[PATCH] Warn about return with a void expression with -Wreturn-type.

[Marcin BaczyÅski <marbacz at gmail dot com>]

PR c/48116.

Botstrapped and tested on x86_64-pc-linux-gnu.

gcc/ChangeLog:

   * c/c-typeck.c (c_finish_return): emit warning about return with a
    void expression in a function returning void if warn_return_type.

gcc/testsuite/ChangeLog:

   * gcc.dg/Wreturn-type3.c: new test.
---
 gcc/c/c-typeck.c                     | 4 ++++
 gcc/testsuite/gcc.dg/Wreturn-type3.c | 6 ++++++
 2 files changed, 10 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/Wreturn-type3.c

diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 1520c20..8ac6cd4 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -9700,6 +9700,10 @@ c_finish_return (location_t loc, tree retval, tree origtype)
 	warned_here = pedwarn
 	  (xloc, 0,
 	   "%<return%> with a value, in function returning void");
+      else if (warn_return_type)
+	warned_here = warning_at
+	  (loc, OPT_Wreturn_type,
+	   "%<return%> with expression, in function returning void");
       else
 	warned_here = pedwarn
 	  (xloc, OPT_Wpedantic, "ISO C forbids "
diff --git a/gcc/testsuite/gcc.dg/Wreturn-type3.c b/gcc/testsuite/gcc.dg/Wreturn-type3.c
new file mode 100644
index 0000000..e83c94b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/Wreturn-type3.c
@@ -0,0 +1,6 @@
+/* PR c/48116 */
+/* { dg-do compile } */
+/* { dg-options "-Wreturn-type" } */
+
+void a() {}
+void b() { return a(); }  /* { dg-warning "return" "returning void" } */
-- 
2.8.3