PR c++/86190 - bogus -Wsign-conversion warning

	PR c++/86190 - bogus -Wsign-conversion warning
	* typeck.c (cp_build_binary_op): Fix formatting.  Add a warning
	sentinel.

	* g++.dg/warn/Wsign-conversion-3.C: New test.
	* g++.dg/warn/Wsign-conversion-4.C: New test.

From-SVN: r262855

gcc/cp/ChangeLog

+2018-07-18  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/86190 - bogus -Wsign-conversion warning
+	* typeck.c (cp_build_binary_op): Fix formatting.  Add a warning
+	sentinel.
+
 2018-07-18  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/59480, DR 136

gcc/cp/typeck.c

@@ -5312,12 +5312,13 @@ cp_build_binary_op (location_t location,
 
       if (short_compare)
 	{
-	  /* We call shorten_compare only for diagnostic-reason.  */
-	  tree xop0 = fold_simple (op0), xop1 = fold_simple (op1),
-	       xresult_type = result_type;
+	  /* We call shorten_compare only for diagnostics.  */
+	  tree xop0 = fold_simple (op0);
+	  tree xop1 = fold_simple (op1);
+	  tree xresult_type = result_type;
 	  enum tree_code xresultcode = resultcode;
 	  shorten_compare (location, &xop0, &xop1, &xresult_type,
-			       &xresultcode);
+			   &xresultcode);
 	}
 
       if ((short_compare || code == MIN_EXPR || code == MAX_EXPR)
@@ -5350,6 +5351,7 @@ cp_build_binary_op (location_t location,
      otherwise, it will be given type RESULT_TYPE.  */
   if (! converted)
     {
+      warning_sentinel w (warn_sign_conversion, short_compare);
       if (TREE_TYPE (op0) != result_type)
 	op0 = cp_convert_and_check (result_type, op0, complain);
       if (TREE_TYPE (op1) != result_type)

gcc/testsuite/ChangeLog

+2018-07-18  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/86190 - bogus -Wsign-conversion warning
+	* g++.dg/warn/Wsign-conversion-3.C: New test.
+	* g++.dg/warn/Wsign-conversion-4.C: New test.
+
 2018-07-18  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/59480, DR 136

gcc/testsuite/g++.dg/warn/Wsign-conversion-3.C

+// PR c++/86190
+// { dg-options "-Wsign-conversion -Wsign-compare" }
+
+typedef unsigned long sz_t;
+sz_t s();
+bool f(int i) { return s() < (unsigned long) i; }
+bool f2(int i) { return s() < static_cast<unsigned long>(i); }
+bool f3(int i) { return s() < i; } // { dg-warning "comparison of integer expressions of different signedness" }
+bool f4(int i) { return s() < (long) i; } // { dg-warning "comparison of integer expressions of different signedness" }
+bool f5(short int i) { return s() < (int) i; } // { dg-warning "comparison of integer expressions of different signedness" }
+bool f6(signed char i) { return s() < (int) i; } // { dg-warning "comparison of integer expressions of different signedness" }
+bool f7(unsigned char i) { return s() < i; }
+bool f8(signed char i) { return s() < i; } // { dg-warning "comparison of integer expressions of different signedness" }

gcc/testsuite/g++.dg/warn/Wsign-conversion-4.C

+// PR c++/86190
+// { dg-options "-Wsign-conversion -Wsign-compare" }
+
+typedef unsigned long size_t;
+
+struct vector {
+  typedef size_t size_type;
+  size_type size();
+};
+
+bool func(vector vec, int var)
+{
+  return vec.size() < static_cast<size_t>(var); // { dg-bogus "may change" }
+}