Salsa: get members of variables whose initialisers are functions

Author: sandersn

src/compiler/binder.ts

@@ -1945,7 +1945,7 @@ namespace ts {
             classPrototype.parent = leftSideOfAssignment;
 
             const funcSymbol = container.locals[constructorFunction.text];
-            if (!funcSymbol || !(funcSymbol.flags & SymbolFlags.Function)) {
+            if (!funcSymbol || !(funcSymbol.flags & SymbolFlags.Function || isDeclarationOfFunctionExpression(funcSymbol))) {
                 return;
             }
 

src/compiler/checker.ts

@@ -11481,8 +11481,12 @@ namespace ts {
                     // When resolved signature is a call signature (and not a construct signature) the result type is any, unless
                     // the declaring function had members created through 'x.prototype.y = expr' or 'this.y = expr' psuedodeclarations
                     // in a JS file
-                    const funcSymbol = checkExpression(node.expression).symbol;
-                    if (funcSymbol && funcSymbol.members && (funcSymbol.flags & SymbolFlags.Function)) {
+                    // Note:JS inferred classes might come from a variable declaration instead of a function declaration.
+                    // In this case, using getResolvedSymbol directly is required to avoid losing the members from the declaration.
+                    const funcSymbol = node.expression.kind === SyntaxKind.Identifier ?
+                        getResolvedSymbol(node.expression as Identifier) :
+                        checkExpression(node.expression).symbol;
+                    if (funcSymbol && funcSymbol.members && (funcSymbol.flags & SymbolFlags.Function || isDeclarationOfFunctionExpression(funcSymbol))) {
                         return getInferredClassType(funcSymbol);
                     }
                     else if (compilerOptions.noImplicitAny) {

src/compiler/utilities.ts

@@ -1257,6 +1257,18 @@ namespace ts {
         return charCode === CharacterCodes.singleQuote || charCode === CharacterCodes.doubleQuote;
     }
 
+    /**
+     * Returns true if the node is a variable declaration whose initializer is a function expression.
+     * This function does not test if the node is in a JavaScript file or not.
+     */
+    export function isDeclarationOfFunctionExpression(s: Symbol) {
+        if (s.valueDeclaration && s.valueDeclaration.kind === SyntaxKind.VariableDeclaration) {
+            const declaration = s.valueDeclaration as VariableDeclaration;
+            return declaration.initializer && declaration.initializer.kind === SyntaxKind.FunctionExpression;
+        }
+        return false;
+    }
+
     /// Given a BinaryExpression, returns SpecialPropertyAssignmentKind for the various kinds of property
     /// assignments we treat as special in the binder
     export function getSpecialPropertyAssignmentKind(expression: Node): SpecialPropertyAssignmentKind {