Feature/28297 make error message at a constant or a read only property more specific

src/compiler/checker.ts

@@ -9455,7 +9455,7 @@ namespace ts {
                     if (accessExpression) {
                         markPropertyAsReferenced(prop, accessExpression, /*isThisAccess*/ accessExpression.expression.kind === SyntaxKind.ThisKeyword);
                         if (isAssignmentTarget(accessExpression) && (isReferenceToReadonlyEntity(accessExpression, prop) || isReferenceThroughNamespaceImport(accessExpression))) {
-                            error(accessExpression.argumentExpression, Diagnostics.Cannot_assign_to_0_because_it_is_a_constant_or_a_read_only_property, symbolToString(prop));
+                            error(accessExpression.argumentExpression, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, symbolToString(prop));
                             return missingType;
                         }
                         if (cacheSymbol) {
@@ -16115,7 +16115,12 @@ namespace ts {
                     return errorType;
                 }
                 if (isReadonlySymbol(localOrExportSymbol)) {
-                    error(node, Diagnostics.Cannot_assign_to_0_because_it_is_a_constant_or_a_read_only_property, symbolToString(symbol));
+                    if (localOrExportSymbol.flags & SymbolFlags.Variable) {
+                        error(node, Diagnostics.Cannot_assign_to_0_because_it_is_a_constant, symbolToString(symbol));
+                    }
+                    else {
+                        error(node, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, symbolToString(symbol));
+                    }
                     return errorType;
                 }
             }
@@ -18700,7 +18705,7 @@ namespace ts {
                 checkPropertyAccessibility(node, left.kind === SyntaxKind.SuperKeyword, apparentType, prop);
                 if (assignmentKind) {
                     if (isReferenceToReadonlyEntity(<Expression>node, prop) || isReferenceThroughNamespaceImport(<Expression>node)) {
-                        error(right, Diagnostics.Cannot_assign_to_0_because_it_is_a_constant_or_a_read_only_property, idText(right));
+                        error(right, Diagnostics.Cannot_assign_to_0_because_it_is_a_read_only_property, idText(right));
                         return errorType;
                     }
                 }

src/compiler/diagnosticMessages.json

@@ -1944,7 +1944,7 @@
         "category": "Error",
         "code": 2539
     },
-    "Cannot assign to '{0}' because it is a constant or a read-only property.": {
+    "Cannot assign to '{0}' because it is a read-only property.": {
         "category": "Error",
         "code": 2540
     },
@@ -2124,6 +2124,10 @@
         "category": "Error",
         "code": 2587
     },
+    "Cannot assign to '{0}' because it is a constant.": {
+        "category": "Error",
+        "code": 2588
+    },
     "JSX element attributes type '{0}' may not be a union type.": {
         "category": "Error",
         "code": 2600

tests/baselines/reference/abstractPropertyNegative.errors.txt

@@ -6,7 +6,7 @@ tests/cases/compiler/abstractPropertyNegative.ts(13,7): error TS2515: Non-abstra
 tests/cases/compiler/abstractPropertyNegative.ts(13,7): error TS2515: Non-abstract class 'C' does not implement inherited abstract member 'readonlyProp' from class 'B'.
 tests/cases/compiler/abstractPropertyNegative.ts(15,5): error TS1244: Abstract methods can only appear within an abstract class.
 tests/cases/compiler/abstractPropertyNegative.ts(16,37): error TS1005: '{' expected.
-tests/cases/compiler/abstractPropertyNegative.ts(19,3): error TS2540: Cannot assign to 'ro' because it is a constant or a read-only property.
+tests/cases/compiler/abstractPropertyNegative.ts(19,3): error TS2540: Cannot assign to 'ro' because it is a read-only property.
 tests/cases/compiler/abstractPropertyNegative.ts(25,5): error TS2416: Property 'num' in type 'WrongTypePropertyImpl' is not assignable to the same property in base type 'WrongTypeProperty'.
   Type 'string' is not assignable to type 'number'.
 tests/cases/compiler/abstractPropertyNegative.ts(31,9): error TS2416: Property 'num' in type 'WrongTypeAccessorImpl' is not assignable to the same property in base type 'WrongTypeAccessor'.
@@ -56,7 +56,7 @@ tests/cases/compiler/abstractPropertyNegative.ts(41,18): error TS2676: Accessors
     let c = new C();
     c.ro = "error: lhs of assignment can't be readonly";
       ~~
-!!! error TS2540: Cannot assign to 'ro' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'ro' because it is a read-only property.
 
     abstract class WrongTypeProperty {
         abstract num: number;

tests/baselines/reference/assignToEnum.errors.txt

@@ -1,7 +1,7 @@
 tests/cases/compiler/assignToEnum.ts(2,1): error TS2539: Cannot assign to 'A' because it is not a variable.
 tests/cases/compiler/assignToEnum.ts(3,1): error TS2539: Cannot assign to 'A' because it is not a variable.
-tests/cases/compiler/assignToEnum.ts(4,3): error TS2540: Cannot assign to 'foo' because it is a constant or a read-only property.
-tests/cases/compiler/assignToEnum.ts(5,3): error TS2540: Cannot assign to 'foo' because it is a constant or a read-only property.
+tests/cases/compiler/assignToEnum.ts(4,3): error TS2540: Cannot assign to 'foo' because it is a read-only property.
+tests/cases/compiler/assignToEnum.ts(5,3): error TS2540: Cannot assign to 'foo' because it is a read-only property.
 
 
 ==== tests/cases/compiler/assignToEnum.ts (4 errors) ====
@@ -14,9 +14,9 @@ tests/cases/compiler/assignToEnum.ts(5,3): error TS2540: Cannot assign to 'foo'
 !!! error TS2539: Cannot assign to 'A' because it is not a variable.
     A.foo = 1;      // invalid LHS
       ~~~
-!!! error TS2540: Cannot assign to 'foo' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'foo' because it is a read-only property.
     A.foo = A.bar;  // invalid LHS
       ~~~
-!!! error TS2540: Cannot assign to 'foo' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'foo' because it is a read-only property.
 
 

tests/baselines/reference/assignments.errors.txt

@@ -1,7 +1,7 @@
 tests/cases/conformance/expressions/valuesAndReferences/assignments.ts(11,1): error TS2708: Cannot use namespace 'M' as a value.
 tests/cases/conformance/expressions/valuesAndReferences/assignments.ts(14,1): error TS2539: Cannot assign to 'C' because it is not a variable.
 tests/cases/conformance/expressions/valuesAndReferences/assignments.ts(17,1): error TS2539: Cannot assign to 'E' because it is not a variable.
-tests/cases/conformance/expressions/valuesAndReferences/assignments.ts(18,3): error TS2540: Cannot assign to 'A' because it is a constant or a read-only property.
+tests/cases/conformance/expressions/valuesAndReferences/assignments.ts(18,3): error TS2540: Cannot assign to 'A' because it is a read-only property.
 tests/cases/conformance/expressions/valuesAndReferences/assignments.ts(21,1): error TS2539: Cannot assign to 'fn' because it is not a variable.
 tests/cases/conformance/expressions/valuesAndReferences/assignments.ts(31,1): error TS2693: 'I' only refers to a type, but is being used as a value here.
 
@@ -32,7 +32,7 @@ tests/cases/conformance/expressions/valuesAndReferences/assignments.ts(31,1): er
 !!! error TS2539: Cannot assign to 'E' because it is not a variable.
     E.A = null; // OK per spec, Error per implementation (509581)
       ~
-!!! error TS2540: Cannot assign to 'A' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'A' because it is a read-only property.
 
