[native_toolchain_c] Fix treeshaking on mac

[mosuem]

By creating a list of symbols to be exported.

Also needs to be tested with ICU4X, but manually setting this seems to do the trick to solve dart-lang/i18n#989

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[github-actions]

Package publishing

Package	Version	Status	Publish tag (post-merge)
package:code_assets	0.19.4	already published at pub.dev
package:data_assets	0.19.1	already published at pub.dev
package:ffi	2.1.5-wip	WIP (no publish necessary)
package:hooks	0.19.5	already published at pub.dev
package:hooks_runner	0.21.0	already published at pub.dev
package:native_doc_dartifier	0.0.1-pre	already published at pub.dev
package:native_toolchain_c	0.17.0	ready to publish	native_toolchain_c-v0.17.0
package:swift2objc	0.0.1-wip	WIP (no publish necessary)
package:swiftgen	0.0.1-wip	WIP (no publish necessary)

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[github-actions]

PR Health

Breaking changes ⚠️

Package	Change	Current Version	New Version	Needed Version	Looking good?
hooks_runner	Breaking	0.21.0	0.21.0	0.22.0 Got "0.21.0" expected >= "0.22.0" (breaking changes)	⚠️
native_toolchain_c	Breaking	0.16.8	0.17.0	0.17.0	✔️

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Changelog Entry ✔️

Package	Changed Files

Changes to files need to be accounted for in their respective changelogs.

API leaks ✔️

The following packages contain symbols visible in the public API, but not exported by the library. Export these symbols or remove them from your publicly visible API.

Package	Leaked API symbols

License Headers ✔️

// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
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Unrelated files missing license headers

Files
pkgs/jni/lib/src/third_party/generated_bindings.dart
pkgs/native_doc_dartifier/lib/native_doc_dartifier.dart
pkgs/native_doc_dartifier/lib/src/native_doc_dartifier_base.dart
pkgs/objective_c/lib/src/ns_input_stream.dart

[coveralls]

coverage: 87.096% (-3.4%) from 90.52%
when pulling 1b27f49 on fixTreeshakeMac
into 3481346 on main.

[dcharkes]

Probably needs a test of some sort

We have tests for binary sizes: pkgs/native_toolchain_c/test/clinker/treeshake_helper.dart Shouldn't pkgs/native_toolchain_c/test/clinker/treeshake_test.dart and pkgs/native_toolchain_c/test/clinker/treeshake_cross_test.dart already invoke those? Why aren't those tests failing before this PR?

[goderbauer]

This will need some sort of a test to verify that a symbol that previously wasn't treeshaken on macos is now removed.

[goderbauer]

We have tests for binary sizes: pkgs/native_toolchain_c/test/clinker/treeshake_helper.dart Shouldn't pkgs/native_toolchain_c/test/clinker/treeshake_test.dart and pkgs/native_toolchain_c/test/clinker/treeshake_cross_test.dart already invoke those?

Yes, those are getting invoked.

Why aren't those tests failing before this PR?

It seems like prior to this PR some symbols were already treeshaken. The existing tests are confirming that. But apparently it doesn't treeshake some other symbols marked as global. We'll need a specific new test for those cases.

[mosuem]

Probably needs a test of some sort - I am open for ideas.

I agree on the calls for a test ;) I'll figure out how to build one.

[dcharkes]

Probably needs a test of some sort - I am open for ideas.

I agree on the calls for a test ;) I'll figure out how to build one.

Are the global symbols visible with dlsym? If yes, we could do DynamicLibrary.open().providesSymbol https://api.flutter.dev/flutter/dart-ffi/DynamicLibrary/providesSymbol.html

Otherwise, maybe add a global symbol that holds on to stuff? E.g. like a very very very long const char*? (In the order of megabytes.)

[goderbauer]

LGTM

[dcharkes]

Great!

Please also roll it into the Dart SDK (setting up the required status file skips for Rust not being there on the CI) and the Flutter repo (Otherwise users get 0.16 instead of 0.17.)