From a284c814545854deaf78bd2eb5157931c0546795 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sun, 2 Nov 2025 11:45:25 -0800
Subject: [PATCH 1/6] Hoist @typedef in classes to containing scope

---
 internal/parser/parser.go | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/internal/parser/parser.go b/internal/parser/parser.go
index a51566f02d..5f8a473d2c 100644
--- a/internal/parser/parser.go
+++ b/internal/parser/parser.go
@@ -498,12 +498,21 @@ func (p *Parser) reparseTopLevelAwait(sourceFile *ast.SourceFile) *ast.Node {
 func (p *Parser) parseListIndex(kind ParsingContext, parseElement func(p *Parser, index int) *ast.Node) []*ast.Node {
 	saveParsingContexts := p.parsingContexts
 	p.parsingContexts |= 1 << kind
+	outerReparseList := p.reparseList
+	p.reparseList = nil
 	list := make([]*ast.Node, 0, 16)
 	for i := 0; !p.isListTerminator(kind); i++ {
 		if p.isListElement(kind, false /*inErrorRecovery*/) {
 			elt := parseElement(p, i)
 			if len(p.reparseList) > 0 {
-				list = append(list, p.reparseList...)
+				for _, e := range p.reparseList {
+					// Propagate @typedef type alias declarations outwards to a context that permits them.
+					if ast.IsJSTypeAliasDeclaration(e) && kind != PCSourceElements && kind != PCBlockStatements {
+						outerReparseList = append(outerReparseList, e)
+					} else {
+						list = append(list, e)
+					}
+				}
 				p.reparseList = nil
 			}
 			list = append(list, elt)
@@ -513,6 +522,7 @@ func (p *Parser) parseListIndex(kind ParsingContext, parseElement func(p *Parser
 			break
 		}
 	}
+	p.reparseList = outerReparseList
 	p.parsingContexts = saveParsingContexts
 	return p.nodeSlicePool.Clone(list)
 }

From f29e9f70c86bfe1b7ad7fe69c60913b5820be3a6 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sun, 2 Nov 2025 11:46:10 -0800
Subject: [PATCH 2/6] Accept new baselines

---
 .../callbackOnConstructor.errors.txt          | 20 --------------
 .../conformance/callbackOnConstructor.js      |  2 +-
 .../conformance/callbackOnConstructor.js.diff |  2 +-
 .../conformance/callbackOnConstructor.symbols |  2 ++
 .../callbackOnConstructor.symbols.diff        |  9 -------
 .../conformance/callbackOnConstructor.types   | 10 +++----
 .../conformance/jsdocTemplateClass.errors.txt |  8 +++++-
 .../conformance/jsdocTemplateClass.types      |  6 ++---
 .../typedefInnerNamepaths.errors.txt          |  8 +++++-
 .../typedefOnSemicolonClassElement.js         | 25 +----------------
 .../typedefOnSemicolonClassElement.js.diff    | 27 ++-----------------
 .../callbackOnConstructor.errors.txt.diff     | 24 -----------------
 .../callbackOnConstructor.types.diff          | 13 +++------
 .../jsdocTemplateClass.errors.txt.diff        | 24 +++++++++++++++++
 .../conformance/jsdocTemplateClass.types.diff | 20 ++++++++++++++
 .../typedefInnerNamepaths.errors.txt.diff     | 19 +++++--------
 16 files changed, 83 insertions(+), 136 deletions(-)
 delete mode 100644 testdata/baselines/reference/submodule/conformance/callbackOnConstructor.errors.txt
 delete mode 100644 testdata/baselines/reference/submodule/conformance/callbackOnConstructor.symbols.diff
 delete mode 100644 testdata/baselines/reference/submoduleAccepted/conformance/callbackOnConstructor.errors.txt.diff
 create mode 100644 testdata/baselines/reference/submoduleAccepted/conformance/jsdocTemplateClass.errors.txt.diff
 create mode 100644 testdata/baselines/reference/submoduleAccepted/conformance/jsdocTemplateClass.types.diff