     function fn() { }
     fn = null; // Should be error

tests/baselines/reference/bigintWithLib.errors.txt

@@ -1,10 +1,10 @@
 tests/cases/compiler/bigintWithLib.ts(4,1): error TS2350: Only a void function can be called with the 'new' keyword.
 tests/cases/compiler/bigintWithLib.ts(16,33): error TS2345: Argument of type 'number[]' is not assignable to parameter of type 'ArrayBuffer | SharedArrayBuffer'.
   Type 'number[]' is missing the following properties from type 'SharedArrayBuffer': byteLength, [Symbol.species], [Symbol.toStringTag]
-tests/cases/compiler/bigintWithLib.ts(21,13): error TS2540: Cannot assign to 'length' because it is a constant or a read-only property.
+tests/cases/compiler/bigintWithLib.ts(21,13): error TS2540: Cannot assign to 'length' because it is a read-only property.
 tests/cases/compiler/bigintWithLib.ts(28,35): error TS2345: Argument of type 'number[]' is not assignable to parameter of type 'ArrayBuffer | SharedArrayBuffer'.
   Type 'number[]' is not assignable to type 'SharedArrayBuffer'.
-tests/cases/compiler/bigintWithLib.ts(33,13): error TS2540: Cannot assign to 'length' because it is a constant or a read-only property.
+tests/cases/compiler/bigintWithLib.ts(33,13): error TS2540: Cannot assign to 'length' because it is a read-only property.
 tests/cases/compiler/bigintWithLib.ts(40,25): error TS2345: Argument of type '-1' is not assignable to parameter of type 'bigint'.
 tests/cases/compiler/bigintWithLib.ts(43,26): error TS2345: Argument of type '123' is not assignable to parameter of type 'bigint'.
 
@@ -37,7 +37,7 @@ tests/cases/compiler/bigintWithLib.ts(43,26): error TS2345: Argument of type '12
     let len: number = bigIntArray.length;
     bigIntArray.length = 10; // should error
                 ~~~~~~
-!!! error TS2540: Cannot assign to 'length' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'length' because it is a read-only property.
     let arrayBufferLike: ArrayBufferView = bigIntArray;
 
     // Test BigUint64Array
@@ -54,7 +54,7 @@ tests/cases/compiler/bigintWithLib.ts(43,26): error TS2345: Argument of type '12
     len = bigIntArray.length;
     bigIntArray.length = 10; // should error
                 ~~~~~~
-!!! error TS2540: Cannot assign to 'length' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'length' because it is a read-only property.
     arrayBufferLike = bigIntArray;
 
     // Test added DataView methods

tests/baselines/reference/checkExportsObjectAssignProperty.errors.txt

@@ -1,10 +1,10 @@
-tests/cases/conformance/jsdoc/validator.ts(17,4): error TS2540: Cannot assign to 'readonlyProp' because it is a constant or a read-only property.
-tests/cases/conformance/jsdoc/validator.ts(18,4): error TS2540: Cannot assign to 'readonlyAccessor' because it is a constant or a read-only property.
+tests/cases/conformance/jsdoc/validator.ts(17,4): error TS2540: Cannot assign to 'readonlyProp' because it is a read-only property.
+tests/cases/conformance/jsdoc/validator.ts(18,4): error TS2540: Cannot assign to 'readonlyAccessor' because it is a read-only property.
 tests/cases/conformance/jsdoc/validator.ts(19,1): error TS2322: Type '"no"' is not assignable to type 'number'.
 tests/cases/conformance/jsdoc/validator.ts(20,1): error TS2322: Type '"no"' is not assignable to type 'number'.
 tests/cases/conformance/jsdoc/validator.ts(21,1): error TS2322: Type '0' is not assignable to type 'string'.
-tests/cases/conformance/jsdoc/validator.ts(37,4): error TS2540: Cannot assign to 'readonlyProp' because it is a constant or a read-only property.
-tests/cases/conformance/jsdoc/validator.ts(38,4): error TS2540: Cannot assign to 'readonlyAccessor' because it is a constant or a read-only property.
+tests/cases/conformance/jsdoc/validator.ts(37,4): error TS2540: Cannot assign to 'readonlyProp' because it is a read-only property.
+tests/cases/conformance/jsdoc/validator.ts(38,4): error TS2540: Cannot assign to 'readonlyAccessor' because it is a read-only property.
 tests/cases/conformance/jsdoc/validator.ts(39,1): error TS2322: Type '0' is not assignable to type 'string'.
 tests/cases/conformance/jsdoc/validator.ts(40,1): error TS2322: Type '"no"' is not assignable to type 'number'.
 tests/cases/conformance/jsdoc/validator.ts(41,1): error TS2322: Type '0' is not assignable to type 'string'.
@@ -29,10 +29,10 @@ tests/cases/conformance/jsdoc/validator.ts(41,1): error TS2322: Type '0' is not
     // disallowed assignments
     m1.readonlyProp = "name";
        ~~~~~~~~~~~~
-!!! error TS2540: Cannot assign to 'readonlyProp' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'readonlyProp' because it is a read-only property.
     m1.readonlyAccessor = 12;
        ~~~~~~~~~~~~~~~~
-!!! error TS2540: Cannot assign to 'readonlyAccessor' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'readonlyAccessor' because it is a read-only property.
     m1.thing = "no";
     ~~~~~~~~
 !!! error TS2322: Type '"no"' is not assignable to type 'number'.
@@ -59,10 +59,10 @@ tests/cases/conformance/jsdoc/validator.ts(41,1): error TS2322: Type '0' is not
     // disallowed assignments
     m2.readonlyProp = "name";
        ~~~~~~~~~~~~
-!!! error TS2540: Cannot assign to 'readonlyProp' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'readonlyProp' because it is a read-only property.
     m2.readonlyAccessor = 12;
        ~~~~~~~~~~~~~~~~
-!!! error TS2540: Cannot assign to 'readonlyAccessor' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'readonlyAccessor' because it is a read-only property.
     m2.thing = 0;
     ~~~~~~~~
 !!! error TS2322: Type '0' is not assignable to type 'string'.

