tweak setting for #5312, fyi @usernamehw

src/vs/editor/common/config/commonEditorConfig.ts

@@ -502,10 +502,15 @@ const editorConfiguration: IConfigurationNode = {
 			default: true,
 			description: nls.localize('wordBasedSuggestions', "Controls whether completions should be computed based on words in the document.")
 		},
-		'editor.wordBasedSuggestionsOnlySameLanguage': {
-			type: 'boolean',
-			default: true,
-			description: nls.localize('wordBasedSuggestionsOnlySameLanguage', "Controls whether word based completions should be included from opened documents of the same language or any language.")
+		'editor.wordBasedSuggestionsMode': {
+			enum: ['currentDocument', 'matchingDocuments', 'allDocuments'],
+			default: 'matchingDocuments',
+			enumDescriptions: [
+				nls.localize('wordBasedSuggestionsMode.currentDocument', 'Only suggest words from the active document.'),
+				nls.localize('wordBasedSuggestionsMode.matchingDocuments', 'Suggest words from all open documents of the same language.'),
+				nls.localize('wordBasedSuggestionsMode.allDocuments', 'Suggest words from all open documents.')
+			],
+			description: nls.localize('wordBasedSuggestionsMode', "Controls form what documents word based completions are computed.")
 		},
 		'editor.semanticHighlighting.enabled': {
 			enum: [true, false, 'configuredByTheme'],

src/vs/editor/common/services/editorWorkerServiceImpl.ts

@@ -148,22 +148,33 @@ class WordBasedCompletionItemProvider implements modes.CompletionItemProvider {
 	}
 
 	async provideCompletionItems(model: ITextModel, position: Position): Promise<modes.CompletionList | undefined> {
-		const { wordBasedSuggestions, wordBasedSuggestionsOnlySameLanguage } = this._configurationService.getValue<{ wordBasedSuggestions?: boolean, wordBasedSuggestionsOnlySameLanguage?: boolean }>(model.uri, position, 'editor');
-		if (!wordBasedSuggestions) {
+		type WordBasedSuggestionsConfig = {
+			wordBasedSuggestions?: boolean,
+			wordBasedSuggestionsMode?: 'currentDocument' | 'matchingDocuments' | 'allDocuments'
+		};
+		const config = this._configurationService.getValue<WordBasedSuggestionsConfig>(model.uri, position, 'editor');
+		if (!config.wordBasedSuggestions) {
 			return undefined;
 		}
 
 		const models: URI[] = [];
-		for (let candidate of this._modelService.getModels()) {
-			if (!canSyncModel(this._modelService, candidate.uri)) {
-				continue;
+		if (config.wordBasedSuggestionsMode === 'currentDocument') {
+			// only current file and only if not too large
+			if (canSyncModel(this._modelService, model.uri)) {
+				models.push(model.uri);
 			}
-			if (candidate === model) {
-				models.unshift(candidate.uri);
-			} else if (!wordBasedSuggestionsOnlySameLanguage) {
-				models.push(candidate.uri);
-			} else if (candidate.getLanguageIdentifier().id === model.getLanguageIdentifier().id) {
-				models.push(candidate.uri);
+		} else {
+			// either all files or files of same language
+			for (const candidate of this._modelService.getModels()) {
+				if (!canSyncModel(this._modelService, candidate.uri)) {
+					continue;
+				}
+				if (candidate === model) {
+					models.unshift(candidate.uri);
+
+				} else if (config.wordBasedSuggestionsMode === 'allDocuments' || candidate.getLanguageIdentifier().id === model.getLanguageIdentifier().id) {
+					models.push(candidate.uri);
+				}
 			}
 		}