[PATCH] D38216: [C++17] Fix class template argument deduction for default constructors without an initializer

Zhihao Yuan via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Sat Nov 11 06:07:10 PST 2017

lichray added a comment.

The standard hasn't allowed deducing any placeholder type without an initializer ( [dcl.type.auto.deduct]/2) yet.

It's unclear to me what

  extern A x;

wants to archive.  Usually when people writing `extern` then expect an initializer to appear somewhere else, but with this declaration, defining

  A x = ...;

later may fail by resolving to a different type, which feels... interesting.


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