7 files changed, 46 insertions, 0 deletions
diff --git a/include/clang/AST/Attr.h b/include/clang/AST/Attr.h
index f7a47364a7..b36ff12293 100644
--- a/include/clang/AST/Attr.h
+++ b/include/clang/AST/Attr.h
@@ -50,6 +50,7 @@ public:
     Annotate,
     AsmLabel, // Represent GCC asm label extension.
     Blocks,
+    CDecl,
     Cleanup,
     Const,
     Constructor,
@@ -442,6 +443,7 @@ DEF_SIMPLE_ATTR(DLLImport);
 DEF_SIMPLE_ATTR(DLLExport);
 DEF_SIMPLE_ATTR(FastCall);
 DEF_SIMPLE_ATTR(StdCall);
+DEF_SIMPLE_ATTR(CDecl);
 DEF_SIMPLE_ATTR(TransparentUnion);
 DEF_SIMPLE_ATTR(ObjCNSObject);
 DEF_SIMPLE_ATTR(ObjCException);
diff --git a/include/clang/Parse/AttributeList.h b/include/clang/Parse/AttributeList.h
index 9fcc845cb0..81bb3007ba 100644
--- a/include/clang/Parse/AttributeList.h
+++ b/include/clang/Parse/AttributeList.h
@@ -57,6 +57,7 @@ public:
     AT_analyzer_noreturn,
     AT_annotate,
     AT_blocks,
+    AT_cdecl,
     AT_cleanup,
     AT_const,
     AT_constructor,
diff --git a/lib/Frontend/PCHReaderDecl.cpp b/lib/Frontend/PCHReaderDecl.cpp
index b9ece21f74..775ce76c92 100644
--- a/lib/Frontend/PCHReaderDecl.cpp
+++ b/lib/Frontend/PCHReaderDecl.cpp
@@ -442,6 +442,8 @@ Attr *PCHReader::ReadAttributes() {
                                   (BlocksAttr::BlocksAttrTypes)Record[Idx++]);
       break;
 
+    SIMPLE_ATTR(CDecl);
+
     case Attr::Cleanup:
       New = ::new (*Context) CleanupAttr(
                                   cast<FunctionDecl>(GetDecl(Record[Idx++])));
diff --git a/lib/Frontend/PCHWriter.cpp b/lib/Frontend/PCHWriter.cpp
index 436428b375..82922a93b5 100644
--- a/lib/Frontend/PCHWriter.cpp
+++ b/lib/Frontend/PCHWriter.cpp
@@ -1768,6 +1768,9 @@ void PCHWriter::WriteAttributeRecord(const Attr *Attr) {
       Record.push_back(cast<BlocksAttr>(Attr)->getType()); // FIXME: stable
       break;
 
+    case Attr::CDecl:
+      break;
+
     case Attr::Cleanup:
       AddDeclRef(cast<CleanupAttr>(Attr)->getFunctionDecl(), Record);
       break;
diff --git a/lib/Parse/AttributeList.cpp b/lib/Parse/AttributeList.cpp
index 344ce9e90e..dde4bc866a 100644
--- a/lib/Parse/AttributeList.cpp
+++ b/lib/Parse/AttributeList.cpp
@@ -59,6 +59,7 @@ AttributeList::Kind AttributeList::getKind(const IdentifierInfo *Name) {
     .Case("mode", AT_mode)
     .Case("used", AT_used)
     .Case("alias", AT_alias)
+    .Case("cdecl", AT_cdecl)
     .Case("const", AT_const)
     .Case("packed", AT_packed)
     .Case("malloc", AT_malloc)
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index 18f57da769..803be138c2 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -1008,6 +1008,38 @@ static void HandleSectionAttr(Decl *D, const AttributeList &Attr, Sema &S) {
 
 }
 
+static void HandleCDeclAttr(Decl *d, const AttributeList &Attr, Sema &S) {
+  // Attribute has no arguments.
+  if (Attr.getNumArgs() != 0) {
+    S.Diag(Attr.getLoc(), diag::err_attribute_wrong_number_arguments) << 0;
+    return;
+  }
+
+  // Attribute can be applied only to functions.
+  if (!isa<FunctionDecl>(d)) {
+    S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
+      << Attr.getName() << 0 /*function*/;
+    return;
+  }
+
+  // cdecl and fastcall attributes are mutually incompatible.
+  if (d->getAttr<FastCallAttr>()) {
+    S.Diag(Attr.getLoc(), diag::err_attributes_are_not_compatible)
+      << "cdecl" << "fastcall";
+    return;
+  }
+
+  // cdecl and stdcall attributes are mutually incompatible.
+  if (d->getAttr<StdCallAttr>()) {
+    S.Diag(Attr.getLoc(), diag::err_attributes_are_not_compatible)
+      << "cdecl" << "stdcall";
+    return;
+  }
+
+  d->addAttr(::new (S.Context) CDeclAttr());
+}
+
+
 static void HandleStdCallAttr(Decl *d, const AttributeList &Attr, Sema &S) {
   // Attribute has no arguments.
   if (Attr.getNumArgs() != 0) {
@@ -1822,6 +1854,7 @@ static void ProcessDeclAttribute(Scope *scope, Decl *D,
   case AttributeList::AT_analyzer_noreturn:
     HandleAnalyzerNoReturnAttr  (D, Attr, S); break;
   case AttributeList::AT_annotate:    HandleAnnotateAttr  (D, Attr, S); break;
+  case AttributeList::AT_cdecl:       HandleCDeclAttr     (D, Attr, S); break;
   case AttributeList::AT_constructor: HandleConstructorAttr(D, Attr, S); break;
   case AttributeList::AT_deprecated:  HandleDeprecatedAttr(D, Attr, S); break;
   case AttributeList::AT_destructor:  HandleDestructorAttr(D, Attr, S); break;
diff --git a/test/Sema/callingconv.c b/test/Sema/callingconv.c
index 102115b3bf..f65aab463f 100644
--- a/test/Sema/callingconv.c
+++ b/test/Sema/callingconv.c
@@ -17,3 +17,7 @@ void __attribute__((fastcall)) test1(void) {
 
 void __attribute__((fastcall)) test2(int a, ...) { // expected-error {{variadic function cannot use 'fastcall' calling convention}}
 }
+
+void __attribute__((cdecl)) ctest0() {}
+
+void __attribute__((cdecl(1))) ctest1(float x) {} // expected-error {{attribute requires 0 argument(s)}}