Respect configured TypeScript diagnostic locale

internal/ls/lsutil/userpreferences.go

@@ -176,6 +176,7 @@ type UserPreferences struct {
 	DisableLineTextInReferences core.Tristate `raw:"disableLineTextInReferences"` // !!!
 	DisplayPartsForJSDoc        core.Tristate `raw:"displayPartsForJSDoc"`        // !!!
 	ReportStyleChecksAsWarnings core.Tristate `raw:"reportStyleChecksAsWarnings" config:"reportStyleChecksAsWarnings"`
+	Locale                      string        `config:"locale"`
 
 	// ------- ATA -------
 

internal/ls/lsutil/userpreferences_test.go

@@ -424,6 +424,21 @@ func TestUserPreferencesParseUnstable(t *testing.T) {
 	}
 }
 
+func TestUserPreferencesLocale(t *testing.T) {
+	t.Parallel()
+
+	prefs := ParseUserPreferences(map[string]any{
+		"typescript": map[string]any{
+			"locale": "de",
+		},
+		"js/ts": map[string]any{
+			"locale": "fr",
+		},
+	})
+
+	assert.Equal(t, prefs.Locale, "fr")
+}
+
 func TestUserPreferencesReportStyleChecksAsWarnings(t *testing.T) {
 	t.Parallel()
 

internal/lsp/server.go

@@ -176,7 +176,11 @@ type Server struct {
 	initializationOptions *lsproto.InitializationOptions
 	clientCapabilities    lsproto.ResolvedClientCapabilities
 	positionEncoding      lsproto.PositionEncodingKind
+	localeMu              sync.RWMutex
 	locale                locale.Locale
+	// initLocale is the locale resolved from the initialize request; it is
+	// used as the fallback when the user's locale preference is "auto".
+	initLocale locale.Locale
 
 	watchEnabled     bool
 	telemetryEnabled bool
@@ -362,6 +366,28 @@ func (s *Server) ProgressFinish(message *diagnostics.Message, args ...any) {
 	}
 }
 
+// GetLocale implements project.Client.
+func (s *Server) GetLocale() locale.Locale {
+	s.localeMu.RLock()
+	defer s.localeMu.RUnlock()
+	return s.locale
+}
+
+// SetLocale implements project.Client.
+func (s *Server) SetLocale(localeString string) {
+	newLocale := s.initLocale
+	if localeString != "auto" {
+		parsed, ok := locale.Parse(localeString)
+		if !ok {
+			return
+		}
+		newLocale = parsed
+	}
+	s.localeMu.Lock()
+	s.locale = newLocale
+	s.localeMu.Unlock()
+}
+
 func (s *Server) RequestConfiguration(ctx context.Context) (lsutil.UserPreferences, error) {
 	caps := lsproto.GetClientCapabilities(ctx)
 	if !caps.Workspace.Configuration {
@@ -539,7 +565,7 @@ func (s *Server) dispatchLoop(ctx context.Context) error {
 		}
 
 		s.lastRequestTimeMs.Store(time.Now().UnixMilli())
-		requestCtx := locale.WithLocale(ctx, s.locale)
+		requestCtx := locale.WithLocale(ctx, s.GetLocale())
 		var cancel context.CancelFunc
 		if req.ID != nil {
 			requestCtx, cancel = context.WithCancel(core.WithRequestID(requestCtx, req.ID.String()))
@@ -1057,6 +1083,7 @@ func (s *Server) handleInitialize(ctx context.Context, params *lsproto.Initializ
 	if s.initializeParams.Locale != nil {
 		s.locale, _ = locale.Parse(*s.initializeParams.Locale)
 	}
+	s.initLocale = s.locale
 
 	if s.startWatchdog != nil && params.ProcessId.Integer != nil {
 		s.startWatchdog(int(*params.ProcessId.Integer))
@@ -1254,7 +1281,6 @@ func (s *Server) handleInitialized(ctx context.Context, params *lsproto.Initiali
 			TelemetryEnabled:       enableTelemetry,
 			DebounceDelay:          500 * time.Millisecond,
 			PushDiagnosticsEnabled: !disablePushDiagnostics,
-			Locale:                 s.locale,
 		},
 		FS:          s.fs,
 		Logger:      s.logger,

internal/project/client.go

@@ -4,6 +4,7 @@ import (
 	"context"
 
 	"github.com/microsoft/typescript-go/internal/diagnostics"
+	"github.com/microsoft/typescript-go/internal/locale"
 	"github.com/microsoft/typescript-go/internal/lsp/lsproto"
 )
 
