https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125983
Bug ID: 125983
Summary: GCC ICE in tsubst with CTAD and decltype call
expression involving dependent type
Product: gcc
Version: 15.2.0
Status: UNCONFIRMED
Keywords: error-recovery, ice-checking, ice-on-invalid-code
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: attackerj1113 at gmail dot com
Target Milestone: ---
This ICE occurs in GCC 12.1–15.2(assertions), but appears to be fixed in GCC
16.1. Reporting for regression tracking and test coverage.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
template<class T>
struct A {
using value_type = typename T::value_type;
static value_type* helper(...);
using pointer = decltype(helper((T*)0));
};
A(int) -> A<int>;
A a(0);
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
https://godbolt.org/z/E594K11P1
The issue seems to require the combination of:
>an invalid dependent member access (typename T::value_type with non-class T)
>a decltype of a call expression involving a dependent argument (helper((T*)0))
>CTAD triggering instantiation
Output:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>: In instantiation of 'struct A<int>':
<source>:12:6: required from here
12 | A a(0);
| ^
<source>:3:9: error: 'int' is not a class, struct, or union type
3 | using value_type = typename T::value_type;
| ^~~~~~~~~~
<source>:7:34: internal compiler error: Segmentation fault
7 | using pointer = decltype(helper((T*)0));
| ~~~~~~^~~~~~~
0x31ce315 diagnostic_context::diagnostic_impl(rich_location*,
diagnostic_metadata const*, diagnostic_option_id, char const*, __va_list_tag
(*) [1], diagnostic_t)
???:0
0x31e52e6 internal_error(char const*, ...)
???:0
0x129abfd tsubst(tree_node*, tree_node*, int, tree_node*)
???:0
0x129b1a4 tsubst(tree_node*, tree_node*, int, tree_node*)
???:0
0x12c68f1 instantiate_class_template(tree_node*)
???:0
0x1136ec7 cp_finish_decl(tree_node*, tree_node*, bool, tree_node*, int,
cp_decomp*)
???:0
0x1263373 c_parse_file()
???:0
0x13c65c9 c_common_parse_file()
???:0
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Compiler returned: 1
