Make C++ feature checks extensible

Turn the feature check for cxx11_unordered_map into a function such that
we can use it for other features as well.  Drop the 11 suffix, as we may
want to check features from other standards.

10 files changed, 50 insertions, 39 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5336208..ae5990e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -67,7 +67,7 @@ if(NOT DEFINED CMAKE_CXX_STANDARD AND NOT CMake_NO_CXX_STANDARD)
   endif()
 endif()
 if(NOT CMake_TEST_EXTERNAL_CMAKE)
-  include(${CMake_SOURCE_DIR}/Source/Checks/cm_cxx11_unordered_map.cmake)
+  include(${CMake_SOURCE_DIR}/Source/Checks/cm_cxx_features.cmake)
 endif()
 
 # option to set the internal encoding of CMake to UTF-8
diff --git a/Source/Checks/cm_cxx11_unordered_map.cmake b/Source/Checks/cm_cxx11_unordered_map.cmake
deleted file mode 100644
index 80fe391..0000000
--- a/Source/Checks/cm_cxx11_unordered_map.cmake
+++ /dev/null
@@ -1,25 +0,0 @@
-
-if(CMAKE_CXX_STANDARD AND NOT DEFINED CMake_HAVE_CXX11_UNORDERED_MAP)
-  message(STATUS "Checking if compiler supports C++11 unordered_map")
-  try_compile(CMake_HAVE_CXX11_UNORDERED_MAP
-    ${CMAKE_CURRENT_BINARY_DIR}
-    ${CMAKE_CURRENT_LIST_DIR}/cm_cxx11_unordered_map.cpp
-    CMAKE_FLAGS -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}
-    OUTPUT_VARIABLE OUTPUT
-    )
-  if(CMake_HAVE_CXX11_UNORDERED_MAP)
-    message(STATUS "Checking if compiler supports C++11 unordered_map - yes")
-    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
-      "Determining if compiler supports C++11 unordered_map passed with the following output:\n"
-      "${OUTPUT}\n"
-      "\n"
-      )
-  else()
-    message(STATUS "Checking if compiler supports C++11 unordered_map - no")
-    file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
-      "Determining if compiler supports C++11 unordered_map failed with the following output:\n"
-      "${OUTPUT}\n"
-      "\n"
-      )
-  endif()
-endif()
diff --git a/Source/Checks/cm_cxx_features.cmake b/Source/Checks/cm_cxx_features.cmake
new file mode 100644
index 0000000..b0ecc4c
--- /dev/null
+++ b/Source/Checks/cm_cxx_features.cmake
@@ -0,0 +1,36 @@
+
+function(cm_check_cxx_feature name)
+  string(TOUPPER ${name} FEATURE)
+  if(NOT DEFINED CMake_HAVE_CXX_${FEATURE})
+    message(STATUS "Checking if compiler supports C++ ${name}")
+    try_compile(CMake_HAVE_CXX_${FEATURE}
+      ${CMAKE_CURRENT_BINARY_DIR}
+      ${CMAKE_CURRENT_LIST_DIR}/cm_cxx_${name}.cxx
+      CMAKE_FLAGS -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD}
+      OUTPUT_VARIABLE OUTPUT
+      )
+    # If using the feature causes warnings, treat it as broken/unavailable.
+    if(OUTPUT MATCHES "warning")
+      set(CMake_HAVE_CXX_${FEATURE} OFF CACHE INTERNAL "TRY_COMPILE" FORCE)
+    endif()
+    if(CMake_HAVE_CXX_${FEATURE})
+      message(STATUS "Checking if compiler supports C++ ${name} - yes")
+      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
+        "Determining if compiler supports C++ ${name} passed with the following output:\n"
+        "${OUTPUT}\n"
+        "\n"
+        )
+    else()
+      message(STATUS "Checking if compiler supports C++ ${name} - no")
+      file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
+        "Determining if compiler supports C++ ${name} failed with the following output:\n"
+        "${OUTPUT}\n"
+        "\n"
+        )
+    endif()
+  endif()
+endfunction()
+
+if(CMAKE_CXX_STANDARD)
+  cm_check_cxx_feature(unordered_map)
+endif()
diff --git a/Source/Checks/cm_cxx11_unordered_map.cpp b/Source/Checks/cm_cxx_unordered_map.cxx
index be3de25..be3de25 100644
--- a/Source/Checks/cm_cxx11_unordered_map.cpp
+++ b/Source/Checks/cm_cxx_unordered_map.cxx
diff --git a/Source/cmConfigure.cmake.h.in b/Source/cmConfigure.cmake.h.in
index 938b10e..4c5ad2a 100644
--- a/Source/cmConfigure.cmake.h.in
+++ b/Source/cmConfigure.cmake.h.in
@@ -29,7 +29,7 @@
 #cmakedefine CMAKE_USE_ELF_PARSER
 #cmakedefine CMAKE_USE_MACH_PARSER
 #cmakedefine CMAKE_ENCODING_UTF8
-#cmakedefine CMake_HAVE_CXX11_UNORDERED_MAP
+#cmakedefine CMake_HAVE_CXX_UNORDERED_MAP
 #define CMAKE_BIN_DIR "/@CMAKE_BIN_DIR@"
 #define CMAKE_DATA_DIR "/@CMAKE_DATA_DIR@"
 
