Implement C++11 semantics for [[noreturn]] attribute. This required splitting

it apart from [[gnu::noreturn]] / __attribute__((noreturn)), since their
semantics are not equivalent (for instance, we treat [[gnu::noreturn]] as
affecting the function type, whereas [[noreturn]] does not).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172691 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 84 insertions, 30 deletions

diff --git a/lib/Sema/AnalysisBasedWarnings.cpp b/lib/Sema/AnalysisBasedWarnings.cpp
index ba23467931..d5fa959bf4 100644
--- a/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/lib/Sema/AnalysisBasedWarnings.cpp
@@ -329,8 +329,7 @@ static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
 
   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
     ReturnsVoid = FD->getResultType()->isVoidType();
-    HasNoReturn = FD->hasAttr<NoReturnAttr>() ||
-       FD->getType()->getAs<FunctionType>()->getNoReturnAttr();
+    HasNoReturn = FD->isNoReturn();
   }
   else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
     ReturnsVoid = MD->getResultType()->isVoidType();
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 5ddc26ab25..728a58ee61 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -2276,6 +2276,18 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, Decl *OldD, Scope *S) {
       }
     }
 
+    // C++11 [dcl.attr.noreturn]p1:
+    //   The first declaration of a function shall specify the noreturn
+    //   attribute if any declaration of that function specifies the noreturn
+    //   attribute.
+    if (New->hasAttr<CXX11NoReturnAttr>() &&
+        !Old->hasAttr<CXX11NoReturnAttr>()) {
+      Diag(New->getAttr<CXX11NoReturnAttr>()->getLocation(),
+           diag::err_noreturn_missing_on_first_decl);
+      Diag(Old->getFirstDeclaration()->getLocation(),
+           diag::note_noreturn_missing_first_decl);
+    }
+
     // (C++98 8.3.5p3):
     //   All declarations for a function shall agree exactly in both the
     //   return type and the parameter-type-list.
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index acd075ee7f..45220f60d3 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -1684,6 +1684,21 @@ static void handleAnalyzerNoReturnAttr(Sema &S, Decl *D,
   D->addAttr(::new (S.Context) AnalyzerNoReturnAttr(Attr.getRange(), S.Context));
 }
 
+static void handleCXX11NoReturnAttr(Sema &S, Decl *D,
+                                    const AttributeList &Attr) {
+  // C++11 [dcl.attr.noreturn]p1:
+  //   The attribute may be applied to the declarator-id in a function
+  //   declaration.
+  FunctionDecl *FD = dyn_cast<FunctionDecl>(D);
+  if (!FD) {
+    S.Diag(Attr.getLoc(), diag::err_attribute_wrong_decl_type)
+      << Attr.getName() << ExpectedFunctionOrMethod;
+    return;
+  }
+
+  D->addAttr(::new (S.Context) CXX11NoReturnAttr(Attr.getRange(), S.Context));
+}
+
 // PS3 PPU-specific.
 static void handleVecReturnAttr(Sema &S, Decl *D, const AttributeList &Attr) {
 /*
@@ -4272,10 +4287,10 @@ static void ProcessNonInheritableDeclAttr(Sema &S, Scope *scope, Decl *D,
 static void ProcessInheritableDeclAttr(Sema &S, Scope *scope, Decl *D,
                                        const AttributeList &Attr) {
   switch (Attr.getKind()) {
-    case AttributeList::AT_IBAction:          handleIBAction(S, D, Attr); break;
-    case AttributeList::AT_IBOutlet:          handleIBOutlet(S, D, Attr); break;
-    case AttributeList::AT_IBOutletCollection:
-      handleIBOutletCollection(S, D, Attr); break;
+  case AttributeList::AT_IBAction:    handleIBAction(S, D, Attr); break;
+  case AttributeList::AT_IBOutlet:    handleIBOutlet(S, D, Attr); break;
+  case AttributeList::AT_IBOutletCollection:
+    handleIBOutletCollection(S, D, Attr); break;
   case AttributeList::AT_AddressSpace:
   case AttributeList::AT_OpenCLImageAccess:
   case AttributeList::AT_ObjCGC:
@@ -4306,6 +4321,9 @@ static void ProcessInheritableDeclAttr(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_Common:      handleCommonAttr      (S, D, Attr); break;
   case AttributeList::AT_CUDAConstant:handleConstantAttr    (S, D, Attr); break;
   case AttributeList::AT_Constructor: handleConstructorAttr (S, D, Attr); break;
+  case AttributeList::AT_CXX11NoReturn:
+    handleCXX11NoReturnAttr(S, D, Attr);
+    break;
   case AttributeList::AT_Deprecated:
     handleAttrWithMessage<DeprecatedAttr>(S, D, Attr, "deprecated");
     break;
@@ -4542,11 +4560,11 @@ static void ProcessInheritableDeclAttr(Sema &S, Scope *scope, Decl *D,
 
 /// ProcessDeclAttribute - Apply the specific attribute to the specified decl if
 /// the attribute applies to decls.  If the attribute is a type attribute, just
-/// silently ignore it if a GNU attribute. FIXME: Applying a C++0x attribute to
-/// the wrong thing is illegal (C++0x [dcl.attr.grammar]/4).
+/// silently ignore it if a GNU attribute.
 static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
                                  const AttributeList &Attr,
-                                 bool NonInheritable, bool Inheritable) {
+                                 bool NonInheritable, bool Inheritable,
+                                 bool IncludeCXX11Attributes) {
   if (Attr.isInvalid())
     return;
 
