Add __sizeof_ptr__ that looks at a pointer expression and

returns the size of the underlying object.

This is different from "sizeof(*expr)" for arrays, where
the array would degenerate to a pointer to one member, and
thus "sizeof(*expr)" gives the size of one entry in the
array.

Why do this? It's useful for things like

   #define memset(a,b,c) ({ \
        (void) __builtin_warning(__sizeof_ptr__(a) > 1, __sizeof_ptr__(a) != (c), "check memset size"); \
        memset(a, b, c); })

where we really want to check the size of the object we're
doing the "memset()" on, but the regular sizeof() just doesn't
cut it.

1 files changed, 1 insertions, 0 deletions

diff --git a/expression.h b/expression.h
index 1bd7923..cb156f2 100644
--- a/expression.h
+++ b/expression.h
@@ -27,6 +27,7 @@ enum expression_type {
 	EXPR_CAST,
 	EXPR_SIZEOF,
 	EXPR_ALIGNOF,
+	EXPR_PTRSIZEOF,
 	EXPR_CONDITIONAL,
 	EXPR_SELECT,		// a "safe" conditional expression
 	EXPR_STATEMENT,