Adds a test showing 'infer' cannot reference other 'infer' in same 'extends'

Author: rbuckton

tests/baselines/reference/inferTypesWithExtends2.errors.txt

@@ -1,14 +1,21 @@
 tests/cases/conformance/types/conditional/inferTypesWithExtends2.ts(3,26): error TS2838: All declarations of 'U' must have identical constraints.
 tests/cases/conformance/types/conditional/inferTypesWithExtends2.ts(3,53): error TS2838: All declarations of 'U' must have identical constraints.
+tests/cases/conformance/types/conditional/inferTypesWithExtends2.ts(8,48): error TS2304: Cannot find name 'U'.
 
 
-==== tests/cases/conformance/types/conditional/inferTypesWithExtends2.ts (2 errors) ====
+==== tests/cases/conformance/types/conditional/inferTypesWithExtends2.ts (3 errors) ====
     // infer twice with different constraints (same behavior as class/interface)
-    type X10<T> =
+    type X1<T> =
         T extends { a: infer U extends string, b: infer U extends number } ? U :
                              ~
 !!! error TS2838: All declarations of 'U' must have identical constraints.
                                                         ~
 !!! error TS2838: All declarations of 'U' must have identical constraints.
         never;
-    
+    
+    // infer cannot reference type params in same 'extends' clause
+    type X2<T> =
+        T extends { a: infer U, b: infer V extends U } ? [U, V] :
+                                                   ~
+!!! error TS2304: Cannot find name 'U'.
+        never;

tests/baselines/reference/inferTypesWithExtends2.js

@@ -1,9 +1,13 @@
 //// [inferTypesWithExtends2.ts]
 // infer twice with different constraints (same behavior as class/interface)
-type X10<T> =
+type X1<T> =
     T extends { a: infer U extends string, b: infer U extends number } ? U :
     never;
-
+
+// infer cannot reference type params in same 'extends' clause
+type X2<T> =
+    T extends { a: infer U, b: infer V extends U } ? [U, V] :
+    never;
 
 //// [inferTypesWithExtends2.js]
 "use strict";

tests/baselines/reference/inferTypesWithExtends2.symbols

@@ -1,11 +1,11 @@
 === tests/cases/conformance/types/conditional/inferTypesWithExtends2.ts ===
 // infer twice with different constraints (same behavior as class/interface)
-type X10<T> =
->X10 : Symbol(X10, Decl(inferTypesWithExtends2.ts, 0, 0))
->T : Symbol(T, Decl(inferTypesWithExtends2.ts, 1, 9))
+type X1<T> =
+>X1 : Symbol(X1, Decl(inferTypesWithExtends2.ts, 0, 0))
+>T : Symbol(T, Decl(inferTypesWithExtends2.ts, 1, 8))
 
     T extends { a: infer U extends string, b: infer U extends number } ? U :
->T : Symbol(T, Decl(inferTypesWithExtends2.ts, 1, 9))
+>T : Symbol(T, Decl(inferTypesWithExtends2.ts, 1, 8))
 >a : Symbol(a, Decl(inferTypesWithExtends2.ts, 2, 15))
 >U : Symbol(U, Decl(inferTypesWithExtends2.ts, 2, 24), Decl(inferTypesWithExtends2.ts, 2, 51))
 >b : Symbol(b, Decl(inferTypesWithExtends2.ts, 2, 42))
@@ -14,3 +14,19 @@ type X10<T> =
 
     never;
 
+// infer cannot reference type params in same 'extends' clause
+type X2<T> =
+>X2 : Symbol(X2, Decl(inferTypesWithExtends2.ts, 3, 10))
+>T : Symbol(T, Decl(inferTypesWithExtends2.ts, 6, 8))
+
+    T extends { a: infer U, b: infer V extends U } ? [U, V] :
+>T : Symbol(T, Decl(inferTypesWithExtends2.ts, 6, 8))
+>a : Symbol(a, Decl(inferTypesWithExtends2.ts, 7, 15))
+>U : Symbol(U, Decl(inferTypesWithExtends2.ts, 7, 24))
+>b : Symbol(b, Decl(inferTypesWithExtends2.ts, 7, 27))
+>V : Symbol(V, Decl(inferTypesWithExtends2.ts, 7, 36))
+>U : Symbol(U)
+>U : Symbol(U, Decl(inferTypesWithExtends2.ts, 7, 24))
+>V : Symbol(V, Decl(inferTypesWithExtends2.ts, 7, 36))
+
+    never;

tests/baselines/reference/inferTypesWithExtends2.types

@@ -1,11 +1,20 @@
 === tests/cases/conformance/types/conditional/inferTypesWithExtends2.ts ===
 // infer twice with different constraints (same behavior as class/interface)
-type X10<T> =
->X10 : X10<T>
+type X1<T> =
+>X1 : X1<T>
 
     T extends { a: infer U extends string, b: infer U extends number } ? U :
 >a : U
 >b : U
 
     never;
 
+// infer cannot reference type params in same 'extends' clause
+type X2<T> =
+>X2 : X2<T>
+
+    T extends { a: infer U, b: infer V extends U } ? [U, V] :
+>a : U
+>b : V
+
+    never;

tests/cases/conformance/types/conditional/inferTypesWithExtends2.ts

@@ -1,6 +1,11 @@
 // @strict: true
 
 // infer twice with different constraints (same behavior as class/interface)
-type X10<T> =
+type X1<T> =
     T extends { a: infer U extends string, b: infer U extends number } ? U :
     never;
+
+// infer cannot reference type params in same 'extends' clause
+type X2<T> =
+    T extends { a: infer U, b: infer V extends U } ? [U, V] :
+    never;