mesonbuild/meson

Support b_lto with clang-cl and lld-link

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#13,095 opened on Apr 15, 2024

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OS:windowscompilersenhancementgood first issue

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Description

Describe the bug When using clang-cl and lld-link, b_lto is not recognized by meson.

$ meson configure -Db_lto=true

ERROR: Unknown options: "b_lto"

Expected behavior clang-cl and lld-link supporting link-time optimization, meson should be able to plug it in too.

system parameters

  • Windows 11, using CC=clang-cl; CXX=clang-cl (lld-link is set as the default linker)
  • Python 3.11.2
  • meson 1.4.0

Contributor guide

Research direction
First, understand how Meson currently supports b lto for other compilers (e.g., GCC, MSVC) by looking at the LTO detection logic in the source code (likely in mesonbuild/compilers/detect.py or similar). Then, add detection for clang cl and lld link, ensuring that the necessary flags (such as flto, /LTCG) are applied correctly. Finally, test the changes in a Windows environment with clang cl and lld link.
Tech stack
python
Domain
build system
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
PythonMesonLLVM/Clang
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55