diff --git a/Source/cmDefinitions.h b/Source/cmDefinitions.h
index 7be0098..8f1813c 100644
--- a/Source/cmDefinitions.h
+++ b/Source/cmDefinitions.h
@@ -17,7 +17,7 @@
 #include "cmLinkedTree.h"
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 #include <unordered_map>
 #else
 #include "cmsys/hash_map.hxx"
@@ -92,7 +92,7 @@ private:
   static Def NoDef;
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
   typedef std::unordered_map<std::string, Def> MapType;
 #else
   typedef cmsys::hash_map<std::string, Def> MapType;
diff --git a/Source/cmFileTimeComparison.cxx b/Source/cmFileTimeComparison.cxx
index 7efe194..9d63505 100644
--- a/Source/cmFileTimeComparison.cxx
+++ b/Source/cmFileTimeComparison.cxx
@@ -13,7 +13,7 @@
 
 // Use a hash table to avoid duplicate file time checks from disk.
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 #include <unordered_map>
 #else
 #include <cmsys/hash_map.hxx>
@@ -47,13 +47,13 @@ private:
   {
   public:
     size_t operator()(const std::string& s) const { return h(s.c_str()); }
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
     std::hash<const char*> h;
 #else
     cmsys::hash<const char*> h;
 #endif
   };
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
   typedef std::unordered_map<std::string,
 #else
   typedef cmsys::hash_map<std::string,
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index 68ff042..789e515 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -25,7 +25,7 @@
 
 #if defined(CMAKE_BUILD_WITH_CMAKE)
 #include "cmFileLockPool.h"
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 #include <unordered_map>
 #else
 #include <cmsys/hash_map.hxx>
@@ -433,7 +433,7 @@ protected:
 
 private:
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
   typedef std::unordered_map<std::string, cmTarget*> TargetMap;
   typedef std::unordered_map<std::string, cmGeneratorTarget*>
     GeneratorTargetMap;
diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index 1680c6a..c68cd1c 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -31,7 +31,7 @@
 #include <cmsys/RegularExpression.hxx>
 #include <cmsys/auto_ptr.hxx>
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 #include <unordered_map>
 #else
 #include <cmsys/hash_map.hxx>
@@ -796,7 +796,7 @@ protected:
   // libraries, classes, and executables
   mutable cmTargets Targets;
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
   typedef std::unordered_map<std::string, cmTarget*> TargetMap;
 #else
   typedef cmsys::hash_map<std::string, cmTarget*> TargetMap;
@@ -915,7 +915,7 @@ private:
 
 // A map for fast output to input look up.
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
   typedef std::unordered_map<std::string, cmSourceFile*> OutputToSourceMap;
 #else
   typedef cmsys::hash_map<std::string, cmSourceFile*> OutputToSourceMap;
diff --git a/Source/cmTarget.h b/Source/cmTarget.h
index f91e5c6..9e095c2 100644
--- a/Source/cmTarget.h
+++ b/Source/cmTarget.h
@@ -21,7 +21,7 @@
 
 #include <cmsys/auto_ptr.hxx>
 #if defined(CMAKE_BUILD_WITH_CMAKE)
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 #include <unordered_map>
 #else
 #include <cmsys/hash_map.hxx>
@@ -331,7 +331,7 @@ private:
 };
 
 #ifdef CMAKE_BUILD_WITH_CMAKE
-#ifdef CMake_HAVE_CXX11_UNORDERED_MAP
+#ifdef CMake_HAVE_CXX_UNORDERED_MAP
 typedef std::unordered_map<std::string, cmTarget> cmTargets;
 #else
 typedef cmsys::hash_map<std::string, cmTarget> cmTargets;