protocolbuffers/protobuf

BUG: pkg-config metadata is incorrect on windows

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#20515 opened on Feb 28, 2025

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cmakehelp wantedwindows

Description

What version of protobuf and what language are you using? Version: v29.1 (but problem remains on main) Language: C++

What operating system (Linux, Windows, ...) and version?

windows

What runtime / compiler are you using (e.g., python version or gcc version)

VS2019

What did you do?

Build protobuf, try to use pkg-config metadata in dependent project

What did you expect to see

Build succeeds

What did you see instead?

LINK : fatal error LNK1181: cannot open input file 'upb.lib'

This is because the windows builds here have a non-default prefix (e.g. libprotobuf.lib instead of protobuf.lib), and so the linker invocation here

https://github.com/protocolbuffers/protobuf/blob/796e49f6ca82f763d1087d2ff7355d2f0d7b71b1/cmake/upb.pc.cmake#L9

is actually looking for the wrong library (upb.lib instead of the libupb.lib that gets installed). Since %INSTALL_PREFIX%\lib\pkgconfig\upb.pc gets installed by default, it should be correct.

Anything else we should know about your project / environment

The error does not appear with CMake, but there's several more pkg-config files that have the same problem AFAICT.

Contributor guide

Tech stack
ccpp
Domain
build systembackend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
basic cmakewindows build environmentpkg config basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
The issue is about the pkg config file `upb.pc.cmake` using an incorrect library name on Windows (expects `upb.lib` but installed as `libupb.lib`). To fix, check the cmake logic that generates the .pc file (likely in `cmake/upb.pc.cmake`) and ensure the library name uses the correct prefix (e.g., `${CMAKE SHARED LIBRARY PREFIX}`). Then verify all other pkg config files in the repository have the same issue and apply consistent fix.