[all-commits] [llvm/llvm-project] 04f519: [llvm] annotate interfaces in Demangle for DLL exp...

[Andrew Rogers via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 04f5198e3ecb5592cec3297a782b8179f95434bf
      https://github.com/llvm/llvm-project/commit/04f5198e3ecb5592cec3297a782b8179f95434bf
  Author: Andrew Rogers <andrurogerz at gmail.com>
  Date:   2025-07-24 (Thu, 24 Jul 2025)

  Changed paths:
    M libcxxabi/src/demangle/DemangleConfig.h
    M libcxxabi/src/demangle/ItaniumDemangle.h
    M llvm/include/llvm/Demangle/Demangle.h
    M llvm/include/llvm/Demangle/DemangleConfig.h
    M llvm/include/llvm/Demangle/ItaniumDemangle.h
    M llvm/include/llvm/Demangle/MicrosoftDemangle.h
    M llvm/include/llvm/Demangle/MicrosoftDemangleNodes.h

  Log Message:
  -----------
  [llvm] annotate interfaces in Demangle for DLL export (#147564)

## Purpose

This patch is one in a series of code-mods that annotate LLVM’s public
interface for export. This patch annotates the `Demangle` interface with
a new `DEMANGLE_ABI` annotation, which behaves like the `LLVM_ABI`. This
annotation currently has no meaningful impact on the LLVM build;
however, it is a prerequisite to support an LLVM Windows DLL (shared
library) build.

## Overview

1. Add a new `Demangle/Visibility.h` header file that defines a new
`DEMANGLE_ABI` macro. The macro resolves to the proper DLL export/import
annotation on Windows and a "default" visibility annotation elsewhere.
2. Add a new `LLVM_ENABLE_DEMANGLE_EXPORT_ANNOTATIONS ` `#cmakedefine`
that is used to gate the definition of `DEMANGLE_ABI`.
3. Code-mod annotate the public `Demangle` interface using the
[Interface Definition Scanner (IDS)](https://github.com/compnerd/ids)
tool.
4. Manually fix-up `#include` statements for consistency.
5. Format the changes with `clang-format`.
6. Add a "stub" version of `Visibility.h` under `libcxxabi/src/demangle`
that always defines `DEMANGLE_ABI` to nothing.
7. Update the canonical `libcxxabi/src/demangle/ItaniumDemangle.h`
instead of the llvm copy, and run `cp-to-llvm.sh` to ensure the llvm
copy matches. NOTE: we rely on `ccp-to-llvm.sh` not copying
`Visibillity.h` as is already the case for `DemangleConfig.h`.

## Background

This PR follows the pattern established with the `llvm-c` changes made
in #141701.

This effort is tracked in #109483. Additional context is provided in
[this
discourse](https://discourse.llvm.org/t/psa-annotating-llvm-public-interface/85307),
and documentation for `LLVM_ABI` and related annotations is found in the
LLVM repo
[here](https://github.com/llvm/llvm-project/blob/main/llvm/docs/InterfaceExportAnnotations.rst).

## Validation

Local builds and tests to validate cross-platform compatibility. This
included llvm, clang, and lldb on the following configurations:

- Windows with MSVC
- Windows with Clang
- Linux with GCC
- Linux with Clang
- Darwin with Clang

---------

Co-authored-by: Louis Dionne <ldionne.2 at gmail.com>



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