Code action to add missing import declarations #2452

PhantomInTheWire · 2026-01-13T21:29:02Z

This PR implements a new code action, AddMissingImports, which provides quick fixes to automatically add import statements for unresolved types or values. It leverages the semantic index to identify defining modules and intelligently inserts the necessary imports into the source file.

Key Features

Automatically detects cannot find '...' in scope and cannot find type '...' in scope diagnostics.
Queries the semantic index to find which modules define the missing type or value.
Filtering strategy
- Filters out modules that are already imported in the current file.
- Excludes the current module to avoid self-imports.
Insertion Strategy:
- Inserts new imports after the last existing import statement if present.
- If no imports exist, inserts at the beginning of the file (after leading trivia/headers).
- Handles spacing and newlines correctly to maintain file formatting.
Sorting: Provides multiple suggestions sorted alphabetically by module name when a type is defined in multiple accessible modules.

ahoppen

Very nice. Left some thoughts inline.

Sources/SKTestSupport/SwiftPMTestProject.swift

Tests/SourceKitLSPTests/AddMissingImportsTests.swift

Sources/SwiftLanguageService/CodeActions/AddMissingImports.swift

…ic matching - Calculate proper import insertion position (after existing imports or file headers) - Filter out current module to avoid self-imports - Check diagnostic code first, fall back to string matching for robustness - Add helper functions: extractModuleName, importInsertionPosition, extractTypeName - Add Diagnostic.codeString extension for code extraction

Signed-off-by: Karan <[email protected]>

… build/indexing part is done Signed-off-by: Karan <[email protected]>

PhantomInTheWire · 2026-02-01T22:28:15Z

ping @ahoppen in case this got lost

ahoppen

Thanks for the ping, @PhantomInTheWire. I indeed missed this PR.

ahoppen · 2026-02-09T09:14:00Z

Sources/SwiftLanguageService/CodeActions/AddMissingImports.swift

+//
+//===----------------------------------------------------------------------===//
+
+internal import BuildServerIntegration


You can remove the internal access modifiers in this file.

ahoppen · 2026-02-09T09:15:01Z

Sources/SwiftLanguageService/CodeActions/AddMissingImports.swift

+    guard case .dictionary(let documentDict)? = dictionary[CodingKeys.textDocument.stringValue] else {
+      return nil
+    }
+    guard let textDocument = TextDocumentIdentifier(fromLSPDictionary: documentDict) else {
+      return nil
+    }


Suggested change

guard case .dictionary(let documentDict)? = dictionary[CodingKeys.textDocument.stringValue] else {

return nil

}

guard let textDocument = TextDocumentIdentifier(fromLSPDictionary: documentDict) else {

return nil

}

guard let textDocument = TextDocumentIdentifier(fromLSPAny: dictionary[CodingKeys.textDocument.stringValue]) else {

return nil

}

ahoppen · 2026-02-09T09:19:32Z

Sources/SwiftLanguageService/Diagnostic.swift


+    // If no educational note available, fall back to diagnostic ID (e.g., "cannot_find_in_scope")
+    if code == nil, let diagnosticID {
+      code = .string(diagnosticID)


The LSP documentation for code says

The diagnostic's code, which might appear in the user interface.

I don’t want to show the diagnostic IDs in the user interface, so I think we should store the diagnostic ID in the data dictionary.

ahoppen · 2026-02-09T09:21:20Z

Sources/SwiftLanguageService/CodeActions/AddMissingImports.swift

+    let relevantDiagnostics = request.context.diagnostics.filter(AddMissingImportsHelper.isMissingTypeOrValueDiagnostic)
+    guard !relevantDiagnostics.isEmpty else { return [] }
+
+    guard let buildSettings = await self.compileCommand(for: request.textDocument.uri, fallbackAfterTimeout: true),


We should only fall back to fallback build settings after timeout if we listen for updated build settings to refresh results (eg. for diagnostics). This isn’t the case here.

Suggested change

guard let buildSettings = await self.compileCommand(for: request.textDocument.uri, fallbackAfterTimeout: true),

guard let buildSettings = await self.compileCommand(for: request.textDocument.uri, fallbackAfterTimeout: false),

ahoppen · 2026-02-09T09:22:30Z

Sources/SwiftLanguageService/CodeActions/AddMissingImports.swift

+
+    guard
+      let workspace = await self.sourceKitLSPServer?.workspaceForDocument(uri: request.textDocument.uri),
+      let index = await workspace.index(checkedFor: .modifiedFiles)


Even if a file is modified, it’s reasonable to assume that the declarations within it are still the same, so we can relax the index check here a little bit.