@@ -18,4 +19,8 @@ type Client interface {
 	ProgressFinish(message *diagnostics.Message, args ...any)
 	SendTelemetry(ctx context.Context, telemetry lsproto.TelemetryEvent) error
 	IsActive() bool
+	// SetLocale updates the locale used for diagnostic messages.
+	SetLocale(locale string)
+	// GetLocale returns the current display locale for diagnostic messages.
+	GetLocale() locale.Locale
 }

internal/project/extendedconfigcache_test.go

@@ -7,6 +7,7 @@ import (
 
 	"github.com/microsoft/typescript-go/internal/bundled"
 	"github.com/microsoft/typescript-go/internal/diagnostics"
+	"github.com/microsoft/typescript-go/internal/locale"
 	"github.com/microsoft/typescript-go/internal/lsp/lsproto"
 	"github.com/microsoft/typescript-go/internal/project/logging"
 	"github.com/microsoft/typescript-go/internal/tsoptions"
@@ -44,6 +45,10 @@ func (noopClient) SendTelemetry(ctx context.Context, telemetry lsproto.Telemetry
 
 func (noopClient) IsActive() bool { return true }
 
+func (noopClient) GetLocale() locale.Locale { return locale.Default }
+
+func (noopClient) SetLocale(locale string) {}
+
 // TestExtendedConfigCacheOwnership tests the invariant that each ExtendedSourceFile
 // of a config in the ConfigFileRegistry is owned exactly once per snapshot that
 // references it, and released exactly once when that snapshot is removed.

internal/project/session.go

@@ -62,7 +62,6 @@ type SessionOptions struct {
 	TelemetryEnabled       bool
 	PushDiagnosticsEnabled bool
 	DebounceDelay          time.Duration
-	Locale                 locale.Locale
 	CheckerPoolOptions     CheckerPoolOptions
 }
 
@@ -268,6 +267,17 @@ func (s *Session) Config() lsutil.UserPreferences {
 	return s.workspaceUserPreferences
 }
 
+func (s *Session) backgroundContext() context.Context {
+	return s.withCurrentLocale(s.backgroundCtx)
+}
+
+func (s *Session) withCurrentLocale(ctx context.Context) context.Context {
+	if s.client == nil {
+		return ctx
+	}
+	return locale.WithLocale(ctx, s.client.GetLocale())
+}
+
 // Trace implements module.ResolutionHost
 func (s *Session) Trace(msg string) {
 	panic("ATA module resolution should not use tracing")
@@ -280,6 +290,10 @@ func (s *Session) Configure(config lsutil.UserPreferences) {
 	oldConfig := s.workspaceUserPreferences
 	s.workspaceUserPreferences = config
 
+	if config.Locale != "" {
+		s.client.SetLocale(config.Locale)
+	}
+
 	// Tell the client to re-request certain commands depending on user preference changes.
 	s.refreshInlayHintsIfNeeded(oldConfig, config)
 	s.refreshCodeLensIfNeeded(oldConfig, config)
@@ -404,7 +418,7 @@ func (s *Session) ScheduleDiagnosticsRefresh() {
 	}
 
 	// Create a new cancellable context for the debounce task
-	debounceCtx, cancel := context.WithCancel(s.backgroundCtx)
+	debounceCtx, cancel := context.WithCancel(s.backgroundContext())
 	s.diagnosticsRefreshGeneration++
 	generation := s.diagnosticsRefreshGeneration
 	s.diagnosticsRefreshCancel = cancel
@@ -433,7 +447,7 @@ func (s *Session) ScheduleDiagnosticsRefresh() {
 		if s.options.LoggingEnabled {
 			s.logger.Log("Running scheduled diagnostics refresh")
 		}
-		if err := s.client.RefreshDiagnostics(s.backgroundCtx); err != nil && s.options.LoggingEnabled {
+		if err := s.client.RefreshDiagnostics(s.backgroundContext()); err != nil && s.options.LoggingEnabled {
 			s.logger.Logf("Error refreshing diagnostics: %v", err)
 		}
 	})
@@ -465,7 +479,7 @@ func (s *Session) ScheduleSnapshotUpdate(reason UpdateReason) {
 	}
 
 	// Create a new cancellable context for the debounce task
-	debounceCtx, cancel := context.WithCancel(s.backgroundCtx)
+	debounceCtx, cancel := context.WithCancel(s.backgroundContext())
 	s.scheduledSnapshotUpdateGeneration++
 	generation := s.scheduledSnapshotUpdateGeneration
 	s.scheduledSnapshotUpdateCancel = cancel
@@ -553,7 +567,7 @@ func (s *Session) scheduleIdleCacheClean() {
 		defer s.snapshotUpdateMu.Unlock()
 		s.cancelScheduledSnapshotUpdate()
 
