Improve error message for computed enums (microsoft#37790)

* Add error message for computed enums

* Add test case for computed enums

* Accept baselines

* Fix returned value when error

src/compiler/checker.ts

@@ -33676,7 +33676,13 @@ namespace ts {
             }
             else {
                 // Only here do we need to check that the initializer is assignable to the enum type.
-                checkTypeAssignableTo(checkExpression(initializer), getDeclaredTypeOfSymbol(getSymbolOfNode(member.parent)), initializer, /*headMessage*/ undefined);
+                const source = checkExpression(initializer);
+                if (!isTypeAssignableToKind(source, TypeFlags.NumberLike)) {
+                    error(initializer, Diagnostics.Only_numeric_enums_can_have_computed_members_but_this_expression_has_type_0_If_you_do_not_need_exhaustiveness_checks_consider_using_an_object_literal_instead, typeToString(source));
+                }
+                else {
+                    checkTypeAssignableTo(source, getDeclaredTypeOfSymbol(getSymbolOfNode(member.parent)), initializer, /*headMessage*/ undefined);
+                }
             }
             return value;
 

src/compiler/diagnosticMessages.json

@@ -5737,5 +5737,9 @@
     "The intersection '{0}' was reduced to 'never' because property '{1}' exists in multiple constituents and is private in some.": {
         "category": "Error",
         "code": 18032
+    },
+    "Only numeric enums can have computed members, but this expression has type '{0}'. If you do not need exhaustiveness checks, consider using an object literal instead.": {
+        "category": "Error",
+        "code": 18033
     }
 }

tests/baselines/reference/arrowFunctionContexts.errors.txt

@@ -1,8 +1,8 @@
 tests/cases/conformance/expressions/functions/arrowFunctionContexts.ts(2,1): error TS2410: The 'with' statement is not supported. All symbols in a 'with' block will have type 'any'.
-tests/cases/conformance/expressions/functions/arrowFunctionContexts.ts(30,9): error TS2322: Type '() => number' is not assignable to type 'E'.
+tests/cases/conformance/expressions/functions/arrowFunctionContexts.ts(30,9): error TS18033: Only numeric enums can have computed members, but this expression has type '() => number'. If you do not need exhaustiveness checks, consider using an object literal instead.
 tests/cases/conformance/expressions/functions/arrowFunctionContexts.ts(31,16): error TS2332: 'this' cannot be referenced in current location.
 tests/cases/conformance/expressions/functions/arrowFunctionContexts.ts(43,5): error TS2410: The 'with' statement is not supported. All symbols in a 'with' block will have type 'any'.
-tests/cases/conformance/expressions/functions/arrowFunctionContexts.ts(71,13): error TS2322: Type '() => number' is not assignable to type 'E'.
+tests/cases/conformance/expressions/functions/arrowFunctionContexts.ts(71,13): error TS18033: Only numeric enums can have computed members, but this expression has type '() => number'. If you do not need exhaustiveness checks, consider using an object literal instead.
 tests/cases/conformance/expressions/functions/arrowFunctionContexts.ts(72,20): error TS2332: 'this' cannot be referenced in current location.
 
 
@@ -40,7 +40,7 @@ tests/cases/conformance/expressions/functions/arrowFunctionContexts.ts(72,20): e
     enum E {
         x = () => 4, // Error expected
             ~~~~~~~
-!!! error TS2322: Type '() => number' is not assignable to type 'E'.
+!!! error TS18033: Only numeric enums can have computed members, but this expression has type '() => number'. If you do not need exhaustiveness checks, consider using an object literal instead.
         y = (() => this).length // error, can't use this in enum
                    ~~~~
 !!! error TS2332: 'this' cannot be referenced in current location.
@@ -87,7 +87,7 @@ tests/cases/conformance/expressions/functions/arrowFunctionContexts.ts(72,20): e
         enum E {
             x = () => 4, // Error expected
                 ~~~~~~~
-!!! error TS2322: Type '() => number' is not assignable to type 'E'.
+!!! error TS18033: Only numeric enums can have computed members, but this expression has type '() => number'. If you do not need exhaustiveness checks, consider using an object literal instead.
             y = (() => this).length
                        ~~~~
 !!! error TS2332: 'this' cannot be referenced in current location.