@@ -4557,6 +4575,11 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   if (Attr.isMSTypespecAttribute())
     return;
 
+  // Ignore C++11 attributes on declarator chunks: they appertain to the type
+  // instead.
+  if (Attr.isCXX11Attribute() && !IncludeCXX11Attributes)
+    return;
+
   if (NonInheritable)
     ProcessNonInheritableDeclAttr(S, scope, D, Attr);
 
@@ -4568,10 +4591,11 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
 /// attribute list to the specified decl, ignoring any type attributes.
 void Sema::ProcessDeclAttributeList(Scope *S, Decl *D,
                                     const AttributeList *AttrList,
-                                    bool NonInheritable, bool Inheritable) {
-  for (const AttributeList* l = AttrList; l; l = l->getNext()) {
-    ProcessDeclAttribute(*this, S, D, *l, NonInheritable, Inheritable);
-  }
+                                    bool NonInheritable, bool Inheritable,
+                                    bool IncludeCXX11Attributes) {
+  for (const AttributeList* l = AttrList; l; l = l->getNext())
+    ProcessDeclAttribute(*this, S, D, *l, NonInheritable, Inheritable,
+                         IncludeCXX11Attributes);
 
   // GCC accepts
   // static int a9 __attribute__((weakref));
@@ -4736,7 +4760,8 @@ void Sema::ProcessDeclAttributes(Scope *S, Decl *D, const Declarator &PD,
   // when X is a decl attribute.
   for (unsigned i = 0, e = PD.getNumTypeObjects(); i != e; ++i)
     if (const AttributeList *Attrs = PD.getTypeObject(i).getAttrs())
-      ProcessDeclAttributeList(S, D, Attrs, NonInheritable, Inheritable);
+      ProcessDeclAttributeList(S, D, Attrs, NonInheritable, Inheritable,
+                               /*IncludeCXX11Attributes=*/false);
 
   // Finally, apply any attributes on the decl itself.
   if (const AttributeList *Attrs = PD.getAttributes())
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index 09c418072d..db314fa50c 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -2419,8 +2419,7 @@ Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
   QualType RelatedRetType;
   if (const FunctionDecl *FD = getCurFunctionDecl()) {
     FnRetType = FD->getResultType();
-    if (FD->hasAttr<NoReturnAttr>() ||
-        FD->getType()->getAs<FunctionType>()->getNoReturnAttr())
+    if (FD->isNoReturn())
       Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
         << FD->getDeclName();
   } else if (ObjCMethodDecl *MD = getCurMethodDecl()) {
diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index e849e05c7b..702954322e 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -4189,24 +4189,43 @@ static void processTypeAttrs(TypeProcessingState &state, QualType &type,
     if (attr.isInvalid())
       continue;
 
-    // [[gnu::...]] attributes are treated as declaration attributes, so may
-    // not appertain to a DeclaratorChunk, even if we handle them as type
-    // attributes.
-    // FIXME: All other C++11 type attributes may *only* appertain to a type,
-    // and should only be considered here if they appertain to a
-    // DeclaratorChunk.
-    if (attr.isCXX11Attribute() && TAL == TAL_DeclChunk &&
-        attr.getScopeName() && attr.getScopeName()->isStr("gnu")) {
-      state.getSema().Diag(attr.getLoc(),
-                           diag::warn_cxx11_gnu_attribute_on_type)
-        << attr.getName();
-      continue;
+    if (attr.isCXX11Attribute()) {
+      // [[gnu::...]] attributes are treated as declaration attributes, so may
+      // not appertain to a DeclaratorChunk, even if we handle them as type
+      // attributes.
+      if (attr.getScopeName() && attr.getScopeName()->isStr("gnu")) {
+        if (TAL == TAL_DeclChunk) {
+          state.getSema().Diag(attr.getLoc(),
+                               diag::warn_cxx11_gnu_attribute_on_type)
+              << attr.getName();
+          continue;
+        }
+      } else if (TAL != TAL_DeclChunk) {
+        // Otherwise, only consider type processing for a C++11 attribute if
+        // it's actually been applied to a type.
+        continue;
+      }
     }
 
     // If this is an attribute we can handle, do so now,
     // otherwise, add it to the FnAttrs list for rechaining.
     switch (attr.getKind()) {
-    default: break;
+    default:
+      // A C++11 attribute on a declarator chunk must appertain to a type.
+      if (attr.isCXX11Attribute() && TAL == TAL_DeclChunk)
+        state.getSema().Diag(attr.getLoc(), diag::err_attribute_not_type_attr)
+          << attr.getName()->getName();
+      break;
+
+    case AttributeList::UnknownAttribute:
+      if (attr.isCXX11Attribute() && TAL == TAL_DeclChunk)
+        state.getSema().Diag(attr.getLoc(),
+                             diag::warn_unknown_attribute_ignored)
+          << attr.getName();
+      break;
+
+    case AttributeList::IgnoredAttribute:
+      break;
 
     case AttributeList::AT_MayAlias:
       // FIXME: This attribute needs to actually be handled, but if we ignore
@@ -4255,7 +4274,7 @@ static void processTypeAttrs(TypeProcessingState &state, QualType &type,
 
     case AttributeList::AT_NSReturnsRetained:
       if (!state.getSema().getLangOpts().ObjCAutoRefCount)
-    break;
+        break;
       // fallthrough into the function attrs
 
     FUNCTION_TYPE_ATTRS_CASELIST: