microsoft · jakebailey · Feb 4, 2026 · Jan 30, 2026
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
@@ -4553,6 +4553,9 @@ export function createProgram(_rootNamesOrOptions: readonly string[] | CreatePro
             if (options.module === ModuleKind.None || options.module === ModuleKind.AMD || options.module === ModuleKind.UMD || options.module === ModuleKind.System) {
                 createDeprecatedDiagnostic("module", ModuleKind[options.module], /*useInstead*/ undefined, /*related*/ undefined);
             }
+            if (options.downlevelIteration !== undefined) {
+                createDeprecatedDiagnostic("downlevelIteration");
+            }
         });
     }
 

diff --git a/src/compiler/types.ts b/src/compiler/types.ts
@@ -7431,6 +7431,7 @@ export interface CompilerOptions {
     disableSourceOfProjectReferenceRedirect?: boolean;
     disableSolutionSearching?: boolean;
     disableReferencedProjectLoad?: boolean;
+    /** @deprecated */
     downlevelIteration?: boolean;
     emitBOM?: boolean;
     emitDecoratorMetadata?: boolean;

diff --git a/tests/baselines/reference/ES5For-of33(target=es2015).errors.txt b/tests/baselines/reference/ES5For-of33(target=es2015).errors.txt
@@ -0,0 +1,8 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+
+
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+==== ES5For-of33.ts (0 errors) ====
+    for (var v of ['a', 'b', 'c']) {
+        console.log(v);
+    }
diff --git a/tests/baselines/reference/ES5For-of33(target=es5).errors.txt b/tests/baselines/reference/ES5For-of33(target=es5).errors.txt
@@ -1,6 +1,8 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== ES5For-of33.ts (0 errors) ====
     for (var v of ['a', 'b', 'c']) {

diff --git a/tests/baselines/reference/ES5For-of34(target=es2015).errors.txt b/tests/baselines/reference/ES5For-of34(target=es2015).errors.txt
@@ -1,6 +1,8 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ES5For-of34.ts(4,6): error TS2322: Type 'string' is not assignable to type 'number'.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== ES5For-of34.ts (1 errors) ====
     function foo() {
         return { x: 0 };

diff --git a/tests/baselines/reference/ES5For-of34(target=es5).errors.txt b/tests/baselines/reference/ES5For-of34(target=es5).errors.txt
@@ -1,7 +1,9 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ES5For-of34.ts(4,6): error TS2322: Type 'string' is not assignable to type 'number'.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== ES5For-of34.ts (1 errors) ====
     function foo() {

diff --git a/tests/baselines/reference/ES5For-of35(target=es2015).errors.txt b/tests/baselines/reference/ES5For-of35(target=es2015).errors.txt
@@ -1,7 +1,9 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ES5For-of35.ts(1,13): error TS2339: Property 'x' does not exist on type 'Number'.
 ES5For-of35.ts(1,23): error TS2339: Property 'y' does not exist on type 'Number'.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== ES5For-of35.ts (2 errors) ====
     for (const {x: a = 0, y: b = 1} of [2, 3]) {
                 ~

diff --git a/tests/baselines/reference/ES5For-of35(target=es5).errors.txt b/tests/baselines/reference/ES5For-of35(target=es5).errors.txt
@@ -1,8 +1,10 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ES5For-of35.ts(1,13): error TS2339: Property 'x' does not exist on type 'Number'.
 ES5For-of35.ts(1,23): error TS2339: Property 'y' does not exist on type 'Number'.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== ES5For-of35.ts (2 errors) ====
     for (const {x: a = 0, y: b = 1} of [2, 3]) {

diff --git a/tests/baselines/reference/ES5For-of36(target=es2015).errors.txt b/tests/baselines/reference/ES5For-of36(target=es2015).errors.txt
@@ -1,6 +1,8 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ES5For-of36.ts(1,10): error TS2488: Type 'number' must have a '[Symbol.iterator]()' method that returns an iterator.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== ES5For-of36.ts (1 errors) ====
     for (let [a = 0, b = 1] of [2, 3]) {
              ~~~~~~~~~~~~~~

diff --git a/tests/baselines/reference/ES5For-of36(target=es5).errors.txt b/tests/baselines/reference/ES5For-of36(target=es5).errors.txt
@@ -1,7 +1,9 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ES5For-of36.ts(1,10): error TS2548: Type 'number' is not an array type or does not have a '[Symbol.iterator]()' method that returns an iterator.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== ES5For-of36.ts (1 errors) ====
     for (let [a = 0, b = 1] of [2, 3]) {