diff --git a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.errors.txt b/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.errors.txt
deleted file mode 100644
index 9b0c649c61..0000000000
--- a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.errors.txt
+++ /dev/null
@@ -1,20 +0,0 @@
-callbackOnConstructor.js(12,12): error TS2304: Cannot find name 'ValueGetter_2'.
-
-
-==== callbackOnConstructor.js (1 errors) ====
-    export class Preferences {
-      assignability = "no"
-      /**
-       * @callback ValueGetter_2
-       * @param {string} name
-       * @returns {boolean|number|string|undefined}
-       */
-      constructor() {}
-    }
-    
-    
-    /** @type {ValueGetter_2} */
-               ~~~~~~~~~~~~~
-!!! error TS2304: Cannot find name 'ValueGetter_2'.
-    var ooscope2 = s => s.length > 0
-    
\ No newline at end of file
diff --git a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.js b/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.js
index 431cb909b3..e9feaf36f4 100644
--- a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.js
+++ b/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.js
@@ -35,9 +35,9 @@ var ooscope2 = s => s.length > 0;
 
 
 //// [callbackOnConstructor.d.ts]
+export type ValueGetter_2 = (name: string) => boolean | number | string | undefined;
 export declare class Preferences {
     assignability: string;
-    export type ValueGetter_2 = (name: string) => boolean | number | string | undefined;
     /**
      * @callback ValueGetter_2
      * @param {string} name
diff --git a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.js.diff b/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.js.diff
index 45a701f8e7..7650b96ec3 100644
--- a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.js.diff
+++ b/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.js.diff
@@ -22,9 +22,9 @@
 
  //// [callbackOnConstructor.d.ts]
 -export class Preferences {
++export type ValueGetter_2 = (name: string) => boolean | number | string | undefined;
 +export declare class Preferences {
      assignability: string;
-+    export type ValueGetter_2 = (name: string) => boolean | number | string | undefined;
 +    /**
 +     * @callback ValueGetter_2
 +     * @param {string} name
diff --git a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.symbols b/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.symbols
index 675c7c5e85..d5559f79e0 100644
--- a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.symbols
+++ b/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.symbols
@@ -20,5 +20,7 @@ export class Preferences {
 var ooscope2 = s => s.length > 0
 >ooscope2 : Symbol(ooscope2, Decl(callbackOnConstructor.js, 12, 3))
 >s : Symbol(s, Decl(callbackOnConstructor.js, 12, 14))
+>s.length : Symbol(String.length, Decl(lib.es5.d.ts, --, --))
 >s : Symbol(s, Decl(callbackOnConstructor.js, 12, 14))
+>length : Symbol(String.length, Decl(lib.es5.d.ts, --, --))
 
diff --git a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.symbols.diff b/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.symbols.diff
deleted file mode 100644
index eeddc1fb04..0000000000
--- a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.symbols.diff
+++ /dev/null
@@ -1,9 +0,0 @@
---- old.callbackOnConstructor.symbols
-+++ new.callbackOnConstructor.symbols
-@@= skipped -19, +19 lines =@@
- var ooscope2 = s => s.length > 0
- >ooscope2 : Symbol(ooscope2, Decl(callbackOnConstructor.js, 12, 3))
- >s : Symbol(s, Decl(callbackOnConstructor.js, 12, 14))
-->s.length : Symbol(String.length, Decl(lib.es5.d.ts, --, --))
- >s : Symbol(s, Decl(callbackOnConstructor.js, 12, 14))
-->length : Symbol(String.length, Decl(lib.es5.d.ts, --, --))
diff --git a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.types b/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.types
index 448a21aa29..ea3a0f2df3 100644
--- a/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.types
+++ b/testdata/baselines/reference/submodule/conformance/callbackOnConstructor.types
@@ -20,11 +20,11 @@ export class Preferences {
 /** @type {ValueGetter_2} */
 var ooscope2 = s => s.length > 0
 >ooscope2 : ValueGetter_2
->s => s.length > 0 : (s: any) => boolean
->s : any
+>s => s.length > 0 : (s: string) => boolean
+>s : string
 >s.length > 0 : boolean
->s.length : any
->s : any
->length : any
+>s.length : number
+>s : string
+>length : number
 >0 : 0
 
diff --git a/testdata/baselines/reference/submodule/conformance/jsdocTemplateClass.errors.txt b/testdata/baselines/reference/submodule/conformance/jsdocTemplateClass.errors.txt
index 75303c2689..02cf3bbbec 100644
