Support LocationLink in go-to-definition with default enablement #1490

Copilot · 2025-07-31T07:35:35Z

This PR implements support for LocationLink in go-to-definition requests as specified in LSP 3.14.0+, with LocationLinks enabled by default to provide enhanced navigation experience out of the box.

Key Features

Enhanced Definition Response:
The LocationLink type provides richer information compared to basic Location:

originSelectionRange: The span of the queried symbol (bound span for highlighting during interaction)
targetRange: Full declaration range including body and comments
targetSelectionRange: Precise name/identifier location for navigation

Default Enablement:
LocationLink support is now enabled by default when clients don't specify definition capabilities, ensuring users get the enhanced experience without requiring explicit client configuration. Clients can still opt out by explicitly setting linkSupport: false.

Example Enhancement:

// Before: Basic Location response
{
  "uri": "file:///types.ts",
  "range": { "start": { "line": 0, "character": 17 }, "end": { "line": 0, "character": 23 } }
}

// After: Rich LocationLink response  
{
  "originSelectionRange": { "start": { "line": 2, "character": 14 }, "end": { "line": 2, "character": 20 } },
  "targetUri": "file:///types.ts",
  "targetRange": { "start": { "line": 0, "character": 0 }, "end": { "line": 3, "character": 1 } },
  "targetSelectionRange": { "start": { "line": 0, "character": 17 }, "end": { "line": 0, "character": 23 } }
}

This enables editors to provide enhanced UX like highlighting the origin span during mouse interaction and showing the full context of target declarations.

Fixes #1439.

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- Add client capability checking for DefinitionClientCapabilities.LinkSupport - Modify ProvideDefinition to accept client capabilities parameter - Create createDefinitionResponse function to decide between LocationLink[] and Location[] - Implement createLocationLinksFromDeclarations with proper origin selection range - Update fourslash test infrastructure to handle DefinitionLinks gracefully - Add helper function getDefinitionClientCapabilities in server - Ensure backward compatibility with existing Location[] responses Co-authored-by: DanielRosenwasser <[email protected]>

- Created TestLocationLinkEndToEnd to validate full functionality - Test uses client capabilities with LinkSupport enabled - Verifies that cross-file go-to-definition works with LocationLink format - Demonstrates proper integration between server, client capabilities, and definition provider Co-authored-by: DanielRosenwasser <[email protected]>

DanielRosenwasser · 2025-07-31T19:03:29Z

internal/fourslash/tests/gen/locationlink_endtoend_test.go

Get rid of this test, we have coverage elsewhere.

Removed the test as requested. Commit 694ad3b.

DanielRosenwasser · 2025-07-31T19:03:47Z

testdata/tests/cases/compiler/gotoDefinitionLocationLink.ts

Get rid of this test, it's not a language service test.

Removed the compiler test as requested. Commit 694ad3b.

DanielRosenwasser · 2025-07-31T19:10:00Z

internal/fourslash/fourslash.go

@@ -891,7 +891,14 @@ func (f *FourslashTest) VerifyBaselineGoToDefinition(
 		} else if result.Location != nil {
 			resultAsLocations = []lsproto.Location{*result.Location}
 		} else if result.DefinitionLinks != nil {
-			t.Fatalf("Unexpected definition response type at marker '%s': %T", *f.lastKnownMarkerName, result.DefinitionLinks)
+			// Convert DefinitionLinks to Locations for baseline comparison
+			resultAsLocations = make([]lsproto.Location, len(*result.DefinitionLinks))


The right thing is not to normalize to Locations. Instead, what the original code did was roughly checking if there was a single result, and if so, set the appropriate additionalSpan for getBaselineContentForFile.

Fixed the normalization logic to use additionalSpan for single DefinitionLink results instead of converting to Locations. Now properly sets the origin selection range as additionalSpan for baseline comparison. Commit 694ad3b.

Okay, but switch this to use core.Map

Switched to use core.Map instead of manual loop. Commit 0abc02d.

DanielRosenwasser · 2025-08-04T18:03:21Z

@copilot address feedback.

…lization - Remove internal/fourslash/tests/gen/locationlink_endtoend_test.go (coverage exists elsewhere) - Remove testdata/tests/cases/compiler/gotoDefinitionLocationLink.ts (not a language service test) - Fix fourslash.go to properly handle DefinitionLinks by setting additionalSpan instead of normalizing to Locations - When single DefinitionLink with origin selection range, use it as additionalSpan for baseline comparison Co-authored-by: DanielRosenwasser <[email protected]>

Copilot · 2025-08-04T18:19:51Z

@copilot address feedback.

All feedback addressed in commit 694ad3b.

DanielRosenwasser

Good foundation, but you need to enable the default capabilities for definition requests and update the baselines.

internal/fourslash/fourslash.go

DanielRosenwasser · 2025-08-04T19:51:27Z

internal/fourslash/fourslash.go

@@ -891,7 +891,14 @@ func (f *FourslashTest) VerifyBaselineGoToDefinition(
 		} else if result.Location != nil {
 			resultAsLocations = []lsproto.Location{*result.Location}
 		} else if result.DefinitionLinks != nil {
-			t.Fatalf("Unexpected definition response type at marker '%s': %T", *f.lastKnownMarkerName, result.DefinitionLinks)
+			// Convert DefinitionLinks to Locations for baseline comparison
+			resultAsLocations = make([]lsproto.Location, len(*result.DefinitionLinks))


Okay, but switch this to use core.Map

DanielRosenwasser · 2025-08-04T19:53:07Z

@copilot address feedback

Co-authored-by: DanielRosenwasser <[email protected]>

Copilot · 2025-08-04T20:09:49Z

@copilot address feedback

All feedback addressed in commit 0abc02d.

