From 73e58ea929e3004b9b8e4a9eb0acef6caf2f88bb Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Thu, 12 May 2022 10:06:10 -0700
Subject: [PATCH] Split tests

---
 src/compiler/checker.ts                       | 12 ++++---
 ...ndingPatternCannotBeOnlyInferenceSource.ts | 25 +++++++++++++++
 ...tternContextualTypeDoesNotCauseWidening.ts |  3 ++
 .../compiler/inferTupleFromBindingPattern.ts  | 31 ++-----------------
 4 files changed, 38 insertions(+), 33 deletions(-)
 create mode 100644 tests/cases/compiler/bindingPatternCannotBeOnlyInferenceSource.ts
 create mode 100644 tests/cases/compiler/bindingPatternContextualTypeDoesNotCauseWidening.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 350bff0aa8a..25fd5004567 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -21248,11 +21248,15 @@ namespace ts {
                 type;
         }
 
-        function getWidenedLiteralLikeTypeForContextualType(type: Type, contextualType: Type | undefined, contextNode?: Node) {
-            if (!isLiteralOfContextualType(type, contextualType) && !(contextNode && isLiteralOfContextualType(type, instantiateContextualType(contextualType, contextNode)))) {
-                type = getWidenedUniqueESSymbolType(getWidenedLiteralType(type));
+        function getWidenedLiteralLikeTypeForContextualType(type: Type, contextualType: Type | undefined, node?: Node) {
+            if (isLiteralOfContextualType(type, contextualType)) {
+                return type;
             }
-            return type;
+            const instantiatedContextualType = node && instantiateContextualType(contextualType, node) || contextualType;
+            if (instantiatedContextualType !== contextualType && isLiteralOfContextualType(type, instantiatedContextualType)) {
+                return type;
+            }
+            return getWidenedUniqueESSymbolType(getWidenedLiteralType(type));
         }
 
         function getWidenedLiteralLikeTypeForContextualReturnTypeIfNeeded(type: Type | undefined, contextualSignatureReturnType: Type | undefined, isAsync: boolean) {
diff --git a/tests/cases/compiler/bindingPatternCannotBeOnlyInferenceSource.ts b/tests/cases/compiler/bindingPatternCannotBeOnlyInferenceSource.ts
new file mode 100644
index 00000000000..0ac5a1f26b8
--- /dev/null
+++ b/tests/cases/compiler/bindingPatternCannotBeOnlyInferenceSource.ts
@@ -0,0 +1,25 @@
+declare function f<T>(): T;
+const {} = f();       // error
+const { p1 } = f();   // error
+const [] = f();       // error
+const [e1, e2] = f(); // error
+
+// Repro from #43605
+type Dispatch<A = { type: any; [extraProps: string]: any }> = { <T extends A>(action: T): T };
+type IFuncs = { readonly [key: string]: (...p: any) => void };
+type IDestructuring<T extends IFuncs> = { readonly [key in keyof T]?: (...p: Parameters<T[key]>) => void };
+type Destructuring<T extends IFuncs, U extends IDestructuring<T>> = (dispatch: Dispatch<any>, funcs: T) => U;
+const funcs1 = {
+    funcA: (a: boolean): void => {},
+    funcB: (b: string, bb: string): void => {},
+    funcC: (c: number, cc: number, ccc: boolean): void => {},
+};
+type TFuncs1 = typeof funcs1;
+declare function useReduxDispatch1<T extends IDestructuring<TFuncs1>>(destructuring: Destructuring<TFuncs1, T>): T;
+const {} = useReduxDispatch1(
+    (d, f) => ({
+        funcA: (...p) => d(f.funcA(...p)), // p should be inferrable
+        funcB: (...p) => d(f.funcB(...p)),
+        funcC: (...p) => d(f.funcC(...p)),
+    })
+);
diff --git a/tests/cases/compiler/bindingPatternContextualTypeDoesNotCauseWidening.ts b/tests/cases/compiler/bindingPatternContextualTypeDoesNotCauseWidening.ts
new file mode 100644
index 00000000000..a86b8918ebf
--- /dev/null
+++ b/tests/cases/compiler/bindingPatternContextualTypeDoesNotCauseWidening.ts
@@ -0,0 +1,3 @@
+declare function pick<O, T extends keyof O>(keys: T[], obj?: O): Pick<O, T>;
+const _    = pick(['b'], { a: 'a', b: 'b' }); // T: "b"
+const {  } = pick(['b'], { a: 'a', b: 'b' }); // T: "b" | "a" ??? (before fix)
diff --git a/tests/cases/compiler/inferTupleFromBindingPattern.ts b/tests/cases/compiler/inferTupleFromBindingPattern.ts
index c839d16f8e8..7c0c1dea981 100644
--- a/tests/cases/compiler/inferTupleFromBindingPattern.ts
+++ b/tests/cases/compiler/inferTupleFromBindingPattern.ts
@@ -1,29 +1,2 @@
-declare function f2<T>(cb: () => T): T;
-const [e1, e2, e3] = f2(() => [1, "hi", true]);
-
-declare function f1<T>(): T;
-const {} = f1();     // error
-const { p1 } = f1(); // error
-
-declare function pick<O, T extends keyof O>(keys: T[], obj?: O): Pick<O, T>;
-const _    = pick(['b'], { a: 'a', b: 'b' }); // T: "b"
-const {  } = pick(['b'], { a: 'a', b: 'b' }); // T: "b" | "a" ???
-
-type Dispatch<A = { type: any; [extraProps: string]: any }> = { <T extends A>(action: T): T };
-type IFuncs = { readonly [key: string]: (...p: any) => void };
-type IDestructuring<T extends IFuncs> = { readonly [key in keyof T]?: (...p: Parameters<T[key]>) => void };
-type Destructuring<T extends IFuncs, U extends IDestructuring<T>> = (dispatch: Dispatch<any>, funcs: T) => U;
-const funcs1 = {
-    funcA: (a: boolean): void => {},
-    funcB: (b: string, bb: string): void => {},
-    funcC: (c: number, cc: number, ccc: boolean): void => {},
-};
-type TFuncs1 = typeof funcs1;
-declare function useReduxDispatch1<T extends IDestructuring<TFuncs1>>(destructuring: Destructuring<TFuncs1, T>): T;
-const {} = useReduxDispatch1(
-    (d, f) => ({
-        funcA: (...p) => d(f.funcA(...p)),
-        funcB: (...p) => d(f.funcB(...p)),
-        funcC: (...p) => d(f.funcC(...p))
-    })
-);
+declare function f<T>(cb: () => T): T;
+const [e1, e2, e3] = f(() => [1, "hi", true]);