[ios,macos] Add Swift Sourcekit LSP support by cbracken · Pull Request #189761 · flutter/flutter

cbracken · 2026-07-21T04:32:17Z

This adds a post-processing pass to complie_commands.json that synthesizes the Swift entries that can be understood by SourceKit LSP and wires up the editor config needed to pick them up.

GN's --export-compile-commands only understands the built-in cc/cxx/objc/objcxx tool types, and doesn't yet have built-in support for injecting swiftc lines, so our custom swift tool (which invokes swiftc.py) never gets an entry there, meaning Swift code in the iOS and macOS embedders isn't indexed by SourceKit LSP and other tooling that reads that file.

Since GN's own compdb export omits the swift targets, _postGn() now shells out (once) to ninja -t compdb for the full compilation database (and falls back to the existing compile_commands.json on disk if that fails), then runs it through expandSwiftcCommands, which turns each swiftc.py-wrapped entry into one or more native swiftc invocations, one per compiled Swift file, with relative paths resolved to absolute against the entry's directory.

We drop -isystem and -Dkey=value flags since that's what swiftc.py does; swiftc only accepts boolean -D defines not key=value flags.

This scans the raw ninja output directly rather than decoding all of compile_commands.json, which can run past 20MB and is too slow to parse wholesale in Dart; only the small handful of matched swiftc.py entries get jsonDecoded -- fewer than 10 lines.

This also wires up .sourcekit-lsp/config.json and the swift.sourcekit-lsp.supported-languages setting in engine.code-workspace/engine-workspace.yaml so that VS Code's Swift extension correctly picks up the generated compdb.

Fixes #185741

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Code Review

This pull request adds support for native swiftc compilation commands in the compilation database by expanding GN swiftc.py wrapper invocations, and configures VS Code workspace settings to support Swift via SourceKit-LSP. Feedback on the changes includes removing accidentally pasted terminal progress output at the top of update_compdb.dart and appending .exe to the ninja executable path on Windows to prevent process execution failures.

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engine/src/flutter/tools/pkg/engine_build_configs/lib/src/update_compdb.dart (1-3)

It looks like a terminal command's progress output was accidentally pasted at the top of this file. This will cause compilation errors and should be removed.

engine/src/flutter/tools/pkg/engine_build_configs/lib/src/build_config_runner.dart (394-399)

On Windows, the ninja executable is named ninja.exe. We should append .exe when running on Windows to avoid process execution failures.

    final String ninjaPath = p.join(
      engineSrcDir.parent.parent.path,
      'third_party',
      'ninja',
      io.Platform.isWindows ? 'ninja.exe' : 'ninja',
    );

cbracken · 2026-07-21T12:50:37Z

Notes for reviewers:

The important things to know:

In the 21MB file, there are fewer than 10 lines that do swiftc.py commands (IIRC it's like 4), I actually expect that number to go down over time as we add more swift.
gn still has poor built-in swift support and doesn't emit the swiftc commands into compile-commands.json. We do JSON-decode the applicable lines but given there are fewer than 10, so the performance hit is negligible, unline for the clang++ commands (hence why @jtmcdole previously went for a regex for handling the RBE case).
Our swiftc build goes via a swiftc.py wrapper python script. Each invocation compiles all Swift files in a module (i.e. a gn source_set) together. But SourceKit LSP, like clangd, wants one one swiftc line per file so the point of this code is to translate that one line, all its crappy flags, and the list of all swift source files in a module into one swiftc line per source file (with the same set of crappy compiler flags).
Could I have used package:args for the flags parsing? Probably, but when I played with it, it added a dependency, and then doing the one-by-one flags translation ended up actually slightly more code than this. If you have ideas, I'm all ears. Fundamentally if gn ever implemnents full Swift support, this will all go away. This code handles that gracefully since it only operates on swiftc.py lines.

jtmcdole

lgtm, but some modern dart changes

jtmcdole

This adds a post-processing pass to `complie_commands.json` that synthesizes the Swift entries that can be understood by SourceKit LSP and wires up the editor config needed to pick them up. GN's `--export-compile-commands` only understands the built-in `cc`/`cxx`/`objc`/`objcxx` tool types, and doesn't yet have built-in support for injecting `swiftc` lines, so our custom `swift` tool (which invokes `swiftc.py`) never gets an entry there, meaning Swift code in the iOS and macOS embedders isn't indexed by SourceKit LSP and other tooling that reads that file. Since GN's own compdb export omits the swift targets, `_postGn()` now shells out (once) to `ninja -t compdb` for the full compilation database (and falls back to the existing `compile_commands.json` on disk if that fails), then runs it through `expandSwiftcCommands`, which turns each `swiftc.py`-wrapped entry into one or more native `swiftc` invocations, one per compiled Swift file, with relative paths resolved to absolute against the entry's `directory`. We drop `-isystem` and `-Dkey=value` flags since that's what `swiftc.py` does; swiftc only accepts boolean -D defines not key=value flags. This scans the raw ninja output directly rather than decoding all of `compile_commands.json`, which can run past 20MB and is too slow to parse wholesale in Dart; only the small handful of matched `swiftc.py` entries get `jsonDecode`d -- fewer than 10 lines. This also wires up `.sourcekit-lsp/config.json` and the `swift.sourcekit-lsp.supported-languages` setting in `engine.code-workspace`/`engine-workspace.yaml` so that VS Code's Swift extension correctly picks up the generated compdb. Fixes flutter#185741

jtmcdole

jtmcdole

jtmcdole · 2026-07-22T15:19:02Z

re-running flakey tests.