--- a/testdata/baselines/reference/submodule/conformance/jsdocTemplateClass.errors.txt
+++ b/testdata/baselines/reference/submodule/conformance/jsdocTemplateClass.errors.txt
@@ -1,7 +1,9 @@
+templateTagOnClasses.js(7,23): error TS2304: Cannot find name 'T'.
+templateTagOnClasses.js(7,29): error TS2304: Cannot find name 'T'.
 templateTagOnClasses.js(25,1): error TS2322: Type 'boolean' is not assignable to type 'number'.
 
 
-==== templateTagOnClasses.js (1 errors) ====
+==== templateTagOnClasses.js (3 errors) ====
     /**
      * @template T
      * @typedef {(t: T) => T} Id
@@ -9,6 +11,10 @@ templateTagOnClasses.js(25,1): error TS2322: Type 'boolean' is not assignable to
     /** @template T */
     class Foo {
         /** @typedef {(t: T) => T} Id2 */
+                          ~
+!!! error TS2304: Cannot find name 'T'.
+                                ~
+!!! error TS2304: Cannot find name 'T'.
         /** @param {T} x */
         constructor (x) {
             this.a = x
diff --git a/testdata/baselines/reference/submodule/conformance/jsdocTemplateClass.types b/testdata/baselines/reference/submodule/conformance/jsdocTemplateClass.types
index 550c90bd8a..4ba0f951be 100644
--- a/testdata/baselines/reference/submodule/conformance/jsdocTemplateClass.types
+++ b/testdata/baselines/reference/submodule/conformance/jsdocTemplateClass.types
@@ -29,14 +29,14 @@ class Foo {
      * @return {T}
      */
     foo(x, y, alpha) {
->foo : (x: T, y: Id<T>, alpha: (t: T) => T) => T
+>foo : (x: T, y: Id<T>, alpha: Id2) => T
 >x : T
 >y : Id<T>
->alpha : (t: T) => T
+>alpha : Id2
 
         return alpha(y(x))
 >alpha(y(x)) : T
->alpha : (t: T) => T
+>alpha : Id2
 >y(x) : T
 >y : Id<T>
 >x : T
diff --git a/testdata/baselines/reference/submodule/conformance/typedefInnerNamepaths.errors.txt b/testdata/baselines/reference/submodule/conformance/typedefInnerNamepaths.errors.txt
index 2aa319ce1c..5a5e1fedf5 100644
--- a/testdata/baselines/reference/submodule/conformance/typedefInnerNamepaths.errors.txt
+++ b/testdata/baselines/reference/submodule/conformance/typedefInnerNamepaths.errors.txt
@@ -1,14 +1,20 @@
+bug25104.js(1,7): error TS2300: Duplicate identifier 'C'.
 bug25104.js(3,19): error TS1005: '}' expected.
+bug25104.js(4,26): error TS2300: Duplicate identifier 'C'.
 bug25104.js(6,18): error TS1005: '}' expected.
 
 
-==== bug25104.js (2 errors) ====
+==== bug25104.js (4 errors) ====
     class C {
+          ~
+!!! error TS2300: Duplicate identifier 'C'.
         /**
          * @typedef {C~A} C~B
                       ~
 !!! error TS1005: '}' expected.
          * @typedef {object} C~A
+                             ~
+!!! error TS2300: Duplicate identifier 'C'.
          */
         /** @param {C~A} o */
                      ~
diff --git a/testdata/baselines/reference/submodule/conformance/typedefOnSemicolonClassElement.js b/testdata/baselines/reference/submodule/conformance/typedefOnSemicolonClassElement.js
index 230abbb8ef..bae46ccae5 100644
--- a/testdata/baselines/reference/submodule/conformance/typedefOnSemicolonClassElement.js
+++ b/testdata/baselines/reference/submodule/conformance/typedefOnSemicolonClassElement.js
@@ -23,31 +23,8 @@ exports.Preferences = Preferences;
 
 
 //// [typedefOnSemicolonClassElement.d.ts]
+export type A = string;
 export declare class Preferences {
-    type A = string;
     /** @type {A} */
     a: A;
 }
-
-
-//// [DtsFileErrors]
-
-
-dist/typedefOnSemicolonClassElement.d.ts(2,5): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-dist/typedefOnSemicolonClassElement.d.ts(4,8): error TS2693: 'A' only refers to a type, but is being used as a value here.
-dist/typedefOnSemicolonClassElement.d.ts(5,1): error TS1128: Declaration or statement expected.
-
-
-==== dist/typedefOnSemicolonClassElement.d.ts (3 errors) ====
-    export declare class Preferences {
-        type A = string;
-        ~~~~
-!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-        /** @type {A} */
-        a: A;
-           ~
-!!! error TS2693: 'A' only refers to a type, but is being used as a value here.
-    }
-    ~
-!!! error TS1128: Declaration or statement expected.
-    
\ No newline at end of file
diff --git a/testdata/baselines/reference/submodule/conformance/typedefOnSemicolonClassElement.js.diff b/testdata/baselines/reference/submodule/conformance/typedefOnSemicolonClassElement.js.diff
index d4a2b25707..d4bf30386b 100644
--- a/testdata/baselines/reference/submodule/conformance/typedefOnSemicolonClassElement.js.diff
+++ b/testdata/baselines/reference/submodule/conformance/typedefOnSemicolonClassElement.js.diff
@@ -18,32 +18,9 @@
 
