https://gcc.gnu.org/g:9f79c7ddff5f1b004803931406ad17eaba095fff
commit r15-3274-g9f79c7ddff5f1b004803931406ad17eaba095fff
Author: Marek Polacek <pola...@redhat.com>
Date: Wed Aug 28 15:45:49 2024 -0400
c++: wrong error due to std::initializer_list opt [PR116476]
Here maybe_init_list_as_array gets elttype=field, init={NON_LVALUE_EXPR <2>}
and it tries to convert the init's element type (int) to field
using implicit_conversion, which works, so overall maybe_init_list_as_array
is successful.
But it constifies init_elttype so we end up with "const int". Later,
when we actually perform the conversion and invoke field::field(T&&),
we end up with this error:
error: binding reference of type 'int&&' to 'const int' discards
qualifiers
So I think maybe_init_list_as_array should try to perform the conversion,
like it does below with fc.
PR c++/116476
gcc/cp/ChangeLog:
* call.cc (maybe_init_list_as_array): Try convert_like and see if it
worked.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/initlist-opt2.C: New test.
Reviewed-by: Jason Merrill <ja...@redhat.com>
Diff:
---
gcc/cp/call.cc | 6 +++++-
gcc/testsuite/g++.dg/cpp0x/initlist-opt2.C | 21 +++++++++++++++++++++
2 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index 623e4c66c117..fa7f05d76f68 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -4319,6 +4319,7 @@ maybe_init_list_as_array (tree elttype, tree init)
/* Check with a stub expression to weed out special cases, and check whether
we call the same function for direct-init as copy-list-init. */
conversion_obstack_sentinel cos;
+ init_elttype = cp_build_qualified_type (init_elttype, TYPE_QUAL_CONST);
tree arg = build_stub_object (init_elttype);
conversion *c = implicit_conversion (elttype, init_elttype, arg, false,
LOOKUP_NORMAL, tf_none);
@@ -4326,6 +4327,10 @@ maybe_init_list_as_array (tree elttype, tree init)
c = next_conversion (c);
if (!c || c->kind != ck_user)
return NULL_TREE;
+ /* Check that we actually can perform the conversion. */
+ if (convert_like (c, arg, tf_none) == error_mark_node)
+ /* Let the normal code give the error. */
+ return NULL_TREE;
tree first = CONSTRUCTOR_ELT (init, 0)->value;
conversion *fc = implicit_conversion (elttype, init_elttype, first, false,
@@ -4358,7 +4363,6 @@ maybe_init_list_as_array (tree elttype, tree init)
if (!is_xible (INIT_EXPR, elttype, copy_argtypes))
return NULL_TREE;
- init_elttype = cp_build_qualified_type (init_elttype, TYPE_QUAL_CONST);
tree arr = build_array_of_n_type (init_elttype, CONSTRUCTOR_NELTS (init));
arr = finish_compound_literal (arr, init, tf_none);
DECL_MERGEABLE (TARGET_EXPR_SLOT (arr)) = true;
diff --git a/gcc/testsuite/g++.dg/cpp0x/initlist-opt2.C
b/gcc/testsuite/g++.dg/cpp0x/initlist-opt2.C
new file mode 100644
index 000000000000..6c71857daabc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/initlist-opt2.C
@@ -0,0 +1,21 @@
+// PR c++/116476
+// { dg-do compile { target c++11 } }
+
+namespace std {
+template <typename T>
+class initializer_list {
+ T *_M_len;
+ __SIZE_TYPE__ size;
+};
+} // namespace std
+
+
+template <class T>
+struct field {
+ field(T &&) {}
+};
+struct vector {
+ vector(std::initializer_list<field<int>>) { }
+};
+
+vector fields_normal{2};
