Cherry-pick PR #44125 into release-4.3 (#44136)

Component commits:
34b80a5 Don’t offer import statement completions at `from` position

afa4d05 Set isGlobalCompletion to false, use indexOf lookup

Co-authored-by: Andrew Branch <andrew@wheream.io>

src/services/completions.ts

@@ -174,6 +174,8 @@ namespace ts.Completions {
                 return jsdocCompletionInfo(JsDoc.getJSDocTagCompletions());
             case CompletionDataKind.JsDocParameterName:
                 return jsdocCompletionInfo(JsDoc.getJSDocParameterNameCompletions(completionData.tag));
+            case CompletionDataKind.Keywords:
+                return specificKeywordCompletionInfo(completionData.keywords);
             default:
                 return Debug.assertNever(completionData);
         }
@@ -183,6 +185,20 @@ namespace ts.Completions {
         return { isGlobalCompletion: false, isMemberCompletion: false, isNewIdentifierLocation: false, entries };
     }
 
+    function specificKeywordCompletionInfo(keywords: readonly SyntaxKind[]): CompletionInfo {
+        return {
+            isGlobalCompletion: false,
+            isMemberCompletion: false,
+            isNewIdentifierLocation: false,
+            entries: keywords.map(k => ({
+                name: tokenToString(k)!,
+                kind: ScriptElementKind.keyword,
+                kindModifiers: ScriptElementKindModifier.none,
+                sortText: SortText.GlobalsOrKeywords,
+            })),
+        };
+    }
+
     function getOptionalReplacementSpan(location: Node | undefined) {
         // StringLiteralLike locations are handled separately in stringCompletions.ts
         return location?.kind === SyntaxKind.Identifier ? createTextSpanFromNode(location) : undefined;
@@ -802,6 +818,8 @@ namespace ts.Completions {
                         return JsDoc.getJSDocTagCompletionDetails(name);
                     case CompletionDataKind.JsDocParameterName:
                         return JsDoc.getJSDocParameterNameCompletionDetails(name);
+                    case CompletionDataKind.Keywords:
+                        return request.keywords.indexOf(stringToToken(name)!) > -1 ? createSimpleDetails(name, ScriptElementKind.keyword, SymbolDisplayPartKind.keyword) : undefined;
                     default:
                         return Debug.assertNever(request);
                 }
@@ -893,7 +911,7 @@ namespace ts.Completions {
         return completion.type === "symbol" ? completion.symbol : undefined;
     }
 
-    const enum CompletionDataKind { Data, JsDocTagName, JsDocTag, JsDocParameterName }
+    const enum CompletionDataKind { Data, JsDocTagName, JsDocTag, JsDocParameterName, Keywords }
     /** true: after the `=` sign but no identifier has been typed yet. Else is the Identifier after the initializer. */
     type IsJsxInitializer = boolean | Identifier;
     interface CompletionData {
@@ -918,7 +936,10 @@ namespace ts.Completions {
         readonly isJsxIdentifierExpected: boolean;
         readonly importCompletionNode?: Node;
     }
-    type Request = { readonly kind: CompletionDataKind.JsDocTagName | CompletionDataKind.JsDocTag } | { readonly kind: CompletionDataKind.JsDocParameterName, tag: JSDocParameterTag };
+    type Request =
+        | { readonly kind: CompletionDataKind.JsDocTagName | CompletionDataKind.JsDocTag }
+        | { readonly kind: CompletionDataKind.JsDocParameterName, tag: JSDocParameterTag }
+        | { readonly kind: CompletionDataKind.Keywords, keywords: readonly SyntaxKind[] };
 
     export const enum CompletionKind {
         ObjectPropertyDeclaration,
@@ -1101,13 +1122,17 @@ namespace ts.Completions {
         let location = getTouchingPropertyName(sourceFile, position);
 
         if (contextToken) {
+            const importCompletionCandidate = getImportCompletionNode(contextToken);
+            if (importCompletionCandidate === SyntaxKind.FromKeyword) {
+                return { kind: CompletionDataKind.Keywords, keywords: [SyntaxKind.FromKeyword] };
+            }
             // Import statement completions use `insertText`, and also require the `data` property of `CompletionEntryIdentifier`
             // added in TypeScript 4.3 to be sent back from the client during `getCompletionEntryDetails`. Since this feature
             // is not backward compatible with older clients, the language service defaults to disabling it, allowing newer clients
             // to opt in with the `includeCompletionsForImportStatements` user preference.
-            importCompletionNode = preferences.includeCompletionsForImportStatements && preferences.includeCompletionsWithInsertText
-                ? getImportCompletionNode(contextToken)
-                : undefined;
+            if (importCompletionCandidate && preferences.includeCompletionsForImportStatements && preferences.includeCompletionsWithInsertText) {
+                importCompletionNode = importCompletionCandidate;
+            }
             // Bail out if this is a known invalid completion location
             if (!importCompletionNode && isCompletionListBlocker(contextToken)) {
                 log("Returning an empty list because completion was requested in an invalid position.");
@@ -3041,17 +3066,21 @@ namespace ts.Completions {
 
     function getImportCompletionNode(contextToken: Node) {
         const candidate = getCandidate();
-        return candidate && rangeIsOnSingleLine(candidate, candidate.getSourceFile()) ? candidate : undefined;
+        return candidate === SyntaxKind.FromKeyword || candidate && rangeIsOnSingleLine(candidate, candidate.getSourceFile()) ? candidate : undefined;
 
         function getCandidate() {
             const parent = contextToken.parent;
             if (isImportEqualsDeclaration(parent)) {
                 return isModuleSpecifierMissingOrEmpty(parent.moduleReference) ? parent : undefined;
             }
             if (isNamedImports(parent) || isNamespaceImport(parent)) {
-                return isModuleSpecifierMissingOrEmpty(parent.parent.parent.moduleSpecifier) && (isNamespaceImport(parent) || parent.elements.length < 2) && !parent.parent.name
-                    ? parent.parent.parent
-                    : undefined;
+                if (isModuleSpecifierMissingOrEmpty(parent.parent.parent.moduleSpecifier) && (isNamespaceImport(parent) || parent.elements.length < 2) && !parent.parent.name) {
+                    // At `import { ... } |` or `import * as Foo |`, the only possible completion is `from`
+                    return contextToken.kind === SyntaxKind.CloseBraceToken || contextToken.kind === SyntaxKind.Identifier
+                        ? SyntaxKind.FromKeyword
+                        : parent.parent.parent;
+                }
+                return undefined;
             }
             if (isImportKeyword(contextToken) && isSourceFile(parent)) {
                 // A lone import keyword with nothing following it does not parse as a statement at all

tests/cases/fourslash/importStatementCompletions1.ts

@@ -73,3 +73,29 @@
     }
   });
 });
+
+// @Filename: /index13.ts
+//// import {} /*13*/
+
+// @Filename: /index14.ts
+//// import {} f/*14*/
+
+// @Filename: /index15.ts
+//// import * as foo /*15*/
+
+// @Filename: /index16.ts
+//// import * as foo f/*16*/
+
+[13, 14, 15, 16].forEach(marker => {
+  verify.completions({
+    marker: "" + marker,
+    exact: {
+      name: "from",
+      sortText: completion.SortText.GlobalsOrKeywords,
+    },
+    preferences: {
+      includeCompletionsForImportStatements: true,
+      includeInsertTextCompletions: true,
+    }
+  });
+});