  //// [typedefOnSemicolonClassElement.d.ts]
 -export class Preferences {
++export type A = string;
 +export declare class Preferences {
-+    type A = string;
      /** @type {A} */
 -    a: string;
 +    a: A;
- }
-+
-+
-+//// [DtsFileErrors]
-+
-+
-+dist/typedefOnSemicolonClassElement.d.ts(2,5): error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-+dist/typedefOnSemicolonClassElement.d.ts(4,8): error TS2693: 'A' only refers to a type, but is being used as a value here.
-+dist/typedefOnSemicolonClassElement.d.ts(5,1): error TS1128: Declaration or statement expected.
-+
-+
-+==== dist/typedefOnSemicolonClassElement.d.ts (3 errors) ====
-+    export declare class Preferences {
-+        type A = string;
-+        ~~~~
-+!!! error TS1068: Unexpected token. A constructor, method, accessor, or property was expected.
-+        /** @type {A} */
-+        a: A;
-+           ~
-+!!! error TS2693: 'A' only refers to a type, but is being used as a value here.
-+    }
-+    ~
-+!!! error TS1128: Declaration or statement expected.
-+    
\ No newline at end of file
+ }
\ No newline at end of file
diff --git a/testdata/baselines/reference/submoduleAccepted/conformance/callbackOnConstructor.errors.txt.diff b/testdata/baselines/reference/submoduleAccepted/conformance/callbackOnConstructor.errors.txt.diff
deleted file mode 100644
index e019fdce7f..0000000000
--- a/testdata/baselines/reference/submoduleAccepted/conformance/callbackOnConstructor.errors.txt.diff
+++ /dev/null
@@ -1,24 +0,0 @@
---- old.callbackOnConstructor.errors.txt
-+++ new.callbackOnConstructor.errors.txt
-@@= skipped -0, +0 lines =@@
--<no content>
-+callbackOnConstructor.js(12,12): error TS2304: Cannot find name 'ValueGetter_2'.
-+
-+
-+==== callbackOnConstructor.js (1 errors) ====
-+    export class Preferences {
-+      assignability = "no"
-+      /**
-+       * @callback ValueGetter_2
-+       * @param {string} name
-+       * @returns {boolean|number|string|undefined}
-+       */
-+      constructor() {}
-+    }
-+    
-+    
-+    /** @type {ValueGetter_2} */
-+               ~~~~~~~~~~~~~
-+!!! error TS2304: Cannot find name 'ValueGetter_2'.
-+    var ooscope2 = s => s.length > 0
-+    
\ No newline at end of file
diff --git a/testdata/baselines/reference/submoduleAccepted/conformance/callbackOnConstructor.types.diff b/testdata/baselines/reference/submoduleAccepted/conformance/callbackOnConstructor.types.diff
index 1f736624c7..2869da9615 100644
--- a/testdata/baselines/reference/submoduleAccepted/conformance/callbackOnConstructor.types.diff
+++ b/testdata/baselines/reference/submoduleAccepted/conformance/callbackOnConstructor.types.diff
@@ -6,15 +6,8 @@
  var ooscope2 = s => s.length > 0
 ->ooscope2 : (name: string) => boolean | number | string | undefined
 ->s => s.length > 0 : (s: string) => string | number | boolean
-->s : string
 +>ooscope2 : ValueGetter_2
-+>s => s.length > 0 : (s: any) => boolean
-+>s : any
++>s => s.length > 0 : (s: string) => boolean
+ >s : string
  >s.length > 0 : boolean
-->s.length : number
-->s : string
-->length : number
-+>s.length : any
-+>s : any
-+>length : any
- >0 : 0
+ >s.length : number
