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authorMarek Polacek <polacek@redhat.com>2020-06-17 09:19:02 -0400
committerMarek Polacek <polacek@redhat.com>2020-06-17 09:19:02 -0400
commitae2ebf011fec926e003645c33c07a03619ea216a (patch)
tree22786700ccebc85f8db4afd3fe82fefb9be4f656
parent4d2b0866d760f822c137b69f14d1c51fc760ce53 (diff)
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c++: ICE with IMPLICIT_CONV_EXPR in array subscript [PR95508]
Since r10-7096 convert_like, when called in a template, creates an IMPLICIT_CONV_EXPR when we're converting to/from array type. In this test, we have e[f], and we're converting f (of type class A) to int, so convert_like in build_new_op_1 created the IMPLICIT_CONV_EXPR that got into cp_build_array_ref which calls maybe_constant_value. My patch above failed to adjust this spot to call fold_non_dependent_expr instead, which can handle codes like I_C_E in a template. Fixed by using a new function maybe_fold_non_dependent_expr, which, if the expr can't be evaluated to a constant, returns the original expression. gcc/cp/ChangeLog: PR c++/95508 * constexpr.c (maybe_fold_non_dependent_expr): New. * cp-tree.h (maybe_fold_non_dependent_expr): Declare. * typeck.c (cp_build_array_ref): Call maybe_fold_non_dependent_expr instead of maybe_constant_value. gcc/testsuite/ChangeLog: PR c++/95508 * g++.dg/template/conv16.C: New test.
-rw-r--r--gcc/cp/constexpr.c13
-rw-r--r--gcc/cp/cp-tree.h2
-rw-r--r--gcc/cp/typeck.c2
-rw-r--r--gcc/testsuite/g++.dg/template/conv16.C17
4 files changed, 33 insertions, 1 deletions
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index c01c42b..f766abd 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -7093,6 +7093,19 @@ fold_non_dependent_expr (tree t,
return maybe_constant_value (t, object, manifestly_const_eval);
}
+/* Like fold_non_dependent_expr, but if EXPR couldn't be folded to a constant,
+ return the original expression. */
+
+tree
+maybe_fold_non_dependent_expr (tree expr,
+ tsubst_flags_t complain/*=tf_warning_or_error*/)
+{
+ tree t = fold_non_dependent_expr (expr, complain);
+ if (t && TREE_CONSTANT (t))
+ return t;
+
+ return expr;
+}
/* Like maybe_constant_init but first fully instantiate the argument. */
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 50d83ad..ee27610 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7933,6 +7933,8 @@ extern tree maybe_constant_init (tree, tree = NULL_TREE, bool = false);
extern tree fold_non_dependent_expr (tree,
tsubst_flags_t = tf_warning_or_error,
bool = false, tree = NULL_TREE);
+extern tree maybe_fold_non_dependent_expr (tree,
+ tsubst_flags_t = tf_warning_or_error);
extern tree fold_non_dependent_init (tree,
tsubst_flags_t = tf_warning_or_error,
bool = false);
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index f01ae65..7e84f11 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -3565,7 +3565,7 @@ cp_build_array_ref (location_t loc, tree array, tree idx,
pointer arithmetic.) */
idx = cp_perform_integral_promotions (idx, complain);
- idx = maybe_constant_value (idx);
+ idx = maybe_fold_non_dependent_expr (idx, complain);
/* An array that is indexed by a non-constant
cannot be stored in a register; we must be able to do
diff --git a/gcc/testsuite/g++.dg/template/conv16.C b/gcc/testsuite/g++.dg/template/conv16.C
new file mode 100644
index 0000000..c0843ef
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/conv16.C
@@ -0,0 +1,17 @@
+// PR c++/95508
+// { dg-do compile }
+
+template <typename>
+struct A;
+template <typename>
+struct B {
+ operator int () { return 0; }
+};
+template <>
+struct A<unsigned> : B<int> {};
+struct D {
+ template <typename>
+ int foo () { return e[f]; }
+ int e[6];
+ A<unsigned> f;
+};