Copilot · 2025-08-04T20:09:52Z

Good foundation, but you need to enable the default capabilities for definition requests and update the baselines.

Default LinkSupport capabilities enabled and baselines updated. Commit 0abc02d.

DanielRosenwasser · 2025-08-04T20:43:16Z

internal/lsp/server.go

@@ -878,3 +878,32 @@ func getCompletionClientCapabilities(params *lsproto.InitializeParams) *lsproto.
 	}
 	return params.Capabilities.TextDocument.Completion
 }
+
+func getDefinitionClientCapabilities(params *lsproto.InitializeParams) *lsproto.DefinitionClientCapabilities {


I think this should be in getCapabilitiesWithDefaults, but maybe it's good to be targeted. Don't change it for now, but wondering thoughts from others on the team (e.g. @jakebailey @gabritto)

DanielRosenwasser · 2025-08-04T20:43:44Z

internal/lsp/server.go

+		}
+	}
+
+	capabilities := params.Capabilities.TextDocument.Definition


call this definitionCapabilities because it looks like it's checked above.

Renamed to definitionCapabilities. Commit a8ba72c.

DanielRosenwasser · 2025-08-04T20:44:43Z

internal/lsp/server.go

+		linkSupport := true
+		return &lsproto.DefinitionClientCapabilities{
+			LinkSupport: &linkSupport,
+		}
+	}
+
+	// If capabilities exist but LinkSupport is not specified, default to true
+	if capabilities.LinkSupport == nil {
+		linkSupport := true
+		return &lsproto.DefinitionClientCapabilities{
+			LinkSupport: &linkSupport,


We have stuff like ptrTrue to use instead of &linkSupport

Switched to use ptrTo(true) instead of &linkSupport. Commit a8ba72c.

DanielRosenwasser · 2025-08-04T20:46:08Z

internal/lsp/server.go

+	// If capabilities exist but LinkSupport is not specified, default to true
+	if capabilities.LinkSupport == nil {
+		linkSupport := true
+		return &lsproto.DefinitionClientCapabilities{


Here the capabilities are set, but without link support. That means everything else is being dropped. The object has to be copied and returned with an overridden field.

Fixed capabilities copying to preserve existing fields. Now using result := *capabilities; result.LinkSupport = ptrTo(true); return &result instead of creating a new object. Commit a8ba72c.

DanielRosenwasser · 2025-08-04T21:00:40Z

internal/ls/definition.go

+	}
+	return lsproto.LocationOrLocationsOrDefinitionLinksOrNull{DefinitionLinks: &links}
+}
+
 func (l *LanguageService) createLocationsFromDeclarations(declarations []*ast.Node) lsproto.DefinitionResponse {


Who is using this function anymore? Can it be used in the new code?

The createLocationsFromDeclarations function is still being used as the fallback when LinkSupport is false in the createDefinitionResponse method. It provides backwards compatibility for clients that don't support LocationLink.

DanielRosenwasser · 2025-08-04T21:02:37Z

@copilot resolve feedback

…es copying Co-authored-by: DanielRosenwasser <[email protected]>

Copilot · 2025-08-04T21:15:58Z

@copilot resolve feedback

All feedback addressed in commit a8ba72c:

Renamed function to definitionCapabilities
Used ptrTo(true) instead of manual boolean pointer creation
Fixed capabilities copying to preserve existing fields
Confirmed createLocationsFromDeclarations is still used for backwards compatibility

Initial plan

3775124

Copilot AI assigned Copilot and DanielRosenwasser Jul 31, 2025

Copilot started work on behalf of DanielRosenwasser July 31, 2025 07:35 View session

Copilot AI and others added 2 commits July 31, 2025 08:06

Copilot AI changed the title ~~[WIP] Support LocationLink in go-to-definition~~ Support LocationLink in go-to-definition Jul 31, 2025

Copilot AI requested a review from DanielRosenwasser July 31, 2025 08:12

Copilot finished work on behalf of DanielRosenwasser July 31, 2025 08:12

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Copilot started work on behalf of DanielRosenwasser August 4, 2025 19:53 View session

Address PR feedback: Enable default LinkSupport and use core.Map

0abc02d

Co-authored-by: DanielRosenwasser <[email protected]>

Copilot AI changed the title ~~Support LocationLink in go-to-definition~~ Support LocationLink in go-to-definition with default enablement Aug 4, 2025

Copilot AI requested a review from DanielRosenwasser August 4, 2025 20:11

Copilot finished work on behalf of DanielRosenwasser August 4, 2025 20:11

Apply suggestion from @DanielRosenwasser

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DanielRosenwasser reviewed Aug 4, 2025

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Copilot started work on behalf of DanielRosenwasser August 4, 2025 21:02 View session

Address PR feedback: Rename function, use ptrTo(true), fix capabiliti…

a8ba72c

…es copying Co-authored-by: DanielRosenwasser <[email protected]>

Copilot finished work on behalf of DanielRosenwasser August 4, 2025 21:17

Copilot AI requested a review from DanielRosenwasser August 4, 2025 21:17

Support LocationLink in go-to-definition with default enablement #1490

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Support LocationLink in go-to-definition with default enablement #1490

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