\ No newline at end of file
diff --git a/testdata/baselines/reference/submoduleAccepted/conformance/jsdocTemplateClass.errors.txt.diff b/testdata/baselines/reference/submoduleAccepted/conformance/jsdocTemplateClass.errors.txt.diff
new file mode 100644
index 0000000000..7aafc7f02d
--- /dev/null
+++ b/testdata/baselines/reference/submoduleAccepted/conformance/jsdocTemplateClass.errors.txt.diff
@@ -0,0 +1,24 @@
+--- old.jsdocTemplateClass.errors.txt
++++ new.jsdocTemplateClass.errors.txt
+@@= skipped -0, +0 lines =@@
++templateTagOnClasses.js(7,23): error TS2304: Cannot find name 'T'.
++templateTagOnClasses.js(7,29): error TS2304: Cannot find name 'T'.
+ templateTagOnClasses.js(25,1): error TS2322: Type 'boolean' is not assignable to type 'number'.
+
+
+-==== templateTagOnClasses.js (1 errors) ====
++==== templateTagOnClasses.js (3 errors) ====
+     /**
+      * @template T
+      * @typedef {(t: T) => T} Id
+@@= skipped -8, +10 lines =@@
+     /** @template T */
+     class Foo {
+         /** @typedef {(t: T) => T} Id2 */
++                          ~
++!!! error TS2304: Cannot find name 'T'.
++                                ~
++!!! error TS2304: Cannot find name 'T'.
+         /** @param {T} x */
+         constructor (x) {
+             this.a = x
\ No newline at end of file
diff --git a/testdata/baselines/reference/submoduleAccepted/conformance/jsdocTemplateClass.types.diff b/testdata/baselines/reference/submoduleAccepted/conformance/jsdocTemplateClass.types.diff
new file mode 100644
index 0000000000..46539f9422
--- /dev/null
+++ b/testdata/baselines/reference/submoduleAccepted/conformance/jsdocTemplateClass.types.diff
@@ -0,0 +1,20 @@
+--- old.jsdocTemplateClass.types
++++ new.jsdocTemplateClass.types
+@@= skipped -28, +28 lines =@@
+      * @return {T}
+      */
+     foo(x, y, alpha) {
+->foo : (x: T, y: Id<T>, alpha: (t: T) => T) => T
++>foo : (x: T, y: Id<T>, alpha: Id2) => T
+ >x : T
+ >y : Id<T>
+->alpha : (t: T) => T
++>alpha : Id2
+
+         return alpha(y(x))
+ >alpha(y(x)) : T
+->alpha : (t: T) => T
++>alpha : Id2
+ >y(x) : T
+ >y : Id<T>
+ >x : T
\ No newline at end of file
diff --git a/testdata/baselines/reference/submoduleAccepted/conformance/typedefInnerNamepaths.errors.txt.diff b/testdata/baselines/reference/submoduleAccepted/conformance/typedefInnerNamepaths.errors.txt.diff
index 668a3e4dd1..db8d8129a0 100644
--- a/testdata/baselines/reference/submoduleAccepted/conformance/typedefInnerNamepaths.errors.txt.diff
+++ b/testdata/baselines/reference/submoduleAccepted/conformance/typedefInnerNamepaths.errors.txt.diff
@@ -1,25 +1,20 @@
 --- old.typedefInnerNamepaths.errors.txt
 +++ new.typedefInnerNamepaths.errors.txt
 @@= skipped -0, +0 lines =@@
--bug25104.js(1,7): error TS2300: Duplicate identifier 'C'.
+ bug25104.js(1,7): error TS2300: Duplicate identifier 'C'.
  bug25104.js(3,19): error TS1005: '}' expected.
--bug25104.js(4,26): error TS2300: Duplicate identifier 'C'.
+ bug25104.js(4,26): error TS2300: Duplicate identifier 'C'.
 -bug25104.js(6,18): error TS8024: JSDoc '@param' tag has name '', but there is no parameter with that name.
  bug25104.js(6,18): error TS1005: '}' expected.
 
