Intel: Fix default C++ dialect detection on Windows

For the Intel Compiler for Windows we have some subtle preprocessor
checks in compiler feature detection to detect C++11 and C++14 modes.
Use these when detecting the default C++ dialect too.

Modules/CMakeCXXCompilerId.cpp.in

@@ -27,10 +27,20 @@ char const *info_cray = "INFO" ":" "compiler_wrapper[CrayPrgEnv]";
 @CMAKE_CXX_COMPILER_ID_PLATFORM_CONTENT@
 @CMAKE_CXX_COMPILER_ID_ERROR_FOR_TEST@
 
-#if defined(_MSC_VER) && defined(_MSVC_LANG)
-#define CXX_STD _MSVC_LANG
+#if defined(__INTEL_COMPILER) && defined(_MSVC_LANG) && _MSVC_LANG < 201403L
+#  if defined(__INTEL_CXX11_MODE__)
+#    if defined(__cpp_aggregate_nsdmi)
+#      define CXX_STD 201402L
+#    else
+#      define CXX_STD 201103L
+#    endif
+#  else
+#    define CXX_STD 199711L
+#  endif
+#elif defined(_MSC_VER) && defined(_MSVC_LANG)
+#  define CXX_STD _MSVC_LANG
 #else
-#define CXX_STD __cplusplus
+#  define CXX_STD __cplusplus
 #endif
 
 const char* info_language_dialect_default = "INFO" ":" "dialect_default["

Tests/CompileFeatures/default_dialect.cpp

@@ -2,7 +2,17 @@
 template <long l>
 struct Outputter;
 
-#if defined(_MSC_VER) && defined(_MSVC_LANG)
+#if defined(__INTEL_COMPILER) && defined(_MSVC_LANG) && _MSVC_LANG < 201403L
+#  if defined(__INTEL_CXX11_MODE__)
+#    if defined(__cpp_aggregate_nsdmi)
+#      define CXX_STD 201402L
+#    else
+#      define CXX_STD 201103L
+#    endif
+#  else
+#    define CXX_STD 199711L
+#  endif
+#elif defined(_MSC_VER) && defined(_MSVC_LANG)
 #  define CXX_STD _MSVC_LANG
 #else
 #  define CXX_STD __cplusplus