[cfe-commits] [PATCH] Extend lexical scope of attributes to include function parameters.

[Douglas Gregor]

On Sep 2, 2011, at 11:42 AM, Delesley Hutchins wrote:

> This patch extends the lexical scope of attributes to include method
> parameters.  The main motivation for this patch is to implement thread
> safety attributes, such as the following:
> 
> class Foo {
>  int foo(Foo *f) __attribute__((exclusive_locks_required(f->mu))) { }
> 
>  Mutex mu;
> };
> 
> The change in scope is only enabled for attributes that are tagged as
> being late parsed, using the previous late parsing patch; this
> currently means that it is enabled only for thread-safety attributes.
> It also works only on methods and not top-level functions, since
> top-level functions do not currently use late parsing.
> 
>  http://codereview.appspot.com/4959055/


Okay. One structural comment on this patch:

@@ -759,8 +759,29 @@ void Parser::ParseLexedAttribute(LateParsedAttribute &LA) {
   ParsedAttributes Attrs(AttrFactory);
   SourceLocation endLoc;
 
+  // For function attributes, enter the function scope
+  FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(LA.D);
+  ParseScope FnScope(this, Scope::FnScope | Scope::DeclScope, FD);
+
+  if (FD) {
+    Actions.PushDeclContext(Actions.CurScope, FD);
+    for (unsigned P = 0, NumParams = FD->getNumParams(); P < NumParams; ++P) {
+      ParmVarDecl *Param = FD->getParamDecl(P);
+      // If the parameter has an identifier, then add it to the scope
+      if (Param->getIdentifier()) {
+        Actions.CurScope->AddDecl(Param);
+        Actions.IdResolver.AddDecl(Param);
+      }
+    }
+  }
+
   ParseGNUAttributeArgs(&LA.AttrName, LA.AttrNameLoc, Attrs, &endLoc);
 
+  if (FD) {
+    Actions.PopDeclContext();
+    FnScope.Exit();  // Pop scope, and remove Decls from IdResolver
+  }
+
   // Late parsed attributes must be attached to Decls by hand.  If the
   // LA.D is not set, then this was not done properly.
   assert(LA.D);
diff --git a/test/SemaCXX/warn-thread-safety-parsing.cpp b/test/SemaCXX/warn-thread-safety-parsing.cpp
index 5063c64..4e5327d 100644
--- a/test/SemaCXX/warn-thread-safety-parsing.cpp
+++ b/test/SemaCXX/warn-thread-safety-parsing.cpp
@@ -1219,3 +1219,27 @@ struct Foomgoper {
 };

We try to avoid looking into the AST within the parser. Please add Sema actions or re-use existing actions (such as ActOnStartDelayedMemberDeclarations) that perform the work of injecting parameter names into the context. The parser should merely parse, and call Sema to update the AST and/or lookup tables.

	- Doug