports( ${name} ${LLVM_EXPORTED_SYMBOL_FILE} )
   endif(LLVM_EXPORTED_SYMBOL_FILE)
 
-  if (DEFINED LLVM_ENABLE_EXPORTED_SYMBOLS_IN_EXECUTABLES AND
+  if (DEFINED LLVM_ENABLE_EXPORTED_SYMBOLS_IN_EXECUTABLES AND 
       NOT LLVM_ENABLE_EXPORTED_SYMBOLS_IN_EXECUTABLES)
     if(LLVM_LINKER_SUPPORTS_NO_EXPORTED_SYMBOLS)
       set_property(TARGET ${name} APPEND_STRING PROPERTY
@@ -1677,7 +1677,7 @@ function(add_unittest test_suite test_name)
 
   if (SUPPORTS_VARIADIC_MACROS_FLAG)
     list(APPEND LLVM_COMPILE_FLAGS "-Wno-variadic-macros")
-  endif()
+  endif ()
   # Some parts of gtest rely on this GNU extension, don't warn on it.
   if(SUPPORTS_GNU_ZERO_VARIADIC_MACRO_ARGUMENTS_FLAG)
     list(APPEND LLVM_COMPILE_FLAGS "-Wno-gnu-zero-variadic-macro-arguments")