tests/baselines/reference/enumErrors.errors.txt

@@ -2,28 +2,30 @@ tests/cases/conformance/enums/enumErrors.ts(2,6): error TS2431: Enum name cannot
 tests/cases/conformance/enums/enumErrors.ts(3,6): error TS2431: Enum name cannot be 'number'.
 tests/cases/conformance/enums/enumErrors.ts(4,6): error TS2431: Enum name cannot be 'string'.
 tests/cases/conformance/enums/enumErrors.ts(5,6): error TS2431: Enum name cannot be 'boolean'.
-tests/cases/conformance/enums/enumErrors.ts(9,9): error TS2322: Type 'Number' is not assignable to type 'E5'.
-tests/cases/conformance/enums/enumErrors.ts(26,9): error TS2322: Type 'true' is not assignable to type 'E11'.
-tests/cases/conformance/enums/enumErrors.ts(27,9): error TS2322: Type 'Date' is not assignable to type 'E11'.
-tests/cases/conformance/enums/enumErrors.ts(28,9): error TS2322: Type 'Window & typeof globalThis' is not assignable to type 'E11'.
-tests/cases/conformance/enums/enumErrors.ts(29,9): error TS2322: Type '{}' is not assignable to type 'E11'.
-tests/cases/conformance/enums/enumErrors.ts(35,9): error TS2553: Computed values are not permitted in an enum with string valued members.
+tests/cases/conformance/enums/enumErrors.ts(9,9): error TS18033: Only numeric enums can have computed members, but this expression has type 'Number'. If you do not need exhaustiveness checks, consider using an object literal instead.
+tests/cases/conformance/enums/enumErrors.ts(26,9): error TS18033: Only numeric enums can have computed members, but this expression has type 'true'. If you do not need exhaustiveness checks, consider using an object literal instead.
+tests/cases/conformance/enums/enumErrors.ts(27,9): error TS18033: Only numeric enums can have computed members, but this expression has type 'Date'. If you do not need exhaustiveness checks, consider using an object literal instead.
+tests/cases/conformance/enums/enumErrors.ts(28,9): error TS18033: Only numeric enums can have computed members, but this expression has type 'Window & typeof globalThis'. If you do not need exhaustiveness checks, consider using an object literal instead.
+tests/cases/conformance/enums/enumErrors.ts(29,9): error TS18033: Only numeric enums can have computed members, but this expression has type '{}'. If you do not need exhaustiveness checks, consider using an object literal instead.
+tests/cases/conformance/enums/enumErrors.ts(30,9): error TS18033: Only numeric enums can have computed members, but this expression has type 'string'. If you do not need exhaustiveness checks, consider using an object literal instead.
 tests/cases/conformance/enums/enumErrors.ts(36,9): error TS2553: Computed values are not permitted in an enum with string valued members.
 tests/cases/conformance/enums/enumErrors.ts(37,9): error TS2553: Computed values are not permitted in an enum with string valued members.
 tests/cases/conformance/enums/enumErrors.ts(38,9): error TS2553: Computed values are not permitted in an enum with string valued members.
-tests/cases/conformance/enums/enumErrors.ts(46,18): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
-tests/cases/conformance/enums/enumErrors.ts(47,24): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
-tests/cases/conformance/enums/enumErrors.ts(47,26): error TS2452: An enum member cannot have a numeric name.
-tests/cases/conformance/enums/enumErrors.ts(48,28): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
-tests/cases/conformance/enums/enumErrors.ts(48,30): error TS2452: An enum member cannot have a numeric name.
-tests/cases/conformance/enums/enumErrors.ts(48,31): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
-tests/cases/conformance/enums/enumErrors.ts(51,16): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
-tests/cases/conformance/enums/enumErrors.ts(51,22): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
-tests/cases/conformance/enums/enumErrors.ts(51,30): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
-tests/cases/conformance/enums/enumErrors.ts(51,33): error TS2452: An enum member cannot have a numeric name.
+tests/cases/conformance/enums/enumErrors.ts(39,9): error TS2553: Computed values are not permitted in an enum with string valued members.
+tests/cases/conformance/enums/enumErrors.ts(40,9): error TS2553: Computed values are not permitted in an enum with string valued members.
+tests/cases/conformance/enums/enumErrors.ts(48,18): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
+tests/cases/conformance/enums/enumErrors.ts(49,24): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
+tests/cases/conformance/enums/enumErrors.ts(49,26): error TS2452: An enum member cannot have a numeric name.
+tests/cases/conformance/enums/enumErrors.ts(50,28): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
+tests/cases/conformance/enums/enumErrors.ts(50,30): error TS2452: An enum member cannot have a numeric name.
+tests/cases/conformance/enums/enumErrors.ts(50,31): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
+tests/cases/conformance/enums/enumErrors.ts(53,16): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
+tests/cases/conformance/enums/enumErrors.ts(53,22): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
+tests/cases/conformance/enums/enumErrors.ts(53,30): error TS1357: An enum member name must be followed by a ',', '=', or '}'.
+tests/cases/conformance/enums/enumErrors.ts(53,33): error TS2452: An enum member cannot have a numeric name.
 
