[all-commits] [llvm/llvm-project] 1cea7a: [demangler] Use standard semantics for StringView:...

[tmiasko via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 1cea7ab4ba13346745d6aa6e117ee2e77995fb07
      https://github.com/llvm/llvm-project/commit/1cea7ab4ba13346745d6aa6e117ee2e77995fb07
  Author: Tomasz Miąsko <tomasz.miasko at gmail.com>
  Date:   2021-04-25 (Sun, 25 Apr 2021)

  Changed paths:
    M libcxxabi/src/demangle/StringView.h
    M llvm/include/llvm/Demangle/StringView.h
    M llvm/unittests/Demangle/CMakeLists.txt
    A llvm/unittests/Demangle/StringViewTest.cpp

  Log Message:
  -----------
  [demangler] Use standard semantics for StringView::substr

The StringView::substr now accepts a substring starting position and its
length instead of previous non-standard `from` & `to` positions.

All uses of two argument StringView::substr are in MicrosoftDemangler
and have 0 as a starting position, so no changes are necessary.

This also fixes a bug where attempting to extract a suffix with substr
(a `to` position equal to size) would return a substring without the
last character.

Fixing the issue should not introduce observable changes in the
demangler, since as currently used, a second argument to
StringView::substr is either: 1) a result of a successful call to
StringView::find and so necessarily smaller than size., or 2) in the
case of Demangler::demangleCharLiteral potentially equal to size, but
with demangler expecting more data to follow later on and failing either
way.

Reviewed By: #libc_abi, ldionne, erik.pilkington

Differential Revision: https://reviews.llvm.org/D100246