fix(checker): don't emit typeof for private-named static methods

[Eugene Kalinin (ekalinin)]

Fixes #61545

Declaration emit produces unparseable output when an inferred type refers to a static #name method:

class Foo {
    static #bar() { }

    static bar() {
        return Foo.#bar;
    }
}

declare class Foo {
    #private;
    static bar(): typeof Foo.<0xFE>#1@#bar;  // TS1003: Identifier expected
}

shouldWriteTypeOfFunctionSymbol only checked that the symbol is a static method and that it's accessible from the enclosing declaration, and a #name member is accessible inside its own class body. So the node builder wrote typeof using the symbol's mangled internal name. Spelled correctly it still wouldn't resolve, since # members are erased to #private; in declarations.

A #name member has no entity name it could be referenced by, so this excludes private-named symbols and lets static methods take the structural fallback that instance #name methods already take:

declare class Foo {
    #private;
    static bar(): () => void;
}

Same bug in Strada, where the name surfaces as typeof Foo.__#1@#bar.

[Eugene Kalinin (ekalinin)]

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[Copilot]

🟢 Approval recommended

The focused fix correctly avoids unrepresentable private-name type queries and has comprehensive regression coverage.

Pull request overview

Prevents declaration emit from generating invalid typeof references to static #private methods.

Changes:

• Excludes private-identifier symbols from static method type queries.
• Adds coverage for basic, generic, recursive, property, and instance cases.

File summaries

File	Description
tsc/internal/checker/nodebuilderimpl.go	Uses structural fallback for static private methods.
tsc/testdata/tests/cases/conformance/classes/members/privateNames/privateNameStaticMethodDeclarationEmit.ts	Adds regression cases.
tsc/testdata/baselines/reference/conformance/privateNameStaticMethodDeclarationEmit.js	Verifies valid declaration output.
tsc/testdata/baselines/reference/conformance/privateNameStaticMethodDeclarationEmit.types	Records inferred types.
tsc/testdata/baselines/reference/conformance/privateNameStaticMethodDeclarationEmit.symbols	Records symbol resolution.

Review details

• Files reviewed: 5/5 changed files
• Comments generated: 0
• Review effort level: Balanced

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[Jake Bailey (jakebailey)]

I found more examples that break in similar ways:

static "quoted-name"() {}
static getQuotedName() {
    return Foo["quoted-name"];
}

static ["computed-name"]() {}
static getComputedName() {
    return Foo["computed-name"];
}

static 1() {}
static getNumericName() {
    return Foo[1];
}

I think IsIdentifierText would work to fix all of these. Probably the test should be renamed too.

[Eugene Kalinin (ekalinin)]

I found more examples that break in similar ways:

static "quoted-name"() {}
static getQuotedName() {
    return Foo["quoted-name"];
}

static ["computed-name"]() {}
static getComputedName() {
    return Foo["computed-name"];
}

static 1() {}
static getNumericName() {
    return Foo[1];
}

I think IsIdentifierText would work to fix all of these. Probably the test should be renamed too.

IsIdentifierText covers all three, and subsumes the private-name case as well. Renamed test to declarationEmitStaticMethodNonIdentifierNames and moved to tests/cases/compiler. It now covers #name, quoted, computed and numeric names, plus identifier-named statics for contrast.

[Copilot]

🟢 Approval recommended

The focused fix produces valid structural fallbacks and includes comprehensive regression coverage.

Review details

• Files reviewed: 5/5 changed files
• Comments generated: 0 new
• Review effort level: Balanced