Report iteration errors on all error nodes

internal/checker/checker.go

@@ -470,7 +470,6 @@ const (
 	IterationUseSpreadFlag               IterationUse = 1 << 5
 	IterationUseDestructuringFlag        IterationUse = 1 << 6
 	IterationUsePossiblyOutOfBounds      IterationUse = 1 << 7
-	IterationUseReportError              IterationUse = 1 << 8
 	// Spread, Destructuring, Array element assignment
 	IterationUseElement                  = IterationUseAllowsSyncIterablesFlag
 	IterationUseSpread                   = IterationUseAllowsSyncIterablesFlag | IterationUseSpreadFlag
@@ -481,7 +480,7 @@ const (
 	IterationUseAsyncYieldStar           = IterationUseAllowsSyncIterablesFlag | IterationUseAllowsAsyncIterablesFlag | IterationUseYieldStarFlag
 	IterationUseGeneratorReturnType      = IterationUseAllowsSyncIterablesFlag
 	IterationUseAsyncGeneratorReturnType = IterationUseAllowsAsyncIterablesFlag
-	IterationUseCacheFlags               = IterationUseAllowsSyncIterablesFlag | IterationUseAllowsAsyncIterablesFlag | IterationUseForOfFlag | IterationUseReportError
+	IterationUseCacheFlags               = IterationUseAllowsSyncIterablesFlag | IterationUseAllowsAsyncIterablesFlag | IterationUseForOfFlag
 )
 
 type IterationTypes struct {
@@ -5900,18 +5899,26 @@ func (c *Checker) getIterationTypesOfIterable(t *Type, use IterationUse, errorNo
 	if IsTypeAny(t) {
 		return IterationTypes{c.anyType, c.anyType, c.anyType}
 	}
-	key := IterationTypesKey{typeId: t.id, use: use&IterationUseCacheFlags | core.IfElse(errorNode != nil, IterationUseReportError, 0)}
+	key := IterationTypesKey{typeId: t.id, use: use & IterationUseCacheFlags}
+	// If we are reporting errors and encounter a cached `noIterationTypes`, we should ignore the cached value and continue as if nothing was cached.
+	// In addition, we should not cache any new results for this call.
+	noCache := false
 	if cached, ok := c.iterationTypesCache[key]; ok {
-		return cached
+		if errorNode == nil || cached.hasTypes() {
+			return cached
+		}
+		noCache = true
+	}
+	result := c.getIterationTypesOfIterableWorker(t, use, errorNode, noCache)
+	if !noCache {
+		c.iterationTypesCache[key] = result
 	}
-	result := c.getIterationTypesOfIterableWorker(t, use, errorNode)
-	c.iterationTypesCache[key] = result
 	return result
 }
 
-func (c *Checker) getIterationTypesOfIterableWorker(t *Type, use IterationUse, errorNode *ast.Node) IterationTypes {
+func (c *Checker) getIterationTypesOfIterableWorker(t *Type, use IterationUse, errorNode *ast.Node, noCache bool) IterationTypes {
 	if t.flags&TypeFlagsUnion != 0 {
-		return c.combineIterationTypes(core.Map(t.Types(), func(t *Type) IterationTypes { return c.getIterationTypesOfIterableWorker(t, use, errorNode) }))
+		return c.combineIterationTypes(core.Map(t.Types(), func(t *Type) IterationTypes { return c.getIterationTypesOfIterableWorker(t, use, errorNode, noCache) }))
 	}
 	if use&IterationUseAllowsAsyncIterablesFlag != 0 {
 		iterationTypes := c.getIterationTypesOfIterableFast(t, c.asyncIterationTypesResolver)

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

@@ -1,9 +1,10 @@
 omittedExpressionForOfLoop.ts(1,19): error TS2304: Cannot find name 'doesNotExist'.
 omittedExpressionForOfLoop.ts(4,19): error TS18050: The value 'undefined' cannot be used here.
 omittedExpressionForOfLoop.ts(7,12): error TS2488: Type 'never' must have a '[Symbol.iterator]()' method that returns an iterator.
+omittedExpressionForOfLoop.ts(10,12): error TS2488: Type 'never' must have a '[Symbol.iterator]()' method that returns an iterator.
 