 
-==== tests/cases/conformance/enums/enumErrors.ts (23 errors) ====
+==== tests/cases/conformance/enums/enumErrors.ts (25 errors) ====
     // Enum named with PredefinedTypes
     enum any { }
          ~~~
@@ -42,7 +44,7 @@ tests/cases/conformance/enums/enumErrors.ts(51,33): error TS2452: An enum member
     enum E5 {
         C = new Number(30)
             ~~~~~~~~~~~~~~
-!!! error TS2322: Type 'Number' is not assignable to type 'E5'.
+!!! error TS18033: Only numeric enums can have computed members, but this expression has type 'Number'. If you do not need exhaustiveness checks, consider using an object literal instead.
     }
 
     enum E9 {
@@ -61,16 +63,19 @@ tests/cases/conformance/enums/enumErrors.ts(51,33): error TS2452: An enum member
     enum E11 {
         A = true,
             ~~~~
-!!! error TS2322: Type 'true' is not assignable to type 'E11'.
+!!! error TS18033: Only numeric enums can have computed members, but this expression has type 'true'. If you do not need exhaustiveness checks, consider using an object literal instead.
         B = new Date(),
             ~~~~~~~~~~
-!!! error TS2322: Type 'Date' is not assignable to type 'E11'.
+!!! error TS18033: Only numeric enums can have computed members, but this expression has type 'Date'. If you do not need exhaustiveness checks, consider using an object literal instead.
         C = window,
             ~~~~~~
-!!! error TS2322: Type 'Window & typeof globalThis' is not assignable to type 'E11'.
-        D = {}
+!!! error TS18033: Only numeric enums can have computed members, but this expression has type 'Window & typeof globalThis'. If you do not need exhaustiveness checks, consider using an object literal instead.
+        D = {},
             ~~
-!!! error TS2322: Type '{}' is not assignable to type 'E11'.
+!!! error TS18033: Only numeric enums can have computed members, but this expression has type '{}'. If you do not need exhaustiveness checks, consider using an object literal instead.
+        E = (() => 'foo')(),
+            ~~~~~~~~~~~~~~~
+!!! error TS18033: Only numeric enums can have computed members, but this expression has type 'string'. If you do not need exhaustiveness checks, consider using an object literal instead.
     }
 
     // Enum with string valued member and computed member initializers
@@ -87,6 +92,9 @@ tests/cases/conformance/enums/enumErrors.ts(51,33): error TS2452: An enum member
 !!! error TS2553: Computed values are not permitted in an enum with string valued members.
         E = 1 + 1,
             ~~~~~
+!!! error TS2553: Computed values are not permitted in an enum with string valued members.
+        F = (() => 'foo')(),
+            ~~~~~~~~~~~~~~~
 !!! error TS2553: Computed values are not permitted in an enum with string valued members.
     }
 

tests/baselines/reference/enumErrors.js

@@ -27,7 +27,8 @@ enum E11 {
     A = true,
     B = new Date(),
     C = window,
-    D = {}
+    D = {},
+    E = (() => 'foo')(),
 }
 
