[PATCH] D146231: [ADT] Add `llvm::range_size` function for generic ranges

[Jakub Kuderski via Phabricator via llvm-commits]

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This function follows `std::ranges::size` from C++20. It is intended
mainly for generic code that does not know the exact range type.
I did not modify the existing `llvm::size` function because it has a strict
guarantee of O(1) running time, and we cannot guarantee that when we delegate
size check to user-defined size functions.

Use `range_size` to optimize size checks in `zip`* and `enumerate`
functions. Before that, we would have to perform linear scans for ranges
without random access iterators.

This is the last change I have planned in the series that overhauls
`zip`* and `enumerate`.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D146231

Files:
  llvm/include/llvm/ADT/STLExtras.h
  llvm/unittests/ADT/IteratorTest.cpp

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