Add [extern_c] attribute for modules, allowing a C module to be imported within an extern "C" block in C++ code.

llvm-svn: 202615

1 files changed, 14 insertions, 2 deletions

diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
index 0523827..0d9cd10 100644
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -906,11 +906,14 @@ namespace clang {
 
   /// \brief The set of attributes that can be attached to a module.
   struct Attributes {
-    Attributes() : IsSystem(), IsExhaustive() { }
+    Attributes() : IsSystem(), IsExternC(), IsExhaustive() { }
 
     /// \brief Whether this is a system module.
     unsigned IsSystem : 1;
 
+    /// \brief Whether this is an extern "C" module.
+    unsigned IsExternC : 1;
+
     /// \brief Whether this is an exhaustive set of configuration macros.
     unsigned IsExhaustive : 1;
   };
@@ -1178,6 +1181,8 @@ namespace {
     AT_unknown,
     /// \brief The 'system' attribute.
     AT_system,
+    /// \brief The 'extern_c' attribute.
+    AT_extern_c,
     /// \brief The 'exhaustive' attribute.
     AT_exhaustive
   };
@@ -1334,7 +1339,9 @@ void ModuleMapParser::parseModuleDecl() {
   ActiveModule->DefinitionLoc = ModuleNameLoc;
   if (Attrs.IsSystem || IsSystem)
     ActiveModule->IsSystem = true;
-  
+  if (Attrs.IsExternC)
+    ActiveModule->IsExternC = true;
+
   bool Done = false;
   do {
     switch (Tok.Kind) {
@@ -2097,6 +2104,7 @@ bool ModuleMapParser::parseOptionalAttributes(Attributes &Attrs) {
     AttributeKind Attribute
       = llvm::StringSwitch<AttributeKind>(Tok.getString())
           .Case("exhaustive", AT_exhaustive)
+          .Case("extern_c", AT_extern_c)
           .Case("system", AT_system)
           .Default(AT_unknown);
     switch (Attribute) {
@@ -2109,6 +2117,10 @@ bool ModuleMapParser::parseOptionalAttributes(Attributes &Attrs) {
       Attrs.IsSystem = true;
       break;
 
+    case AT_extern_c:
+      Attrs.IsExternC = true;
+      break;
+
     case AT_exhaustive:
       Attrs.IsExhaustive = true;
       break;