diff --git a/tests/baselines/reference/ES5For-of37(target=es2015).errors.txt b/tests/baselines/reference/ES5For-of37(target=es2015).errors.txt
@@ -0,0 +1,20 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+
+
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+==== ES5For-of37.ts (0 errors) ====
+    // https://github.com/microsoft/TypeScript/issues/30083
+
+    for (const i of [0, 1, 2, 3, 4]) {
+        try {
+            // Ensure catch binding for the following loop is reset per iteration:
+            for (const j of [1, 2, 3]) {
+                if (i === 2) {
+                    throw new Error('ERR');
+                }
+            }
+            console.log(i);
+        } catch (err) {
+            console.log('E %s %s', i, err);
+        }
+    }
diff --git a/tests/baselines/reference/ES5For-of37(target=es5).errors.txt b/tests/baselines/reference/ES5For-of37(target=es5).errors.txt
@@ -1,6 +1,8 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== ES5For-of37.ts (0 errors) ====
     // https://github.com/microsoft/TypeScript/issues/30083

diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
@@ -7033,6 +7033,7 @@ declare namespace ts {
         disableSourceOfProjectReferenceRedirect?: boolean;
         disableSolutionSearching?: boolean;
         disableReferencedProjectLoad?: boolean;
+        /** @deprecated */
         downlevelIteration?: boolean;
         emitBOM?: boolean;
         emitDecoratorMetadata?: boolean;

diff --git a/tests/baselines/reference/arrayLiteralSpreadES5iterable(target=es2015).errors.txt b/tests/baselines/reference/arrayLiteralSpreadES5iterable(target=es2015).errors.txt
@@ -0,0 +1,28 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+
+
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+==== arrayLiteralSpreadES5iterable.ts (0 errors) ====
+    function f0() {
+        var a = [1, 2, 3];
+        var a1 = [...a];
+        var a2 = [1, ...a];
+        var a3 = [1, 2, ...a];
+        var a4 = [...a, 1];
+        var a5 = [...a, 1, 2];
+        var a6 = [1, 2, ...a, 1, 2];
+        var a7 = [1, ...a, 2, ...a];
+        var a8 = [...a, ...a, ...a];
+    }
+
+    function f1() {
+        var a = [1, 2, 3];
+        var b = ["hello", ...a, true];
+        var b: (string | number | boolean)[];
+    }
+
+    function f2() {
+        var a = [...[...[...[...[...[]]]]]];
+        var b = [...[...[...[...[...[5]]]]]];
+    }
+
diff --git a/tests/baselines/reference/arrayLiteralSpreadES5iterable(target=es5).errors.txt b/tests/baselines/reference/arrayLiteralSpreadES5iterable(target=es5).errors.txt
@@ -1,6 +1,8 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== arrayLiteralSpreadES5iterable.ts (0 errors) ====
     function f0() {

diff --git a/tests/baselines/reference/asyncArrowFunction11_es5(target=es2015).errors.txt b/tests/baselines/reference/asyncArrowFunction11_es5(target=es2015).errors.txt
@@ -0,0 +1,12 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+
+
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+==== asyncArrowFunction11_es5.ts (0 errors) ====
+    // https://github.com/Microsoft/TypeScript/issues/24722
+    class A {
+        b = async (...args: any[]) => {
+            await Promise.resolve();
+            const obj = { ["a"]: () => this }; // computed property name after `await` triggers case
+        };
+    }
diff --git a/tests/baselines/reference/asyncArrowFunction11_es5(target=es5).errors.txt b/tests/baselines/reference/asyncArrowFunction11_es5(target=es5).errors.txt
@@ -1,6 +1,8 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== asyncArrowFunction11_es5.ts (0 errors) ====
     // https://github.com/Microsoft/TypeScript/issues/24722

diff --git a/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator(target=es2015).errors.txt b/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator(target=es2015).errors.txt
@@ -0,0 +1,11 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+
+
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
+==== blockScopedBindingsInDownlevelGenerator.ts (0 errors) ====
+    function* a() {
+      for (const i of [1,2,3]) {
+        (() => i)()
+        yield i
+      }
+    }
diff --git a/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator(target=es2015).types b/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator(target=es2015).types
@@ -29,6 +29,7 @@ function* a() {
 
     yield i
 >yield i : any
+>        : ^^^
 >i : number
 >  : ^^^^^^
   }

diff --git a/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator(target=es5).errors.txt b/tests/baselines/reference/blockScopedBindingsInDownlevelGenerator(target=es5).errors.txt
@@ -1,6 +1,8 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== blockScopedBindingsInDownlevelGenerator.ts (0 errors) ====
     function* a() {

diff --git a/.../baselines/reference/destructuringArrayBindingPatternAndAssignment1ES5iterable.errors.txt b/.../baselines/reference/destructuringArrayBindingPatternAndAssignment1ES5iterable.errors.txt
@@ -1,8 +1,10 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 destructuringArrayBindingPatternAndAssignment1ES5iterable.ts(43,6): error TS2493: Tuple type '[]' of length '0' has no element at index '0'.
 destructuringArrayBindingPatternAndAssignment1ES5iterable.ts(44,8): error TS2493: Tuple type '[]' of length '0' has no element at index '0'.
 destructuringArrayBindingPatternAndAssignment1ES5iterable.ts(44,18): error TS2493: Tuple type '[]' of length '0' has no element at index '0'.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== destructuringArrayBindingPatternAndAssignment1ES5iterable.ts (3 errors) ====
     /* AssignmentPattern:
      *      ObjectAssignmentPattern

