From af0424c010076c325041d67e5c859ae5e168c62e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Fri, 1 Mar 2024 01:00:36 +0100
Subject: [PATCH] Fixed a crash when computing flow type of destructured never
 (#57586)

---
 src/compiler/checker.ts                       |  4 ++-
 ...ngDestructuringFromNeverNoCrash.errors.txt | 19 +++++++++++++
 ...UsingDestructuringFromNeverNoCrash.symbols | 24 +++++++++++++++++
 ...edUsingDestructuringFromNeverNoCrash.types | 27 +++++++++++++++++++
 ...ignedUsingDestructuringFromNeverNoCrash.ts | 15 +++++++++++
 5 files changed, 88 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.errors.txt
 create mode 100644 tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.symbols
 create mode 100644 tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.types
 create mode 100644 tests/cases/compiler/autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 27f9ed6f1b1..81dc893976c 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -43214,7 +43214,9 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
     function getIteratedTypeOrElementType(use: IterationUse, inputType: Type, sentType: Type, errorNode: Node | undefined, checkAssignability: boolean): Type | undefined {
         const allowAsyncIterables = (use & IterationUse.AllowsAsyncIterablesFlag) !== 0;
         if (inputType === neverType) {
-            reportTypeNotIterableError(errorNode!, inputType, allowAsyncIterables); // TODO: GH#18217
+            if (errorNode) {
+                reportTypeNotIterableError(errorNode, inputType, allowAsyncIterables);
+            }
             return undefined;
         }
 
diff --git a/tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.errors.txt b/tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.errors.txt
new file mode 100644
index 00000000000..e2a60126961
--- /dev/null
+++ b/tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.errors.txt
@@ -0,0 +1,19 @@
+autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts(9,3): error TS2488: Type 'never' must have a '[Symbol.iterator]()' method that returns an iterator.
+
+
+==== autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts (1 errors) ====
+    // https://github.com/microsoft/TypeScript/issues/57582
+    
+    declare const b: null;
+    let file;
+    
+    if (b === null) {
+      // empty
+    } else {
+      [file] = b;
+      ~~~~~~
+!!! error TS2488: Type 'never' must have a '[Symbol.iterator]()' method that returns an iterator.
+    }
+    
+    file; // request flow type here
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.symbols b/tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.symbols
new file mode 100644
index 00000000000..4dd3e3d0bb9
--- /dev/null
+++ b/tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.symbols
@@ -0,0 +1,24 @@
+//// [tests/cases/compiler/autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts] ////
+
+=== autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts ===
+// https://github.com/microsoft/TypeScript/issues/57582
+
+declare const b: null;
+>b : Symbol(b, Decl(autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts, 2, 13))
+
+let file;
+>file : Symbol(file, Decl(autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts, 3, 3))
+
+if (b === null) {
+>b : Symbol(b, Decl(autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts, 2, 13))
+
+  // empty
+} else {
+  [file] = b;
+>file : Symbol(file, Decl(autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts, 3, 3))
+>b : Symbol(b, Decl(autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts, 2, 13))
+}
+
+file; // request flow type here
+>file : Symbol(file, Decl(autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts, 3, 3))
+
diff --git a/tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.types b/tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.types
new file mode 100644
index 00000000000..f540b98debb
--- /dev/null
+++ b/tests/baselines/reference/autoTypeAssignedUsingDestructuringFromNeverNoCrash.types
@@ -0,0 +1,27 @@
+//// [tests/cases/compiler/autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts] ////
+
+=== autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts ===
+// https://github.com/microsoft/TypeScript/issues/57582
+
+declare const b: null;
+>b : null
+
+let file;
+>file : any
+
+if (b === null) {
+>b === null : boolean
+>b : null
+
+  // empty
+} else {
+  [file] = b;
+>[file] = b : never
+>[file] : [any]
+>file : any
+>b : never
+}
+
+file; // request flow type here
+>file : any
+
diff --git a/tests/cases/compiler/autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts b/tests/cases/compiler/autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts
new file mode 100644
index 00000000000..bb864cead0b
--- /dev/null
+++ b/tests/cases/compiler/autoTypeAssignedUsingDestructuringFromNeverNoCrash.ts
@@ -0,0 +1,15 @@
+// @strict: true
+// @noEmit: true
+
+// https://github.com/microsoft/TypeScript/issues/57582
+
+declare const b: null;
+let file;
+
+if (b === null) {
+  // empty
+} else {
+  [file] = b;
+}
+
+file; // request flow type here