https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100091
Bug ID: 100091
Summary: decltype([]{}) rejected as a default template
parameter
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: pilarlatiesa at gmail dot com
Target Milestone: ---
This piece of code is accepted by 10.2, but rejected by yesterday's (20210414)
snapshot:
$ cat test.cpp
template<typename = decltype([]{})>
void f() {}
$ ../GCC-11/bin/g++ -std=c++20 -c test.cpp
test.cpp:2:30: error: lambda-expression in template parameter type
2 | template<typename = decltype([]{})>
|
It's a recent change in behaviour. Possibly caused by
r11-8166-ge1666ebd9ad31dbd8b9b933c883bdd882cfd1522.
I'm labeling this as rejects-valid because I believe [basic.def.odr]/14 allows
such an use of a lambda, but I hardly understand that wording.
