fix(46433): forbid using keywords as parameter names (microsoft#46459)

Author: a-tarasyuk

src/compiler/diagnosticMessages.json

@@ -1164,6 +1164,10 @@
         "category": "Error",
         "code": 1389
     },
+    "'{0}' is not allowed as a parameter name.": {
+        "category": "Error",
+        "code": 1390
+    },
     "An import alias cannot use 'import type'": {
         "category": "Error",
         "code": 1392

src/compiler/parser.ts

@@ -2611,7 +2611,10 @@ namespace ts {
                 case ParsingContext.ObjectLiteralMembers: return parseErrorAtCurrentToken(Diagnostics.Property_assignment_expected);
                 case ParsingContext.ArrayLiteralMembers: return parseErrorAtCurrentToken(Diagnostics.Expression_or_comma_expected);
                 case ParsingContext.JSDocParameters: return parseErrorAtCurrentToken(Diagnostics.Parameter_declaration_expected);
-                case ParsingContext.Parameters: return parseErrorAtCurrentToken(Diagnostics.Parameter_declaration_expected);
+                case ParsingContext.Parameters:
+                    return isKeyword(token())
+                        ? parseErrorAtCurrentToken(Diagnostics._0_is_not_allowed_as_a_parameter_name, tokenToString(token()))
+                        : parseErrorAtCurrentToken(Diagnostics.Parameter_declaration_expected);
                 case ParsingContext.TypeParameters: return parseErrorAtCurrentToken(Diagnostics.Type_parameter_declaration_expected);
                 case ParsingContext.TypeArguments: return parseErrorAtCurrentToken(Diagnostics.Type_argument_expected);
                 case ParsingContext.TupleElementTypes: return parseErrorAtCurrentToken(Diagnostics.Type_expected);

tests/baselines/reference/reservedWords2.errors.txt

@@ -118,5 +118,4 @@ tests/cases/compiler/reservedWords2.ts(12,17): error TS1138: Parameter declarati
 !!! error TS1359: Identifier expected. 'null' is a reserved word that cannot be used here.
                     ~
 !!! error TS1138: Parameter declaration expected.
-    
 

tests/baselines/reference/reservedWords2.js

@@ -11,7 +11,6 @@ var [debugger, if] = [1, 2];
 enum void {}
 function f(default: number) {}
 class C { m(null: string) {} }
-
 
 
 //// [reservedWords2.js]

tests/baselines/reference/reservedWords2.symbols

@@ -40,4 +40,3 @@ class C { m(null: string) {} }
 > : Symbol((Missing), Decl(reservedWords2.ts, 11, 12))
 >string : Symbol(string, Decl(reservedWords2.ts, 11, 17))
 
-

tests/baselines/reference/reservedWords2.types

@@ -74,4 +74,3 @@ class C { m(null: string) {} }
 > : any
 >string : any
 
-

tests/baselines/reference/reservedWords3.errors.txt

@@ -0,0 +1,45 @@
+tests/cases/compiler/reservedWords3.ts(1,13): error TS1390: 'enum' is not allowed as a parameter name.
+tests/cases/compiler/reservedWords3.ts(1,17): error TS2567: Enum declarations can only merge with namespace or other enum declarations.
+tests/cases/compiler/reservedWords3.ts(1,17): error TS1003: Identifier expected.
+tests/cases/compiler/reservedWords3.ts(2,13): error TS1390: 'class' is not allowed as a parameter name.
+tests/cases/compiler/reservedWords3.ts(2,18): error TS1005: '{' expected.
+tests/cases/compiler/reservedWords3.ts(3,13): error TS1390: 'function' is not allowed as a parameter name.
+tests/cases/compiler/reservedWords3.ts(3,21): error TS2567: Enum declarations can only merge with namespace or other enum declarations.
+tests/cases/compiler/reservedWords3.ts(3,21): error TS1003: Identifier expected.
+tests/cases/compiler/reservedWords3.ts(4,13): error TS1390: 'while' is not allowed as a parameter name.
+tests/cases/compiler/reservedWords3.ts(4,18): error TS1005: '(' expected.
+tests/cases/compiler/reservedWords3.ts(5,13): error TS1390: 'for' is not allowed as a parameter name.
+tests/cases/compiler/reservedWords3.ts(5,16): error TS1005: '(' expected.
+
+
+==== tests/cases/compiler/reservedWords3.ts (12 errors) ====
+    function f1(enum) {}
+                ~~~~
+!!! error TS1390: 'enum' is not allowed as a parameter name.
+                    
+!!! error TS2567: Enum declarations can only merge with namespace or other enum declarations.
+                    ~
+!!! error TS1003: Identifier expected.
+    function f2(class) {}
+                ~~~~~
+!!! error TS1390: 'class' is not allowed as a parameter name.
+                     ~
+!!! error TS1005: '{' expected.
+    function f3(function) {}
+                ~~~~~~~~
+!!! error TS1390: 'function' is not allowed as a parameter name.
+                        
+!!! error TS2567: Enum declarations can only merge with namespace or other enum declarations.
+                        ~
+!!! error TS1003: Identifier expected.
+    function f4(while) {}
+                ~~~~~
+!!! error TS1390: 'while' is not allowed as a parameter name.
+                     ~
+!!! error TS1005: '(' expected.
+    function f5(for) {}
+                ~~~
+!!! error TS1390: 'for' is not allowed as a parameter name.
+                   ~
+!!! error TS1005: '(' expected.
+    

tests/baselines/reference/reservedWords3.js

@@ -0,0 +1,28 @@
+//// [reservedWords3.ts]
+function f1(enum) {}
+function f2(class) {}
+function f3(function) {}
+function f4(while) {}
+function f5(for) {}
+
+
+//// [reservedWords3.js]
+function f1() { }
+var ;
+(function () {
+})( || ( = {}));
+{ }
+function f2() { }
+var default_1 = /** @class */ (function () {
+    function default_1() {
+    }
+    return default_1;
+}());
+{ }
+function f3() { }
+function () { }
+{ }
+function f4() { }
+while () { }
+function f5() { }
+for (;;) { }

tests/baselines/reference/reservedWords3.symbols

@@ -0,0 +1,18 @@
+=== tests/cases/compiler/reservedWords3.ts ===
+function f1(enum) {}
+>f1 : Symbol(f1, Decl(reservedWords3.ts, 0, 0))
+> : Symbol((Missing), Decl(reservedWords3.ts, 0, 12))
+
+function f2(class) {}
+>f2 : Symbol(f2, Decl(reservedWords3.ts, 0, 20))
+
+function f3(function) {}
+>f3 : Symbol(f3, Decl(reservedWords3.ts, 1, 21))
+> : Symbol((Missing), Decl(reservedWords3.ts, 2, 12))
+
+function f4(while) {}
+>f4 : Symbol(f4, Decl(reservedWords3.ts, 2, 24))
+
+function f5(for) {}
+>f5 : Symbol(f5, Decl(reservedWords3.ts, 3, 21))
+

tests/baselines/reference/reservedWords3.types

@@ -0,0 +1,20 @@
+=== tests/cases/compiler/reservedWords3.ts ===
+function f1(enum) {}
+>f1 : () => any
+> : (Missing)
+
+function f2(class) {}
+>f2 : () => any
+
+function f3(function) {}
+>f3 : () => any
+> : () => any
+
+function f4(while) {}
+>f4 : () => any
+> : any
+
+function f5(for) {}
+>f5 : () => any
+> : any
+