Suggested change

let index = await workspace.index(checkedFor: .modifiedFiles)

let index = await workspace.index(checkedFor: .deletedFiles)

ahoppen · 2026-02-09T09:30:48Z

Sources/SwiftLanguageService/CodeActions/AddMissingImports.swift

+    if isSorted,
+      let insertBeforeImport = importDecls.first(where: { importDecl in
+        guard let firstPath = importDecl.path.first?.name.text else { return false }
+        return firstPath > newModule
+      })
+    {
+      return snapshot.position(of: insertBeforeImport.position)
+    } else if let lastImport = importDecls.last {
+      return snapshot.position(of: lastImport.endPosition)
+    }


I think we can always use the isSorted case here. That way we try and find some reasonable sorted-ish location even if a single import statement doesn’t match alphabetical order.

ahoppen · 2026-02-09T09:32:51Z

Sources/SwiftLanguageService/CodeActions/AddMissingImports.swift

+extension SwiftLanguageService {
+  /// Finds missing import code actions for diagnostics indicating unresolved symbols.
+  /// Exposed for unit testing.
+  package static func findMissingImports(


Am I blind or is this only called by tests? In which case we aren’t testing the actual implementation in the tests this one. I would have probably relied a lot more on tests that use SwiftPMTestProject instead of writing tests that exercise this alternate code path.

That being said, if you manage to write more unit-style tests with minimal amount of alternative code, that would of course be great.

ahoppen · 2026-02-09T09:34:01Z

Tests/SourceKitLSPTests/AddMissingImportsTests.swift

+    // This test relies on the index, so it needs to run where we can build and index.
+    try SkipUnless.longTestsEnabled()
+


I don’t think this test is any slower than other tests that we have, relying on the index. Generally a slow test is a test that takes more than 1 or 2 seconds to execute, which I’d be surprised if this one does. So, I’d remove this check.

ahoppen · 2026-02-09T09:34:40Z

Tests/SourceKitLSPTests/AddMissingImportsTests.swift

+      DocumentDiagnosticsRequest(textDocument: TextDocumentIdentifier(uri))
+    )
+    diagnostic = diags.fullReport?.items.first { $0.message.contains("LibStruct") }
+    XCTAssert(diagnostic != nil)


Not necessary because we XCTUnwrap below.

ahoppen · 2026-02-09T09:35:15Z

Tests/SourceKitLSPTests/AddMissingImportsTests.swift

+        [
+          uri: [
+            TextEdit(range: Range(positions["1️⃣"]), newText: "import Lib\n")
+          ]
+        ]


Suggested change

[

uri: [

TextEdit(range: Range(positions["1️⃣"]), newText: "import Lib\n")

]

]

[

uri: [TextEdit(range: Range(positions["1️⃣"]), newText: "import Lib\n")]

]

PhantomInTheWire requested review from ahoppen, hamishknight and rintaro as code owners January 13, 2026 21:29

ahoppen reviewed Jan 13, 2026

View reviewed changes

PhantomInTheWire added 15 commits January 17, 2026 01:31

Add imports initial implementation

0957084

Add unit tests for missing imports

ea9250c

Add integration tests for missing imports

eee70b7

Add 7 edge case regression tests for AddMissingImports

10a0aa4

Fix Diagnostic initializers in edge case tests

c291aa1

Fix test expectations for import insertion position

f25e07a

Expand diagnostic matching to handle cannot_find_type_in_scope

7a57b85

Refactor AddMissingImports Action

4832264

Add Doc Comments

56afdb7

Signed-off-by: Karan <[email protected]>

Bug Fixes

db2aeac

Signed-off-by: Karan <[email protected]>

Add addmissingimports.swift to cmake

b3ed63e

Refactor test infrastructure and Add Missing Imports unit tests

3f0ea01

Refactor Add Missing Imports core logic and diagnostic matching

4fc0485

Implement deferred computation pattern and update integration tests

135db1d

PhantomInTheWire force-pushed the feat/add-imports branch from 582c014 to 135db1d Compare January 16, 2026 20:03

PhantomInTheWire added 2 commits January 17, 2026 04:58

Remove polling from test since you can directly get diagnostics since…

e3caf26

… build/indexing part is done Signed-off-by: Karan <[email protected]>

Use positionmarkers in tests

039ed97

PhantomInTheWire changed the title ~~Add missing imports~~ Code action to add missing import declarations Jan 17, 2026

PhantomInTheWire added 4 commits January 18, 2026 04:11

Add imports after the header

56ad935

Fix Diagnostic code

198a2da

Unsorted imports fallback

7efe972

Simplify Imports

1657d49

PhantomInTheWire force-pushed the feat/add-imports branch from 6a8765a to 1657d49 Compare January 18, 2026 03:27

PhantomInTheWire requested a review from ahoppen January 18, 2026 03:36

ahoppen reviewed Feb 9, 2026

View reviewed changes

	guard let buildSettings = await self.compileCommand(for: request.textDocument.uri, fallbackAfterTimeout: true),
	guard let buildSettings = await self.compileCommand(for: request.textDocument.uri, fallbackAfterTimeout: false),

	let index = await workspace.index(checkedFor: .modifiedFiles)
	let index = await workspace.index(checkedFor: .deletedFiles)

		// This test relies on the index, so it needs to run where we can build and index.
		try SkipUnless.longTestsEnabled()

Code action to add missing import declarations #2452

Are you sure you want to change the base?

Code action to add missing import declarations #2452

Conversation

PhantomInTheWire commented Jan 13, 2026

Uh oh!

ahoppen left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

PhantomInTheWire commented Feb 1, 2026

Uh oh!

ahoppen left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants