[all-commits] [llvm/llvm-project] fdc41e: [libc++] Implement LWG1203

[Louis Dionne via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: fdc41e11f9687a50c97e2a59663bf2d541ff5489
      https://github.com/llvm/llvm-project/commit/fdc41e11f9687a50c97e2a59663bf2d541ff5489
  Author: Louis Dionne <ldionne at apple.com>
  Date:   2020-09-22 (Tue, 22 Sep 2020)

  Changed paths:
    M libcxx/include/istream
    M libcxx/include/ostream
    A libcxx/test/std/input.output/iostream.format/input.streams/istream.rvalue/not_istreamable.verify.cpp
    M libcxx/test/std/input.output/iostream.format/input.streams/istream.rvalue/rvalue.pass.cpp
    R libcxx/test/std/input.output/iostream.format/output.streams/ostream.rvalue/CharT_pointer.pass.cpp
    A libcxx/test/std/input.output/iostream.format/output.streams/ostream.rvalue/not_ostreamable.verify.cpp
    A libcxx/test/std/input.output/iostream.format/output.streams/ostream.rvalue/rvalue.pass.cpp
    M libcxx/www/cxx2a_status.html

  Log Message:
  -----------
  [libc++] Implement LWG1203

Libc++ had an issue where nonsensical code like

  decltype(std::stringstream{} << std::vector<int>{});

would compile, as long as you kept the expression inside decltype in
an unevaluated operand. This turned out to be that we didn't implement
LWG1203, which clarifies what we should do in that case.

rdar://58769296