[cfe-dev] Written name of conversion operator

[Douglas Gregor]

On Jun 4, 2010, at 2:38 PM, Abramo Bagnara wrote:

> Il 04/06/2010 22:52, Douglas Gregor ha scritto:
>> I have a different idea of how to address this issue, for which I had previously filed this bug report:
>> 
>> 	http://llvm.org/bugs/show_bug.cgi?id=6357
>> 
>> Essentially, it suggests adding a DeclarationNameLoc type that, similarly to TypeLoc, contains information about the exact spelling of and the source locations for a declaration name. DeclarationNameLoc should remain small (IdentifierInfo* + SourceLocation for the common case), and use separate storage when we need to store extra information (e.g., a conversion operator would refer to the TypeSourceInfo * of the conversion type as written). 
>> 
>> There would have to be a way---probably via the ASTContext---to extract a DeclarationName from a DeclarationNameLoc, for name-lookup purposes.
>> 
>> We would use DeclarationNameLoc within the ASTs (MemberExpr, DeclRefExpr, etc.) in lieu of DeclarationName.
> 
> You're more inclined toward:
> 
> struct DeclarationNameLoc {
>  DeclarationName Name;
>  char Extra[0];
> };
> 
> and to have a field DeclarationNameLoc* NameLoc inside AST nodes
> 
> or
> 
> struct DeclarationNameLoc {
>  DeclarationName Name;
>  void* Extra;
> };
> 
> and to have a field DeclarationNameLoc NameLoc inside AST nodes?

Something like the latter, since we absolutely must make sure that the common case of (IdentifierInfo*, SourceLocation) doesn't require an extra memory allocation. I would probably end up creating something similar to DeclarationName itself, with a bit-mangled pointer for the name and storage for the first two locations.

	struct DeclarationNameLoc {
	  void *Ptr;
	  SourceLocations Locs[2];
	};


> Another possibility is to have Extra data allocated at end of containing
> node, but I think this might become too messy.

I think that would be too messy.

	- Doug