-		ctx := s.backgroundCtx
+		ctx := s.backgroundContext()
 		fileChanges, overlays, ataChanges, newConfig := s.flushChanges(ctx)
 		s.UpdateSnapshot(ctx, overlays, SnapshotChange{
 			reason:         UpdateReasonIdleCleanDiskCache,
@@ -584,7 +598,7 @@ func (s *Session) StartPerformanceTelemetry() {
 	if !s.options.TelemetryEnabled {
 		return
 	}
-	ctx, cancel := context.WithCancel(s.backgroundCtx)
+	ctx, cancel := context.WithCancel(s.backgroundContext())
 	s.performanceTelemetryCancel = cancel
 	s.backgroundQueue.Enqueue(ctx, func(ctx context.Context) {
 		ticker := time.NewTicker(performanceTelemetryInterval)
@@ -736,7 +750,7 @@ func (s *Session) sendProjectInfoTelemetryForNewProjects(oldSnapshot *Snapshot,
 	if !s.options.TelemetryEnabled {
 		return
 	}
-	ctx := s.backgroundCtx
+	ctx := s.backgroundContext()
 	collections.DiffOrderedMaps(
 		oldSnapshot.ProjectCollection.ProjectsByPath(),
 		newSnapshot.ProjectCollection.ProjectsByPath(),
@@ -1170,7 +1184,7 @@ func (s *Session) adoptSnapshotChangeInBackground(baseSnapshot, newSnapshot *Sna
 	// The clone's initial ref (1) is transferred to adoptSnapshotChange,
 	// which will either promote it as the session's current snapshot or
 	// release it if the session has moved on.
-	s.backgroundQueue.Enqueue(s.backgroundCtx, func(ctx context.Context) {
+	s.backgroundQueue.Enqueue(s.backgroundContext(), func(ctx context.Context) {
 		s.adoptSnapshotChange(baseSnapshot, newSnapshot)
 	})
 }
@@ -1245,7 +1259,7 @@ func (s *Session) updateSnapshot(ctx context.Context, overlays map[tspath.Path]*
 
 	// Enqueue logging, watch updates, and diagnostic refresh tasks
 	// !!! userPreferences/configuration updates
-	s.backgroundQueue.Enqueue(s.backgroundCtx, func(ctx context.Context) {
+	s.backgroundQueue.Enqueue(s.backgroundContext(), func(ctx context.Context) {
 		if s.options.LoggingEnabled {
 			s.logger.Logf("Adopted snapshot %d (parent %d) as current session snapshot (replacing %d)", newSnapshot.id, newSnapshot.parentId, oldSnapshot.id)
 			s.logger.Log(newSnapshot.builderLogs.String())
@@ -1355,7 +1369,7 @@ func updateWatch[T any](ctx context.Context, session *Session, logger logging.Lo
 func (s *Session) updateWatches(oldSnapshot *Snapshot, newSnapshot *Snapshot) error {
 	var errors []error
 	start := time.Now()
-	ctx := s.backgroundCtx
+	ctx := s.backgroundContext()
 	core.DiffMapsFunc(
 		oldSnapshot.ConfigFileRegistry.configs,
 		newSnapshot.ConfigFileRegistry.configs,
@@ -1577,15 +1591,15 @@ func (s *Session) NpmInstall(cwd string, npmInstallArgs []string) ([]byte, error
 
 func (s *Session) refreshInlayHintsIfNeeded(oldPrefs lsutil.UserPreferences, newPrefs lsutil.UserPreferences) {
 	if oldPrefs.InlayHints != newPrefs.InlayHints {
-		if err := s.client.RefreshInlayHints(s.backgroundCtx); err != nil && s.options.LoggingEnabled {
+		if err := s.client.RefreshInlayHints(s.backgroundContext()); err != nil && s.options.LoggingEnabled {
 			s.logger.Logf("Error refreshing inlay hints: %v", err)
 		}
 	}
 }
 
 func (s *Session) refreshCodeLensIfNeeded(oldPrefs lsutil.UserPreferences, newPrefs lsutil.UserPreferences) {
 	if oldPrefs.CodeLens != newPrefs.CodeLens {
-		if err := s.client.RefreshCodeLens(s.backgroundCtx); err != nil && s.options.LoggingEnabled {
+		if err := s.client.RefreshCodeLens(s.backgroundContext()); err != nil && s.options.LoggingEnabled {
 			s.logger.Logf("Error refreshing code lens: %v", err)
 		}
 	}
@@ -1617,13 +1631,13 @@ func (s *Session) publishProgramDiagnostics(oldSnapshot *Snapshot, newSnapshot *
 		}
 		for configFilePath, oldProject := range oldSnapshot.ProjectCollection.ProjectsByPath().Entries() {
 			if oldProject.Kind == KindConfigured && oldSnapshot.ProjectCollection.GetOpenConfiguredProjects().Has(configFilePath) {
-				s.publishProjectDiagnostics(s.backgroundCtx, string(configFilePath), nil, oldSnapshot.converters)
+				s.publishProjectDiagnostics(s.backgroundContext(), string(configFilePath), nil, oldSnapshot.converters)
 			}
 		}
 		return
 	}
 
