re PR c++/84590 (-fsanitize=undefined internal compiler error: tree check:…

re PR c++/84590 (-fsanitize=undefined internal compiler error: tree check: expected constructor, have target_expr in split_nonconstant_init_1, at cp/typeck2.c:629)

	PR c++/84590
	* cp-gimplify.c (cp_fully_fold): Unwrap TARGET_EXPR or a CONSTRUCTOR
	wrapped in VIEW_CONVERT_EXPR.

	* c-c++-common/ubsan/shift-11.c: New test.

From-SVN: r258132

gcc/cp/ChangeLog

+2018-03-02  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/84590
+	* cp-gimplify.c (cp_fully_fold): Unwrap TARGET_EXPR or a CONSTRUCTOR
+	wrapped in VIEW_CONVERT_EXPR.
+
 2018-03-01  Martin Sebor  <msebor@redhat.com>
 
 	PR c++/84294

gcc/cp/cp-gimplify.c

@@ -2037,7 +2037,17 @@ cp_fully_fold (tree x)
   /* FIXME cp_fold ought to be a superset of maybe_constant_value so we don't
      have to call both.  */
   if (cxx_dialect >= cxx11)
-    x = maybe_constant_value (x);
+    {
+      x = maybe_constant_value (x);
+      /* Sometimes we are given a CONSTRUCTOR but the call above wraps it into
+	 a TARGET_EXPR; undo that here.  */
+      if (TREE_CODE (x) == TARGET_EXPR)
+	x = TARGET_EXPR_INITIAL (x);
+      else if (TREE_CODE (x) == VIEW_CONVERT_EXPR
+	       && TREE_CODE (TREE_OPERAND (x, 0)) == CONSTRUCTOR
+	       && TREE_TYPE (TREE_OPERAND (x, 0)) == TREE_TYPE (x))
+	x = TREE_OPERAND (x, 0);
+    }
   return cp_fold_rvalue (x);
 }
 

gcc/testsuite/ChangeLog

+2018-03-02  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/84590
+	* c-c++-common/ubsan/shift-11.c: New test.
+
 2018-03-02  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	* gcc.dg/vect/vect-alias-check-13.c: New test.

gcc/testsuite/c-c++-common/ubsan/shift-11.c

+/* PR c++/84590 */
+/* { dg-do compile } */
+/* { dg-options "-fsanitize=shift" } */
+
+struct S {
+  int b;
+};
+
+void
+fn (void)
+{
+  struct S c1 = { 1 << -1 }; /* { dg-warning "left shift" } */
+}