[cfe-dev] WIP patch for qualified-ids in class member access

[Douglas Gregor]

On Jul 8, 2009, at 7:53 PM, Douglas Gregor wrote:

> Hi James,
>
> On Jul 6, 2009, at 9:27 PM, James Porter wrote:
>> Index: lib/Parse/ParseExpr.cpp
>> ===================================================================
>> --- lib/Parse/ParseExpr.cpp	(revision 74890)
>> +++ lib/Parse/ParseExpr.cpp	(working copy)
>> @@ -915,6 +915,14 @@
>>       tok::TokenKind OpKind = Tok.getKind();
>>       SourceLocation OpLoc = ConsumeToken();  // Eat the "." or "- 
>> >" token.
>>
>> +      CXXScopeSpec SS;
>> +      if (getLang().CPlusPlus) {
>> +        if( !Actions.ActOnCXXEnterMemberScope(CurScope,LHS) )
>> +          return ExprError();
>> +        ParseOptionalCXXScopeSpecifier(SS);
>> +        Actions.ActOnCXXExitMemberScope(CurScope,LHS,SS);
>> +      }
>> +
>
> Oh, this is interesting. I completely expected to have something like:
>
>
>> +      CXXScopeSpec SS;
>> +      if (getLang().CPlusPlus) {
>> +        if( !Actions.ActOnCXXEnterMemberScope(CurScope,LHS) )
>> +          return ExprError();
>> +        ParseOptionalCXXScopeSpecifier(SS);
>
> followed by a call to ActOnMemberReferenceExpr, then
>
>   if (getLang().CPlusPlus)
>     Actions.ActOnCXXExitMemberScope(CurScope,LHS,SS);
>
> In other words, I expected that we would enter the member scope,  
> process the member-reference expression within that scope (so that  
> name lookup would be based on that scope), then exit the member  
> scope at the end. \


Thinking about this further, I think you had the right idea after all.  
At least, I can see both ways working, and they need to produce the  
same results. The really, really tricky case is with a conversion  
function, e.g., x.operator T(). C++  [basic.lookup.classref]p7 says  
this:

	If the id-expression is a conversion-function-id, its conversion-type- 
id shall denote the same type in both the context in which the entire  
postfix-expression occurs and in the context of the class of the  
object expression (or the class pointed to by the pointer expression).

Since the conversion-function-id is the only place where I could  
imagine your approach and my suggestion to differ, and in theory we  
have to do *both*, let's go with your approach: it requires fewer  
changes, and we can think about diagnosing paragraph 7 later.

	- Doug
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