Re: strict-aliasing and typedefs

[Gabriel Dos Reis <gdr@integrable-solutions.net>]

Brad Lucier <lucier@math.purdue.edu> writes:

| I've read the documentation and done a google and gcc search, but
| I still have this question.
| 
| If I have the typedefs and variables
| 
| typedef int stackslot;
| typedef int heapslot;
| 
| stackslot *sp;
| heapslot *hp;
| 
| then can sp and hp point to the same location in memory with
| ISO C's aliasing rules?

Yes, that is because typedef-name acts like a keyword that is
synonymous for the original type, hence sp and hp can alias the same
object. 

|  I'm wondering if a Scheme->C compiler
| can use typedefs and ISO C's aliasing rules to tell gcc that certain
| memory locations cannot alias each other.

No, a typedef does not introduce a distinct type:  It just introduces a
new type-name -- it is all syntactical.

-- Gaby