Add repro from comment in #49226

Author: ahejlsberg

tests/baselines/reference/inferFromNestedSameShapeTuple.errors.txt

@@ -0,0 +1,54 @@
+tests/cases/compiler/inferFromNestedSameShapeTuple.ts(42,5): error TS2322: Type 'T1<U>' is not assignable to type 'T2<U>'.
+  Type at position 0 in source is not compatible with type at position 0 in target.
+    Type 'number' is not assignable to type '42'.
+
+
+==== tests/cases/compiler/inferFromNestedSameShapeTuple.ts (1 errors) ====
+    // repro #48524
+    
+    type Magic<X> = X extends [[infer Y, ...infer _], ...infer __] ? Y : never;
+    
+    type R = Magic<[[number]]>
+    
+    // repro #52722
+    
+    type Recursive<Id> = {
+        id: Id
+        children: readonly Recursive<Id>[]
+    }
+    
+    declare function getIds<Id>(items: readonly Recursive<Id>[]): Id[];
+    
+    const items = [{
+        id: 'a',
+        children: [{
+            id: 'b',
+            children: []
+        }]
+    }] as const satisfies readonly Recursive<string>[]
+    
+    const foo = getIds(items)
+    
+    // variant with a fresh argument
+    const foo2 = getIds([{
+        id: 'a',
+        children: [{
+            id: 'b',
+            children: []
+        }]
+    }] as const)
+    
+    // Repro from comment in #49226
+    
+    type T1<T> = [number, T1<{ x: T }>];
+    type T2<T> = [42, T2<{ x: T }>];
+    
+    function qq<U>(x: T1<U>, y: T2<U>) {
+        x = y;
+        y = x;  // Error
+        ~
+!!! error TS2322: Type 'T1<U>' is not assignable to type 'T2<U>'.
+!!! error TS2322:   Type at position 0 in source is not compatible with type at position 0 in target.
+!!! error TS2322:     Type 'number' is not assignable to type '42'.
+    }
+    

tests/baselines/reference/inferFromNestedSameShapeTuple.symbols

@@ -84,3 +84,38 @@ const foo2 = getIds([{
 }] as const)
 >const : Symbol(const)
 
+// Repro from comment in #49226
+
+type T1<T> = [number, T1<{ x: T }>];
+>T1 : Symbol(T1, Decl(inferFromNestedSameShapeTuple.ts, 32, 12))
+>T : Symbol(T, Decl(inferFromNestedSameShapeTuple.ts, 36, 8))
+>T1 : Symbol(T1, Decl(inferFromNestedSameShapeTuple.ts, 32, 12))
+>x : Symbol(x, Decl(inferFromNestedSameShapeTuple.ts, 36, 26))
+>T : Symbol(T, Decl(inferFromNestedSameShapeTuple.ts, 36, 8))
+
+type T2<T> = [42, T2<{ x: T }>];
+>T2 : Symbol(T2, Decl(inferFromNestedSameShapeTuple.ts, 36, 36))
+>T : Symbol(T, Decl(inferFromNestedSameShapeTuple.ts, 37, 8))
+>T2 : Symbol(T2, Decl(inferFromNestedSameShapeTuple.ts, 36, 36))
+>x : Symbol(x, Decl(inferFromNestedSameShapeTuple.ts, 37, 22))
+>T : Symbol(T, Decl(inferFromNestedSameShapeTuple.ts, 37, 8))
+
+function qq<U>(x: T1<U>, y: T2<U>) {
+>qq : Symbol(qq, Decl(inferFromNestedSameShapeTuple.ts, 37, 32))
+>U : Symbol(U, Decl(inferFromNestedSameShapeTuple.ts, 39, 12))
+>x : Symbol(x, Decl(inferFromNestedSameShapeTuple.ts, 39, 15))
+>T1 : Symbol(T1, Decl(inferFromNestedSameShapeTuple.ts, 32, 12))
+>U : Symbol(U, Decl(inferFromNestedSameShapeTuple.ts, 39, 12))
+>y : Symbol(y, Decl(inferFromNestedSameShapeTuple.ts, 39, 24))
+>T2 : Symbol(T2, Decl(inferFromNestedSameShapeTuple.ts, 36, 36))
+>U : Symbol(U, Decl(inferFromNestedSameShapeTuple.ts, 39, 12))
+
+    x = y;
+>x : Symbol(x, Decl(inferFromNestedSameShapeTuple.ts, 39, 15))
+>y : Symbol(y, Decl(inferFromNestedSameShapeTuple.ts, 39, 24))
+
+    y = x;  // Error
+>y : Symbol(y, Decl(inferFromNestedSameShapeTuple.ts, 39, 24))
+>x : Symbol(x, Decl(inferFromNestedSameShapeTuple.ts, 39, 15))
+}
+

tests/baselines/reference/inferFromNestedSameShapeTuple.types

@@ -84,3 +84,30 @@ const foo2 = getIds([{
 
     }]
 }] as const)
+
+// Repro from comment in #49226
+
+type T1<T> = [number, T1<{ x: T }>];
+>T1 : T1<T>
+>x : T
+
+type T2<T> = [42, T2<{ x: T }>];
+>T2 : T2<T>
+>x : T
+
+function qq<U>(x: T1<U>, y: T2<U>) {
+>qq : <U>(x: T1<U>, y: T2<U>) => void
+>x : T1<U>
+>y : T2<U>
+
+    x = y;
+>x = y : T2<U>
+>x : T1<U>
+>y : T2<U>
+
+    y = x;  // Error
+>y = x : T1<U>
+>y : T2<U>
+>x : T1<U>
+}
+

tests/cases/compiler/inferFromNestedSameShapeTuple.ts

@@ -33,4 +33,14 @@ const foo2 = getIds([{
         id: 'b',
         children: []
     }]
-}] as const)
+}] as const)
+
+// Repro from comment in #49226
+
+type T1<T> = [number, T1<{ x: T }>];
+type T2<T> = [42, T2<{ x: T }>];
+
+function qq<U>(x: T1<U>, y: T2<U>) {
+    x = y;
+    y = x;  // Error
+}