Fix error chaining for iterator parameter validation

Co-authored-by: andrewbranch <[email protected]>

Author: Copilot

internal/checker/checker.go

@@ -6071,7 +6071,7 @@ func (c *Checker) getIterationTypesOfIterableSlow(t *Type, r *IterationTypesReso
 		})
 		if len(validSignatures) == 0 {
 			if errorNode != nil && len(allSignatures) > 0 {
-				c.checkTypeAssignableTo(t, r.getGlobalIterableType(), errorNode, nil /*headMessage*/)
+				c.checkTypeAssignableToEx(t, r.getGlobalIterableType(), errorNode, nil /*headMessage*/, diagnosticOutput)
 			}
 			return IterationTypes{}
 		}

testdata/baselines/reference/submodule/compiler/asyncIteratorExtraParameters.errors.txt

@@ -1,16 +1,8 @@
-asyncIteratorExtraParameters.ts(11,27): error TS2322: Type '{ [Symbol.asyncIterator](_: number): AsyncGenerator<number, void, unknown>; }' is not assignable to type 'AsyncIterable<T, TReturn, TNext>'.
-  Types of property '[Symbol.asyncIterator]' are incompatible.
-    Type '(_: number) => AsyncGenerator<number, void, unknown>' is not assignable to type '() => AsyncIterator<T, TReturn, TNext>'.
-      Target signature provides too few arguments. Expected 1 or more, but got 0.
 asyncIteratorExtraParameters.ts(11,27): error TS2504: Type '{ [Symbol.asyncIterator](_: number): AsyncGenerator<number, void, unknown>; }' must have a '[Symbol.asyncIterator]()' method that returns an async iterator.
-asyncIteratorExtraParameters.ts(13,12): error TS2322: Type '{ [Symbol.asyncIterator](_: number): AsyncGenerator<number, void, unknown>; }' is not assignable to type 'AsyncIterable<T, TReturn, TNext>'.
-  Types of property '[Symbol.asyncIterator]' are incompatible.
-    Type '(_: number) => AsyncGenerator<number, void, unknown>' is not assignable to type '() => AsyncIterator<T, TReturn, TNext>'.
-      Target signature provides too few arguments. Expected 1 or more, but got 0.
 asyncIteratorExtraParameters.ts(13,12): error TS2504: Type '{ [Symbol.asyncIterator](_: number): AsyncGenerator<number, void, unknown>; }' must have a '[Symbol.asyncIterator]()' method that returns an async iterator.
 
