https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114911
Bug ID: 114911
Summary: Anonymous unions can cause ICE when the name of their
type escapes
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: ice-checking, ice-on-valid-code
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Take:
```
void g();
template<typename T>
struct Capture;
template<typename T>
struct Capture<T*> {
friend void g() {
&T::a;
}
};
struct X;
void f() {
union {
int a = sizeof(Capture<decltype(this)>);
};
g();
}
```
GCC ICEs with:
```
<source>: In instantiation of 'void g()':
<source>:19:6: required from here
19 | g();
| ~^~
<source>:9:9: internal compiler error: tree check: expected class 'type', have
'declaration' (function_decl) in build_offset_type, at tree.cc:7718
9 | &T::a;
| ^~~~~
0x267adac internal_error(char const*, ...)
???:0
0x966cd9 tree_class_check_failed(tree_node const*, tree_code_class, char
const*, int, char const*)
???:0
0xd20f91 build_x_unary_op(unsigned int, tree_code, cp_expr, tree_node*, int)
???:0
0xc95413 instantiate_decl(tree_node*, bool, bool)
???:0
0xcbeb3b instantiate_pending_templates(int)
???:0
0xb59819 c_parse_final_cleanups()
???:0
0xdb2668 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.
```
Note this is the same testcase as the clang bug:
https://github.com/llvm/llvm-project/issues/90751 just that GCC ICEs too.
Note also this seems not to ICE with release checking .
