CMake/meson fixes, Windows support for shared lib build #1225

BalkanMadman · 2025-11-01T17:08:22Z

Hello!

We've been packaging QuickJS-ng in Gentoo and we've found meson to be the most versatile amongst the added build systems. Huge thanks for taking care of QuickJS and implementing modern build systems -- it makes the life of us, packagers, much much easier.

This PR bundles two simple fixes for meson.build

meson.build

BalkanMadman · 2025-11-04T19:22:06Z

As far as I'm aware, the CI failures are not caused by these changes

BalkanMadman · 2025-11-18T17:06:21Z

Ping. Any updates?

saghul · 2025-11-18T19:29:37Z

I've triggered the CI again. IIRC the failures were directly related to this change, but let's see.

bnoordhuis · 2025-11-18T19:29:48Z

I'm fine with this change. @saghul?

edit: cross-wired

BalkanMadman · 2025-11-19T01:22:13Z

I've been going through CI and stumbled upon this: https://github.com/quickjs-ng/quickjs/actions/runs/19475324220/job/55744866380?pr=1225#step:7:42

meson.build:624: WARNING: Trying to use ['address', 'undefined'] sanitizer on Clang with b_lundef.

BalkanMadman · 2025-11-19T01:22:35Z

I can reproduce the failure on my machine too (albeit with clang only).

BalkanMadman · 2025-11-19T01:25:23Z

https://github.com/google/sanitizers/wiki/AddressSanitizer#faq:

Q: When I link my shared library with -fsanitize=address, it fails due to some undefined ASan symbols (e.g. asan_init_v4)?

A: Most probably you link with -Wl,-z,defs or -Wl,--no-undefined. These flags don't work with ASan unless you also use -shared-libasan (which is the default mode for GCC, but not for Clang).

BalkanMadman · 2025-11-19T01:25:58Z

Meson option b_lundef defaults to true, e.g. -Wl,--no-undefined is added to CFLAGS.

BalkanMadman · 2025-11-19T01:42:01Z

Passing -shared-libasan seems to fix the error.

BalkanMadman · 2025-11-19T02:35:37Z

Should fix the CI.

saghul · 2025-11-19T11:08:06Z

Yeah so as I said, the meson CI needs updating now to statically link by default.

BalkanMadman · 2025-11-21T20:09:24Z

Would you like to me to do the CI update (including the fix for the failing CI for this PR) in this PR or separately?

saghul · 2025-11-21T20:33:59Z

Would you like to me to do the CI update (including the fix for the failing CI for this PR) in this PR or separately?

In this PR please, we like to avoid merging failing PRs.

BalkanMadman · 2025-11-22T21:41:09Z

Would you like to me to do the CI update (including the fix for the failing CI for this PR) in this PR or separately?

In this PR please, we like to avoid merging failing PRs.

Your release CI builds QuickJS-NG with CMake so this PR shouldn't affect that. ~~The PR already contains a fix for PR CI.~~ My apologies, screwed up the quoting

BalkanMadman · 2025-11-22T22:05:42Z

Apparently, for MSVC CI, we're hitting mesonbuild/meson#13892. Will add a commit forcing MSVC-based builds to use static libs.

bnoordhuis · 2025-12-20T18:53:28Z

@BalkanMadman ping, seems this was close to done?

BalkanMadman · 2025-12-24T06:30:05Z

Hello! Sorry for the delay, could you please try running the CI again? The two new commits should fix two issues in building QuickJS-NG shared.

quickjs.h

BalkanMadman · 2025-12-24T09:09:16Z

Okay, I also need to guard all the dll{export,import} shenanigans if we're building static libqjs🔥🔥🔥

Because obviously just exporting symbols isn't enough and on Windows you need separate exports for DLLs and static libs👍

saghul · 2025-12-24T12:25:12Z

Not sure I get the unconditional define in quickjs.c. Shouldn't it be set by Meson depending on the build type?

saghul · 2025-12-26T11:53:58Z

Looks like there are conflicts, can you rebase?

bnoordhuis · 2026-02-01T13:42:58Z

CMakeLists.txt

+    # We shouldn't really support building examples with static qjs..
+    # Anyways, this is required for fib.so and point.so to link properly.


Suggested change

# We shouldn't really support building examples with static qjs..

# Anyways, this is required for fib.so and point.so to link properly.

# Required for fib.so and point.so to link properly.

Because why shouldn't we support it?

That's a good question, you're right. I'll adjust the check.

Completely revamped the check. Since runtime modules shouldn't link to qjs directly but rather use its symbols at runtime, I added an INTERFACE library for modules in CMake and the same dep in meson.

quickjs-libc.h

quickjs.h

BalkanMadman · 2026-02-01T21:02:45Z

All suggestions applied. Will test the JS_MODULE_EXTERN commit on Windows right now.

BalkanMadman · 2026-02-01T22:19:17Z

Oh yes the classic "our platform is crippled and we can't resolve symbols at runtime".

