19 files changed, 121 insertions, 41 deletions
diff --git a/Modules/CMakeCCompiler.cmake.in b/Modules/CMakeCCompiler.cmake.in
index 6818381..2b24ff2 100644
--- a/Modules/CMakeCCompiler.cmake.in
+++ b/Modules/CMakeCCompiler.cmake.in
@@ -5,6 +5,7 @@ set(CMAKE_C_COMPILER_VERSION "@CMAKE_C_COMPILER_VERSION@")
 set(CMAKE_C_COMPILER_VERSION_INTERNAL "@CMAKE_C_COMPILER_VERSION_INTERNAL@")
 set(CMAKE_C_COMPILER_WRAPPER "@CMAKE_C_COMPILER_WRAPPER@")
 set(CMAKE_C_STANDARD_COMPUTED_DEFAULT "@CMAKE_C_STANDARD_COMPUTED_DEFAULT@")
+set(CMAKE_C_EXTENSIONS_COMPUTED_DEFAULT "@CMAKE_C_EXTENSIONS_COMPUTED_DEFAULT@")
 set(CMAKE_C_COMPILE_FEATURES "@CMAKE_C_COMPILE_FEATURES@")
 set(CMAKE_C90_COMPILE_FEATURES "@CMAKE_C90_COMPILE_FEATURES@")
 set(CMAKE_C99_COMPILE_FEATURES "@CMAKE_C99_COMPILE_FEATURES@")
diff --git a/Modules/CMakeCCompilerId.c.in b/Modules/CMakeCCompilerId.c.in
index 1f19c00..43ede3e 100644
--- a/Modules/CMakeCCompilerId.c.in
+++ b/Modules/CMakeCCompilerId.c.in
@@ -41,23 +41,34 @@ char const *info_cray = "INFO" ":" "compiler_wrapper[CrayPrgEnv]";
 
 #if !defined(__STDC__) && !defined(__clang__)
 # if defined(_MSC_VER) || defined(__ibmxl__) || defined(__IBMC__)
-#  define C_DIALECT "90"
+#  define C_VERSION "90"
 # else
-#  define C_DIALECT
+#  define C_VERSION
 # endif
 #elif __STDC_VERSION__ > 201710L
-# define C_DIALECT "23"
+# define C_VERSION "23"
 #elif __STDC_VERSION__ >= 201710L
-# define C_DIALECT "17"
+# define C_VERSION "17"
 #elif __STDC_VERSION__ >= 201000L
-# define C_DIALECT "11"
+# define C_VERSION "11"
 #elif __STDC_VERSION__ >= 199901L
-# define C_DIALECT "99"
+# define C_VERSION "99"
 #else
-# define C_DIALECT "90"
+# define C_VERSION "90"
 #endif
-const char* info_language_dialect_default =
-  "INFO" ":" "dialect_default[" C_DIALECT "]";
+const char* info_language_standard_default =
+  "INFO" ":" "standard_default[" C_VERSION "]";
+
+const char* info_language_extensions_default = "INFO" ":" "extensions_default["
+// !defined(_MSC_VER) to exclude Clang's MSVC compatibility mode.
+#if (defined(__clang__) || defined(__GNUC__) ||                               \
+     defined(__TI_COMPILER_VERSION__)) &&                                     \
+  !defined(__STRICT_ANSI__) && !defined(_MSC_VER)
+  "ON"
+#else
+  "OFF"
+#endif
+"]";
 
