report type & size on non-power-of-2 pointer subtraction

The option -Wptr-subtraction-blows warns when pointer subtraction
is done and the base size is not a power-of-2.
However, the current message doesn't give much context.

Change this by giving the base type and the size in the warning.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/evaluate.c b/evaluate.c
index 4be4e8e5..402fa04a 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -847,8 +847,10 @@ static struct symbol *evaluate_ptr_sub(struct expression *expr)
 		val->value = value;
 
 		if (value & (value-1)) {
-			if (Wptr_subtraction_blows)
+			if (Wptr_subtraction_blows) {
 				warning(expr->pos, "potentially expensive pointer subtraction");
+				info(expr->pos, "    '%s' has a non-power-of-2 size: %lu", show_typename(lbase), value);
+			}
 		}
 
 		sub->op = '-';