fix(language-service): Function alias should be callable

This commit fixes a long standing bug whereby a template variable that
gets initialized to a class method gets resolved to the Any type, thus
when it is called the language service produces error "Member X is not
callable".

PR closes angular#16643
PR closes angular/vscode-ng-language-service#234

packages/compiler-cli/src/diagnostics/expression_diagnostics.ts

@@ -90,29 +90,6 @@ function getDefinitionOf(info: DiagnosticTemplateInfo, ast: TemplateAst): Defini
   }
 }
 
-/**
- * Resolve the specified `variable` from the `directives` list and return the
- * corresponding symbol. If resolution fails, return the `any` type.
- * @param variable template variable to resolve
- * @param directives template context
- * @param query
- */
-function findSymbolForVariableInDirectives(
-    variable: VariableAst, directives: DirectiveAst[], query: SymbolQuery): Symbol {
-  for (const d of directives) {
-    // Get the symbol table for the directive's StaticSymbol
-    const table = query.getTemplateContext(d.directive.type.reference);
-    if (!table) {
-      continue;
-    }
-    const symbol = table.get(variable.value);
-    if (symbol) {
-      return symbol;
-    }
-  }
-  return query.getBuiltinType(BuiltinType.Any);
-}
-
 /**
  * Resolve all variable declarations in a template by traversing the specified
  * `path`.
@@ -126,9 +103,8 @@ function getVarDeclarations(
     if (!(current instanceof EmbeddedTemplateAst)) {
       continue;
     }
-    const {directives, variables} = current;
-    for (const variable of variables) {
-      let symbol = findSymbolForVariableInDirectives(variable, directives, info.query);
+    for (const variable of current.variables) {
+      let symbol = info.members.get(variable.value) || info.query.getBuiltinType(BuiltinType.Any);
       const kind = info.query.getTypeKind(symbol);
       if (kind === BuiltinType.Any || kind === BuiltinType.Unbound) {
         // For special cases such as ngFor and ngIf, the any type is not very useful.

packages/compiler-cli/src/diagnostics/expression_type.ts

@@ -363,7 +363,6 @@ export class AstType implements AstVisitor {
     if (this.isAny(receiverType)) {
       return this.anyType;
     }
-
     // The type of a method is the selected methods result type.
     const method = receiverType.members().get(ast.name);
     if (!method) return this.reportError(`Unknown method '${ast.name}'`, ast);

packages/language-service/src/typescript_host.ts

@@ -198,7 +198,6 @@ export class TypeScriptServiceHost implements LanguageServiceHost {
    */
   private upToDate(): boolean {
     const {lastProgram, program} = this;
-    console.error("last program === program ?", lastProgram === program);
     if (lastProgram === program) {
       return true;
     }

packages/language-service/test/diagnostics_spec.ts

@@ -109,6 +109,16 @@ describe('diagnostics', () => {
         .toBe(`Identifier 'age' is not defined. 'Hero' does not contain such a member`);
   });
 
+  it('should not report error for variable initialized as class method', () => {
+    mockHost.override(TEST_TEMPLATE, `
+      <ng-template let-greet="myClick">
+        <span (click)="greet()"></span>
+      </ng-template>
+    `);
+    const diagnostics = ngLS.getDiagnostics(TEST_TEMPLATE);
+    expect(diagnostics).toEqual([]);
+  });
+
   describe('in expression-cases.ts', () => {
     it('should report access to an unknown field', () => {
       const diags = ngLS.getDiagnostics(EXPRESSION_CASES).map(d => d.messageText);