fix(language-service): fix autocomplete info display for some cases (#42472)

Before this commit, attribute completion display parts were retrieved
but not assigned. In addition, the switch case was non-exhaustive
because it did not include `StructuralDirectiveAttribute`.

PR Close #42472

packages/language-service/ivy/completions.ts

@@ -579,6 +579,7 @@ export class CompletionBuilder<N extends TmplAstNode|AST> {
         displayParts = info.displayParts;
         documentation = info.documentation;
         break;
+      case AttributeCompletionKind.StructuralDirectiveAttribute:
       case AttributeCompletionKind.DirectiveInput:
       case AttributeCompletionKind.DirectiveOutput:
         const propertySymbol = getAttributeCompletionSymbol(completion, this.typeChecker);
@@ -586,11 +587,17 @@ export class CompletionBuilder<N extends TmplAstNode|AST> {
           return undefined;
         }
 
+        let kind: DisplayInfoKind;
+        if (completion.kind === AttributeCompletionKind.DirectiveInput) {
+          kind = DisplayInfoKind.PROPERTY;
+        } else if (completion.kind === AttributeCompletionKind.DirectiveOutput) {
+          kind = DisplayInfoKind.EVENT;
+        } else {
+          kind = DisplayInfoKind.DIRECTIVE;
+        }
+
         info = getTsSymbolDisplayInfo(
-            this.tsLS, this.typeChecker, propertySymbol,
-            completion.kind === AttributeCompletionKind.DirectiveInput ? DisplayInfoKind.PROPERTY :
-                                                                         DisplayInfoKind.EVENT,
-            completion.directive.tsSymbol.name);
+            this.tsLS, this.typeChecker, propertySymbol, kind, completion.directive.tsSymbol.name);
         if (info === null) {
           return undefined;
         }
@@ -602,7 +609,7 @@ export class CompletionBuilder<N extends TmplAstNode|AST> {
       name: entryName,
       kind: unsafeCastDisplayInfoKindToScriptElementKind(kind),
       kindModifiers: ts.ScriptElementKindModifier.none,
-      displayParts: [],
+      displayParts,
       documentation,
     };
   }

packages/language-service/ivy/display_parts.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {isNamedClassDeclaration} from '@angular/compiler-cli/src/ngtsc/reflection';
 import {DirectiveInScope, ReferenceSymbol, ShimLocation, Symbol, SymbolKind, VariableSymbol} from '@angular/compiler-cli/src/ngtsc/typecheck/api';
 import * as ts from 'typescript';
 
@@ -155,7 +156,9 @@ export function getTsSymbolDisplayInfo(
     tsLS: ts.LanguageService, checker: ts.TypeChecker, symbol: ts.Symbol, kind: DisplayInfoKind,
     ownerName: string|null): DisplayInfo|null {
   const decl = symbol.valueDeclaration;
-  if (decl === undefined || (!ts.isPropertyDeclaration(decl) && !ts.isMethodDeclaration(decl)) ||
+  if (decl === undefined ||
+      (!ts.isPropertyDeclaration(decl) && !ts.isMethodDeclaration(decl) &&
+       !isNamedClassDeclaration(decl)) ||
       !ts.isIdentifier(decl.name)) {
     return null;
   }

packages/language-service/ivy/test/completions_spec.ts

@@ -586,6 +586,10 @@ describe('completions', () => {
                  unsafeCastDisplayInfoKindToScriptElementKind(DisplayInfoKind.DIRECTIVE),
                  ['ngFor']);
              expectReplacementText(completions, templateFile.contents, 'ng');
+             const details = templateFile.getCompletionEntryDetails(
+                 'ngFor', /* formatOptions */ undefined,
+                 /* preferences */ undefined)!;
+             expect(toText(details.displayParts)).toEqual('(directive) NgFor.NgFor: NgFor');
            });
 
         it('should return structural directive completions for just the structural marker', () => {