fix(45114): throw an error when using '#' as an identifier (#45124)

src/compiler/scanner.ts

@@ -2047,8 +2047,15 @@ namespace ts {
                             pos++;
                             return token = SyntaxKind.Unknown;
                         }
-                        pos++;
-                        scanIdentifier(codePointAt(text, pos), languageVersion);
+
+                        if (isIdentifierStart(codePointAt(text, pos + 1), languageVersion)) {
+                            pos++;
+                            scanIdentifier(codePointAt(text, pos), languageVersion);
+                        }
+                        else {
+                            tokenValue = String.fromCharCode(codePointAt(text, pos));
+                            error(Diagnostics.Invalid_character, pos++, charSize(ch));
+                        }
                         return token = SyntaxKind.PrivateIdentifier;
                     default:
                         const identifierKind = scanIdentifier(ch, languageVersion);

tests/baselines/reference/privateNameHashCharName.errors.txt

@@ -0,0 +1,25 @@
+tests/cases/conformance/classes/members/privateNames/privateNameHashCharName.ts(1,1): error TS1127: Invalid character.
+tests/cases/conformance/classes/members/privateNames/privateNameHashCharName.ts(1,1): error TS2304: Cannot find name '#'.
+tests/cases/conformance/classes/members/privateNames/privateNameHashCharName.ts(4,5): error TS1127: Invalid character.
+tests/cases/conformance/classes/members/privateNames/privateNameHashCharName.ts(7,14): error TS1127: Invalid character.
+
+
+==== tests/cases/conformance/classes/members/privateNames/privateNameHashCharName.ts (4 errors) ====
+    #
+    ~
+!!! error TS1127: Invalid character.
+    ~
+!!! error TS2304: Cannot find name '#'.
+    
+    class C {
+        #
+        ~
+!!! error TS1127: Invalid character.
+    
+        m() {
+            this.#
+                 ~
+!!! error TS1127: Invalid character.
+        }
+    }
+    

tests/baselines/reference/privateNameHashCharName.js

@@ -0,0 +1,29 @@
+//// [privateNameHashCharName.ts]
+#
+
+class C {
+    #
+
+    m() {
+        this.#
+    }
+}
+
+
+//// [privateNameHashCharName.js]
+var __classPrivateFieldGet = (this && this.__classPrivateFieldGet) || function (receiver, state, kind, f) {
+    if (kind === "a" && !f) throw new TypeError("Private accessor was defined without a getter");
+    if (typeof state === "function" ? receiver !== state || !f : !state.has(receiver)) throw new TypeError("Cannot read private member from an object whose class did not declare it");
+    return kind === "m" ? f : kind === "a" ? f.call(receiver) : f ? f.value : state.get(receiver);
+};
+var _C_;
+#;
+class C {
+    constructor() {
+        _C_.set(this, void 0);
+    }
+    m() {
+        __classPrivateFieldGet(this, _C_, "f");
+    }
+}
+_C_ = new WeakMap();

tests/baselines/reference/privateNameHashCharName.symbols

@@ -0,0 +1,18 @@
+=== tests/cases/conformance/classes/members/privateNames/privateNameHashCharName.ts ===
+#
+
+class C {
+>C : Symbol(C, Decl(privateNameHashCharName.ts, 0, 1))
+
+    #
+># : Symbol(C[#], Decl(privateNameHashCharName.ts, 2, 9))
+
+    m() {
+>m : Symbol(C.m, Decl(privateNameHashCharName.ts, 3, 5))
+
+        this.#
+>this.# : Symbol(C[#], Decl(privateNameHashCharName.ts, 2, 9))
+>this : Symbol(C, Decl(privateNameHashCharName.ts, 0, 1))
+    }
+}
+

tests/baselines/reference/privateNameHashCharName.types

@@ -0,0 +1,19 @@
+=== tests/cases/conformance/classes/members/privateNames/privateNameHashCharName.ts ===
+#
+># : any
+
+class C {
+>C : C
+
+    #
+># : any
+
+    m() {
+>m : () => void
+
+        this.#
+>this.# : any
+>this : this
+    }
+}
+

tests/cases/conformance/classes/members/privateNames/privateNameHashCharName.ts

@@ -0,0 +1,11 @@
+// @target: es6
+
+#
+
+class C {
+    #
+
+    m() {
+        this.#
+    }
+}