Error handling test

src/compiler/checker.ts

@@ -40789,6 +40789,9 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 if (checkForDisallowedESSymbolOperand(operator)) {
                     leftType = getBaseTypeOfLiteralTypeForComparison(checkNonNullType(leftType, left));
                     rightType = getBaseTypeOfLiteralTypeForComparison(checkNonNullType(rightType, right));
+                    if (leftType.flags === TypeFlags.String && rightType.flags === TypeFlags.String) {
+                        error(errorNode, Diagnostics.Cannot_compare_strings);
+                    }
                     reportOperatorErrorUnless((left, right) => {
                         if (isTypeAny(left) || isTypeAny(right)) {
                             return true;

src/compiler/diagnosticMessages.json

@@ -8519,5 +8519,9 @@
     "'{0}' is not a valid meta-property for keyword 'import'. Did you mean 'meta' or 'defer'?": {
         "category": "Error",
         "code": 18061
+    },
+    "Cannot compare strings": {
+        "category": "Error",
+        "code": 18062
     }
 }

tests/baselines/reference/stringComp.js

@@ -0,0 +1,6 @@
+//// [tests/cases/compiler/stringComp.ts] ////
+
+//// [stringComp.ts]
+
+
+//// [stringComp.js]

tests/baselines/reference/stringComp.symbols

@@ -0,0 +1,4 @@
+//// [tests/cases/compiler/stringComp.ts] ////
+
+=== stringComp.ts ===
+

tests/baselines/reference/stringComp.types

@@ -0,0 +1,4 @@
+//// [tests/cases/compiler/stringComp.ts] ////
+
+=== stringComp.ts ===
+

tests/cases/compiler/stringComp.ts

@@ -0,0 +1,3 @@
+if ("bar" <= "foo") {
+  console.log("Really?")
+}