tests/baselines/reference/checkExportsObjectAssignPrototypeProperty.errors.txt

@@ -1,5 +1,5 @@
-tests/cases/conformance/jsdoc/validator.ts(19,4): error TS2540: Cannot assign to 'readonlyProp' because it is a constant or a read-only property.
-tests/cases/conformance/jsdoc/validator.ts(20,4): error TS2540: Cannot assign to 'readonlyAccessor' because it is a constant or a read-only property.
+tests/cases/conformance/jsdoc/validator.ts(19,4): error TS2540: Cannot assign to 'readonlyProp' because it is a read-only property.
+tests/cases/conformance/jsdoc/validator.ts(20,4): error TS2540: Cannot assign to 'readonlyAccessor' because it is a read-only property.
 tests/cases/conformance/jsdoc/validator.ts(21,1): error TS2322: Type '"no"' is not assignable to type 'number'.
 tests/cases/conformance/jsdoc/validator.ts(22,1): error TS2322: Type '"no"' is not assignable to type 'number'.
 tests/cases/conformance/jsdoc/validator.ts(23,1): error TS2322: Type '0' is not assignable to type 'string'.
@@ -26,10 +26,10 @@ tests/cases/conformance/jsdoc/validator.ts(23,1): error TS2322: Type '0' is not
     // disallowed assignments
     m1.readonlyProp = "name";
        ~~~~~~~~~~~~
-!!! error TS2540: Cannot assign to 'readonlyProp' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'readonlyProp' because it is a read-only property.
     m1.readonlyAccessor = 12;
        ~~~~~~~~~~~~~~~~
-!!! error TS2540: Cannot assign to 'readonlyAccessor' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'readonlyAccessor' because it is a read-only property.
     m1.thing = "no";
     ~~~~~~~~
 !!! error TS2322: Type '"no"' is not assignable to type 'number'.

tests/baselines/reference/checkObjectDefineProperty.errors.txt

@@ -1,7 +1,7 @@
-tests/cases/conformance/jsdoc/validate.ts(14,3): error TS2540: Cannot assign to 'lastName' because it is a constant or a read-only property.
-tests/cases/conformance/jsdoc/validate.ts(15,3): error TS2540: Cannot assign to 'houseNumber' because it is a constant or a read-only property.
+tests/cases/conformance/jsdoc/validate.ts(14,3): error TS2540: Cannot assign to 'lastName' because it is a read-only property.
+tests/cases/conformance/jsdoc/validate.ts(15,3): error TS2540: Cannot assign to 'houseNumber' because it is a read-only property.
 tests/cases/conformance/jsdoc/validate.ts(16,1): error TS2322: Type '12' is not assignable to type 'string'.
-tests/cases/conformance/jsdoc/validate.ts(17,3): error TS2540: Cannot assign to 'middleInit' because it is a constant or a read-only property.
+tests/cases/conformance/jsdoc/validate.ts(17,3): error TS2540: Cannot assign to 'middleInit' because it is a read-only property.
 
