Improve JSC_NOT_A_CONSTRUCTOR error message by printing the found type

PiperOrigin-RevId: 563176327

Author: rahul-kamat

src/com/google/javascript/jscomp/TypeCheck.java

@@ -142,7 +142,8 @@ public final class TypeCheck implements NodeTraversal.Callback, CompilerPass {
           "Property {0} never defined on {1}. Did you mean {2}?");
 
   static final DiagnosticType NOT_A_CONSTRUCTOR =
-      DiagnosticType.warning("JSC_NOT_A_CONSTRUCTOR", "cannot instantiate non-constructor");
+      DiagnosticType.warning(
+          "JSC_NOT_A_CONSTRUCTOR", "cannot instantiate non-constructor, found type: {0}");
 
   static final DiagnosticType INSTANTIATE_ABSTRACT_CLASS =
       DiagnosticType.warning("JSC_INSTANTIATE_ABSTRACT_CLASS", "cannot instantiate abstract class");
@@ -2410,7 +2411,7 @@ private void visitNew(Node n) {
     if (!couldBeAConstructor(type)
         || type.equals(typeRegistry.getNativeType(SYMBOL_OBJECT_FUNCTION_TYPE))
         || type.equals(typeRegistry.getNativeType(BIGINT_OBJECT_FUNCTION_TYPE))) {
-      report(n, NOT_A_CONSTRUCTOR);
+      report(n, NOT_A_CONSTRUCTOR, type.toString());
       ensureTyped(n);
       return;
     }

test/com/google/javascript/jscomp/TypeCheckBigIntTest.java

@@ -482,7 +482,12 @@ public void testBigIntArrayIndex() {
   @Test
   public void testBigIntConstructorWithNew() {
     // BigInt object function type cannot be called with "new" keyword
-    newTest().addSource("new BigInt(1)").addDiagnostic("cannot instantiate non-constructor").run();
+    newTest()
+        .addSource("new BigInt(1)")
+        .addDiagnostic(
+            "cannot instantiate non-constructor, found type: function(new:BigInt,"
+                + " (bigint|number|string)): bigint")
+        .run();
   }
 
   @Test

test/com/google/javascript/jscomp/TypeCheckNoTranspileTest.java

@@ -1978,7 +1978,8 @@ public void testGenerator_notAConstructor() {
             "  yield 1;",
             "}",
             "var g = new gen;")
-        .addDiagnostic("cannot instantiate non-constructor")
+        .addDiagnostic(
+            "cannot instantiate non-constructor, found type: function(): Generator<number,?,?>")
         .run();
   }
 
@@ -2147,7 +2148,7 @@ public void testMemberFunctionDef2() {
   public void testMemberFunctionDef3() {
     newTest()
         .addSource("var obj = { method() {} }; new obj.method();")
-        .addDiagnostic("cannot instantiate non-constructor")
+        .addDiagnostic("cannot instantiate non-constructor, found type: function(): undefined")
         .run();
   }
 

test/com/google/javascript/jscomp/TypeCheckTest.java

@@ -8921,15 +8921,18 @@ public void testHigherOrderFunctions2() {
   public void testHigherOrderFunctions3() {
     newTest()
         .addSource("/** @type {function(this:Array):Date} */var f; new f")
-        .addDiagnostic("cannot instantiate non-constructor")
+        .addDiagnostic(
+            "cannot instantiate non-constructor, found type: function(this:Array): (Date|null)")
         .run();
   }
 
   @Test
   public void testHigherOrderFunctions4() {
     newTest()
         .addSource("/** @type {function(this:Array, ...number):Date} */var f; new f")
-        .addDiagnostic("cannot instantiate non-constructor")
+        .addDiagnostic(
+            "cannot instantiate non-constructor, found type: function(this:Array, ...number):"
+                + " (Date|null)")
         .run();
   }
 
@@ -11535,14 +11538,21 @@ public void testAssignToUntypedProperty() {
 
   @Test
   public void testNew1() {
-    newTest().addSource("new 4").addDiagnostic(TypeCheck.NOT_A_CONSTRUCTOR).run();
+    newTest()
+        .addSource("new 4")
+        .addDiagnostic("cannot instantiate non-constructor, found type: number")
+        .run();
+    newTest()
+        .addSource("new 4")
+        .addDiagnostic("cannot instantiate non-constructor, found type: number")
+        .run();
   }
 
   @Test
   public void testNew2() {
     newTest()
         .addSource("var Math = {}; new Math()")
-        .addDiagnostic(TypeCheck.NOT_A_CONSTRUCTOR)
+        .addDiagnostic("cannot instantiate non-constructor, found type: {}")
         .run();
   }
 
@@ -11560,7 +11570,7 @@ public void testNew4() {
   public void testNew5() {
     newTest()
         .addSource("function A(){}; new A();")
-        .addDiagnostic(TypeCheck.NOT_A_CONSTRUCTOR)
+        .addDiagnostic("cannot instantiate non-constructor, found type: function(): undefined")
         .run();
   }
 
@@ -11629,7 +11639,7 @@ public void testNew11() {
                 + "  var c2 = function(){};"
                 + "  c1.prototype = new c2;"
                 + "}")
-        .addDiagnostic(TypeCheck.NOT_A_CONSTRUCTOR)
+        .addDiagnostic("cannot instantiate non-constructor, found type: function(): undefined")
         .run();
   }
 
@@ -11697,7 +11707,7 @@ public void testNew16() {
   public void testNew17() {
     newTest()
         .addSource("var goog = {}; goog.x = 3; new goog.x")
-        .addDiagnostic("cannot instantiate non-constructor")
+        .addDiagnostic("cannot instantiate non-constructor, found type: number")
         .run();
   }
 
@@ -14908,7 +14918,7 @@ public void testStaticDataPropertyOnNestedInterface() {
   public void testInterfaceInstantiation() {
     newTest()
         .addSource("/** @interface */var f = function(){}; new f")
-        .addDiagnostic("cannot instantiate non-constructor")
+        .addDiagnostic("cannot instantiate non-constructor, found type: (typeof f)")
         .run();
   }
 
@@ -16935,7 +16945,7 @@ public void testTypeCheckStandaloneAST() {
 
     assertThat(compiler.getWarningCount()).isEqualTo(1);
     assertThat(compiler.getWarnings().get(0).getDescription())
-        .isEqualTo("cannot instantiate non-constructor");
+        .isEqualTo("cannot instantiate non-constructor, found type: function(): undefined");
   }
 
   @Test
@@ -21446,7 +21456,7 @@ public void testSymbol2() {
         .addSource(
             "/** @const */", //
             "var o = new Symbol();")
-        .addDiagnostic("cannot instantiate non-constructor")
+        .addDiagnostic("cannot instantiate non-constructor, found type: (typeof Symbol)")
         .includeDefaultExterns()
         .run();
   }