https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104765
Bug ID: 104765
Summary: Expression statement with a return in a
lambda-parameter-default causes segfault when called
in a different function
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: erich.keane at intel dot com
Target Milestone: ---
See this example:
template<typename T>
void call_lambda(T&& L) {
L();
}
int g() {
auto x = [](char c = ({return 5;'c';})){};
call_lambda(x);
return 0;
}
int main() {
return g();
}
:https://godbolt.org/z/T1cs766cM
Output is:
during RTL pass: expand
<source>: In function 'void call_lambda(T&&) [with T = g()::<lambda(char)>&]':
<source>:3:6: internal compiler error: Segmentation fault
3 | void call_lambda(T&& L) {
| ^~~~~~~~~~~
0x217ccb9 internal_error(char const*, ...)
???:0
0x1288575 coalesce_ssa_name(_var_map*)
???:0
0x120fadb rewrite_out_of_ssa(ssaexpand*)
???: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
This gets somewhat more interesting when the return value of 'call_lambda' is
non-int:
https://godbolt.org/z/rE619qbz3
<source>: In function 'long int call_lambda(T&&)':
<source>:5:1: warning: no return statement in function returning non-void
[-Wreturn-type]
5 | }
| ^
<source>: In function 'long int call_lambda(T&&) [with T =
g()::<lambda(char)>&]':
<source>:3:6: error: invalid conversion in return statement
3 | long call_lambda(T&& L) {
| ^~~~~~~~~~~
long int
int
return D.2194;
<source>:3:6: internal compiler error: 'verify_gimple' failed
0x217ccb9 internal_error(char const*, ...)
???:0
0x1183efd verify_gimple_in_seq(gimple*)
???:0
0xdf13b1 gimplify_body(tree_node*, bool)
???:0
0xdf1677 gimplify_function_tree(tree_node*)
???:0
0xbf78f7 cgraph_node::analyze()
???:0
0xbfbe0d symbol_table::finalize_compilation_unit()
???: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
IMO, expression-statements in default-lambda parameters are... awkward and
perhaps worth just prohibiting.
