re PR c/66341 (Some casts wrongly produce a lvalue)

	PR c/66341
	* c-typeck.c (build_c_cast): Wrap VALUE into NON_LVALUE_EXPR if
	it is a lvalue.

	* gcc.dg/lvalue-8.c: New test.

From-SVN: r224115

gcc/c/ChangeLog

+2015-06-04  Marek Polacek  <polacek@redhat.com>
+
+	PR c/66341
+	* c-typeck.c (build_c_cast): Wrap VALUE into NON_LVALUE_EXPR if
+	it is a lvalue.
+
 2015-06-03  Prathamesh Kulkarni  <prathamesh.kulkarni@linaro.org>
 
 	* c-decl.c (warn_cxx_compat_finish_struct): New parameters code, record_loc.

gcc/c/c-typeck.c

@@ -5195,7 +5195,7 @@ build_c_cast (location_t loc, tree type, tree expr)
     }
 
   /* Don't let a cast be an lvalue.  */
-  if (value == expr)
+  if (lvalue_p (value))
     value = non_lvalue_loc (loc, value);
 
   /* Don't allow the results of casting to floating-point or complex

gcc/testsuite/ChangeLog

+2015-06-04  Marek Polacek  <polacek@redhat.com>
+
+	PR c/66341
+	* gcc.dg/lvalue-8.c: New test.
+
 2015-06-03  Manuel López-Ibáñez  <manu@gcc.gnu.org>
 	    Paolo Carlini  <paolo.carlini@oracle.com>
 

gcc/testsuite/gcc.dg/lvalue-8.c

+/* PR c/66341 */
+/* { dg-do compile } */
+
+void
+foo (int *p)
+{
+  p = 0;
+  /* A cast does not yield an lvalue.  */
+  (int *) p = 0; /* { dg-error "lvalue required as left operand of assignment" } */
+  /* A cast to a qualified type has the same effect as a cast
+     to the unqualified version of the type.  */
+  (int *const) p = 0; /* { dg-error "lvalue required as left operand of assignment" } */
+  (int *) (char *) p = 0; /* { dg-error "lvalue required as left operand of assignment" } */
+  (int *) (char *) (int *) p = 0; /* { dg-error "lvalue required as left operand of assignment" } */
+  (int *) (char *) (int *) (char *) p = 0; /* { dg-error "lvalue required as left operand of assignment" } */
+  (int *) (double *) p = 0; /* { dg-error "lvalue required as left operand of assignment" } */
+  (int *) (int *) p = 0; /* { dg-error "lvalue required as left operand of assignment" } */
+  (int *) (int *const) p = 0; /* { dg-error "lvalue required as left operand of assignment" } */
+}