 /*--------------------------------------------------------------------------*/
 
@@ -89,7 +100,8 @@ int main(int argc, char* argv[])
 #if defined(__CRAYXT_COMPUTE_LINUX_TARGET)
   require += info_cray[argc];
 #endif
-  require += info_language_dialect_default[argc];
+  require += info_language_standard_default[argc];
+  require += info_language_extensions_default[argc];
   (void)argv;
   return require;
 }
diff --git a/Modules/CMakeCUDACompiler.cmake.in b/Modules/CMakeCUDACompiler.cmake.in
index 56ae732..2f3e9a8 100644
--- a/Modules/CMakeCUDACompiler.cmake.in
+++ b/Modules/CMakeCUDACompiler.cmake.in
@@ -6,6 +6,7 @@ set(CMAKE_CUDA_COMPILER_VERSION "@CMAKE_CUDA_COMPILER_VERSION@")
 set(CMAKE_CUDA_DEVICE_LINKER "@CMAKE_CUDA_DEVICE_LINKER@")
 set(CMAKE_CUDA_FATBINARY "@CMAKE_CUDA_FATBINARY@")
 set(CMAKE_CUDA_STANDARD_COMPUTED_DEFAULT "@CMAKE_CUDA_STANDARD_COMPUTED_DEFAULT@")
+set(CMAKE_CUDA_EXTENSIONS_COMPUTED_DEFAULT "@CMAKE_CUDA_EXTENSIONS_COMPUTED_DEFAULT@")
 set(CMAKE_CUDA_COMPILE_FEATURES "@CMAKE_CUDA_COMPILE_FEATURES@")
 set(CMAKE_CUDA03_COMPILE_FEATURES "@CMAKE_CUDA03_COMPILE_FEATURES@")
 set(CMAKE_CUDA11_COMPILE_FEATURES "@CMAKE_CUDA11_COMPILE_FEATURES@")
diff --git a/Modules/CMakeCUDACompilerId.cu.in b/Modules/CMakeCUDACompilerId.cu.in
index 91039e5..bc685a7 100644
--- a/Modules/CMakeCUDACompilerId.cu.in
+++ b/Modules/CMakeCUDACompilerId.cu.in
@@ -16,7 +16,7 @@ char const* info_simulate = "INFO" ":" "simulate[" SIMULATE_ID "]";
 @CMAKE_CUDA_COMPILER_ID_PLATFORM_CONTENT@
 @CMAKE_CUDA_COMPILER_ID_ERROR_FOR_TEST@
 
-const char* info_language_dialect_default = "INFO" ":" "dialect_default["
+const char* info_language_standard_default = "INFO" ":" "standard_default["
 #if __cplusplus > 202002L
   "23"
 #elif __cplusplus > 201703L
@@ -32,6 +32,16 @@ const char* info_language_dialect_default = "INFO" ":" "dialect_default["
 #endif
 "]";
 
+const char* info_language_extensions_default = "INFO" ":" "extensions_default["
+// !defined(_MSC_VER) to exclude Clang's MSVC compatibility mode.
+#if (defined(__clang__) || defined(__GNUC__)) && !defined(__STRICT_ANSI__) && \
+  !defined(_MSC_VER)
+  "ON"
+#else
+  "OFF"
+#endif
+"]";
+
 /*--------------------------------------------------------------------------*/
 
 int main(int argc, char* argv[])
@@ -48,7 +58,8 @@ int main(int argc, char* argv[])
 #ifdef SIMULATE_VERSION_MAJOR
   require += info_simulate_version[argc];
 #endif
-  require += info_language_dialect_default[argc];
+  require += info_language_standard_default[argc];
+  require += info_language_extensions_default[argc];
   (void)argv;
   return require;
 }
diff --git a/Modules/CMakeCXXCompiler.cmake.in b/Modules/CMakeCXXCompiler.cmake.in
index 7aad9e2..534e960 100644
--- a/Modules/CMakeCXXCompiler.cmake.in
+++ b/Modules/CMakeCXXCompiler.cmake.in
@@ -5,6 +5,7 @@ set(CMAKE_CXX_COMPILER_VERSION "@CMAKE_CXX_COMPILER_VERSION@")
 set(CMAKE_CXX_COMPILER_VERSION_INTERNAL "@CMAKE_CXX_COMPILER_VERSION_INTERNAL@")
 set(CMAKE_CXX_COMPILER_WRAPPER "@CMAKE_CXX_COMPILER_WRAPPER@")
 set(CMAKE_CXX_STANDARD_COMPUTED_DEFAULT "@CMAKE_CXX_STANDARD_COMPUTED_DEFAULT@")
+set(CMAKE_CXX_EXTENSIONS_COMPUTED_DEFAULT "@CMAKE_CXX_EXTENSIONS_COMPUTED_DEFAULT@")
 set(CMAKE_CXX_COMPILE_FEATURES "@CMAKE_CXX_COMPILE_FEATURES@")
 set(CMAKE_CXX98_COMPILE_FEATURES "@CMAKE_CXX98_COMPILE_FEATURES@")
 set(CMAKE_CXX11_COMPILE_FEATURES "@CMAKE_CXX11_COMPILE_FEATURES@")
diff --git a/Modules/CMakeCXXCompilerId.cpp.in b/Modules/CMakeCXXCompilerId.cpp.in
index 7362a08..cdf9c18 100644
--- a/Modules/CMakeCXXCompilerId.cpp.in
+++ b/Modules/CMakeCXXCompilerId.cpp.in
@@ -49,7 +49,7 @@ char const *info_cray = "INFO" ":" "compiler_wrapper[CrayPrgEnv]";
 #  define CXX_STD __cplusplus
 #endif
 
