Use same error for iteration in <=ES5 (microsoft#48881)

* Use the same error for iterating over an Iterable in ES5 or lower.

* Accepted baselines.

Author: DanielRosenwasser

src/compiler/checker.ts

@@ -38250,7 +38250,7 @@ namespace ts {
 
             return (use & IterationUse.PossiblyOutOfBounds) ? includeUndefinedInIndexSignature(arrayElementType) : arrayElementType;
 
-            function getIterationDiagnosticDetails(allowsStrings: boolean, downlevelIteration: boolean | undefined): [DiagnosticMessage, boolean] {
+            function getIterationDiagnosticDetails(allowsStrings: boolean, downlevelIteration: boolean | undefined): [error: DiagnosticMessage, maybeMissingAwait: boolean] {
                 if (downlevelIteration) {
                     return allowsStrings
                         ? [Diagnostics.Type_0_is_not_an_array_type_or_a_string_type_or_does_not_have_a_Symbol_iterator_method_that_returns_an_iterator, true]
@@ -38260,7 +38260,7 @@ namespace ts {
                 const yieldType = getIterationTypeOfIterable(use, IterationTypeKind.Yield, inputType, /*errorNode*/ undefined);
 
                 if (yieldType) {
-                    return [Diagnostics.Type_0_is_not_an_array_type_or_a_string_type_Use_compiler_option_downlevelIteration_to_allow_iterating_of_iterators, false];
+                    return [Diagnostics.Type_0_can_only_be_iterated_through_when_using_the_downlevelIteration_flag_or_with_a_target_of_es2015_or_higher, false];
                 }
 
                 if (isES2015OrLaterIterable(inputType.symbol?.escapedName)) {

src/compiler/diagnosticMessages.json

@@ -2511,10 +2511,7 @@
         "category": "Error",
         "code": 2568
     },
-    "Type '{0}' is not an array type or a string type. Use compiler option '--downlevelIteration' to allow iterating of iterators.": {
-        "category": "Error",
-        "code": 2569
-    },
+
     "Could not find name '{0}'. Did you mean '{1}'?": {
         "category": "Error",
         "code": 2570

src/services/codefixes/addMissingAwait.ts

@@ -17,7 +17,7 @@ namespace ts.codefix {
         Diagnostics.This_condition_will_always_return_true_since_this_0_is_always_defined.code,
         Diagnostics.Type_0_is_not_an_array_type.code,
         Diagnostics.Type_0_is_not_an_array_type_or_a_string_type.code,
-        Diagnostics.Type_0_is_not_an_array_type_or_a_string_type_Use_compiler_option_downlevelIteration_to_allow_iterating_of_iterators.code,
+        Diagnostics.Type_0_can_only_be_iterated_through_when_using_the_downlevelIteration_flag_or_with_a_target_of_es2015_or_higher.code,
         Diagnostics.Type_0_is_not_an_array_type_or_a_string_type_or_does_not_have_a_Symbol_iterator_method_that_returns_an_iterator.code,
         Diagnostics.Type_0_is_not_an_array_type_or_does_not_have_a_Symbol_iterator_method_that_returns_an_iterator.code,
         Diagnostics.Type_0_must_have_a_Symbol_iterator_method_that_returns_an_iterator.code,

tests/baselines/reference/ES5For-ofTypeCheck13.errors.txt

@@ -1,4 +1,4 @@
-tests/cases/conformance/statements/for-ofStatements/ES5For-ofTypeCheck13.ts(4,19): error TS2569: Type 'Set<string>' is not an array type or a string type. Use compiler option '--downlevelIteration' to allow iterating of iterators.
+tests/cases/conformance/statements/for-ofStatements/ES5For-ofTypeCheck13.ts(4,19): error TS2802: Type 'Set<string>' can only be iterated through when using the '--downlevelIteration' flag or with a '--target' of 'es2015' or higher.
 
 
 ==== tests/cases/conformance/statements/for-ofStatements/ES5For-ofTypeCheck13.ts (1 errors) ====
@@ -7,4 +7,4 @@ tests/cases/conformance/statements/for-ofStatements/ES5For-ofTypeCheck13.ts(4,19
     strSet.add('World')
     for (const str of strSet) { }
                       ~~~~~~
-!!! error TS2569: Type 'Set<string>' is not an array type or a string type. Use compiler option '--downlevelIteration' to allow iterating of iterators.
+!!! error TS2802: Type 'Set<string>' can only be iterated through when using the '--downlevelIteration' flag or with a '--target' of 'es2015' or higher.

tests/baselines/reference/ES5For-ofTypeCheck14.errors.txt

@@ -1,8 +1,8 @@
-tests/cases/conformance/statements/for-ofStatements/ES5For-ofTypeCheck14.ts(2,17): error TS2569: Type 'Set<number>' is not an array type or a string type. Use compiler option '--downlevelIteration' to allow iterating of iterators.
+tests/cases/conformance/statements/for-ofStatements/ES5For-ofTypeCheck14.ts(2,17): error TS2802: Type 'Set<number>' can only be iterated through when using the '--downlevelIteration' flag or with a '--target' of 'es2015' or higher.
 
 
 ==== tests/cases/conformance/statements/for-ofStatements/ES5For-ofTypeCheck14.ts (1 errors) ====
     var union: string | Set<number>
     for (const e of union) { }
                     ~~~~~
-!!! error TS2569: Type 'Set<number>' is not an array type or a string type. Use compiler option '--downlevelIteration' to allow iterating of iterators.
+!!! error TS2802: Type 'Set<number>' can only be iterated through when using the '--downlevelIteration' flag or with a '--target' of 'es2015' or higher.