Finish semantic analysis for [[carries_dependency]] attribute.

This required plumbing through a new flag to determine whether a ParmVarDecl is
actually a parameter of a function declaration (as opposed to a function
typedef etc, where the attribute is prohibited). Weirdly, this attribute (just
like [[noreturn]]) cannot be applied to a function type, just to a function
declaration (and its parameters).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173726 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index fb63953..e8d14e6 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -1911,6 +1911,9 @@
 /// mergeDeclAttributes - Copy attributes from the Old decl to the New one.
 void Sema::mergeDeclAttributes(NamedDecl *New, Decl *Old,
                                AvailabilityMergeKind AMK) {
+  if (!Old->hasAttrs() && !New->hasAttrs())
+    return;
+
   // attributes declared post-definition are currently ignored
   checkNewAttributesAfterDef(*this, New, Old);
 
@@ -1956,7 +1959,25 @@
 /// to the new one.
 static void mergeParamDeclAttributes(ParmVarDecl *newDecl,
                                      const ParmVarDecl *oldDecl,
-                                     ASTContext &C) {
+                                     Sema &S) {
+  // C++11 [dcl.attr.depend]p2:
+  //   The first declaration of a function shall specify the
+  //   carries_dependency attribute for its declarator-id if any declaration
+  //   of the function specifies the carries_dependency attribute.
+  if (newDecl->hasAttr<CarriesDependencyAttr>() &&
+      !oldDecl->hasAttr<CarriesDependencyAttr>()) {
+    S.Diag(newDecl->getAttr<CarriesDependencyAttr>()->getLocation(),
+           diag::err_carries_dependency_missing_on_first_decl) << 1/*Param*/;
+    // Find the first declaration of the parameter.
+    // FIXME: Should we build redeclaration chains for function parameters?
+    const FunctionDecl *FirstFD =
+      cast<FunctionDecl>(oldDecl->getDeclContext())->getFirstDeclaration();
+    const ParmVarDecl *FirstVD =
+      FirstFD->getParamDecl(oldDecl->getFunctionScopeIndex());
+    S.Diag(FirstVD->getLocation(),
+           diag::note_carries_dependency_missing_first_decl) << 1/*Param*/;
+  }
+
   if (!oldDecl->hasAttrs())
     return;
 
@@ -1970,7 +1991,8 @@
        i = oldDecl->specific_attr_begin<InheritableParamAttr>(),
        e = oldDecl->specific_attr_end<InheritableParamAttr>(); i != e; ++i) {
     if (!DeclHasAttr(newDecl, *i)) {
-      InheritableAttr *newAttr = cast<InheritableParamAttr>((*i)->clone(C));
+      InheritableAttr *newAttr =
+        cast<InheritableParamAttr>((*i)->clone(S.Context));
       newAttr->setInherited(true);
       newDecl->addAttr(newAttr);
       foundAny = true;
@@ -2295,6 +2317,18 @@
            diag::note_noreturn_missing_first_decl);
     }
 
+    // C++11 [dcl.attr.depend]p2:
+    //   The first declaration of a function shall specify the
+    //   carries_dependency attribute for its declarator-id if any declaration
+    //   of the function specifies the carries_dependency attribute.
+    if (New->hasAttr<CarriesDependencyAttr>() &&
+        !Old->hasAttr<CarriesDependencyAttr>()) {
+      Diag(New->getAttr<CarriesDependencyAttr>()->getLocation(),
+           diag::err_carries_dependency_missing_on_first_decl) << 0/*Function*/;
+      Diag(Old->getFirstDeclaration()->getLocation(),
+           diag::note_carries_dependency_missing_first_decl) << 0/*Function*/;
+    }
+
     // (C++98 8.3.5p3):
     //   All declarations for a function shall agree exactly in both the
     //   return type and the parameter-type-list.
@@ -2487,7 +2521,7 @@
   if (New->getNumParams() == Old->getNumParams())
     for (unsigned i = 0, e = New->getNumParams(); i != e; ++i)
       mergeParamDeclAttributes(New->getParamDecl(i), Old->getParamDecl(i),
-                               Context);
+                               *this);
 
   if (getLangOpts().CPlusPlus)
     return MergeCXXFunctionDecl(New, Old, S);
@@ -2514,7 +2548,7 @@
   for (ObjCMethodDecl::param_iterator
          ni = newMethod->param_begin(), ne = newMethod->param_end();
        ni != ne && oi != oe; ++ni, ++oi)
-    mergeParamDeclAttributes(*ni, *oi, Context);
+    mergeParamDeclAttributes(*ni, *oi, *this);
 
   CheckObjCMethodOverride(newMethod, oldMethod);
 }
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index bb77adf..adeb8e6 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -24,6 +24,7 @@
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/DelayedDiagnostic.h"
 #include "clang/Sema/Lookup.h"
+#include "clang/Sema/Scope.h"
 #include "llvm/ADT/StringExtras.h"
 using namespace clang;
 using namespace sema;
@@ -1815,13 +1816,25 @@
                            Attr.getAttributeSpellingListIndex()));
 }
 
-static void handleDependencyAttr(Sema &S, Decl *D, const AttributeList &Attr) {
-  if (!isa<FunctionDecl>(D) && !isa<ParmVarDecl>(D)) {
+static void handleDependencyAttr(Sema &S, Scope *Scope, Decl *D,
+                                 const AttributeList &Attr) {
+  if (isa<ParmVarDecl>(D)) {
+    // [[carries_dependency]] can only be applied to a parameter if it is a
+    // parameter of a function declaration or lambda.
+    if (!(Scope->getFlags() & clang::Scope::FunctionDeclarationScope)) {
+      S.Diag(Attr.getLoc(),
+             diag::err_carries_dependency_param_not_function_decl);
+      return;
+    }
+  } else if (!isa<FunctionDecl>(D)) {
     S.Diag(Attr.getLoc(), diag::err_attribute_wrong_decl_type)
       << Attr.getName() << ExpectedFunctionMethodOrParameter;
     return;
   }
-  // FIXME: Actually store the attribute on the declaration
+
+  D->addAttr(::new (S.Context) CarriesDependencyAttr(
+                                   Attr.getRange(), S.Context,
+                                   Attr.getAttributeSpellingListIndex()));
 }
 
 static void handleUnusedAttr(Sema &S, Decl *D, const AttributeList &Attr) {
@@ -4494,7 +4507,8 @@
   case AttributeList::AT_Annotate:    handleAnnotateAttr    (S, D, Attr); break;
   case AttributeList::AT_Availability:handleAvailabilityAttr(S, D, Attr); break;
   case AttributeList::AT_CarriesDependency:
-                                      handleDependencyAttr  (S, D, Attr); break;
+    handleDependencyAttr(S, scope, D, Attr);
+    break;
   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;