-const char* info_language_dialect_default = "INFO" ":" "dialect_default["
+const char* info_language_standard_default = "INFO" ":" "standard_default["
 #if CXX_STD > 202002L
   "23"
 #elif CXX_STD > 201703L
@@ -65,6 +65,17 @@ const char* info_language_dialect_default = "INFO" ":" "dialect_default["
 #endif
 "]";
 
+const char* info_language_extensions_default = "INFO" ":" "extensions_default["
+// !defined(_MSC_VER) to exclude Clang's MSVC compatibility mode.
+#if (defined(__clang__) || defined(__GNUC__) ||                               \
+     defined(__TI_COMPILER_VERSION__)) &&                                     \
+  !defined(__STRICT_ANSI__) && !defined(_MSC_VER)
+  "ON"
+#else
+  "OFF"
+#endif
+"]";
+
 /*--------------------------------------------------------------------------*/
 
 int main(int argc, char* argv[])
@@ -87,7 +98,8 @@ int main(int argc, char* argv[])
 #if defined(__CRAYXT_COMPUTE_LINUX_TARGET)
   require += info_cray[argc];
 #endif
-  require += info_language_dialect_default[argc];
+  require += info_language_standard_default[argc];
+  require += info_language_extensions_default[argc];
   (void)argv;
   return require;
 }
diff --git a/Modules/CMakeDetermineCUDACompiler.cmake b/Modules/CMakeDetermineCUDACompiler.cmake
index 342425c..d06315e 100644
--- a/Modules/CMakeDetermineCUDACompiler.cmake
+++ b/Modules/CMakeDetermineCUDACompiler.cmake
@@ -441,9 +441,10 @@ elseif(CMAKE_CUDA_COMPILER_ID STREQUAL "NVIDIA")
       if("${_nvcc_output_line}" MATCHES "^ *nvlink")
         string(APPEND _nvcc_log "    ignoring nvlink line\n")
       elseif(_nvcc_libraries)
-        if("${_nvcc_output_line}" MATCHES "(@\"?tmp/a\\.exe\\.res\"?)")
+        if("${_nvcc_output_line}" MATCHES "(@\"?((tmp/)?a\\.exe\\.res)\"?)")
           set(_nvcc_link_res_arg "${CMAKE_MATCH_1}")
-          set(_nvcc_link_res "${CMAKE_PLATFORM_INFO_DIR}/CompilerIdCUDA/tmp/a.exe.res")
+          set(_nvcc_link_res_file "${CMAKE_MATCH_2}")
+          set(_nvcc_link_res "${CMAKE_PLATFORM_INFO_DIR}/CompilerIdCUDA/${_nvcc_link_res_file}")
           if(EXISTS "${_nvcc_link_res}")
             file(READ "${_nvcc_link_res}" _nvcc_link_res_content)
             string(REPLACE "${_nvcc_link_res_arg}" "${_nvcc_link_res_content}" _nvcc_output_line "${_nvcc_output_line}")
diff --git a/Modules/CMakeDetermineCompilerId.cmake b/Modules/CMakeDetermineCompilerId.cmake
index d54e2b0..b38de8a 100644
--- a/Modules/CMakeDetermineCompilerId.cmake
+++ b/Modules/CMakeDetermineCompilerId.cmake
@@ -267,6 +267,7 @@ function(CMAKE_DETERMINE_COMPILER_ID lang flagvar src)
   set(CMAKE_${lang}_SIMULATE_ID "${CMAKE_${lang}_SIMULATE_ID}" PARENT_SCOPE)
   set(CMAKE_${lang}_SIMULATE_VERSION "${CMAKE_${lang}_SIMULATE_VERSION}" PARENT_SCOPE)
   set(CMAKE_${lang}_STANDARD_COMPUTED_DEFAULT "${CMAKE_${lang}_STANDARD_COMPUTED_DEFAULT}" PARENT_SCOPE)
+  set(CMAKE_${lang}_EXTENSIONS_COMPUTED_DEFAULT "${CMAKE_${lang}_EXTENSIONS_COMPUTED_DEFAULT}" PARENT_SCOPE)
   set(CMAKE_${lang}_COMPILER_PRODUCED_OUTPUT "${COMPILER_${lang}_PRODUCED_OUTPUT}" PARENT_SCOPE)
   set(CMAKE_${lang}_COMPILER_PRODUCED_FILES "${COMPILER_${lang}_PRODUCED_FILES}" PARENT_SCOPE)
 endfunction()
@@ -881,9 +882,12 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
       if("${info}" MATCHES "INFO:qnxnto\\[\\]")
         set(COMPILER_QNXNTO 1)
       endif()
-      if("${info}" MATCHES "INFO:dialect_default\\[([^]\"]*)\\]")
+      if("${info}" MATCHES "INFO:standard_default\\[([^]\"]*)\\]")
         set(CMAKE_${lang}_STANDARD_COMPUTED_DEFAULT "${CMAKE_MATCH_1}")
       endif()
+      if("${info}" MATCHES "INFO:extensions_default\\[([^]\"]*)\\]")
+        set(CMAKE_${lang}_EXTENSIONS_COMPUTED_DEFAULT "${CMAKE_MATCH_1}")
+      endif()
     endforeach()
 