@mainactor

flutter/flutter@2a2a79d...b65f4d9 2026-07-24 jason-simmons@users.noreply.github.com Add dart_runtime_service_vm_aot.dart.snapshot to the snapshot list in the macOS code signing configuration (flutter/flutter#189981) 2026-07-24 engine-flutter-autoroll@skia.org Roll Fuchsia Test Scripts from wLST_A-xfOeGT_5mj... to E8hJ1AfK8CtGtaES0... (flutter/flutter#189956) 2026-07-23 chingjun@google.com Consolidate AndroidArch and DarwinArch into CpuArch (flutter/flutter#189315) 2026-07-23 engine-flutter-autoroll@skia.org Roll Dart SDK from 9258584f98b8 to e3fc57eae9eb (7 revisions) (flutter/flutter#189949) 2026-07-23 jason-simmons@users.noreply.github.com [flutter_tools] Do not always wait for the full timeout when running Spotlight to locate Android Studio on macOS (flutter/flutter#189952) 2026-07-23 engine-flutter-autoroll@skia.org Roll Skia from 1d8bf9270d8c to 6e9c4687c001 (15 revisions) (flutter/flutter#189954) 2026-07-23 jason-simmons@users.noreply.github.com [flutter_tools] Initialize Cache.flutterRoot at the start of the upgrade_test suite (flutter/flutter#189937) 2026-07-23 faheemabbas766@gmail.com Parse AndroidX property in gradle.properties (flutter/flutter#188372) 2026-07-23 60122246+xiaowei-guan@users.noreply.github.com [Impeller]Use the IO context for OpenGL program setup (flutter/flutter#185723) 2026-07-23 43089218+chika3742@users.noreply.github.com Allow building projects lacking Runner.xcworkspace (flutter/flutter#186239) 2026-07-23 bkonyi@google.com [flutter_tools] Invalidate WebEntrypointTarget when plugin set changes (flutter/flutter#189460) 2026-07-23 srawlins@google.com Bump devtools_shared to 13.1.0 (flutter/flutter#189507) 2026-07-23 matt.boetger@gmail.com forceNdkDownload should skip configuring cmake when ndk-build is used (flutter/flutter#187201) 2026-07-23 jason-simmons@users.noreply.github.com Disable execution order shuffling for the flutter_tools upgrade_test suite (flutter/flutter#189920) 2026-07-23 matej.knopp@gmail.com Move WindowManager outside of WidgetsApp (flutter/flutter#188866) 2026-07-23 engine-flutter-autoroll@skia.org Roll Skia from 3424966b8a2b to 1d8bf9270d8c (3 revisions) (flutter/flutter#189901) 2026-07-23 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from GswhlPRO-D1qSNclx... to 9org0yL3yZkp80x5S... (flutter/flutter#189898) 2026-07-23 116356835+AbdeMohlbi@users.noreply.github.com Remove outdated logs that were added to track #172636 (flutter/flutter#189282) 2026-07-23 engine-flutter-autoroll@skia.org Roll Skia from 5e183e5aeac5 to 3424966b8a2b (33 revisions) (flutter/flutter#189890) 2026-07-23 srawlins@google.com [examples] Use super parameters in missed spots (flutter/flutter#186194) 2026-07-23 bkonyi@google.com [flutter_tools] Bound Spotlight mdfind execution with timeout on macOS (flutter/flutter#189461) 2026-07-23 codedoctor@linwood.dev Fix non primary buttons not being captured on windows (flutter/flutter#188394) 2026-07-22 matt.boetger@gmail.com Listen to log reader before VM Service and make delay configurable (flutter/flutter#187202) 2026-07-22 engine-flutter-autoroll@skia.org Roll Dart SDK from 1e65011ee004 to 9258584f98b8 (7 revisions) (flutter/flutter#189883) 2026-07-22 30870216+gaaclarke@users.noreply.github.com Adds skill for generating engine diffs for new releases. (flutter/flutter#189869) 2026-07-22 chris@bracken.jp [ios,macos] Add Swift Sourcekit LSP support (flutter/flutter#189761) 2026-07-22 chris@bracken.jp [iOS] Mark DisplayLinkManager.shared and init() @mainactor (flutter/flutter#189815) 2026-07-22 97480502+b-luk@users.noreply.github.com Fix `Rect::ExpandToMinTransformedSize` to return the input rectangle when no expansion is needed, and remove 1-pixel roundrect to rect simplification (flutter/flutter#189808) 2026-07-22 15619084+vashworth@users.noreply.github.com Skip emulator.getEmulators test (flutter/flutter#189879) 2026-07-22 codedoctor@linwood.dev Fix null terminator in input truncates clipboard (flutter/flutter#188652) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC bmparr@google.com,stuartmorgan@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

flar · 2026-09-04T23:55:19Z

This change broke ccls in VSCode for me. It can no longer index the engine and provide accurate syntax highlighting or click-through-to-reference functions.

