allow arithmetic operations in constant expressions, handle infinity\NaN results

src/compiler/checker.ts

@@ -7686,6 +7686,15 @@ module ts {
                             checkTypeAssignableTo(checkExpression(initializer), enumType, initializer, /*headMessage*/ undefined);
                             }
                         }
+                        else if (enumIsConst) {
+                            if (isNaN(autoValue)) {
+                                error(initializer, Diagnostics.const_enum_member_initializer_was_evaluated_to_NaN);
+                            }
+                            else if (!isFinite(autoValue)) {
+                                error(initializer, Diagnostics.const_enum_member_initializer_was_evaluated_to_a_non_finite_number);
+                            }
+                        }
+
                     }
                     else if (ambient && !enumIsConst) {
                         autoValue = undefined;
@@ -7735,6 +7744,11 @@ module ts {
                                 case SyntaxKind.GreaterThanGreaterThanGreaterThanToken: return left >>> right;
                                 case SyntaxKind.LessThanLessThanToken: return left << right;
                                 case SyntaxKind.CaretToken: return left ^ right;
+                                case SyntaxKind.AsteriskToken: return left * right;
+                                case SyntaxKind.SlashToken: return left / right;
+                                case SyntaxKind.PlusToken: return left + right;
+                                case SyntaxKind.MinusToken: return left - right;
+                                case SyntaxKind.PercentToken: return left % right;
                             }
                             return undefined;
                         case SyntaxKind.NumericLiteral:

src/compiler/diagnosticInformationMap.generated.ts

@@ -354,6 +354,8 @@ module ts {
         In_const_enum_declarations_member_initializer_must_be_constant_expression: { code: 4083, category: DiagnosticCategory.Error, key: "In 'const' enum declarations member initializer must be constant expression." },
         const_enums_can_only_be_used_in_property_access_expressions: { code: 4084, category: DiagnosticCategory.Error, key: "'const' enums can only be used in property access expressions." },
         Index_expression_arguments_in_const_enums_must_be_of_type_string: { code: 4085, category: DiagnosticCategory.Error, key: "Index expression arguments in 'const' enums must be of type 'string'." },
+        const_enum_member_initializer_was_evaluated_to_a_non_finite_number: { code: 4086, category: DiagnosticCategory.Error, key: "'const' enum member initializer was evaluated to a non-finite number." },
+        const_enum_member_initializer_was_evaluated_to_NaN: { code: 4087, category: DiagnosticCategory.Error, key: "'const' enum member initializer was evaluated to NaN." },
         The_current_host_does_not_support_the_0_option: { code: 5001, category: DiagnosticCategory.Error, key: "The current host does not support the '{0}' option." },
         Cannot_find_the_common_subdirectory_path_for_the_input_files: { code: 5009, category: DiagnosticCategory.Error, key: "Cannot find the common subdirectory path for the input files." },
         Cannot_read_file_0_Colon_1: { code: 5012, category: DiagnosticCategory.Error, key: "Cannot read file '{0}': {1}" },

src/compiler/diagnosticMessages.json

@@ -1417,6 +1417,14 @@
         "category": "Error",
         "code": 4085
     },
+    "'const' enum member initializer was evaluated to a non-finite number.": {
+        "category": "Error",
+        "code": 4086
+    },
+    "'const' enum member initializer was evaluated to NaN.": {
+        "category": "Error",
+        "code": 4087
+    },
     "The current host does not support the '{0}' option.": {
         "category": "Error",
         "code": 5001

tests/baselines/reference/constEnumErrors.errors.txt

@@ -8,9 +8,12 @@ tests/cases/compiler/constEnumErrors.ts(24,13): error TS4085: Index expression a
 tests/cases/compiler/constEnumErrors.ts(26,9): error TS4084: 'const' enums can only be used in property access expressions.
 tests/cases/compiler/constEnumErrors.ts(27,10): error TS4084: 'const' enums can only be used in property access expressions.
 tests/cases/compiler/constEnumErrors.ts(32,5): error TS4084: 'const' enums can only be used in property access expressions.
+tests/cases/compiler/constEnumErrors.ts(40,9): error TS4086: 'const' enum member initializer was evaluated to a non-finite number.
+tests/cases/compiler/constEnumErrors.ts(41,9): error TS4086: 'const' enum member initializer was evaluated to a non-finite number.
+tests/cases/compiler/constEnumErrors.ts(42,9): error TS4087: 'const' enum member initializer was evaluated to NaN.
 
 
-==== tests/cases/compiler/constEnumErrors.ts (10 errors) ====
+==== tests/cases/compiler/constEnumErrors.ts (13 errors) ====
     const enum E {
                ~
 !!! error TS2300: Duplicate identifier 'E'.
@@ -62,4 +65,21 @@ tests/cases/compiler/constEnumErrors.ts(32,5): error TS4084: 'const' enums can o
     
     foo(E2);
         ~~
-!!! error TS4084: 'const' enums can only be used in property access expressions.
+!!! error TS4084: 'const' enums can only be used in property access expressions.
+    
+    const enum NaNOrInfinity {
+        A = 9007199254740992,
+        B = A * A,
+        C = B * B,
+        D = C * C,
+        E = D * D,
+        F = E * E, // overflow
+            ~~~~~
+!!! error TS4086: 'const' enum member initializer was evaluated to a non-finite number.
+        G = 1 / 0, // overflow
+            ~~~~~
+!!! error TS4086: 'const' enum member initializer was evaluated to a non-finite number.
+        H = 0 / 0  // NaN
+            ~~~~~
+!!! error TS4087: 'const' enum member initializer was evaluated to NaN.
+    }

tests/baselines/reference/constEnumErrors.js

@@ -30,7 +30,18 @@ var y = [E2];
 function foo(t: any): void {
 }
 
-foo(E2);
+foo(E2);
+
+const enum NaNOrInfinity {
+    A = 9007199254740992,
+    B = A * A,
+    C = B * B,
+    D = C * C,
+    E = D * D,
+    F = E * E, // overflow
+    G = 1 / 0, // overflow
+    H = 0 / 0  // NaN
+}
 
 //// [constEnumErrors.js]
 var E;

tests/cases/compiler/constEnumErrors.ts

@@ -29,4 +29,15 @@ var y = [E2];
 function foo(t: any): void {
 }
 
-foo(E2);
+foo(E2);
+
+const enum NaNOrInfinity {
+    A = 9007199254740992,
+    B = A * A,
+    C = B * B,
+    D = C * C,
+    E = D * D,
+    F = E * E, // overflow
+    G = 1 / 0, // overflow
+    H = 0 / 0  // NaN
+}