Always check index type validity for all types when an error node is present so we always issue an error

src/compiler/checker.ts

@@ -9356,13 +9356,24 @@ namespace ts {
             const apparentObjectType = getApparentType(objectType);
             if (indexType.flags & TypeFlags.Union && !(indexType.flags & TypeFlags.Boolean)) {
                 const propTypes: Type[] = [];
+                let wasMissingProp = false;
                 for (const t of (<UnionType>indexType).types) {
                     const propType = getPropertyTypeForIndexType(apparentObjectType, t, accessNode, /*cacheSymbol*/ false, missingType);
                     if (propType === missingType) {
-                        return missingType;
+                        if (!accessNode) {
+                            // If there's no error node, we can immeditely stop, since error reporting is off
+                            return missingType;
+                        }
+                        else {
+                            // Otherwise we set a flag and return at the end of the loop so we still mark all errors
+                            wasMissingProp = true;
+                        }
                     }
                     propTypes.push(propType);
                 }
+                if (wasMissingProp) {
+                    return missingType;
+                }
                 return getUnionType(propTypes);
             }
             return getPropertyTypeForIndexType(apparentObjectType, indexType, accessNode, /*cacheSymbol*/ true, missingType);

tests/baselines/reference/arrayIndexWithArrayFails.errors.txt

@@ -0,0 +1,9 @@
+tests/cases/compiler/arrayIndexWithArrayFails.ts(3,16): error TS2538: Type 'string[]' cannot be used as an index type.
+
+
+==== tests/cases/compiler/arrayIndexWithArrayFails.ts (1 errors) ====
+    declare const arr1: (string | string[])[];
+    declare const arr2: number[];
+    const j = arr2[arr1[0]]; // should error
+                   ~~~~~~~
+!!! error TS2538: Type 'string[]' cannot be used as an index type.

tests/baselines/reference/arrayIndexWithArrayFails.js

@@ -0,0 +1,7 @@
+//// [arrayIndexWithArrayFails.ts]
+declare const arr1: (string | string[])[];
+declare const arr2: number[];
+const j = arr2[arr1[0]]; // should error
+
+//// [arrayIndexWithArrayFails.js]
+var j = arr2[arr1[0]]; // should error

tests/baselines/reference/arrayIndexWithArrayFails.symbols

@@ -0,0 +1,12 @@
+=== tests/cases/compiler/arrayIndexWithArrayFails.ts ===
+declare const arr1: (string | string[])[];
+>arr1 : Symbol(arr1, Decl(arrayIndexWithArrayFails.ts, 0, 13))
+
+declare const arr2: number[];
+>arr2 : Symbol(arr2, Decl(arrayIndexWithArrayFails.ts, 1, 13))
+
+const j = arr2[arr1[0]]; // should error
+>j : Symbol(j, Decl(arrayIndexWithArrayFails.ts, 2, 5))
+>arr2 : Symbol(arr2, Decl(arrayIndexWithArrayFails.ts, 1, 13))
+>arr1 : Symbol(arr1, Decl(arrayIndexWithArrayFails.ts, 0, 13))
+

tests/baselines/reference/arrayIndexWithArrayFails.types

@@ -0,0 +1,15 @@
+=== tests/cases/compiler/arrayIndexWithArrayFails.ts ===
+declare const arr1: (string | string[])[];
+>arr1 : (string | string[])[]
+
+declare const arr2: number[];
+>arr2 : number[]
+
+const j = arr2[arr1[0]]; // should error
+>j : any
+>arr2[arr1[0]] : any
+>arr2 : number[]
+>arr1[0] : string | string[]
+>arr1 : (string | string[])[]
+>0 : 0
+

tests/baselines/reference/keyofAndIndexedAccessErrors.errors.txt

@@ -8,9 +8,12 @@ tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(25,18): error
 tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(26,18): error TS2538: Type 'void' cannot be used as an index type.
 tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(27,18): error TS2538: Type 'undefined' cannot be used as an index type.
 tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(28,18): error TS2538: Type '{ x: string; }' cannot be used as an index type.
+tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(29,18): error TS2537: Type 'Shape' has no matching index signature for type 'number'.
 tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(29,18): error TS2537: Type 'Shape' has no matching index signature for type 'string'.
 tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(30,18): error TS2538: Type 'string & number' cannot be used as an index type.
 tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(31,18): error TS2537: Type 'Shape' has no matching index signature for type 'string'.
+tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(31,18): error TS2538: Type 'false' cannot be used as an index type.
+tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(31,18): error TS2538: Type 'true' cannot be used as an index type.
 tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(35,21): error TS2537: Type 'string[]' has no matching index signature for type 'string'.
 tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(36,21): error TS2538: Type 'boolean' cannot be used as an index type.
 tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(41,31): error TS2538: Type 'boolean' cannot be used as an index type.
@@ -60,7 +63,7 @@ tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(117,5): error
   Type 'T' is not assignable to type 'U'.
 
 
-==== tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts (33 errors) ====
+==== tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts (36 errors) ====
     class Shape {
         name: string;
         width: number;
@@ -111,13 +114,19 @@ tests/cases/conformance/types/keyof/keyofAndIndexedAccessErrors.ts(117,5): error
 !!! error TS2538: Type '{ x: string; }' cannot be used as an index type.
     type T20 = Shape[string | number];  // Error
                      ~~~~~~~~~~~~~~~
+!!! error TS2537: Type 'Shape' has no matching index signature for type 'number'.
+                     ~~~~~~~~~~~~~~~
 !!! error TS2537: Type 'Shape' has no matching index signature for type 'string'.
     type T21 = Shape[string & number];  // Error
                      ~~~~~~~~~~~~~~~
 !!! error TS2538: Type 'string & number' cannot be used as an index type.
     type T22 = Shape[string | boolean];  // Error
                      ~~~~~~~~~~~~~~~~
 !!! error TS2537: Type 'Shape' has no matching index signature for type 'string'.
+                     ~~~~~~~~~~~~~~~~
+!!! error TS2538: Type 'false' cannot be used as an index type.
+                     ~~~~~~~~~~~~~~~~
+!!! error TS2538: Type 'true' cannot be used as an index type.
 
     type T30 = string[]["length"];
     type T31 = string[][number];

tests/cases/compiler/arrayIndexWithArrayFails.ts

@@ -0,0 +1,3 @@
+declare const arr1: (string | string[])[];
+declare const arr2: number[];
+const j = arr2[arr1[0]]; // should error