     # Construct compiler version from components if needed.
@@ -993,6 +997,7 @@ function(CMAKE_DETERMINE_COMPILER_ID_CHECK lang file)
   set(CMAKE_${lang}_SIMULATE_VERSION "${CMAKE_${lang}_SIMULATE_VERSION}" PARENT_SCOPE)
   set(COMPILER_QNXNTO "${COMPILER_QNXNTO}" PARENT_SCOPE)
   set(CMAKE_${lang}_STANDARD_COMPUTED_DEFAULT "${CMAKE_${lang}_STANDARD_COMPUTED_DEFAULT}" PARENT_SCOPE)
+  set(CMAKE_${lang}_EXTENSIONS_COMPUTED_DEFAULT "${CMAKE_${lang}_EXTENSIONS_COMPUTED_DEFAULT}" PARENT_SCOPE)
 endfunction()
 
 #-----------------------------------------------------------------------------
diff --git a/Modules/CMakeHIPCompiler.cmake.in b/Modules/CMakeHIPCompiler.cmake.in
index 17633a8..ce4e2cf 100644
--- a/Modules/CMakeHIPCompiler.cmake.in
+++ b/Modules/CMakeHIPCompiler.cmake.in
@@ -2,6 +2,7 @@ set(CMAKE_HIP_COMPILER "@CMAKE_HIP_COMPILER@")
 set(CMAKE_HIP_COMPILER_ID "@CMAKE_HIP_COMPILER_ID@")
 set(CMAKE_HIP_COMPILER_VERSION "@CMAKE_HIP_COMPILER_VERSION@")
 set(CMAKE_HIP_STANDARD_COMPUTED_DEFAULT "@CMAKE_HIP_STANDARD_COMPUTED_DEFAULT@")
+set(CMAKE_HIP_EXTENSIONS_COMPUTED_DEFAULT "@CMAKE_HIP_EXTENSIONS_COMPUTED_DEFAULT@")
 set(CMAKE_HIP_COMPILE_FEATURES "@CMAKE_HIP_COMPILE_FEATURES@")
 set(CMAKE_HIP98_COMPILE_FEATURES "@CMAKE_HIP03_COMPILE_FEATURES@")
 set(CMAKE_HIP11_COMPILE_FEATURES "@CMAKE_HIP11_COMPILE_FEATURES@")
diff --git a/Modules/CMakeHIPCompilerId.hip.in b/Modules/CMakeHIPCompilerId.hip.in
index 5258efb..3c4a1d4 100644
--- a/Modules/CMakeHIPCompilerId.hip.in
+++ b/Modules/CMakeHIPCompilerId.hip.in
@@ -16,7 +16,7 @@ char const* info_simulate = "INFO" ":" "simulate[" SIMULATE_ID "]";
 @CMAKE_HIP_COMPILER_ID_PLATFORM_CONTENT@
 @CMAKE_HIP_COMPILER_ID_ERROR_FOR_TEST@
 
