[PATCH] D27525: Improve format member detection in llvm::formatv

[Pavel Labath via Phabricator via llvm-commits]

labath created this revision.
labath added a reviewer: zturner.
labath added a subscriber: llvm-commits.

The existing detection of a format member function has a couple of deficiencies:

- the member function does not get detected if one calls formatv with an lvalue, because the template parameter gets deduced as T&, which fails the is_class check.
- it also did not work if the function was called with a const variable because the template parameter would get deduced as const T&, again failing the is_class check.

This fixes the problem by stripping the references in the uses_format_member
template, to make sure the type is correctly detected as class. It also provides
specializations of the has_FormatMember template for const and non-const members
of the types in order to enable declaring the format member as a "const"
function. I have added tests that verify that formatv can be now called in these
scenarios. As some scenarios could not be verified at runtime (e.g. making sure
that calling a non-const format member on a const object does *not* compile), I
have also added some static_asserts which test the behaviour of the template
classes used internally by formatv().


https://reviews.llvm.org/D27525

Files:
  include/llvm/Support/FormatVariadicDetails.h
  unittests/Support/FormatVariadicTest.cpp

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