 
 ==== tests/cases/conformance/jsdoc/validate.ts (4 errors) ====
@@ -20,16 +20,16 @@ tests/cases/conformance/jsdoc/validate.ts(17,3): error TS2540: Cannot assign to
 
     x.lastName = "should fail";
       ~~~~~~~~
-!!! error TS2540: Cannot assign to 'lastName' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'lastName' because it is a read-only property.
     x.houseNumber = 12; // should also fail
       ~~~~~~~~~~~
-!!! error TS2540: Cannot assign to 'houseNumber' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'houseNumber' because it is a read-only property.
     x.zipStr = 12; // should fail
     ~~~~~~~~
 !!! error TS2322: Type '12' is not assignable to type 'string'.
     x.middleInit = "R"; // should also fail
       ~~~~~~~~~~
-!!! error TS2540: Cannot assign to 'middleInit' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'middleInit' because it is a read-only property.
 
 ==== tests/cases/conformance/jsdoc/index.js (0 errors) ====
     const x = {};

tests/baselines/reference/checkOtherObjectAssignProperty.errors.txt

@@ -2,9 +2,9 @@ tests/cases/conformance/jsdoc/importer.js(3,5): error TS2339: Property 'other' d
 tests/cases/conformance/jsdoc/importer.js(4,5): error TS2339: Property 'prop' does not exist on type 'typeof import("tests/cases/conformance/jsdoc/mod1")'.
 tests/cases/conformance/jsdoc/importer.js(11,5): error TS2339: Property 'other' does not exist on type 'typeof import("tests/cases/conformance/jsdoc/mod1")'.
 tests/cases/conformance/jsdoc/importer.js(12,5): error TS2339: Property 'prop' does not exist on type 'typeof import("tests/cases/conformance/jsdoc/mod1")'.
-tests/cases/conformance/jsdoc/importer.js(13,5): error TS2540: Cannot assign to 'bad1' because it is a constant or a read-only property.
-tests/cases/conformance/jsdoc/importer.js(14,5): error TS2540: Cannot assign to 'bad2' because it is a constant or a read-only property.
-tests/cases/conformance/jsdoc/importer.js(15,5): error TS2540: Cannot assign to 'bad3' because it is a constant or a read-only property.
+tests/cases/conformance/jsdoc/importer.js(13,5): error TS2540: Cannot assign to 'bad1' because it is a read-only property.
+tests/cases/conformance/jsdoc/importer.js(14,5): error TS2540: Cannot assign to 'bad2' because it is a read-only property.
+tests/cases/conformance/jsdoc/importer.js(15,5): error TS2540: Cannot assign to 'bad3' because it is a read-only property.
 
 
 ==== tests/cases/conformance/jsdoc/importer.js (7 errors) ====
@@ -30,13 +30,13 @@ tests/cases/conformance/jsdoc/importer.js(15,5): error TS2540: Cannot assign to
 !!! error TS2339: Property 'prop' does not exist on type 'typeof import("tests/cases/conformance/jsdoc/mod1")'.
     mod.bad1 = 0;
         ~~~~
-!!! error TS2540: Cannot assign to 'bad1' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'bad1' because it is a read-only property.
     mod.bad2 = 0;
         ~~~~
-!!! error TS2540: Cannot assign to 'bad2' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'bad2' because it is a read-only property.
     mod.bad3 = 0;
         ~~~~
-!!! error TS2540: Cannot assign to 'bad3' because it is a constant or a read-only property.
+!!! error TS2540: Cannot assign to 'bad3' because it is a read-only property.
 
 ==== tests/cases/conformance/jsdoc/mod1.js (0 errors) ====
     const obj = { value: 42, writable: true };