-const char* info_language_dialect_default = "INFO" ":" "dialect_default["
+const char* info_language_standard_default = "INFO" ":" "standard_default["
 #if __cplusplus > 202002L
   "23"
 #elif __cplusplus > 201703L
@@ -32,6 +32,14 @@ const char* info_language_dialect_default = "INFO" ":" "dialect_default["
 #endif
 "]";
 
+const char* info_language_extensions_default = "INFO" ":" "extensions_default["
+#if (defined(__clang__) || defined(__GNUC__)) && !defined(__STRICT_ANSI__)
+  "ON"
+#else
+  "OFF"
+#endif
+"]";
+
 /*--------------------------------------------------------------------------*/
 
 int main(int argc, char* argv[])
@@ -48,7 +56,8 @@ int main(int argc, char* argv[])
 #ifdef SIMULATE_VERSION_MAJOR
   require += info_simulate_version[argc];
 #endif
-  require += info_language_dialect_default[argc];
+  require += info_language_standard_default[argc];
+  require += info_language_extensions_default[argc];
   (void)argv;
   return require;
 }
diff --git a/Modules/CMakeOBJCCompiler.cmake.in b/Modules/CMakeOBJCCompiler.cmake.in
index ab67bf3..36f6ec1 100644
--- a/Modules/CMakeOBJCCompiler.cmake.in
+++ b/Modules/CMakeOBJCCompiler.cmake.in
@@ -5,6 +5,7 @@ set(CMAKE_OBJC_COMPILER_VERSION "@CMAKE_OBJC_COMPILER_VERSION@")
 set(CMAKE_OBJC_COMPILER_VERSION_INTERNAL "@CMAKE_OBJC_COMPILER_VERSION_INTERNAL@")
 set(CMAKE_OBJC_COMPILER_WRAPPER "@CMAKE_OBJC_COMPILER_WRAPPER@")
 set(CMAKE_OBJC_STANDARD_COMPUTED_DEFAULT "@CMAKE_OBJC_STANDARD_COMPUTED_DEFAULT@")
+set(CMAKE_OBJC_EXTENSIONS_COMPUTED_DEFAULT "@CMAKE_OBJC_EXTENSIONS_COMPUTED_DEFAULT@")
 set(CMAKE_OBJC_COMPILE_FEATURES "@CMAKE_OBJC_COMPILE_FEATURES@")
 set(CMAKE_OBJC90_COMPILE_FEATURES "@CMAKE_OBJC90_COMPILE_FEATURES@")
 set(CMAKE_OBJC99_COMPILE_FEATURES "@CMAKE_OBJC99_COMPILE_FEATURES@")
diff --git a/Modules/CMakeOBJCCompilerId.m.in b/Modules/CMakeOBJCCompilerId.m.in
index 418fd48..89bfe02 100644
--- a/Modules/CMakeOBJCCompilerId.m.in
+++ b/Modules/CMakeOBJCCompilerId.m.in
@@ -23,23 +23,31 @@ char const* qnxnto = "INFO" ":" "qnxnto[]";
 #if !defined(__STDC__)
 # if (defined(_MSC_VER) && !defined(__clang__)) \
   || (defined(__ibmxl__) || defined(__IBMC__))
-#  define C_DIALECT "90"
+#  define C_VERSION "90"
 # else
-#  define C_DIALECT
+#  define C_VERSION
 # endif
 #elif __STDC_VERSION__ > 201710L
-# define C_DIALECT "23"
+# define C_VERSION "23"
 #elif __STDC_VERSION__ >= 201710L
-# define C_DIALECT "17"
+# define C_VERSION "17"
 #elif __STDC_VERSION__ >= 201000L
-# define C_DIALECT "11"
+# define C_VERSION "11"
 #elif __STDC_VERSION__ >= 199901L
-# define C_DIALECT "99"
+# define C_VERSION "99"
 #else
-# define C_DIALECT "90"
+# define C_VERSION "90"
 #endif
-const char* info_language_dialect_default =
-  "INFO" ":" "dialect_default[" C_DIALECT "]";
+const char* info_language_standard_default =
+  "INFO" ":" "standard_default[" C_VERSION "]";
+
+const char* info_language_extensions_default = "INFO" ":" "extensions_default["
+#if (defined(__clang__) || defined(__GNUC__)) && !defined(__STRICT_ANSI__)
+  "ON"
+#else
+  "OFF"
+#endif
+"]";
 
