The following improves the location for "statement with no effect" warning by
using the location of the expression if available. Can't use EXPR_LOCATION as
*_DECLs still don't carry a location.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2015-12-16 Marek Polacek <pola...@redhat.com>
PR c/64637
* c-typeck.c (c_process_expr_stmt): Use location of the expression if
available.
* gcc.dg/pr64637.c: New test.
diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
index 9d6c604..a147ac6 100644
--- gcc/c/c-typeck.c
+++ gcc/c/c-typeck.c
@@ -10131,7 +10131,7 @@ c_process_expr_stmt (location_t loc, tree expr)
out which is the result. */
if (!STATEMENT_LIST_STMT_EXPR (cur_stmt_list)
&& warn_unused_value)
- emit_side_effect_warnings (loc, expr);
+ emit_side_effect_warnings (EXPR_LOC_OR_LOC (expr, loc), expr);
exprv = expr;
while (TREE_CODE (exprv) == COMPOUND_EXPR)
diff --git gcc/testsuite/gcc.dg/pr64637.c gcc/testsuite/gcc.dg/pr64637.c
index e69de29..779ff50 100644
--- gcc/testsuite/gcc.dg/pr64637.c
+++ gcc/testsuite/gcc.dg/pr64637.c
@@ -0,0 +1,25 @@
+/* PR c/64637 */
+/* { dg-do compile } */
+/* { dg-options "-Wunused" } */
+
+void g ();
+
+void
+f (int b)
+{
+ for (int i = 0; i < b; i + b) /* { dg-warning "28:statement with no effect"
} */
+ g ();
+ // PARM_DECLs still don't have a location, don't expect an exact location.
+ for (int i = 0; i < b; b) /* { dg-warning "statement with no effect" } */
+ g ();
+ for (int i = 0; i < b; !i) /* { dg-warning "26:statement with no effect" } */
+ g ();
+ for (!b;;) /* { dg-warning "8:statement with no effect" } */
+ g ();
+ for (;; b * 2) /* { dg-warning "13:statement with no effect" } */
+ g ();
+ ({
+ b / 5; /* { dg-warning "8:statement with no effect" } */
+ b ^ 5;
+ });
+}
Marek
