Advertize support for constexpr.

llvm-svn: 150524

clang/docs/LanguageExtensions.html

@@ -668,7 +668,7 @@ parsing with C++11's square bracket notation is enabled.</p>
 
 <p>Use <tt>__has_feature(cxx_constexpr)</tt> to determine if support
 for generalized constant expressions (e.g., <tt>constexpr</tt>) is
-enabled. Clang does not currently implement this feature.</p> 
+enabled.</p>
 
 <h4 id="cxx_decltype">C++11 <tt>decltype()</tt></h4>
 

clang/lib/Lex/PPMacroExpansion.cpp

@@ -638,7 +638,7 @@ static bool HasFeature(const Preprocessor &PP, const IdentifierInfo *II) {
            .Case("cxx_atomic", LangOpts.CPlusPlus0x)
            .Case("cxx_attributes", LangOpts.CPlusPlus0x)
            .Case("cxx_auto_type", LangOpts.CPlusPlus0x)
-         //.Case("cxx_constexpr", false);
+           .Case("cxx_constexpr", LangOpts.CPlusPlus0x)
            .Case("cxx_decltype", LangOpts.CPlusPlus0x)
            .Case("cxx_default_function_template_args", LangOpts.CPlusPlus0x)
            .Case("cxx_defaulted_functions", LangOpts.CPlusPlus0x)

clang/test/Lexer/has_feature_cxx0x.cpp

@@ -217,3 +217,12 @@ int no_unicode_literals();
 
 // CHECK-0X: has_unicode_literals
 // CHECK-NO-0X: no_unicode_literals
+
+#if __has_feature(cxx_constexpr)
+int has_constexpr();
+#else
+int no_constexpr();
+#endif
+
+// CHECK-0X: has_constexpr
+// CHECK-NO-0X: no_constexpr