On 5/5/26 3:40 AM, Jakub Jelinek wrote:
Hi!
https://eel.is/c++draft/meta.reflection.extract#5.2 requests that
is_convertible_v<remove_reference_t<U>(*)[], remove_reference_t<T>(*)[]>
is tested and if it not true, the function throws.
If U/T are references to function/method/array[], we try to build
array of types which are not valid in arrays and ICE shortly after that.
The following patch makes sure we don't create arrays in that case
and instead just throw the exception. We can't have references to void
or references to references, so I think the other problematic cases
of creating arrays can't trigger.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk/16.2?
OK...
2026-05-05 Jakub Jelinek <[email protected]>
PR c++/125111
* reflect.cc (extract_ref): Throw instead of trying to build
arrays of functions, methods or arrays with NULL TYPE_DOMAIN.
* g++.dg/reflect/extract12.C: New test.
--- gcc/cp/reflect.cc.jj 2026-05-01 21:47:53.656712280 +0200
+++ gcc/cp/reflect.cc 2026-05-04 16:27:43.017528465 +0200
@@ -7453,6 +7453,10 @@ extract_ref (location_t loc, const const
{
if (TYPE_REF_P (type))
type = TREE_TYPE (type);
+ if (FUNC_OR_METHOD_TYPE_P (type)
+ || (TREE_CODE (type) == ARRAY_TYPE
+ && TYPE_DOMAIN (type) == NULL_TREE))
...but it would be nice to share this with tsubst.
+ return error_mark_node;
type = build_cplus_array_type (type, NULL_TREE);
return build_pointer_type (type);
};
@@ -7462,7 +7466,11 @@ extract_ref (location_t loc, const const
{
/* The wording is saying that U is the type of r. */
tree U = TREE_TYPE (r);
- if (is_convertible (adjust_type (U), adjust_type (T))
+ tree adju = adjust_type (U);
+ tree adjt = adjust_type (T);
+ if (adju != error_mark_node
+ && adjt != error_mark_node
+ && is_convertible (adju, adjt)
&& (!var_p || is_constant_expression (r)))
{
if (TYPE_REF_P (TREE_TYPE (r)))
--- gcc/testsuite/g++.dg/reflect/extract12.C.jj 2026-05-04 16:29:25.477853239
+0200
+++ gcc/testsuite/g++.dg/reflect/extract12.C 2026-05-04 16:30:28.990815200
+0200
@@ -0,0 +1,14 @@
+// PR c++/125111
+// { dg-do compile { target c++26 } }
+// { dg-additional-options "-freflection" }
+
+#include <meta>
+
+using A = void ();
+extern A &a;
+constexpr auto b = ^^a;
+constexpr auto c = std::meta::extract <A &> (b); // { dg-error "uncaught
exception of type 'std::meta::exception'; 'what\\\(\\\)': 'value cannot be extracted'" }
+using B = int [];
+extern B &d;
+constexpr auto e = ^^d;
+constexpr auto f = std::meta::extract <B &> (e); // { dg-error "uncaught
exception of type 'std::meta::exception'; 'what\\\(\\\)': 'value cannot be extracted'" }
Jakub