 
 -==== bug25104.js (5 errors) ====
-+==== bug25104.js (2 errors) ====
++==== bug25104.js (4 errors) ====
      class C {
--          ~
--!!! error TS2300: Duplicate identifier 'C'.
-         /**
-          * @typedef {C~A} C~B
-                       ~
- !!! error TS1005: '}' expected.
-          * @typedef {object} C~A
--                             ~
--!!! error TS2300: Duplicate identifier 'C'.
+           ~
+ !!! error TS2300: Duplicate identifier 'C'.
+@@= skipped -17, +16 lines =@@
+ !!! error TS2300: Duplicate identifier 'C'.
           */
          /** @param {C~A} o */
 -                     

From 4e98df1a6a8b9057958bfade0963ef2f04a3174a Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sun, 2 Nov 2025 11:46:20 -0800
Subject: [PATCH 3/6] Add regression test

---
 .../compiler/typedefHoisting.errors.txt       | 13 +++++++++++++
 .../reference/compiler/typedefHoisting.js     | 19 +++++++++++++++++++
 .../compiler/typedefHoisting.symbols          | 12 ++++++++++++
 .../reference/compiler/typedefHoisting.types  | 13 +++++++++++++
 .../tests/cases/compiler/typedefHoisting.ts   |  9 +++++++++
 5 files changed, 66 insertions(+)
 create mode 100644 testdata/baselines/reference/compiler/typedefHoisting.errors.txt
 create mode 100644 testdata/baselines/reference/compiler/typedefHoisting.js
 create mode 100644 testdata/baselines/reference/compiler/typedefHoisting.symbols
 create mode 100644 testdata/baselines/reference/compiler/typedefHoisting.types
 create mode 100644 testdata/tests/cases/compiler/typedefHoisting.ts

diff --git a/testdata/baselines/reference/compiler/typedefHoisting.errors.txt b/testdata/baselines/reference/compiler/typedefHoisting.errors.txt
new file mode 100644
index 0000000000..596e5b3b4e
--- /dev/null
+++ b/testdata/baselines/reference/compiler/typedefHoisting.errors.txt
@@ -0,0 +1,13 @@
+error TS5055: Cannot write file 'x.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.
+
+
+!!! error TS5055: Cannot write file 'x.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.
+==== x.js (0 errors) ====
+    class C {
+        /** @typedef {string} Foo */
+        /** @type {Foo} */
+        foo = "abc"
+    }
+    
\ No newline at end of file
diff --git a/testdata/baselines/reference/compiler/typedefHoisting.js b/testdata/baselines/reference/compiler/typedefHoisting.js
new file mode 100644
index 0000000000..9c0f38d810
--- /dev/null
+++ b/testdata/baselines/reference/compiler/typedefHoisting.js
@@ -0,0 +1,19 @@
+//// [tests/cases/compiler/typedefHoisting.ts] ////
+
+//// [x.js]
+class C {
+    /** @typedef {string} Foo */
+    /** @type {Foo} */
+    foo = "abc"
+}
+
+
+
+
+//// [x.d.ts]
+type Foo = string;
+declare class C {
+    /** @typedef {string} Foo */
+    /** @type {Foo} */
+    foo: Foo;
+}
diff --git a/testdata/baselines/reference/compiler/typedefHoisting.symbols b/testdata/baselines/reference/compiler/typedefHoisting.symbols
new file mode 100644
index 0000000000..bf0c9f43a4
--- /dev/null
+++ b/testdata/baselines/reference/compiler/typedefHoisting.symbols
@@ -0,0 +1,12 @@
+//// [tests/cases/compiler/typedefHoisting.ts] ////
+
+=== x.js ===
+class C {
+>C : Symbol(C, Decl(x.js, 0, 0))
+
+    /** @typedef {string} Foo */
+    /** @type {Foo} */
+    foo = "abc"
+>foo : Symbol(C.foo, Decl(x.js, 0, 9))
+}
+
diff --git a/testdata/baselines/reference/compiler/typedefHoisting.types b/testdata/baselines/reference/compiler/typedefHoisting.types
new file mode 100644
index 0000000000..3c2fc590bc
--- /dev/null
+++ b/testdata/baselines/reference/compiler/typedefHoisting.types
@@ -0,0 +1,13 @@
+//// [tests/cases/compiler/typedefHoisting.ts] ////
+
+=== x.js ===
+class C {
+>C : C
+
+    /** @typedef {string} Foo */
+    /** @type {Foo} */
+    foo = "abc"
+>foo : string
+>"abc" : "abc"
+}
+
diff --git a/testdata/tests/cases/compiler/typedefHoisting.ts b/testdata/tests/cases/compiler/typedefHoisting.ts
new file mode 100644
index 0000000000..d64a34edad
--- /dev/null
+++ b/testdata/tests/cases/compiler/typedefHoisting.ts
@@ -0,0 +1,9 @@
+// @allowJs: true
+// @checkJs: true
+// @declaration: true
+// @Filename: x.js
+class C {
+    /** @typedef {string} Foo */
+    /** @type {Foo} */
+    foo = "abc"
+}

From 9a747f91676062a1ab4023badcb5e46b7ddcb694 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sun, 2 Nov 2025 11:56:06 -0800
Subject: [PATCH 4/6] Address CR feedback

