[llvm-bugs] [Bug 47386] New: ICE when not unpacking variadic template into concept

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=47386

            Bug ID: 47386
           Summary: ICE when not unpacking variadic template into concept
           Product: clang
           Version: 10.0
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: C++2a
          Assignee: unassignedclangbugs at nondot.org
          Reporter: matt+llvm at offtopica.uk
                CC: blitzrakete at gmail.com, erik.pilkington at gmail.com,
                    llvm-bugs at lists.llvm.org, richard-llvm at metafoo.co.uk

Compiling this causes an ICE:


template <typename... Ts>
concept Foo = true;

template <typename... Ts> requires Foo<Ts /* ... */>
class Bar {};

Bar<int> bar;


GCC 10.2.0 fails gracefully with an error, stating that the parameter pack
isn't expanded.


$ g++ -std=c++2a -c foo.cc 
foo.cc:4:36: error: parameter packs not expanded with '...':
    4 | template <typename... Ts> requires Foo<Ts /* ... */>
      |                                    ^~~~~~~~~~~~~~~~~
foo.cc:4:36: note:         'Ts'
foo.cc:7:8: error: template constraint failure for 'template<class ... Ts> 
requires  <erroneous-expression> class Bar'
    7 | Bar<int> bar;
      |        ^
foo.cc:7:8: note: constraints not satisfied

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20200901/e60f879e/attachment.html>