 
-==== asyncIteratorExtraParameters.ts (4 errors) ====
+==== asyncIteratorExtraParameters.ts (2 errors) ====
     // https://github.com/microsoft/TypeScript/issues/57130
     const iter = {
         async *[Symbol.asyncIterator](_: number) {
@@ -23,20 +15,18 @@ asyncIteratorExtraParameters.ts(13,12): error TS2504: Type '{ [Symbol.asyncItera
     async function* f() {
         for await (const _ of iter);
                               ~~~~
-!!! error TS2322: Type '{ [Symbol.asyncIterator](_: number): AsyncGenerator<number, void, unknown>; }' is not assignable to type 'AsyncIterable<T, TReturn, TNext>'.
-!!! error TS2322:   Types of property '[Symbol.asyncIterator]' are incompatible.
-!!! error TS2322:     Type '(_: number) => AsyncGenerator<number, void, unknown>' is not assignable to type '() => AsyncIterator<T, TReturn, TNext>'.
-!!! error TS2322:       Target signature provides too few arguments. Expected 1 or more, but got 0.
-                              ~~~~
 !!! error TS2504: Type '{ [Symbol.asyncIterator](_: number): AsyncGenerator<number, void, unknown>; }' must have a '[Symbol.asyncIterator]()' method that returns an async iterator.
+!!! related TS2322 asyncIteratorExtraParameters.ts:11:27: Type '{ [Symbol.asyncIterator](_: number): AsyncGenerator<number, void, unknown>; }' is not assignable to type 'AsyncIterable<T, TReturn, TNext>'.
+  Types of property '[Symbol.asyncIterator]' are incompatible.
+    Type '(_: number) => AsyncGenerator<number, void, unknown>' is not assignable to type '() => AsyncIterator<T, TReturn, TNext>'.
+      Target signature provides too few arguments. Expected 1 or more, but got 0.
 
         yield* iter;
                ~~~~
-!!! error TS2322: Type '{ [Symbol.asyncIterator](_: number): AsyncGenerator<number, void, unknown>; }' is not assignable to type 'AsyncIterable<T, TReturn, TNext>'.
-!!! error TS2322:   Types of property '[Symbol.asyncIterator]' are incompatible.
-!!! error TS2322:     Type '(_: number) => AsyncGenerator<number, void, unknown>' is not assignable to type '() => AsyncIterator<T, TReturn, TNext>'.
-!!! error TS2322:       Target signature provides too few arguments. Expected 1 or more, but got 0.
-               ~~~~
 !!! error TS2504: Type '{ [Symbol.asyncIterator](_: number): AsyncGenerator<number, void, unknown>; }' must have a '[Symbol.asyncIterator]()' method that returns an async iterator.
+!!! related TS2322 asyncIteratorExtraParameters.ts:13:12: Type '{ [Symbol.asyncIterator](_: number): AsyncGenerator<number, void, unknown>; }' is not assignable to type 'AsyncIterable<T, TReturn, TNext>'.
+  Types of property '[Symbol.asyncIterator]' are incompatible.
+    Type '(_: number) => AsyncGenerator<number, void, unknown>' is not assignable to type '() => AsyncIterator<T, TReturn, TNext>'.
+      Target signature provides too few arguments. Expected 1 or more, but got 0.
     }
 

testdata/baselines/reference/submodule/compiler/asyncIteratorExtraParameters.errors.txt.diff

@@ -1,16 +1,8 @@
-iteratorExtraParameters.ts(11,21): error TS2322: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
-  Types of property '[Symbol.iterator]' are incompatible.
-    Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
-      Target signature provides too few arguments. Expected 1 or more, but got 0.
 iteratorExtraParameters.ts(11,21): error TS2488: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' must have a '[Symbol.iterator]()' method that returns an iterator.
-iteratorExtraParameters.ts(13,12): error TS2322: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
-  Types of property '[Symbol.iterator]' are incompatible.
-    Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
-      Target signature provides too few arguments. Expected 1 or more, but got 0.
 iteratorExtraParameters.ts(13,12): error TS2488: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' must have a '[Symbol.iterator]()' method that returns an iterator.
 
 
-==== iteratorExtraParameters.ts (4 errors) ====
+==== iteratorExtraParameters.ts (2 errors) ====
     // https://github.com/microsoft/TypeScript/issues/57130
     const iter = {
         *[Symbol.iterator](_: number) {
@@ -23,21 +15,19 @@ iteratorExtraParameters.ts(13,12): error TS2488: Type '{ [Symbol.iterator](_: nu
     function* f() {
         for (const _ of iter);
                         ~~~~
-!!! error TS2322: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
-!!! error TS2322:   Types of property '[Symbol.iterator]' are incompatible.
-!!! error TS2322:     Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
-!!! error TS2322:       Target signature provides too few arguments. Expected 1 or more, but got 0.
-                        ~~~~
 !!! error TS2488: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' must have a '[Symbol.iterator]()' method that returns an iterator.
+!!! related TS2322 iteratorExtraParameters.ts:11:21: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
+  Types of property '[Symbol.iterator]' are incompatible.
+    Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
+      Target signature provides too few arguments. Expected 1 or more, but got 0.
 
         yield* iter;
                ~~~~
-!!! error TS2322: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
-!!! error TS2322:   Types of property '[Symbol.iterator]' are incompatible.
-!!! error TS2322:     Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
-!!! error TS2322:       Target signature provides too few arguments. Expected 1 or more, but got 0.
-               ~~~~
 !!! error TS2488: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' must have a '[Symbol.iterator]()' method that returns an iterator.
+!!! related TS2322 iteratorExtraParameters.ts:13:12: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
+  Types of property '[Symbol.iterator]' are incompatible.
+    Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
+      Target signature provides too few arguments. Expected 1 or more, but got 0.
 