 // Enum with string valued member and computed member initializers
@@ -37,6 +38,7 @@ enum E12 {
     C = window,
     D = {},
     E = 1 + 1,
+    F = (() => 'foo')(),
 }
 
 // Enum with incorrect syntax
@@ -90,6 +92,7 @@ var E11;
     E11[E11["B"] = new Date()] = "B";
     E11[E11["C"] = window] = "C";
     E11[E11["D"] = {}] = "D";
+    E11[E11["E"] = (function () { return 'foo'; })()] = "E";
 })(E11 || (E11 = {}));
 // Enum with string valued member and computed member initializers
 var E12;
@@ -99,6 +102,7 @@ var E12;
     E12[E12["C"] = 0] = "C";
     E12[E12["D"] = 0] = "D";
     E12[E12["E"] = 0] = "E";
+    E12[E12["F"] = 0] = "F";
 })(E12 || (E12 = {}));
 // Enum with incorrect syntax
 var E13;

tests/baselines/reference/enumErrors.symbols

@@ -65,62 +65,68 @@ enum E11 {
 >C : Symbol(E11.C, Decl(enumErrors.ts, 26, 19))
 >window : Symbol(window, Decl(lib.dom.d.ts, --, --))
 
-    D = {}
+    D = {},
 >D : Symbol(E11.D, Decl(enumErrors.ts, 27, 15))
+
+    E = (() => 'foo')(),
+>E : Symbol(E11.E, Decl(enumErrors.ts, 28, 11))
 }
 
 // Enum with string valued member and computed member initializers
 enum E12 {
->E12 : Symbol(E12, Decl(enumErrors.ts, 29, 1))
+>E12 : Symbol(E12, Decl(enumErrors.ts, 30, 1))
 
     A = '',
->A : Symbol(E12.A, Decl(enumErrors.ts, 32, 10))
+>A : Symbol(E12.A, Decl(enumErrors.ts, 33, 10))
 
     B = new Date(),
->B : Symbol(E12.B, Decl(enumErrors.ts, 33, 11))
+>B : Symbol(E12.B, Decl(enumErrors.ts, 34, 11))
 >Date : Symbol(Date, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.scripthost.d.ts, --, --))
 
     C = window,
->C : Symbol(E12.C, Decl(enumErrors.ts, 34, 19))
+>C : Symbol(E12.C, Decl(enumErrors.ts, 35, 19))
 >window : Symbol(window, Decl(lib.dom.d.ts, --, --))
 
     D = {},
->D : Symbol(E12.D, Decl(enumErrors.ts, 35, 15))
+>D : Symbol(E12.D, Decl(enumErrors.ts, 36, 15))
 
     E = 1 + 1,
->E : Symbol(E12.E, Decl(enumErrors.ts, 36, 11))
+>E : Symbol(E12.E, Decl(enumErrors.ts, 37, 11))
+
+    F = (() => 'foo')(),
+>F : Symbol(E12.F, Decl(enumErrors.ts, 38, 14))
 }
 
 // Enum with incorrect syntax
 enum E13 {
->E13 : Symbol(E13, Decl(enumErrors.ts, 38, 1))
+>E13 : Symbol(E13, Decl(enumErrors.ts, 40, 1))
 
     postComma,
->postComma : Symbol(E13.postComma, Decl(enumErrors.ts, 41, 10))
+>postComma : Symbol(E13.postComma, Decl(enumErrors.ts, 43, 10))
 
     postValueComma = 1,
->postValueComma : Symbol(E13.postValueComma, Decl(enumErrors.ts, 42, 14))
+>postValueComma : Symbol(E13.postValueComma, Decl(enumErrors.ts, 44, 14))
 