 
-==== omittedExpressionForOfLoop.ts (3 errors) ====
+==== omittedExpressionForOfLoop.ts (4 errors) ====
     for (const [,] of doesNotExist) {
                       ~~~~~~~~~~~~
 !!! error TS2304: Cannot find name 'doesNotExist'.
@@ -20,4 +21,6 @@ omittedExpressionForOfLoop.ts(7,12): error TS2488: Type 'never' must have a '[Sy
     }
 
     for (const [] of []) {
+               ~~
+!!! error TS2488: Type 'never' must have a '[Symbol.iterator]()' method that returns an iterator.
     }

testdata/baselines/reference/submodule/conformance/for-of16.errors.txt

@@ -1,7 +1,8 @@
 for-of16.ts(8,11): error TS2488: Type 'MyStringIterator' must have a '[Symbol.iterator]()' method that returns an iterator.
+for-of16.ts(10,11): error TS2488: Type 'MyStringIterator' must have a '[Symbol.iterator]()' method that returns an iterator.
 
 
-==== for-of16.ts (1 errors) ====
+==== for-of16.ts (2 errors) ====
     class MyStringIterator {
         [Symbol.iterator]() {
             return this;
@@ -14,4 +15,7 @@ for-of16.ts(8,11): error TS2488: Type 'MyStringIterator' must have a '[Symbol.it
 !!! error TS2488: Type 'MyStringIterator' must have a '[Symbol.iterator]()' method that returns an iterator.
 !!! related TS2489 for-of16.ts:8:11: An iterator must have a 'next()' method.
 
-    for (v of new MyStringIterator) { } // Should still fail (related errors should still be shown even though type is cached).
+    for (v of new MyStringIterator) { } // Should still fail (related errors should still be shown even though type is cached).
+              ~~~~~~~~~~~~~~~~~~~~
+!!! error TS2488: Type 'MyStringIterator' must have a '[Symbol.iterator]()' method that returns an iterator.
+!!! related TS2489 for-of16.ts:10:11: An iterator must have a 'next()' method.

testdata/baselines/reference/submodule/conformance/types.forAwait.es2018.2.errors.txt

@@ -3,9 +3,10 @@ types.forAwait.es2018.2.ts(8,21): error TS2504: Type '{}' must have a '[Symbol.a
 types.forAwait.es2018.2.ts(10,16): error TS2322: Type 'number' is not assignable to type 'string'.
 types.forAwait.es2018.2.ts(12,16): error TS2322: Type 'number' is not assignable to type 'string'.
 types.forAwait.es2018.2.ts(14,21): error TS2488: Type 'AsyncIterable<number>' must have a '[Symbol.iterator]()' method that returns an iterator.
+types.forAwait.es2018.2.ts(16,15): error TS2488: Type 'AsyncIterable<number>' must have a '[Symbol.iterator]()' method that returns an iterator.
 
 
-==== types.forAwait.es2018.2.ts (5 errors) ====
+==== types.forAwait.es2018.2.ts (6 errors) ====
     declare const asyncIterable: AsyncIterable<number>;
     declare const iterable: Iterable<number>;
     async function f() {
@@ -33,6 +34,9 @@ types.forAwait.es2018.2.ts(14,21): error TS2488: Type 'AsyncIterable<number>' mu
 !!! related TS2773 types.forAwait.es2018.2.ts:14:21: Did you forget to use 'await'?
         }
         for (y of asyncIterable) {
+                  ~~~~~~~~~~~~~
+!!! error TS2488: Type 'AsyncIterable<number>' must have a '[Symbol.iterator]()' method that returns an iterator.
+!!! related TS2773 types.forAwait.es2018.2.ts:16:15: Did you forget to use 'await'?
         }
     }