---
 testdata/tests/cases/compiler/typedefHoisting.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/testdata/tests/cases/compiler/typedefHoisting.ts b/testdata/tests/cases/compiler/typedefHoisting.ts
index d64a34edad..7920086a95 100644
--- a/testdata/tests/cases/compiler/typedefHoisting.ts
+++ b/testdata/tests/cases/compiler/typedefHoisting.ts
@@ -1,7 +1,7 @@
 // @allowJs: true
 // @checkJs: true
 // @declaration: true
-// @Filename: x.js
+// @filename: x.js
 class C {
     /** @typedef {string} Foo */
     /** @type {Foo} */

From 73c6546b7f069c98b5b95afd2dd9044ead91b815 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Mon, 3 Nov 2025 08:02:04 -0800
Subject: [PATCH 5/6] Also hoist @import tags

---
 internal/ast/ast.go       | 4 ++++
 internal/parser/parser.go | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/internal/ast/ast.go b/internal/ast/ast.go
index 57f92fbbfa..82d4f26e37 100644
--- a/internal/ast/ast.go
+++ b/internal/ast/ast.go
@@ -4845,6 +4845,10 @@ func IsImportDeclaration(node *Node) bool {
 	return node.Kind == KindImportDeclaration
 }
 
+func IsJSImportDeclaration(node *Node) bool {
+	return node.Kind == KindJSImportDeclaration
+}
+
 func IsImportDeclarationOrJSImportDeclaration(node *Node) bool {
 	return node.Kind == KindImportDeclaration || node.Kind == KindJSImportDeclaration
 }
diff --git a/internal/parser/parser.go b/internal/parser/parser.go
index 5f8a473d2c..7ad377c237 100644
--- a/internal/parser/parser.go
+++ b/internal/parser/parser.go
@@ -507,7 +507,7 @@ func (p *Parser) parseListIndex(kind ParsingContext, parseElement func(p *Parser
 			if len(p.reparseList) > 0 {
 				for _, e := range p.reparseList {
 					// Propagate @typedef type alias declarations outwards to a context that permits them.
-					if ast.IsJSTypeAliasDeclaration(e) && kind != PCSourceElements && kind != PCBlockStatements {
+					if (ast.IsJSTypeAliasDeclaration(e) || ast.IsJSImportDeclaration(e)) && kind != PCSourceElements && kind != PCBlockStatements {
 						outerReparseList = append(outerReparseList, e)
 					} else {
 						list = append(list, e)

From 97c3a6e69ff4433556534509d7de1b3efaed56a6 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Mon, 3 Nov 2025 08:02:11 -0800
Subject: [PATCH 6/6] Update test

---
 .../compiler/typedefHoisting.errors.txt       | 18 ++++++++++--
 .../reference/compiler/typedefHoisting.js     | 29 ++++++++++++++-----
 .../compiler/typedefHoisting.symbols          | 20 +++++++++++--
 .../reference/compiler/typedefHoisting.types  | 24 ++++++++++++---
 .../tests/cases/compiler/typedefHoisting.ts   | 15 ++++++++--
 5 files changed, 86 insertions(+), 20 deletions(-)

diff --git a/testdata/baselines/reference/compiler/typedefHoisting.errors.txt b/testdata/baselines/reference/compiler/typedefHoisting.errors.txt
index 596e5b3b4e..d4264baa84 100644
--- a/testdata/baselines/reference/compiler/typedefHoisting.errors.txt
+++ b/testdata/baselines/reference/compiler/typedefHoisting.errors.txt
@@ -1,13 +1,25 @@
 error TS5055: Cannot write file 'x.js' because it would overwrite input file.
   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.
+error TS5055: Cannot write file 'y.js' because it would overwrite input file.
+  Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.
 
 
 !!! error TS5055: Cannot write file 'x.js' because it would overwrite input file.
 !!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.
+!!! error TS5055: Cannot write file 'y.js' because it would overwrite input file.
+!!! error TS5055:   Adding a tsconfig.json file will help organize projects that contain both TypeScript and JavaScript files. Learn more at https://aka.ms/tsconfig.
 ==== x.js (0 errors) ====
     class C {
-        /** @typedef {string} Foo */
-        /** @type {Foo} */
-        foo = "abc"
+        /** @import {Bar} from "./y" */
+        /** @typedef {Bar[]} Bars */
+        /** @type {Bars} */
+        foo = ["abc", "def"]
+        bar(/** @type {Bar} */ x) {
+            return x
+        }
     }
+    
+==== y.js (0 errors) ====
+    /** @typedef {string} Bar */
+    export {}
     
