Merge topic 'clang-gnulike-support'

a4657ef670 Merge branch 'backport-clang-gnulike-support' into clang-gnulike-support
161b33f12b Help/guide/tutorial: Revert "require C++14 for the Tutorial"
4f15a6a5c2 Tests: Revert "require C++14 for the Tutorial"
5cfc39127e Merge branch 'backport-clang-gnulike-support' into clang-gnulike-support
d50b31be35 Clang: For MSVC ABI do not use modes older than C++14

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !3592

19 files changed, 39 insertions, 42 deletions

diff --git a/Help/guide/tutorial/Complete/CMakeLists.txt b/Help/guide/tutorial/Complete/CMakeLists.txt
index e84f932..bea611c 100644
--- a/Help/guide/tutorial/Complete/CMakeLists.txt
+++ b/Help/guide/tutorial/Complete/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 project(Tutorial)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
 
 # set the version number
 set(Tutorial_VERSION_MAJOR 1)
diff --git a/Help/guide/tutorial/Consumer/CMakeLists.txt b/Help/guide/tutorial/Consumer/CMakeLists.txt
index 5097917..4033b4d 100644
--- a/Help/guide/tutorial/Consumer/CMakeLists.txt
+++ b/Help/guide/tutorial/Consumer/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 
 if(NOT DEFINED CMAKE_CXX_STANDARD)
-  set(CMAKE_CXX_STANDARD 14)
+  set(CMAKE_CXX_STANDARD 11)
+  set(CMAKE_CXX_STANDARD_REQUIRED True)
 endif()
 
 
diff --git a/Help/guide/tutorial/Step10/CMakeLists.txt b/Help/guide/tutorial/Step10/CMakeLists.txt
index 5819272..25bc0c1 100644
--- a/Help/guide/tutorial/Step10/CMakeLists.txt
+++ b/Help/guide/tutorial/Step10/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 project(Tutorial)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
 
 # Set the version number
 set(Tutorial_VERSION_MAJOR 1)
diff --git a/Help/guide/tutorial/Step11/CMakeLists.txt b/Help/guide/tutorial/Step11/CMakeLists.txt
index 2e5cb15..8f29fe2 100644
--- a/Help/guide/tutorial/Step11/CMakeLists.txt
+++ b/Help/guide/tutorial/Step11/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 project(Tutorial)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
 
 # set the version number
 set(Tutorial_VERSION_MAJOR 1)
diff --git a/Help/guide/tutorial/Step2/CMakeLists.txt b/Help/guide/tutorial/Step2/CMakeLists.txt
index 1f43b2b..059b89a 100644
--- a/Help/guide/tutorial/Step2/CMakeLists.txt
+++ b/Help/guide/tutorial/Step2/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 project(Tutorial)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
 
 # set the version number
 set(Tutorial_VERSION_MAJOR 1)
diff --git a/Help/guide/tutorial/Step3/CMakeLists.txt b/Help/guide/tutorial/Step3/CMakeLists.txt
index 966c38a..9804abf 100644
--- a/Help/guide/tutorial/Step3/CMakeLists.txt
+++ b/Help/guide/tutorial/Step3/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 project(Tutorial)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
 
 # should we use our own math functions
 option(USE_MYMATH "Use tutorial provided math implementation" ON)
diff --git a/Help/guide/tutorial/Step4/CMakeLists.txt b/Help/guide/tutorial/Step4/CMakeLists.txt
index a157bda..0ae2648 100644
--- a/Help/guide/tutorial/Step4/CMakeLists.txt
+++ b/Help/guide/tutorial/Step4/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 project(Tutorial)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
 
 # should we use our own math functions
 option(USE_MYMATH "Use tutorial provided math implementation" ON)
diff --git a/Help/guide/tutorial/Step5/CMakeLists.txt b/Help/guide/tutorial/Step5/CMakeLists.txt
index 76b9179..dac9b45 100644
--- a/Help/guide/tutorial/Step5/CMakeLists.txt
+++ b/Help/guide/tutorial/Step5/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 project(Tutorial)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
 
