[libcxx-commits] [PATCH] D92776: [libc++] ADL-proof <algorithm> by adding _VSTD:: qualification on calls.

[Arthur O'Dwyer via Phabricator via libcxx-commits]

Quuxplusone created this revision.
Quuxplusone added a reviewer: ldionne.
Quuxplusone added a project: libc++.
Quuxplusone requested review of this revision.
Herald added a reviewer: jdoerfert.
Herald added subscribers: libcxx-commits, sstefan1.
Herald added a reviewer: libc++.

I intend to land this PR as two separate commits:

(1) [libc++] ADL-proof by adding _VSTD:: qualifications to memmove etc.

  
  Many of these calls aren't vulnerable to ADL because they involve only
  primitive types; but some (such as the ones in <list>) *are* vulnerable,
  and absolutely zero of them *need* ADL to happen; so in my opinion
  they should all be consistently qualified, just like calls to any
  other (non-user-customizable) functions in namespace std.
  
  The following names are covered by this patch:
  memmove, wmemmove, memcpy, wmemcpy, memcmp, wmemcmp, memchr, wmemchr, strcmp, strlen, wcslen
  
  I checked the following names but these aren't actually called anywhere:
  strcpy, strncpy, strncmp, wcscmp
  
  I didn't touch these headers:
  <ext/__hash> uses strlen, safely
  <support/ibm/locale_mgmt_aix.h> uses memcpy, safely
  <string.h> uses memchr and strchr, safely
  <wchar.h> uses wcschr, safely
  <__bsd_locale_fallbacks.h> uses wcsnrtombs, safely

(2) [libc++] Add _VSTD:: qualifications to ADL-proof <algorithm>.

  
  Relevant blog post: https://quuxplusone.github.io/blog/2019/09/26/uglification-doesnt-stop-adl/

@ldionne: In the <algorithm> commit, I noticed that there are several places where otherwise-well-formed code has been commented out; e.g. look at the codepath in `__nth_element` following `not_sorted:`. The commented-out stuff dates back to @howard.hinnant's initial commit. Can I just remove the commented-out stuff, in a separate "NFC" commit?


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D92776

Files:
  libcxx/include/__hash_table
  libcxx/include/__locale
  libcxx/include/__string
  libcxx/include/algorithm
  libcxx/include/atomic
  libcxx/include/charconv
  libcxx/include/fstream
  libcxx/include/iterator
  libcxx/include/list
  libcxx/include/locale
  libcxx/include/string
  libcxx/include/strstream
  libcxx/include/vector
  libcxx/test/std/algorithms/robust_against_adl.pass.cpp

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