\ No newline at end of file
diff --git a/testdata/baselines/reference/compiler/typedefHoisting.js b/testdata/baselines/reference/compiler/typedefHoisting.js
index 9c0f38d810..6803d6b512 100644
--- a/testdata/baselines/reference/compiler/typedefHoisting.js
+++ b/testdata/baselines/reference/compiler/typedefHoisting.js
@@ -2,18 +2,33 @@
 
 //// [x.js]
 class C {
-    /** @typedef {string} Foo */
-    /** @type {Foo} */
-    foo = "abc"
+    /** @import {Bar} from "./y" */
+    /** @typedef {Bar[]} Bars */
+    /** @type {Bars} */
+    foo = ["abc", "def"]
+    bar(/** @type {Bar} */ x) {
+        return x
+    }
 }
 
+//// [y.js]
+/** @typedef {string} Bar */
+export {}
 
 
 
+
+//// [y.d.ts]
+export type Bar = string;
+/** @typedef {string} Bar */
+export {};
 //// [x.d.ts]
-type Foo = string;
+import type { Bar } from "./y";
+type Bars = Bar[];
 declare class C {
-    /** @typedef {string} Foo */
-    /** @type {Foo} */
-    foo: Foo;
+    /** @import {Bar} from "./y" */
+    /** @typedef {Bar[]} Bars */
+    /** @type {Bars} */
+    foo: Bars;
+    bar(/** @type {Bar} */ x: Bar): string;
 }
diff --git a/testdata/baselines/reference/compiler/typedefHoisting.symbols b/testdata/baselines/reference/compiler/typedefHoisting.symbols
index bf0c9f43a4..7202639df6 100644
--- a/testdata/baselines/reference/compiler/typedefHoisting.symbols
+++ b/testdata/baselines/reference/compiler/typedefHoisting.symbols
@@ -4,9 +4,23 @@
 class C {
 >C : Symbol(C, Decl(x.js, 0, 0))
 
-    /** @typedef {string} Foo */
-    /** @type {Foo} */
-    foo = "abc"
+    /** @import {Bar} from "./y" */
+    /** @typedef {Bar[]} Bars */
+    /** @type {Bars} */
+    foo = ["abc", "def"]
 >foo : Symbol(C.foo, Decl(x.js, 0, 9))
+
+    bar(/** @type {Bar} */ x) {
+>bar : Symbol(C.bar, Decl(x.js, 4, 24))
+>x : Symbol(x, Decl(x.js, 5, 8))
+
+        return x
+>x : Symbol(x, Decl(x.js, 5, 8))
+    }
 }
 
+=== y.js ===
+
+/** @typedef {string} Bar */
+export {}
+
diff --git a/testdata/baselines/reference/compiler/typedefHoisting.types b/testdata/baselines/reference/compiler/typedefHoisting.types
index 3c2fc590bc..5b60cac604 100644
--- a/testdata/baselines/reference/compiler/typedefHoisting.types
+++ b/testdata/baselines/reference/compiler/typedefHoisting.types
@@ -4,10 +4,26 @@
 class C {
 >C : C
 
-    /** @typedef {string} Foo */
-    /** @type {Foo} */
-    foo = "abc"
->foo : string
+    /** @import {Bar} from "./y" */
+    /** @typedef {Bar[]} Bars */
+    /** @type {Bars} */
+    foo = ["abc", "def"]
+>foo : Bars
+>["abc", "def"] : string[]
 >"abc" : "abc"
+>"def" : "def"
+
+    bar(/** @type {Bar} */ x) {
+>bar : (x: string) => string
+>x : string
+
+        return x
+>x : string
+    }
 }
 
+=== y.js ===
+
+/** @typedef {string} Bar */
+export {}
+
diff --git a/testdata/tests/cases/compiler/typedefHoisting.ts b/testdata/tests/cases/compiler/typedefHoisting.ts
index 7920086a95..80683421ee 100644
--- a/testdata/tests/cases/compiler/typedefHoisting.ts
+++ b/testdata/tests/cases/compiler/typedefHoisting.ts
@@ -1,9 +1,18 @@
 // @allowJs: true
 // @checkJs: true
 // @declaration: true
+
 // @filename: x.js
 class C {
-    /** @typedef {string} Foo */
-    /** @type {Foo} */
-    foo = "abc"
+    /** @import {Bar} from "./y" */
+    /** @typedef {Bar[]} Bars */
+    /** @type {Bars} */
+    foo = ["abc", "def"]
+    bar(/** @type {Bar} */ x) {
+        return x
+    }
 }
+
+// @filename: y.js
+/** @typedef {string} Bar */
+export {}