[cfe-dev] Trouble understand DeclContext

[David Fontaine via cfe-dev]

On 02/08/2017 12:37 AM, Stephan Bergmann via cfe-dev wrote:
> On 02/08/2017 12:53 AM, David Fontaine via cfe-dev wrote:
>> Purely from a semantic perspective, hanging ParmVarDecls off of a
>> VarDecl or FieldDecl seems the correct solution for function pointer
>> parameters.  Going through the type information and the redeclaration
>> chain seems highly unfortunate even if it might be less code motion.
>
> And if such a ParmVarDecl is of function pointer type, you'd 
> recursively hang any ParmVarDecls off that ParmVarDecl?
Correct.  That structure would directly mirror the input source.

> But what about a FunctionDecl whose return type is a function pointer 
> type?
I hadn't considered that case.

int (*ugh(int x))(int y);

For my specific use case, I'm fine with x being in the AST and y not 
(exactly as it is today), because the attributes I'm interested in 
(-Wthread-safety) apply to declarations, not types.  (Are there 
attributes that apply to types?  I don't actually know this.)

If we wanted to "fix" this case as well, then the way I see it, clang 
would need to understand that individual occurrences of _types_ (at 
least, function types) can themselves contain nested declarations.  
Which sounds like a far more drastic change than making VarDecl and 
FieldDecl inherit DeclContext.

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