 # should we use our own math functions
 option(USE_MYMATH "Use tutorial provided math implementation" ON)
diff --git a/Help/guide/tutorial/Step6/CMakeLists.txt b/Help/guide/tutorial/Step6/CMakeLists.txt
index 5829891..1465e46 100644
--- a/Help/guide/tutorial/Step6/CMakeLists.txt
+++ b/Help/guide/tutorial/Step6/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 project(Tutorial)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
 
 # set the version number
 set(Tutorial_VERSION_MAJOR 1)
diff --git a/Help/guide/tutorial/Step7/CMakeLists.txt b/Help/guide/tutorial/Step7/CMakeLists.txt
index 17e6a60..a1efa77 100644
--- a/Help/guide/tutorial/Step7/CMakeLists.txt
+++ b/Help/guide/tutorial/Step7/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 project(Tutorial)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
 
 # set the version number
 set(Tutorial_VERSION_MAJOR 1)
diff --git a/Help/guide/tutorial/Step8/CMakeLists.txt b/Help/guide/tutorial/Step8/CMakeLists.txt
index 86725e8..a0316a0 100644
--- a/Help/guide/tutorial/Step8/CMakeLists.txt
+++ b/Help/guide/tutorial/Step8/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 project(Tutorial)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
 
 # set the version number
 set(Tutorial_VERSION_MAJOR 1)
diff --git a/Help/guide/tutorial/Step9/CMakeLists.txt b/Help/guide/tutorial/Step9/CMakeLists.txt
index 07ab90a..e610b99 100644
--- a/Help/guide/tutorial/Step9/CMakeLists.txt
+++ b/Help/guide/tutorial/Step9/CMakeLists.txt
@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.3)
 project(Tutorial)
 
-set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD_REQUIRED True)
 
 # set the version number
 set(Tutorial_VERSION_MAJOR 1)
diff --git a/Modules/Compiler/Clang-CXX.cmake b/Modules/Compiler/Clang-CXX.cmake
index 17f3917..61709f8 100644
--- a/Modules/Compiler/Clang-CXX.cmake
+++ b/Modules/Compiler/Clang-CXX.cmake
@@ -58,6 +58,13 @@ if("x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xGNU")
   unset(_clang_version_std17)
 
   if("x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC")
+    # The MSVC standard library requires C++14, and MSVC itself has no
+    # notion of operating in a mode not aware of at least that standard.
+    set(CMAKE_CXX98_STANDARD_COMPILE_OPTION "-std=c++14")
+    set(CMAKE_CXX98_EXTENSION_COMPILE_OPTION "-std=gnu++14")
+    set(CMAKE_CXX11_STANDARD_COMPILE_OPTION "-std=c++14")
+    set(CMAKE_CXX11_EXTENSION_COMPILE_OPTION "-std=gnu++14")
+
     # This clang++ is missing some features because of MSVC compatibility.
     unset(CMAKE_CXX11_STANDARD__HAS_FULL_SUPPORT)
     unset(CMAKE_CXX14_STANDARD__HAS_FULL_SUPPORT)
diff --git a/Tests/AliasTarget/CMakeLists.txt b/Tests/AliasTarget/CMakeLists.txt
index 6271988..fc70135 100644
--- a/Tests/AliasTarget/CMakeLists.txt
+++ b/Tests/AliasTarget/CMakeLists.txt
@@ -7,7 +7,7 @@ set(CMAKE_CXX_STANDARD 98)
 # Clang/C2 in C++98 mode cannot properly handle some of MSVC headers
 if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND
     CMAKE_CXX_SIMULATE_ID STREQUAL "MSVC")
-  set(CMAKE_CXX_STANDARD 14)
+  set(CMAKE_CXX_STANDARD 11)
 endif()
 
 add_library(foo SHARED empty.cpp)
diff --git a/Tests/Complex/CMakeLists.txt b/Tests/Complex/CMakeLists.txt
index fef83f6..2e41754 100644
--- a/Tests/Complex/CMakeLists.txt
+++ b/Tests/Complex/CMakeLists.txt
@@ -446,11 +446,6 @@ if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND
   set(CMAKE_CXX_STANDARD 11)
 endif()
 
