[cfe-commits] r90306 - in /cfe/trunk: include/clang/AST/ASTContext.h include/clang/AST/TemplateName.h lib/AST/ASTContext.cpp lib/AST/TemplateName.cpp lib/Sema/SemaDecl.cpp lib/Sema/SemaExpr.cpp lib/Sema/SemaTemplate.cpp
John McCall
rjmccall at apple.com
Wed Dec 2 16:28:30 PST 2009
On Dec 2, 2009, at 4:20 PM, Chris Lattner wrote:
> On Dec 2, 2009, at 11:22 AM, John McCall wrote:
>> On Dec 2, 2009, at 10:02 AM, Chris Lattner wrote:
>>> On Dec 2, 2009, at 12:04 AM, John McCall wrote:
>>>> Author: rjmccall
>>>> Date: Wed Dec 2 02:04:21 2009
>>>> New Revision: 90306
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=90306&view=rev
>>>> Log:
>>>> Push overloaded function templates through the parser using a totally different
>>>> leaked data structure than before.
>>>
>>> 'leaked'?
>>
>>
>> In the lesser sense that the memory belongs to the ASTContext. The problem is that we need to tell the parser that a TemplateTy actually refers to N overloaded function templates, and like all the other opaque types, it only allows a single pointer, so we need to allocate something to store them, even if temporary (or change the parser to store these differently, but that requires fussing with the token-annotation system &c.). As it happens, an overloaded TemplateTy is going to be either (1) quickly consumed as an expression when the template arguments are parsed or (2) discarded as ill-formed in the current location. In principle you could exploit that to avoid leaking the overload storage, but that's hard to make actually work; either Sema would need to be told when the parser discards a TemplateTy (tough because of token annotations) or Sema would have to track it somehow (tough because you can have several in-flight at once).
>
> Hrm, that's annoying. If there was only one in flight at a time, it could just be in sema and return a pointer to it. Since there are multiple in flight, that won't work: do these things have a LIFO ordering that would allow Sema to have a stack of these?
I think so, yes. To enforce the stack discipline, we'd need the parser to promise to tell Sema when it's finished with a TemplateTy (or at least a TemplateTy of function-template kind). I don't know how easy that'd be.
John.
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