In this testcase we find ourselves in split_nonconstant_init:
init = cp_fully_fold (init);
code = push_stmt_list ();
if (split_nonconstant_init_1 (dest, init))
where initially INIT was a CONSTRUCTOR, but cp_fully_fold returned
a TARGET_EXPR. This confuses split_nonconstant_init_1 which only expects
a CONSTRUCTOR or a VECTOR_CST. Jason suggested stripping TARGET_EXPRs /
VIEW_CONVERT_EXPRs, so here it is.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2018-03-01 Marek Polacek <pola...@redhat.com>
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.
diff --git gcc/cp/cp-gimplify.c gcc/cp/cp-gimplify.c
index 55a9d278dbe..1fa9c466e6b 100644
--- gcc/cp/cp-gimplify.c
+++ gcc/cp/cp-gimplify.c
@@ -2038,7 +2038,18 @@ cp_fully_fold (tree x)
have to call both. */
if (cxx_dialect >= cxx11)
x = maybe_constant_value (x);
- return cp_fold_rvalue (x);
+ x = cp_fold_rvalue (x);
+
+ /* Sometimes we are given a CONSTRUCTOR but cxx_eval_outermost_constant_expr
+ 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 x;
}
/* c-common interface to cp_fold. If IN_INIT, this is in a static initializer
diff --git gcc/testsuite/c-c++-common/ubsan/shift-11.c
gcc/testsuite/c-c++-common/ubsan/shift-11.c
index e69de29bb2d..03a72e217a2 100644
--- gcc/testsuite/c-c++-common/ubsan/shift-11.c
+++ gcc/testsuite/c-c++-common/ubsan/shift-11.c
@@ -0,0 +1,13 @@
+/* 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" } */
+}
Marek