         [...iter]
 

testdata/baselines/reference/submodule/compiler/iteratorExtraParameters.errors.txt

@@ -1,48 +1,21 @@
 --- old.iteratorExtraParameters.errors.txt
 +++ new.iteratorExtraParameters.errors.txt
 @@= skipped -0, +0 lines =@@
-+iteratorExtraParameters.ts(11,21): error TS2322: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
-+  Types of property '[Symbol.iterator]' are incompatible.
-+    Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
-+      Target signature provides too few arguments. Expected 1 or more, but got 0.
  iteratorExtraParameters.ts(11,21): error TS2488: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' must have a '[Symbol.iterator]()' method that returns an iterator.
-+iteratorExtraParameters.ts(13,12): error TS2322: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
-+  Types of property '[Symbol.iterator]' are incompatible.
-+    Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
-+      Target signature provides too few arguments. Expected 1 or more, but got 0.
  iteratorExtraParameters.ts(13,12): error TS2488: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' must have a '[Symbol.iterator]()' method that returns an iterator.
 -iteratorExtraParameters.ts(15,9): error TS2488: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' must have a '[Symbol.iterator]()' method that returns an iterator.
 -iteratorExtraParameters.ts(17,10): error TS2488: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' must have a '[Symbol.iterator]()' method that returns an iterator.
-
-
- ==== iteratorExtraParameters.ts (4 errors) ====
-@@= skipped -16, +22 lines =@@
-     function* f() {
-         for (const _ of iter);
-                         ~~~~
-+!!! error TS2322: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
-+!!! error TS2322:   Types of property '[Symbol.iterator]' are incompatible.
-+!!! error TS2322:     Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
-+!!! error TS2322:       Target signature provides too few arguments. Expected 1 or more, but got 0.
-+                        ~~~~
- !!! error TS2488: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' must have a '[Symbol.iterator]()' method that returns an iterator.
--!!! related TS2322 iteratorExtraParameters.ts:11:21: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
--  Types of property '[Symbol.iterator]' are incompatible.
--    Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
--      Target signature provides too few arguments. Expected 1 or more, but got 0.
-     
-         yield* iter;
-                ~~~~
-+!!! error TS2322: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
-+!!! error TS2322:   Types of property '[Symbol.iterator]' are incompatible.
-+!!! error TS2322:     Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
-+!!! error TS2322:       Target signature provides too few arguments. Expected 1 or more, but got 0.
-+               ~~~~
- !!! error TS2488: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' must have a '[Symbol.iterator]()' method that returns an iterator.
--!!! related TS2322 iteratorExtraParameters.ts:13:12: Type '{ [Symbol.iterator](_: number): Generator<number, void, unknown>; }' is not assignable to type 'Iterable<T, TReturn, TNext>'.
--  Types of property '[Symbol.iterator]' are incompatible.
--    Type '(_: number) => Generator<number, void, unknown>' is not assignable to type '() => Iterator<T, TReturn, TNext>'.
--      Target signature provides too few arguments. Expected 1 or more, but got 0.
+-
+-
+-==== iteratorExtraParameters.ts (4 errors) ====
++
++
++==== iteratorExtraParameters.ts (2 errors) ====
+     // https://github.com/microsoft/TypeScript/issues/57130
+     const iter = {
+         *[Symbol.iterator](_: number) {
+@@= skipped -31, +29 lines =@@
+       Target signature provides too few arguments. Expected 1 or more, but got 0.
 
          [...iter]
 -            ~~~~