 /*--------------------------------------------------------------------------*/
 
@@ -61,7 +69,8 @@ int main(int argc, char* argv[])
 #ifdef SIMULATE_VERSION_MAJOR
   require += info_simulate_version[argc];
 #endif
-  require += info_language_dialect_default[argc];
+  require += info_language_standard_default[argc];
+  require += info_language_extensions_default[argc];
   (void)argv;
   return require;
 }
diff --git a/Modules/CMakeOBJCXXCompiler.cmake.in b/Modules/CMakeOBJCXXCompiler.cmake.in
index a24582b..4f27100 100644
--- a/Modules/CMakeOBJCXXCompiler.cmake.in
+++ b/Modules/CMakeOBJCXXCompiler.cmake.in
@@ -5,6 +5,7 @@ set(CMAKE_OBJCXX_COMPILER_VERSION "@CMAKE_OBJCXX_COMPILER_VERSION@")
 set(CMAKE_OBJCXX_COMPILER_VERSION_INTERNAL "@CMAKE_OBJCXX_COMPILER_VERSION_INTERNAL@")
 set(CMAKE_OBJCXX_COMPILER_WRAPPER "@CMAKE_OBJCXX_COMPILER_WRAPPER@")
 set(CMAKE_OBJCXX_STANDARD_COMPUTED_DEFAULT "@CMAKE_OBJCXX_STANDARD_COMPUTED_DEFAULT@")
+set(CMAKE_OBJCXX_EXTENSIONS_COMPUTED_DEFAULT "@CMAKE_OBJCXX_EXTENSIONS_COMPUTED_DEFAULT@")
 set(CMAKE_OBJCXX_COMPILE_FEATURES "@CMAKE_OBJCXX_COMPILE_FEATURES@")
 set(CMAKE_OBJCXX98_COMPILE_FEATURES "@CMAKE_OBJCXX98_COMPILE_FEATURES@")
 set(CMAKE_OBJCXX11_COMPILE_FEATURES "@CMAKE_OBJCXX11_COMPILE_FEATURES@")
diff --git a/Modules/CMakeOBJCXXCompilerId.mm.in b/Modules/CMakeOBJCXXCompilerId.mm.in
index e2ac35d..2145b40 100644
--- a/Modules/CMakeOBJCXXCompilerId.mm.in
+++ b/Modules/CMakeOBJCXXCompilerId.mm.in
@@ -29,7 +29,7 @@ char const* qnxnto = "INFO" ":" "qnxnto[]";
 #define CXX_STD __cplusplus
 #endif
 
-const char* info_language_dialect_default = "INFO" ":" "dialect_default["
+const char* info_language_standard_default = "INFO" ":" "standard_default["
 #if CXX_STD > 202002L
   "23"
 #elfif CXX_STD > 201703L
@@ -45,6 +45,14 @@ const char* info_language_dialect_default = "INFO" ":" "dialect_default["
 #endif
 "]";
 