Previously, irrespective of the setting of -Dlibc, quickjs-libc would be built as a static library. In case -Dlibc=true is set, the static library is linked in libqjs only. In case -Dlibc=false is set, the archive is linked to every quickjs-libc consumer. In the former case (-Dlibc=true), building quickjs-libc as static library introduces useless indirection, since quickjs-libc is going to be linked only to libqjs anyway. CMake just adds the libc's sources to qjs's and calls it a day. This commit changes meson.build. If -Dlibc=true is set, quickjs-libc's sources are compiled as a part of libqjs. If not, it compiled as a static library, as was done before. In both cases, a direct dependency of quickjs-libc has been changed into a `dependency` on qjs_libc_dep which conveniently abstracts both configuration. So, if quickjs-libc needs to be linked to, just add `dependencies: qjs_libc_dep`. Signed-off-by: Zurab Kvachadze <zurabid2016@gmail.com>

Previously, if QJS_BUILD_LIBC was false, quickjs-libc would be built with every consumer. This made it harder to specify and trace the dependencies/compiler definitions of quickjs-libc itself. With this change, if -DQJS_BUILD_LIBC=false is passed to CMake, quickjs-libc is built as a normal static library, with its own compiler definitions and dependencies. This changes CMake to match the Meson behaviour. Additionally, since CMake does not allow mixing keyword and non-keyword declarations, this commit adds explicit `PRIVATE` to all `target_link_libraries` declarations. Signed-off-by: Zurab Kvachadze <zurabid2016@gmail.com>

BalkanMadman · 2026-02-03T17:32:41Z

Okay, restored the old behaviour of linking to qjs on Windows, should be okay now.

bnoordhuis · 2026-02-04T21:09:22Z

There's still a windows-mingw-shared build error:

cmake --build build -j 4
ninja: error: build.ninja:312: multiple rules generate libqjs.dll.a

BalkanMadman · 2026-02-05T19:20:44Z

Well, that's a new one. I gotta look through CMakeLists.txt again.

BalkanMadman · 2026-02-08T20:29:13Z

Figured it out: both libqjs and qjs export symbols with implib having the same name which trips Ninja. Should be fixed now.

Copilot

Pull request overview

Updates QuickJS-NG’s public headers and build scripts (Meson/CMake) to better support Windows DLL builds and consistent symbol export/import behavior across the core library, libc, and binary modules.

Changes:

Introduces platform/compiler-aware JS_EXTERN/JS_LIBC_EXTERN/JS_MODULE_EXTERN macros and updates module/libc headers and examples to use them.
Refactors Meson and CMake builds to separate cutils.c into its own library and adjusts link/dependency wiring for shared builds and Windows modules.
Tweaks CI Meson sanitizer configurations to disable undefined-symbol enforcement in certain Clang sanitizer jobs.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
`quickjs.h`	Adds export/import and module/libc extern macros for Windows/shared builds.
`quickjs-libc.h`	Switches libc API declarations to `JS_LIBC_EXTERN`.
`meson.build`	Refactors build graph (new `cutils` lib), adds shared/DLL compile defs, adjusts dependencies and pkg-config flags.
`examples/fib.c`	Uses `<quickjs.h>` and `JS_MODULE_EXTERN` for module entrypoint.
`examples/point.c`	Uses `<quickjs.h>` and `JS_MODULE_EXTERN` for module entrypoint.
`examples/meson.build`	Updates module build dependencies to use `qjs_module_dep` and hidden visibility.
`CMakeLists.txt`	Refactors build graph (new `cutils` lib), adds shared/DLL compile defs, introduces module interface target.
`.github/workflows/ci.yml`	Adds `-Db_lundef=false` to certain Meson Clang sanitizer modes.

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quickjs.h

meson.build

CMakeLists.txt

saghul · 2026-02-09T09:50:31Z

Ops, I clicked the copilot button by mistake! It did have some interesting things to say though!

Since the macros like JS_EXTERN are used in more than one place, it is quite reasonable and helpful to declare them in one place. Additionally, the Windows support with the __declspec tango was missing. This commit, in addition to reorganising definitions, also plumbs Windows support for JS_EXTERN and JS_LIBC_EXTERN. Signed-off-by: Zurab Kvachadze <zurabid2016@gmail.com>

The new macro is a counterpart to JS_EXTERN, but for binary C modules. This commit introduces one more preprocessor define that must be set when building C modules. This commit changes examples/fib.c and examples/point.c to use the new macro, while also removing redundant JS_SHARED_LIBRARY. Additionally, the includes use the angled brackets now since quickjs.h is supposed to be external to the binary modules. meson.build is fixed to properly add the include directory; the manual header copying has also been removed as it is redundant. Signed-off-by: Zurab Kvachadze <zurabid2016@gmail.com>

Clang cannot handle building shared libraries with sanitizers and -Wl,--no-undefined (set by default unless explicitly disabled with -Db_lundef=false). This commit prefixes CI in case shared libraries are built with sanitisers. Signed-off-by: Zurab Kvachadze <zurabid2016@gmail.com>

During the build, the default library can be overridden via the -Ddefault_library=type flag. Presetting this key in meson.build makes life harder for distributions which almost always want to build shared libraries. Those requiring static libraries can always force that via the aforementioned flag. Signed-off-by: Zurab Kvachadze <zurabid2016@gmail.com>

bnoordhuis

LGTM at a quick glance. Thanks!

saghul

LGTM, nice work!

BalkanMadman · 2026-02-09T20:23:47Z

Thank you!

saghul reviewed Nov 1, 2025

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saghul merged commit f2f5843 into quickjs-ng:master Feb 9, 2026
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saghul mentioned this pull request Feb 9, 2026

Added libonly option to meson #1310

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BalkanMadman deleted the meson-fixes branch February 9, 2026 13:37

		# We shouldn't really support building examples with static qjs..
		# Anyways, this is required for fib.so and point.so to link properly.

	# We shouldn't really support building examples with static qjs..
	# Anyways, this is required for fib.so and point.so to link properly.
	# Required for fib.so and point.so to link properly.

CMake/meson fixes, Windows support for shared lib build #1225

CMake/meson fixes, Windows support for shared lib build #1225

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