re PR c++/81607 (Conditional operator: "type mismatch in shift expression" error)

	PR c++/81607
	* cp-gimplify.c (cp_fold): If folding exposed a branch of
	a COND_EXPR, convert it to the original type of the COND_EXPR, if
	they differ.		   

	* g++.dg/other/bitfield6.C: New test.

From-SVN: r250948

gcc/cp/ChangeLog

+2017-08-08  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/81607
+	* cp-gimplify.c (cp_fold): If folding exposed a branch of
+	a COND_EXPR, convert it to the original type of the COND_EXPR, if
+	they differ.		   
+
 2017-08-08  Martin Liska  <mliska@suse.cz>
 
 	* call.c: Include header files.

gcc/cp/cp-gimplify.c

@@ -2316,9 +2316,9 @@ cp_fold (tree x)
 
       /* A COND_EXPR might have incompatible types in branches if one or both
 	 arms are bitfields.  If folding exposed such a branch, fix it up.  */
-      if (TREE_CODE (x) != code)
-	if (tree type = is_bitfield_expr_with_lowered_type (x))
-	  x = fold_convert (type, x);
+      if (TREE_CODE (x) != code
+	  && !useless_type_conversion_p (TREE_TYPE (org_x), TREE_TYPE (x)))
+	x = fold_convert (TREE_TYPE (org_x), x);
 
       break;
 

gcc/testsuite/ChangeLog

+2017-08-08  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/81607
+	* g++.dg/other/bitfield6.C: New test.
+
 2017-08-07  Michael Meissner  <meissner@linux.vnet.ibm.com>
 
 	PR target/81593

gcc/testsuite/g++.dg/other/bitfield6.C

+// PR c++/81607
+
+int a;
+
+struct b {
+  long c : 32;
+} d;
+
+char f = (903092 ? int(d.c) : 0) << a;