+const char* info_language_extensions_default = "INFO" ":" "extensions_default["
+#if (defined(__clang__) || defined(__GNUC__)) && !defined(__STRICT_ANSI__)
+  "ON"
+#else
+  "OFF"
+#endif
+"]";
+
 /*--------------------------------------------------------------------------*/
 
 int main(int argc, char* argv[])
@@ -64,7 +72,8 @@ int main(int argc, char* argv[])
 #ifdef SIMULATE_VERSION_MAJOR
   require += info_simulate_version[argc];
 #endif
-  require += info_language_dialect_default[argc];
+  require += info_language_standard_default[argc];
+  require += info_language_extensions_default[argc];
   (void)argv;
   return require;
 }
diff --git a/Modules/Compiler/CMakeCommonCompilerMacros.cmake b/Modules/Compiler/CMakeCommonCompilerMacros.cmake
index c86af98..2f220d4 100644
--- a/Modules/Compiler/CMakeCommonCompilerMacros.cmake
+++ b/Modules/Compiler/CMakeCommonCompilerMacros.cmake
@@ -38,20 +38,26 @@ macro(__compiler_check_default_language_standard lang stdver1 std1)
   # support for language standards, then don't bother.
   if (CMAKE_${lang}_COMPILER_VERSION VERSION_GREATER_EQUAL "${stdver1}")
     if (NOT CMAKE_${lang}_COMPILER_FORCED)
-      if (NOT CMAKE_${lang}_STANDARD_COMPUTED_DEFAULT)
-        message(FATAL_ERROR "CMAKE_${lang}_STANDARD_COMPUTED_DEFAULT should be set for ${CMAKE_${lang}_COMPILER_ID} (${CMAKE_${lang}_COMPILER}) version ${CMAKE_${lang}_COMPILER_VERSION}")
+      if (NOT CMAKE_${lang}_STANDARD_COMPUTED_DEFAULT OR NOT DEFINED CMAKE_${lang}_EXTENSIONS_COMPUTED_DEFAULT)
+        message(FATAL_ERROR "CMAKE_${lang}_STANDARD_COMPUTED_DEFAULT and CMAKE_${lang}_EXTENSIONS_COMPUTED_DEFAULT should be set for ${CMAKE_${lang}_COMPILER_ID} (${CMAKE_${lang}_COMPILER}) version ${CMAKE_${lang}_COMPILER_VERSION}")
       endif ()
       set(CMAKE_${lang}_STANDARD_DEFAULT ${CMAKE_${lang}_STANDARD_COMPUTED_DEFAULT})
+      set(CMAKE_${lang}_EXTENSIONS_DEFAULT ${CMAKE_${lang}_EXTENSIONS_COMPUTED_DEFAULT})
     else ()
       list(REVERSE __std_ver_pairs)
       foreach (__std_ver_pair IN LISTS __std_ver_pairs)
         string(REGEX MATCH "([^ ]+) (.+)" __std_ver_pair "${__std_ver_pair}")
         set(__stdver ${CMAKE_MATCH_1})
         set(__std ${CMAKE_MATCH_2})
-        if (CMAKE_${lang}_COMPILER_VERSION VERSION_GREATER_EQUAL __stdver AND
-          NOT DEFINED CMAKE_${lang}_STANDARD_DEFAULT)
-          # Compiler id was forced so just guess the default standard level.
-          set(CMAKE_${lang}_STANDARD_DEFAULT ${__std})
+        # Compiler id was forced so just guess the defaults.
+        if (CMAKE_${lang}_COMPILER_VERSION VERSION_GREATER_EQUAL __stdver)
+          if(NOT DEFINED CMAKE_${lang}_EXTENSIONS_DEFAULT)
+            # Currently known compilers default to enabling extensions.
+            set(CMAKE_${lang}_EXTENSIONS_DEFAULT ON)
+          endif()
+          if(NOT DEFINED CMAKE_${lang}_STANDARD_DEFAULT)
+            set(CMAKE_${lang}_STANDARD_DEFAULT ${__std})
+          endif()
         endif ()
         unset(__std)
         unset(__stdver)
diff --git a/Modules/Compiler/IAR-ASM.cmake b/Modules/Compiler/IAR-ASM.cmake
index 750ac2f..bae0fbd 100644
--- a/Modules/Compiler/IAR-ASM.cmake
+++ b/Modules/Compiler/IAR-ASM.cmake
@@ -25,7 +25,7 @@ set(CMAKE_ASM_COMPILE_OBJECT "<CMAKE_ASM_COMPILER> ${_CMAKE_IAR_SILENCER_FLAG} <
 