Previously, `_postGn` ran immediately after GN and rewrote GN's `compile_commands.json` in-place with the output of `ninja -t compdb` in order to pick up additional commands not emitted by `gn` but needed by language servers, such as `swiftc` invocations. However, `ninja -t compdb` includes every edge in the build graph, including copy and link commands, not just compiles. LSPs key off the `file` field, and the additional non-compile edges produced additional entries for some files that shadow the compile command that LSPs need. Among others, some of the public header copy rules ended up causing symbols in `embedder.h` and others to stop resolving correctly. This reverts the post-build rewriting of `compile-commands.json` to what it was before flutter#189761: just stripping RBE rewrapper prefxies from C++/Objective-C++ compile commands. The in-place rewriting is still required because `clang_tidy` and `clangd_check` use it directly and don't understand rewrapper prefixes. Once the in-place cleanup is done, we now run `ninja -t compdb swift` to get *just* the Swift compilation commands required rather than the whole graph, and tack those onto a new output at `lsp/compile-commands.json` which can be used by LSPs. This has the additional benefit of sticking around in case any tools (run_test.py for example) issue `gn` invocations directly, which stomps the compilation database. Followup to: flutter#189761 Fixes: flutter#185741

Previously, `_postGn` ran immediately after GN and rewrote GN's `compile_commands.json` in-place with the output of `ninja -t compdb` in order to pick up additional commands not emitted by `gn` but needed by language servers, such as `swiftc` invocations. However, `ninja -t compdb` includes every edge in the build graph, including copy and link commands, not just compiles. LSPs key off the `file` field, and the additional non-compile edges produced additional entries for some files that shadow the compile command that LSPs need. Among others, some of the public header copy rules ended up causing symbols in `embedder.h` and others to stop resolving correctly. This reverts the post-build rewriting of `compile-commands.json` to what it was before flutter#189761: just stripping RBE rewrapper prefxies from C++/Objective-C++ compile commands. The in-place rewriting is still required because `clang_tidy` and `clangd_check` use it directly and don't understand rewrapper prefixes. Once the in-place cleanup is done, we now run `ninja -t compdb swift` to get *just* the Swift compilation commands required rather than the whole graph, and tack those onto a new output at `lsp/compile-commands.json` which can be used by LSPs. This has the additional benefit of sticking around in case any tools (run_test.py for example) issue `gn` invocations directly, which stomps the compilation database. Followup to: flutter#189761 Fixes: flutter#185741  ## Pre-launch Checklist - [X] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [X] I read the [AI contribution guidelines] and understand my responsibilities, or I am not using AI tools. - [X] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [X] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [X] I signed the [CLA]. - [X] I listed at least one issue that this PR fixes in the description above. - [X] I updated/added relevant in-code documentation (doc comments with `///`). - [X] If this PR introduces a new feature or capability, I created and linked a website documentation issue or PR in [flutter/website] (or verified none is needed). - [X] I added new tests to check the change I am making, or this PR is [test-exempt]. - [X] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [X] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord]. If this change needs to override an active code freeze, provide a comment explaining why. The code freeze workflow can be overridden by code reviewers. See pinned issues for any active code freezes with guidance. **Note**: The Flutter team is currently trialing the use of [Gemini Code Assist for GitHub](https://developers.google.com/gemini-code-assist/docs/review-github-code). Comments from the `gemini-code-assist` bot should not be taken as authoritative feedback from the Flutter team. If you find its comments useful you can update your code accordingly, but if you are unsure or disagree with the feedback, please feel free to wait for a Flutter team member's review for guidance on which automated comments should be addressed.  [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [AI contribution guidelines]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#ai-contribution-guidelines [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [flutter/website]: https://github.com/flutter/website [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

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Remove some explicit types

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Update build tests

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Now with MORE TYPES to appease the linter

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Merge branch 'master' into add-sourcekit-support

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feat(web): support --web-content-hash for entrypoint files #190153

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et: Fix compile_commands.json post-processing #192395

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[ios,macos] Add Swift Sourcekit LSP support - #189761

[ios,macos] Add Swift Sourcekit LSP support#189761
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engine/src/flutter/tools/pkg/engine_build_configs/lib/src/update_compdb.dart (1-3)

engine/src/flutter/tools/pkg/engine_build_configs/lib/src/build_config_runner.dart (394-399)

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