https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121408
Bug ID: 121408
Summary: ICE when using dynamic_cast inside a lambda in a
template parameter with C++20/C++23
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jirehguo at tju dot edu.cn
Target Milestone: ---
The following invalid code causes an internal compiler error when compiled with
-std=c++20 or -std=c++23 since gcc-10.1
Reproducer link: https://godbolt.org/z/4Wf1e1brP
Code:
----------------------------------
#include <memory>
template <class T>
void spam(decltype([] {
std::weak_ptr<int> weakRef = std::make_shared<int>(42);
auto sharedRef = weakRef.lock();
if (sharedRef) {
int *rawPtr = sharedRef.get();
if (dynamic_cast<std::string *>(rawPtr)) {
}
}
}) (*s)[sizeof(T)]) {}
int main() { spam<char>(1); }
Command:
--------
g++ test.cpp -std=c++20
Output:
-------------
<source>: In substitution of 'template<class T> void spam(decltype (<lambda>)
(*)[sizeof (T)]) [with T = char]':
<source>:14:24: required from here
14 | int main() { spam<char>(1); }
| ~~~~~~~~~~^~~
<source>:9:9: error: cannot 'dynamic_cast' 'rawPtr' (of type 'int*') to type
'std::string*' {aka 'class std::__cxx11::basic_string<char>*'} (source is not a
pointer to class)
9 | if (dynamic_cast<std::string *>(rawPtr)) {
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:9:9: error: cannot 'dynamic_cast' 'rawPtr' (of type 'int*') to type
'std::string*' {aka 'class std::__cxx11::basic_string<char>*'} (source is not a
pointer to class)
<source>: In function 'int main()':
<source>:14:25: error: invalid conversion from 'int' to '<lambda()> (*)[1]'
[-fpermissive]
14 | int main() { spam<char>(1); }
| ^
| |
| int
internal compiler error: error reporting routines re-entered.
0x288b1ee
diagnostics::context::report_diagnostic(diagnostics::diagnostic_info*)
???:0
0x288b305 diagnostics::context::diagnostic_impl(rich_location*,
diagnostics::metadata const*, diagnostics::option_id, char const*,
__va_list_tag (*) [1], diagnostics::kind)
???:0
0x288049f error_at(unsigned long, char const*, ...)
???:0
0xd9211f build_dynamic_cast(unsigned long, tree_node*, tree_node*, int)
???:0
0xd75de5 tsubst_lambda_expr(tree_node*, tree_node*, int, tree_node*)
???:0
0xd59a0d tsubst(tree_node*, tree_node*, int, tree_node*)
???:0
0x28eb883 pretty_printer::format(text_info&)
???:0
0x288ae4e
diagnostics::context::report_diagnostic(diagnostics::diagnostic_info*)
???:0
0x288b305 diagnostics::context::diagnostic_impl(rich_location*,
diagnostics::metadata const*, diagnostics::option_id, char const*,
__va_list_tag (*) [1], diagnostics::kind)
???:0
0x287f1a0 inform(rich_location*, char const*, ...)
???:0
0xb2e05e build_new_function_call(tree_node*, vec<tree_node*, va_gc,
vl_embed>**, int)
???:0
0xda6e4c finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**, bool,
bool, int)
???:0
0xd24503 c_parse_file()
???:0
0xe8f0f9 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
