fix(language-service): bug of accessing a string index signature using dot notation

packages/language-service/src/typescript_symbols.ts

@@ -244,10 +244,7 @@ class TypeWrapper implements Symbol {
     }
   }
 
-  get name(): string {
-    const symbol = this.tsType.symbol;
-    return (symbol && symbol.name) || '<anonymous>';
-  }
+  get name(): string { return this.context.checker.typeToString(this.tsType); }
 
   public readonly kind: DeclarationKind = 'type';
 
@@ -308,6 +305,12 @@ class TypeWrapper implements Symbol {
   }
 }
 
+// If stringIndexType a primitive type(e.g. 'string'), the Symbol is undefined;
+// and in AstType.resolvePropertyRead method, the Symbol.type should get the right type.
+class StringIndexTypeWrapper extends TypeWrapper {
+  public readonly type = new TypeWrapper(this.tsType, this.context);
+}
+
 class SymbolWrapper implements Symbol {
   private symbol: ts.Symbol;
   private _members?: SymbolTable;
@@ -506,10 +509,7 @@ class SymbolTableWrapper implements SymbolTable {
       //   obj.stringIndex // equivalent to obj['stringIndex'];
       //
       // In this case, return the type indexed by an arbitrary string key.
-      const symbol = this.stringIndexType.getSymbol();
-      if (symbol) {
-        return new SymbolWrapper(symbol, this.context, this.stringIndexType);
-      }
+      return new StringIndexTypeWrapper(this.stringIndexType, this.context);
     }
 
     return undefined;
@@ -608,15 +608,10 @@ class PipeSymbol implements Symbol {
         let resultType: ts.Type|undefined = undefined;
         switch (this.name) {
           case 'async':
-            switch (parameterType.name) {
-              case 'Observable':
-              case 'Promise':
-              case 'EventEmitter':
-                resultType = getTypeParameterOf(parameterType.tsType, parameterType.name);
-                break;
-              default:
-                resultType = getTsTypeFromBuiltinType(BuiltinType.Any, this.context);
-                break;
+            // Get symbol of 'Observable', 'Promise', or 'EventEmitter' type.
+            const symbol = parameterType.tsType.symbol;
+            if (symbol) {
+              resultType = getTypeParameterOf(parameterType.tsType, symbol.name);
             }
             break;
           case 'slice':

packages/language-service/test/completions_spec.ts

@@ -146,6 +146,13 @@ describe('completions', () => {
         const completions = ngLS.getCompletionsAt(TEST_TEMPLATE, marker.start);
         expectContain(completions, CompletionKind.PROPERTY, ['id', 'name']);
       });
+
+      it('should work with dot notation if stringIndexType is a primitive type', () => {
+        mockHost.override(TEST_TEMPLATE, `{{ primitiveIndexType.test.~{string-primitive-type}}}`);
+        const marker = mockHost.getLocationMarkerFor(TEST_TEMPLATE, 'string-primitive-type');
+        const completions = ngLS.getCompletionsAt(TEST_TEMPLATE, marker.start);
+        expectContain(completions, CompletionKind.METHOD, ['substring']);
+      });
     });
   });
 

packages/language-service/test/diagnostics_spec.ts

@@ -147,6 +147,13 @@ describe('diagnostics', () => {
         expect(diags[0].messageText)
             .toBe(`Identifier 'badProperty' is not defined. 'Hero' does not contain such a member`);
       });
+
+      it('should not produce errors with dot notation if stringIndexType is a primitive type',
+         () => {
+           mockHost.override(TEST_TEMPLATE, `{{primitiveIndexType.test}}`);
+           const diags = ngLS.getDiagnostics(TEST_TEMPLATE);
+           expect(diags.length).toBe(0);
+         });
     });
   });
 

packages/language-service/test/project/app/parsing-cases.ts

@@ -192,6 +192,7 @@ export class TemplateReference {
   tupleArray: [string, Hero] = ['test', this.hero];
   league: Hero[][] = [this.heroes];
   heroesByName: {[name: string]: Hero} = {};
+  primitiveIndexType: {[name: string]: string} = {};
   anyValue: any;
   myClick(event: any) {}
 }