-if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND
-    CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "GNU")
-  set(CMAKE_CXX_STANDARD 14)
-endif()
-
 #
 # Create the libs and the main exe
 #
diff --git a/Tests/ComplexOneConfig/CMakeLists.txt b/Tests/ComplexOneConfig/CMakeLists.txt
index 77baa4c..628cd4e 100644
--- a/Tests/ComplexOneConfig/CMakeLists.txt
+++ b/Tests/ComplexOneConfig/CMakeLists.txt
@@ -403,11 +403,6 @@ if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND
   set(CMAKE_CXX_STANDARD 11)
 endif()
 
-if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND
-    CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "GNU")
-  set(CMAKE_CXX_STANDARD 14)
-endif()
-
 #
 # Create the libs and the main exe
 #
diff --git a/Tests/Module/WriteCompilerDetectionHeader/CMakeLists.txt b/Tests/Module/WriteCompilerDetectionHeader/CMakeLists.txt
index b30928d..cffef5a 100644
--- a/Tests/Module/WriteCompilerDetectionHeader/CMakeLists.txt
+++ b/Tests/Module/WriteCompilerDetectionHeader/CMakeLists.txt
@@ -133,9 +133,7 @@ endif()
 
 # for msvc the compiler version determines which c++11 features are available.
 if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC"
-    OR (CMAKE_CXX_COMPILER_ID STREQUAL "Clang"
-    AND "x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC"
-    AND "x${CMAKE_CXX_COMPILER_FRONTEND_VARIANT}" STREQUAL "xMSVC" ))
+    OR (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND "x${CMAKE_CXX_SIMULATE_ID}" STREQUAL "xMSVC"))
   if(";${CMAKE_CXX_COMPILE_FEATURES};" MATCHES ";cxx_delegating_constructors;")
     list(APPEND true_defs EXPECTED_COMPILER_CXX_DELEGATING_CONSTRUCTORS)
     list(APPEND true_defs EXPECTED_COMPILER_CXX_VARIADIC_TEMPLATES)
diff --git a/Tests/Plugin/CMakeLists.txt b/Tests/Plugin/CMakeLists.txt
index c4540db..8e8fa07 100644
--- a/Tests/Plugin/CMakeLists.txt
+++ b/Tests/Plugin/CMakeLists.txt
@@ -5,17 +5,6 @@ project(Plugin)
 # We need proper C++98 support from the compiler
 set(CMAKE_CXX_STANDARD 98)
 
-# Clang/C2 in C++98 mode cannot properly handle some of MSVC headers
-if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND
-    CMAKE_CXX_SIMULATE_ID STREQUAL "MSVC")
-  set(CMAKE_CXX_STANDARD 11)
-endif()
-
-if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND
-    CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "GNU")
-  set(CMAKE_CXX_STANDARD 14)
-endif()
-
 # Test per-target output directory properties.
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${Plugin_BINARY_DIR}/bin)
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${Plugin_BINARY_DIR}/lib/plugin)
@@ -40,6 +29,12 @@ include_directories(
   ${Plugin_SOURCE_DIR}/include
   )
 
+# Clang/C2 in C++98 mode cannot properly handle some of MSVC headers
+if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND
+    CMAKE_CXX_SIMULATE_ID STREQUAL "MSVC")
+  set(CMAKE_CXX_STANDARD 11)
+endif()
+
 # Create an executable that exports an API for use by plugins.
 add_executable(example_exe src/example_exe.cxx)
 set_target_properties(example_exe PROPERTIES
diff --git a/Tests/RunCMake/GenerateExportHeader/GEH.cmake b/Tests/RunCMake/GenerateExportHeader/GEH.cmake
index b3f1c7f..ae9a84c 100644
--- a/Tests/RunCMake/GenerateExportHeader/GEH.cmake
+++ b/Tests/RunCMake/GenerateExportHeader/GEH.cmake
@@ -51,11 +51,6 @@ if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND
   set(CMAKE_CXX_STANDARD 11)
 endif()
 
-if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND
-    CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "GNU")
-  set(CMAKE_CXX_STANDARD 14)
-endif()
-
 add_subdirectory(lib_shared_and_static)
 
 if(CMAKE_SYSTEM_NAME MATCHES "AIX" AND CMAKE_CXX_COMPILER_ID STREQUAL "GNU"