-	ctx := s.backgroundCtx
+	ctx := s.backgroundContext()
 	oldProjects := oldSnapshot.ProjectCollection.ProjectsByPath()
 	newProjects := newSnapshot.ProjectCollection.ProjectsByPath()
 	oldOpenProjects := oldSnapshot.ProjectCollection.GetOpenConfiguredProjects()
@@ -1683,6 +1697,7 @@ func (s *Session) publishProjectDiagnostics(ctx context.Context, configFilePath
 	if s.Config().EnableValidation.IsFalse() {
 		diagnostics = nil
 	}
+	ctx = s.withCurrentLocale(ctx)
 	lspDiagnostics := make([]*lsproto.Diagnostic, 0, len(diagnostics))
 	for _, diag := range diagnostics {
 		lspDiagnostics = append(lspDiagnostics, lsconv.DiagnosticToLSPPush(ctx, converters, diag))
@@ -1704,7 +1719,7 @@ func (s *Session) EnqueuePublishGlobalDiagnostics() {
 		return
 	}
 	if s.globalDiagPublishPending.CompareAndSwap(false, true) {
-		s.backgroundQueue.Enqueue(s.backgroundCtx, s.publishGlobalDiagnostics)
+		s.backgroundQueue.Enqueue(s.backgroundContext(), s.publishGlobalDiagnostics)
 	}
 }
 
@@ -1730,7 +1745,7 @@ func (s *Session) publishGlobalDiagnostics(ctx context.Context) {
 func (s *Session) triggerATAForUpdatedProjects(newSnapshot *Snapshot) {
 	for _, project := range newSnapshot.ProjectCollection.Projects() {
 		if project.ShouldTriggerATA(newSnapshot.ID()) {
-			s.backgroundQueue.Enqueue(s.backgroundCtx, func(ctx context.Context) {
+			s.backgroundQueue.Enqueue(s.backgroundContext(), func(ctx context.Context) {
 				var logTree *logging.LogTree
 				if s.options.LoggingEnabled {
 					logTree = logging.NewLogTree("Triggering ATA for project " + project.Name())

internal/project/session_test.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/microsoft/typescript-go/internal/bundled"
 	"github.com/microsoft/typescript-go/internal/core"
+	"github.com/microsoft/typescript-go/internal/locale"
 	"github.com/microsoft/typescript-go/internal/ls/lsutil"
 	"github.com/microsoft/typescript-go/internal/lsp/lsproto"
 	"github.com/microsoft/typescript-go/internal/project"
@@ -1406,6 +1407,39 @@ export const value = content;`,
 		assert.Equal(t, len(inlayHintsRefreshCalls), 1, "expected one RefreshInlayHints call after inlay hints preference change")
 	})
 
+	t.Run("sets locale when configured", func(t *testing.T) {
+		t.Parallel()
+		session, utils := projecttestutil.Setup(map[string]any{})
+		prefs := lsutil.NewDefaultUserPreferences()
+		prefs.Locale = "fr"
+
+		session.Configure(prefs)
+
+		setLocaleCalls := utils.Client().SetLocaleCalls()
+		assert.Equal(t, len(setLocaleCalls), 1)
+		assert.Equal(t, setLocaleCalls[0].LocaleMoqParam, "fr")
+	})
+
+	t.Run("adds locale to background contexts", func(t *testing.T) {
+		t.Parallel()
+		session, utils := projecttestutil.Setup(map[string]any{})
+		fr, ok := locale.Parse("fr")
+		assert.Assert(t, ok)
+		utils.Client().GetLocaleFunc = func() locale.Locale {
+			return fr
+		}
+		utils.Client().RefreshCodeLensFunc = func(ctx context.Context) error {
+			assert.Equal(t, locale.FromContext(ctx), fr)
+			return nil
+		}
+		prefs := lsutil.NewDefaultUserPreferences()
+		prefs.CodeLens.ReferencesCodeLensEnabled = core.TSTrue
+
+		session.Configure(prefs)
+
+		assert.Equal(t, len(utils.Client().RefreshCodeLensCalls()), 1)
+	})
+
 	t.Run("schedules diagnostics refresh when reportStyleChecksAsWarnings changes", func(t *testing.T) {
 		t.Parallel()
 		files := map[string]any{