PR c/48116 - -Wreturn-type does not work as advertised

gcc/ChangeLog:
2016-06-04  Martin Sebor  <msebor@redhat.com>
	    Marcin Baczyński <marbacz@gmail.com>

	PR c/48116
	* doc/invoke.texi (-Wreturn-type): Mention not warning on return with
	a void expression in a void function.

Co-Authored-By: Marcin Baczyński <marbacz@gmail.com>

From-SVN: r237093

gcc/ChangeLog

+2016-06-04  Martin Sebor  <msebor@redhat.com>
+	    Marcin Baczyński <marbacz@gmail.com>
+
+	PR c/48116
+	* doc/invoke.texi (-Wreturn-type): Mention not warning on return with
+	a void expression in a void function.
+
 2016-06-03  Jan Hubicka  <hubicka@ucw.cz>
 
 	* tree-ssa-loop-ch.c (should_duplicate_loop_header_p): Do not check

gcc/doc/invoke.texi

@@ -4055,8 +4055,12 @@ Warn whenever a function is defined with a return type that defaults
 to @code{int}.  Also warn about any @code{return} statement with no
 return value in a function whose return type is not @code{void}
 (falling off the end of the function body is considered returning
-without a value), and about a @code{return} statement with an
-expression in a function whose return type is @code{void}.
+without a value).
+
+For C only, warn about a @code{return} statement with an expression in a
+function whose return type is @code{void}, unless the expression type is
+also @code{void}.  As a GNU extension, the latter case is accepted
+without a warning unless @option{-Wpedantic} is used.
 
 For C++, a function without return type always produces a diagnostic
 message, even when @option{-Wno-return-type} is specified.  The only