[cfe-dev] Tentative typeid Parser/AST implementation

[Sebastian Redl]

Doug Gregor wrote:
> One trick I found while looking at this... instead of having a bit for
> isTypeOp, you can split the SourceRange into two SourceLocations:
>
>   SourceLocation OpLoc; // location of the 'typeid', 'sizeof', or 'alignof'
>   SourceLocation RParenLoc; // location of the right paren, if this
> we're storing a type
>
> When RParenLoc is a valid location, the Operand is a type and
> RParenLoc will be the source location of the right paren. When
> RParenLoc is invalid, the Operand is an expression (and the
> expression's getSourceRange will tell us where the end of the
> expression is). getSourceRange gets slightly more complicated, but
> we'll save ourselves 4 bytes per typeid/sizeof/alignof.
>   
I can do that for sizeof/alignof, but not really for typeid, because the 
right paren is part of typeid's own syntax. In other words, "typeid a + 
2" is illegal code. I'd have to do some ugly trickery to have a valid 
typeid parsed as a parenthesized expression - do I really want to do this?

Also, we don't save anything for sizeof/alignof, because there's already 
a boolean (isSizeof) there, and I can collapse that to a single bit, 
which gives me plenty of space for the isTypeOperand bit.

Sebastian