[llvm-bugs] [Bug 49747] New: implicit instantiation of undefined template 'std::tuple_size<auto>'

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=49747

            Bug ID: 49747
           Summary: implicit instantiation of undefined template
                    'std::tuple_size<auto>'
           Product: libc++
           Version: 11.0
          Hardware: PC
                OS: All
            Status: NEW
          Severity: release blocker
          Priority: P
         Component: All Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: pro.guillaume.dua at gmail.com
                CC: llvm-bugs at lists.llvm.org, mclow.lists at gmail.com

Not sure if this is error is caused by the way `std::tuple_size` 's SFINAE is
implemented, and/or the way template-template-parameters are instanciated in
such context.

https://godbolt.org/z/GGs7ndKE4

```log
error: implicit instantiation of undefined template 'std::tuple_size<auto>'
```

Also, Clang-CL add this error message previously to the one mentioned above :

```log
error : cannot mangle this 'auto' type yet
```

See also the original discussion on SO :
https://stackoverflow.com/questions/66821952/clang-error-implicit-instantiation-of-undefined-template-stdtuple-sizeauto/66822584

-- 
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/20210328/9dabbc21/attachment.html>