[cfe-dev] Who owns declarations?

[Sebastian Redl]

Douglas Gregor wrote:
>
> On Dec 22, 2008, at 7:38 PM, Sebastian Redl wrote:
>
>>
>> By the way, why does CXXConditionalDeclExpr derive from DeclRefExpr?
>
> I believe it's because IfStmt's condition is an Expr*, so 
> CXXConditionalDeclExpr is an Expr that also declares a variable. The 
> derivation from DeclRefExpr allows the rest of semantic analysis (that 
> knows how to treat a DeclRefExpr as a boolean expression) to deal with 
> the declaration.
>
>> That's counter-intuitive from several viewpoints.
>
>
> How so?
>
A CXXConditionalDeclExpr declares a variable, it doesn't reference it. 
That's the most important difference between the two, and it doesn't 
lend itself to using derivation - note that CXXConditionalDeclExpr 
doesn't have serialization implemented, precisely because it owns the 
Decl and DeclRefExpr doesn't, which causes confusion.

Sebastian