[all-commits] [llvm/llvm-project] 21e16a: [clang][ABI] New C++20 module mangling scheme

[Nathan Sidwell via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 21e16ab6b8ddaccb70d2344bb35419e214a32ec9
      https://github.com/llvm/llvm-project/commit/21e16ab6b8ddaccb70d2344bb35419e214a32ec9
  Author: Nathan Sidwell <nathan at acm.org>
  Date:   2022-03-08 (Tue, 08 Mar 2022)

  Changed paths:
    M clang/include/clang/AST/Mangle.h
    M clang/lib/AST/Decl.cpp
    M clang/lib/AST/ItaniumMangle.cpp
    M clang/test/CXX/modules-ts/basic/basic.def.odr/p4/module.cpp
    M clang/test/CXX/modules-ts/basic/basic.def.odr/p4/module.cppm
    M clang/test/CXX/modules-ts/basic/basic.def.odr/p4/user.cpp
    M clang/test/CXX/modules-ts/basic/basic.link/p3.cppm
    M clang/test/CXX/modules-ts/codegen-basics.cppm
    A clang/test/CodeGenCXX/Inputs/cxx20-module-impl-1a.cpp
    A clang/test/CodeGenCXX/Inputs/cxx20-module-std-subst-2a.cpp
    A clang/test/CodeGenCXX/cxx20-module-decomp-1.cpp
    A clang/test/CodeGenCXX/cxx20-module-extern-1.cppm
    A clang/test/CodeGenCXX/cxx20-module-impl-1a.cpp
    A clang/test/CodeGenCXX/cxx20-module-nested-1.cppm
    A clang/test/CodeGenCXX/cxx20-module-nested-2.cppm
    A clang/test/CodeGenCXX/cxx20-module-part-1a.cpp
    A clang/test/CodeGenCXX/cxx20-module-part-1b.cpp
    A clang/test/CodeGenCXX/cxx20-module-part-1c.cpp
    A clang/test/CodeGenCXX/cxx20-module-std-subst-1.cppm
    A clang/test/CodeGenCXX/cxx20-module-std-subst-2b.cpp
    A clang/test/CodeGenCXX/cxx20-module-std-subst-2c.cpp
    A clang/test/CodeGenCXX/cxx20-module-sub-1a.cppm
    A clang/test/CodeGenCXX/cxx20-module-sub-1b.cppm
    A clang/test/CodeGenCXX/cxx20-module-tmpl-1.cppm

  Log Message:
  -----------
  [clang][ABI] New C++20 module mangling scheme

The existing module symbol mangling scheme turns out to be
undemangleable.  It is also desirable to switch to the
strong-ownership model as the hoped-for C++17 compatibility turns out
to be fragile, and we also now have a better way of controlling that.

The issue is captured on the ABI list at:
  https://github.com/itanium-cxx-abi/cxx-abi/issues/134

A document describing the issues and new mangling is at:
  https://drive.google.com/file/d/1qQjqptzOFT_lfXH8L6-iD9nCRi34wjft/view

This patch is the code-generation part.  I have a demangler too, but
that patch is based on some to-be-landed refactoring of the demangler.

The old mangling is unceremoniously dropped.  No backwards
compatibility, no deprectated old-mangling flag.  It was always
labelled experimental.  (Old and new manglings cannot be confused.)

Reviewed By: ChuanqiXu

Differential Revision: https://reviews.llvm.org/D118352