[Bug] PrivateIdentifier nodes are omitted from 2020 semantic classifications

从 src/services/classifier2020.ts 中的 collectTokens 开始，检查标识符节点现有的 declaration-kind 映射。添加涵盖 private 字段和方法声明及引用的相关 fourslash 回归测试，然后验证这些节点是否获得 property 或 method 分类以及 declaration modifiers。

Bug Report

🔎 Search Terms

semantic highlighting, semantic token, PrivateIdentifier, private field, private method, encodedSemanticClassifications

🕗 Version & Regression Information

• TypeScript 6.0.3 (bundled with VS Code)
• Also present in the v5.9 classifier implementation
• This is not a theme-specific issue

💻 Code

class Foo {
    field = 1;
    #privateField = 1;

    method() {}
    #privateMethod() {}

    test() {
        this.field;
        this.#privateField;

        this.method();
        this.#privateMethod();
    }
}

🙁 Actual behavior

In VS Code's Developer: Inspect Editor Tokens and Scopes:

• field and method receive semantic token types.
• #privateField and #privateMethod receive no semantic token and fall back to TextMate scopes.
• As a result, editor.semanticTokenColorCustomizations rules for property and method do not apply to ECMAScript private members.

🙂 Expected behavior

• #privateField should be classified as property.
• #privateMethod should be classified as method.
• Declarations should also receive the declaration modifier.

Root cause

VS Code requests encodedSemanticClassifications-full with format "2020".

In src/services/classifier2020.ts, collectTokens only enters the semantic-classification path for isIdentifier(node):

if (isIdentifier(node) && ...) {
    let symbol = typeChecker.getSymbolAtLocation(node);
    // ...
}

ECMAScript private names are separate SyntaxKind.PrivateIdentifier nodes, so they are skipped before getSymbolAtLocation is called.

Relevant source:
https://github.com/microsoft/TypeScript/blob/050880ce59e30b356b686bd3144efe24f875ebc8/src/services/classifier2020.ts#L121-L203

Proposed fix

+    isPrivateIdentifier,
     isPropertyAccessExpression,

-        if (isIdentifier(node) && ...) {
+        if ((isIdentifier(node) || isPrivateIdentifier(node)) && ...) {

The existing declaration-kind mapping already classifies private fields and methods correctly once these nodes reach the symbol-classification path.

I tested the equivalent change against TypeScript 6.0.3:

• #privateField declaration/reference → property
• #privateMethod declaration/reference → member internally, mapped by VS Code to method
• declaration occurrences receive the declaration modifier
• added fourslash regression test passes

Related issue

https://github.com/microsoft/TypeScript/issues/44483 requests new private/protected semantic modifiers. This report is different: ECMAScript PrivateIdentifier nodes currently receive no semantic classification at all.