[PATCH] D87563: [Sema] Improve overload resolution

[Mark de Wever via Phabricator via cfe-commits]

Mordante created this revision.
Mordante added reviewers: lvoufo, rsmith.
Mordante added a project: clang.
Mordante requested review of this revision.

The overload resolution for initializer lists was incomplete. It did not
properly take the number of elements in the target array into account.  The
size comparison already allows for an array of unknown boud, per P0338 'Permit
conversions to arrays of unknown bound'. However currently this is dead code.

This fixes the overload resolution for cases like:

  void f(int(&&)[2]);
  
  void g() {
    f({1});
    f({1, 2});
    f({1, 2, 3});
  }

The patch adds extra members to `ImplicitConversionSequence`, making it larger
for members only used for an initializer list. The largest member of the class'
union is `UserDefinedConversion`. An initializer list can be used with a user
defined conversion sequence, so it's not possible to use unused space in the
union. I'm open to suggestions how to avoid the enlargement of the class.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D87563

Files:
  clang/include/clang/Sema/Overload.h
  clang/lib/Sema/SemaOverload.cpp
  clang/test/SemaCXX/overload-call.cpp

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