diff --git a/...elines/reference/destructuringArrayBindingPatternAndAssignment4(target=es2015).errors.txt b/...elines/reference/destructuringArrayBindingPatternAndAssignment4(target=es2015).errors.txt
@@ -1,6 +1,8 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 destructuringArrayBindingPatternAndAssignment4.ts(5,7): error TS2488: Type 'number[] | null' must have a '[Symbol.iterator]()' method that returns an iterator.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== destructuringArrayBindingPatternAndAssignment4.ts (1 errors) ====
     // #35497
 

diff --git a/...baselines/reference/destructuringArrayBindingPatternAndAssignment4(target=es5).errors.txt b/...baselines/reference/destructuringArrayBindingPatternAndAssignment4(target=es5).errors.txt
@@ -1,7 +1,9 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 destructuringArrayBindingPatternAndAssignment4.ts(5,7): error TS2548: Type 'number[] | null' is not an array type or does not have a '[Symbol.iterator]()' method that returns an iterator.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== destructuringArrayBindingPatternAndAssignment4.ts (1 errors) ====
     // #35497

diff --git a/tests/baselines/reference/destructuringParameterDeclaration1ES5iterable.errors.txt b/tests/baselines/reference/destructuringParameterDeclaration1ES5iterable.errors.txt
@@ -1,3 +1,4 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 destructuringParameterDeclaration1ES5iterable.ts(12,4): error TS2345: Argument of type '[number, number, string[][], number]' is not assignable to parameter of type '[number, number, string[][]]'.
   Source has 4 element(s) but target allows only 3.
 destructuringParameterDeclaration1ES5iterable.ts(23,5): error TS7010: 'b5', which lacks return-type annotation, implicitly has an 'any' return type.
@@ -62,6 +63,7 @@ destructuringParameterDeclaration1ES5iterable.ts(95,25): error TS7031: Binding e
 destructuringParameterDeclaration1ES5iterable.ts(95,32): error TS7031: Binding element 'any' implicitly has an 'any' type.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== destructuringParameterDeclaration1ES5iterable.ts (60 errors) ====
     // A parameter declaration may specify either an identifier or a binding pattern.
     // The identifiers specified in parameter declarations and binding patterns

diff --git a/...selines/reference/destructuringParameterDeclaration3ES5iterable(target=es2015).errors.txt b/...selines/reference/destructuringParameterDeclaration3ES5iterable(target=es2015).errors.txt
@@ -1,3 +1,4 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 destructuringParameterDeclaration3ES5iterable.ts(12,13): error TS7019: Rest parameter 'a' implicitly has an 'any[]' type.
 destructuringParameterDeclaration3ES5iterable.ts(16,14): error TS7031: Binding element 'a' implicitly has an 'any' type.
 destructuringParameterDeclaration3ES5iterable.ts(16,17): error TS7031: Binding element 'b' implicitly has an 'any' type.
@@ -13,6 +14,7 @@ destructuringParameterDeclaration3ES5iterable.ts(30,5): error TS2345: Argument o
   Source has 2 element(s) but target requires 3.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== destructuringParameterDeclaration3ES5iterable.ts (11 errors) ====
     // If the parameter is a rest parameter, the parameter type is any[]
     // A type annotation for a rest parameter must denote an array type.

diff --git a/.../baselines/reference/destructuringParameterDeclaration3ES5iterable(target=es5).errors.txt b/.../baselines/reference/destructuringParameterDeclaration3ES5iterable(target=es5).errors.txt
@@ -1,3 +1,4 @@
+error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 destructuringParameterDeclaration3ES5iterable.ts(12,13): error TS7019: Rest parameter 'a' implicitly has an 'any[]' type.
 destructuringParameterDeclaration3ES5iterable.ts(16,14): error TS7031: Binding element 'a' implicitly has an 'any' type.
@@ -14,6 +15,7 @@ destructuringParameterDeclaration3ES5iterable.ts(30,5): error TS2345: Argument o
   Source has 2 element(s) but target requires 3.
 
 
+!!! error TS5101: Option 'downlevelIteration' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 !!! error TS5107: Option 'target=ES5' is deprecated and will stop functioning in TypeScript 7.0. Specify compilerOption '"ignoreDeprecations": "6.0"' to silence this error.
 ==== destructuringParameterDeclaration3ES5iterable.ts (11 errors) ====
     // If the parameter is a rest parameter, the parameter type is any[]
-Original file line number
+Diff line change
@@ Expand Up / @@ -29,6 +29,7 @@ function* a() { @@
         yield i
     >yield i : any
+    >        : ^^^
     >i : number
     >  : ^^^^^^
       }
@@ Expand Down @@