     postSemicolon;
->postSemicolon : Symbol(E13.postSemicolon, Decl(enumErrors.ts, 43, 23))
+>postSemicolon : Symbol(E13.postSemicolon, Decl(enumErrors.ts, 45, 23))
 
     postColonValueComma: 2,
->postColonValueComma : Symbol(E13.postColonValueComma, Decl(enumErrors.ts, 45, 18))
->2 : Symbol(E13[2], Decl(enumErrors.ts, 46, 24))
+>postColonValueComma : Symbol(E13.postColonValueComma, Decl(enumErrors.ts, 47, 18))
+>2 : Symbol(E13[2], Decl(enumErrors.ts, 48, 24))
 
     postColonValueSemicolon: 3;
->postColonValueSemicolon : Symbol(E13.postColonValueSemicolon, Decl(enumErrors.ts, 46, 27))
->3 : Symbol(E13[3], Decl(enumErrors.ts, 47, 28))
+>postColonValueSemicolon : Symbol(E13.postColonValueSemicolon, Decl(enumErrors.ts, 48, 27))
+>3 : Symbol(E13[3], Decl(enumErrors.ts, 49, 28))
 
 };
 
 enum E14 { a, b: any "hello" += 1, c, d}
->E14 : Symbol(E14, Decl(enumErrors.ts, 48, 2))
->a : Symbol(E14.a, Decl(enumErrors.ts, 50, 10))
->b : Symbol(E14.b, Decl(enumErrors.ts, 50, 13))
->any : Symbol(E14.any, Decl(enumErrors.ts, 50, 16))
->"hello" : Symbol(E14["hello"], Decl(enumErrors.ts, 50, 20))
->1 : Symbol(E14[1], Decl(enumErrors.ts, 50, 31))
->c : Symbol(E14.c, Decl(enumErrors.ts, 50, 34))
->d : Symbol(E14.d, Decl(enumErrors.ts, 50, 37))
+>E14 : Symbol(E14, Decl(enumErrors.ts, 50, 2))
+>a : Symbol(E14.a, Decl(enumErrors.ts, 52, 10))
+>b : Symbol(E14.b, Decl(enumErrors.ts, 52, 13))
+>any : Symbol(E14.any, Decl(enumErrors.ts, 52, 16))
+>"hello" : Symbol(E14["hello"], Decl(enumErrors.ts, 52, 20))
+>1 : Symbol(E14[1], Decl(enumErrors.ts, 52, 31))
+>c : Symbol(E14.c, Decl(enumErrors.ts, 52, 34))
+>d : Symbol(E14.d, Decl(enumErrors.ts, 52, 37))
 

tests/baselines/reference/enumErrors.types

@@ -69,9 +69,16 @@ enum E11 {
 >C : E11
 >window : Window & typeof globalThis
 
-    D = {}
+    D = {},
 >D : E11
 >{} : {}
+
+    E = (() => 'foo')(),
+>E : E11
+>(() => 'foo')() : string
+>(() => 'foo') : () => string
+>() => 'foo' : () => string
+>'foo' : "foo"
 }
 
 // Enum with string valued member and computed member initializers
@@ -100,6 +107,13 @@ enum E12 {
 >1 + 1 : number
 >1 : 1
 >1 : 1
+
+    F = (() => 'foo')(),
+>F : E12.B
+>(() => 'foo')() : string
+>(() => 'foo') : () => string
+>() => 'foo' : () => string
+>'foo' : "foo"
 }
 
 // Enum with incorrect syntax

tests/cases/conformance/enums/enumErrors.ts

@@ -26,7 +26,8 @@ enum E11 {
     A = true,
     B = new Date(),
     C = window,
-    D = {}
+    D = {},
+    E = (() => 'foo')(),
 }
 
 // Enum with string valued member and computed member initializers
@@ -36,6 +37,7 @@ enum E12 {
     C = window,
     D = {},
     E = 1 + 1,
+    F = (() => 'foo')(),
 }
 
 // Enum with incorrect syntax