fix 'Invalid Arguments' error for create/update constructor in factory

Author: rbuckton

src/compiler/debug.ts

@@ -30,6 +30,7 @@ namespace ts {
         export let currentLogLevel = LogLevel.Warning;
         export let isDebugging = false;
         export let loggingHost: LoggingHost | undefined;
+        export let enableDeprecationWarnings = true;
         /* eslint-enable prefer-const */
 
         type AssertionKeys = MatchingKeys<typeof Debug, AnyFunction>;
@@ -732,7 +733,7 @@ namespace ts {
         function createWarningDeprecation(name: string, errorAfter: Version | undefined, since: Version | undefined, message: string | undefined) {
             let hasWrittenDeprecation = false;
             return () => {
-                if (!hasWrittenDeprecation) {
+                if (enableDeprecationWarnings && !hasWrittenDeprecation) {
                     log.warn(formatDeprecationMessage(name, /*error*/ false, errorAfter, since, message));
                     hasWrittenDeprecation = true;
                 }

src/deprecatedCompat/4.8/mergeDecoratorsAndModifiers.ts

@@ -477,7 +477,7 @@ namespace ts {
                     (decorators === undefined || !some(decorators, isModifier)) &&
                     (modifiers === undefined || !some(modifiers, isParameter)) &&
                     (parameters === undefined || isArray(parameters)) &&
-                    (body === undefined || !isBlock(body)),
+                    (body === undefined || isBlock(body)),
             })
             .deprecate({
                 1: DISALLOW_DECORATORS
@@ -505,7 +505,7 @@ namespace ts {
                     (decorators === undefined || !some(decorators, isModifier)) &&
                     (modifiers === undefined || !some(modifiers, isParameter)) &&
                     (parameters === undefined || isArray(parameters)) &&
-                    (body === undefined || !isBlock(body)),
+                    (body === undefined || isBlock(body)),
             })
             .deprecate({
                 1: DISALLOW_DECORATORS

src/testRunner/unittests/factory.ts

@@ -81,5 +81,40 @@ namespace ts {
                 checkRhs(SyntaxKind.QuestionQuestionEqualsToken, /*expectParens*/ false);
             });
         });
+
+        describe("deprecations", () => {
+            beforeEach(() => {
+                Debug.enableDeprecationWarnings = false;
+            });
+
+            afterEach(() => {
+                Debug.enableDeprecationWarnings = true;
+            });
+
+            // https://github.com/microsoft/TypeScript/issues/50259
+            it("deprecated createConstructorDeclaration overload does not throw", () => {
+                const body = factory.createBlock([]);
+                assert.doesNotThrow(() => factory.createConstructorDeclaration(
+                    /*decorators*/ undefined,
+                    /*modifiers*/ undefined,
+                    /*parameters*/ [],
+                    body,
+                ));
+            });
+
+            // https://github.com/microsoft/TypeScript/issues/50259
+            it("deprecated updateConstructorDeclaration overload does not throw", () => {
+                const body = factory.createBlock([]);
+                const ctor = factory.createConstructorDeclaration(/*modifiers*/ undefined, [], body);
+                assert.doesNotThrow(() => factory.updateConstructorDeclaration(
+                    ctor,
+                    ctor.decorators,
+                    ctor.modifiers,
+                    ctor.parameters,
+                    ctor.body,
+                ));
+            });
+        });
+
     });
 }