re PR c/60036 (Spurious signedness conversion warning with relational operator)

	PR c/60036
c-family/
	* c-common.c (conversion_warning): Unwrap C_MAYBE_CONST_EXPR and/or
	SAVE_EXPR.
testsuite/
	* gcc.dg/pr60036.c: New test.

From-SVN: r207481

gcc/c-family/ChangeLog

+2014-02-04  Marek Polacek  <polacek@redhat.com>
+
+	PR c/60036
+	* c-common.c (conversion_warning): Unwrap C_MAYBE_CONST_EXPR and/or
+	SAVE_EXPR.
+
 2014-02-03  Marc Glisse  <marc.glisse@inria.fr>
 
 	PR c++/53017

gcc/c-family/c-common.c

@@ -2714,6 +2714,14 @@ conversion_warning (location_t loc, tree type, tree expr)
   if (!warn_conversion && !warn_sign_conversion && !warn_float_conversion)
     return;
 
+  /* This may happen, because for LHS op= RHS we preevaluate
+     RHS and create C_MAYBE_CONST_EXPR <SAVE_EXPR <RHS>>, which
+     means we could no longer see the code of the EXPR.  */
+  if (TREE_CODE (expr) == C_MAYBE_CONST_EXPR)
+    expr = C_MAYBE_CONST_EXPR_EXPR (expr);
+  if (TREE_CODE (expr) == SAVE_EXPR)
+    expr = TREE_OPERAND (expr, 0);
+
   switch (TREE_CODE (expr))
     {
     case EQ_EXPR:

gcc/testsuite/ChangeLog

+2014-02-04  Marek Polacek  <polacek@redhat.com>
+
+	PR c/60036
+	* gcc.dg/pr60036.c: New test.
+
 2014-02-04  Markus Trippelsdorf  <markus@trippelsdorf.de>
 
 	PR ipa/60058

gcc/testsuite/gcc.dg/pr60036.c

+/* PR c/60036 */
+/* { dg-do compile } */
+/* { dg-options "-Wconversion" } */
+
+extern int fn (void);
+
+void
+foo (int i)
+{
+  unsigned int f = 9;
+
+  /* Don't warn on these.  */
+  f += fn () || i;
+  f += fn () && i;
+  f += ! fn ();
+  f -= fn () == i;
+  f |= fn () != i;
+  f &= fn () < i;
+  f ^= fn () > i;
+  f &= fn () <= i;
+  f ^= fn () >= i;
+
+  /* But warn on the following.  */
+  f += fn (); /* { dg-warning "conversion" } */
+  f += fn () | i; /* { dg-warning "conversion" } */
+  f += fn () & i; /* { dg-warning "conversion" } */
+  f += fn () ^ i; /* { dg-warning "conversion" } */
+}