https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88557
Bug ID: 88557
Summary: Lambda in template parameter list compiler
segmentation fault (ICE)
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: vittorio.romeo at outlook dot com
Target Milestone: ---
The following code
template<int = []{ return 0; }()>
void f() { }
causes an internal compiler error on gcc 9.x version 20181218:
<source>: In lambda function:
<source>:1:31: error: invalid use of 'auto'
1 | template<int = []{ return 0; }()>
| ^
<source>:1:31: error: could not convert '0' from 'int' to 'auto'
<source>: At global scope:
<source>:1:20: error: use of '<lambda()>' before deduction of 'auto'
1 | template<int = []{ return 0; }()>
| ^~~~~~~~~~~~~~~
<source>: In static member function 'static auto<lambda()>::_FUN()':
<source>:1:20: error: invalid use of 'auto'
<source>: At global scope:
<source>:1:36: internal compiler error: Segmentation fault
1 | template<int = []{ return 0; }()>
| ^
Live example on godbolt.org:
https://gcc.godbolt.org/z/zSKWsv
---
Similarly, the following code
template<int = []<typename>(){ return 0; }.operator()<int>()>
void f() { }
produces another ICE:
<source>: In member function '<lambda()>::operator decltype
(((const<lambda()>*)((const<lambda()>* const)0))->operator()()) (*)()() const':
<source>:1:20: internal compiler error: in type_dependent_expression_p, at
cp/pt.c:25602
1 | template<int = []<typename>(){ return 0; }.operator()<int>()>
|
Live example on godbolt.org:
https://gcc.godbolt.org/z/uOfYy5
