Use the existing checkCrossProductUnion helper

Author: amcasey

src/compiler/checker.ts

@@ -13394,6 +13394,7 @@ namespace ts {
         function checkCrossProductUnion(types: readonly Type[]) {
             const size = reduceLeft(types, (n, t) => n * (t.flags & TypeFlags.Union ? (<UnionType>t).types.length : t.flags & TypeFlags.Never ? 0 : 1), 1);
             if (size >= 100000) {
+                tracing.instant(tracing.Phase.Check, "checkCrossProductUnion_DepthLimit", { typeIds: types.map(t => t.id), size });
                 error(currentNode, Diagnostics.Expression_produces_a_union_type_that_is_too_complex_to_represent);
                 return false;
             }
@@ -14458,14 +14459,18 @@ namespace ts {
                 if (merged) {
                     return getSpreadType(merged, right, symbol, objectFlags, readonly);
                 }
-                return errorTypeIfTooLarge() ?? mapType(left, t => getSpreadType(t, right, symbol, objectFlags, readonly));
+                return checkCrossProductUnion([left, right])
+                    ? mapType(left, t => getSpreadType(t, right, symbol, objectFlags, readonly))
+                    : errorType;
             }
             if (right.flags & TypeFlags.Union) {
                 const merged = tryMergeUnionOfObjectTypeAndEmptyObject(right as UnionType, readonly);
                 if (merged) {
                     return getSpreadType(left, merged, symbol, objectFlags, readonly);
                 }
-                return errorTypeIfTooLarge() ?? mapType(right, t => getSpreadType(left, t, symbol, objectFlags, readonly));
+                return checkCrossProductUnion([left, right])
+                    ? mapType(right, t => getSpreadType(left, t, symbol, objectFlags, readonly))
+                    : errorType;
             }
             if (right.flags & (TypeFlags.BooleanLike | TypeFlags.NumberLike | TypeFlags.BigIntLike | TypeFlags.StringLike | TypeFlags.EnumLike | TypeFlags.NonPrimitive | TypeFlags.Index)) {
                 return left;
@@ -14544,17 +14549,6 @@ namespace ts {
                 getIndexInfoWithReadonly(numberIndexInfo, readonly));
             spread.objectFlags |= ObjectFlags.ObjectLiteral | ObjectFlags.ContainsObjectOrArrayLiteral | ObjectFlags.ContainsSpread | objectFlags;
             return spread;
-
-            function errorTypeIfTooLarge(): Type | undefined {
-                if (left.flags & right.flags & TypeFlags.Union) {
-                    const resultSize = (left as UnionType).types.length * (right as UnionType).types.length;
-                    if (resultSize > 100000) {
-                        tracing.instant(tracing.Phase.Check, "getSpreadType_DepthLimit", { leftId: left.id, rightId: right.id });
-                        error(currentNode, Diagnostics.Spread_expression_produces_a_union_type_that_is_too_complex_to_represent);
-                        return errorType;
-                    }
-                }
-            }
         }
 
         /** We approximate own properties as non-methods plus methods that are inside the object literal */

src/compiler/diagnosticMessages.json

@@ -3048,10 +3048,6 @@
         "category": "Error",
         "code": 2795
     },
-    "Spread expression produces a union type that is too complex to represent.": {
-        "category": "Error",
-        "code": 2796
-    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",

tests/baselines/reference/objectSpreadRepeatedComplexity.errors.txt

@@ -1,4 +1,4 @@
-tests/cases/conformance/types/spread/objectSpreadRepeatedComplexity.ts(3,12): error TS2796: Spread expression produces a union type that is too complex to represent.
+tests/cases/conformance/types/spread/objectSpreadRepeatedComplexity.ts(3,12): error TS2590: Expression produces a union type that is too complex to represent.
 
 
 ==== tests/cases/conformance/types/spread/objectSpreadRepeatedComplexity.ts (1 errors) ====
@@ -166,5 +166,5 @@ tests/cases/conformance/types/spread/objectSpreadRepeatedComplexity.ts(3,12): er
     ~~~~~~~~~~~
         };
     ~~~~~
-!!! error TS2796: Spread expression produces a union type that is too complex to represent.
+!!! error TS2590: Expression produces a union type that is too complex to represent.
     }