 if("${CMAKE_ASM${ASM_DIALECT}_COMPILER_ARCHITECTURE_ID}" IN_LIST _CMAKE_IAR_ITOOLS)
   __compiler_iar_ilink(ASM)
-  set(CMAKE_ASM_SOURCE_FILE_EXTENSIONS s;asm;msa)
+  set(CMAKE_ASM_SOURCE_FILE_EXTENSIONS s;asm;msa;S)
 
 elseif("${CMAKE_ASM${ASM_DIALECT}_COMPILER_ARCHITECTURE_ID}" IN_LIST _CMAKE_IAR_XTOOLS)
   __compiler_iar_xlink(ASM)
diff --git a/Modules/Compiler/IAR-C.cmake b/Modules/Compiler/IAR-C.cmake
index 9629279..0ef1a2a 100644
--- a/Modules/Compiler/IAR-C.cmake
+++ b/Modules/Compiler/IAR-C.cmake
@@ -14,6 +14,7 @@ if(NOT DEFINED CMAKE_C_COMPILER_VERSION)
   message(FATAL_ERROR "CMAKE_C_COMPILER_VERSION not detected.  This should be automatic.")
 endif()
 
+# Unused after CMP0128
 set(CMAKE_C_EXTENSION_COMPILE_OPTION -e)
 
 if(CMAKE_C_COMPILER_VERSION_INTERNAL VERSION_GREATER 7)
diff --git a/Modules/Compiler/IAR-CXX.cmake b/Modules/Compiler/IAR-CXX.cmake
index b102aa6..a3f1dbc 100644
--- a/Modules/Compiler/IAR-CXX.cmake
+++ b/Modules/Compiler/IAR-CXX.cmake
@@ -27,7 +27,7 @@ if(NOT CMAKE_IAR_CXX_FLAG)
 endif()
 
 set(CMAKE_CXX_STANDARD_COMPILE_OPTION "")
-set(CMAKE_CXX_EXTENSION_COMPILE_OPTION -e)
+set(CMAKE_CXX_EXTENSION_COMPILE_OPTION -e) # Unused after CMP0128
 
 set(CMAKE_CXX${CMAKE_CXX_STANDARD_COMPUTED_DEFAULT}_STANDARD_COMPILE_OPTION "")
 set(CMAKE_CXX${CMAKE_CXX_STANDARD_COMPUTED_DEFAULT}_EXTENSION_COMPILE_OPTION -e)
diff --git a/Modules/FortranCInterface/Detect.cmake b/Modules/FortranCInterface/Detect.cmake
index 9e5726b..4d3cb00 100644
--- a/Modules/FortranCInterface/Detect.cmake
+++ b/Modules/FortranCInterface/Detect.cmake
@@ -8,11 +8,10 @@ configure_file(${FortranCInterface_SOURCE_DIR}/Input.cmake.in
 # configuration changes.
 if(NOT EXISTS ${FortranCInterface_BINARY_DIR}/Output.cmake
     OR NOT EXISTS ${FortranCInterface_BINARY_DIR}/Input.cmake
-    OR NOT EXISTS ${FortranCInterface_BINARY_DIR}/Output.cmake.in
     OR NOT ${FortranCInterface_BINARY_DIR}/Output.cmake
       IS_NEWER_THAN ${FortranCInterface_BINARY_DIR}/Input.cmake
     OR NOT ${FortranCInterface_SOURCE_DIR}/Output.cmake
-      IS_NEWER_THAN ${FortranCInterface_BINARY_DIR}/Output.cmake.in
+      IS_NEWER_THAN ${FortranCInterface_SOURCE_DIR}/Output.cmake.in
     OR NOT ${FortranCInterface_BINARY_DIR}/Output.cmake
       IS_NEWER_THAN ${FortranCInterface_SOURCE_DIR}/CMakeLists.txt
     OR NOT ${FortranCInterface_BINARY_DIR}/Output.cmake