Fix spurious _N suffix on type parameters of sibling object-literal methods in declaration emit

[Copilot]

Type parameters of sibling methods in an object literal were being renamed with a _N suffix in emitted .d.ts files even when no name collision existed:

export const o = {
    foo<M extends string>(): void {},
    bar<M extends string>(): void {},
};

Emitted before:

export declare const o: {
    foo<M extends string>(): void;
    bar<M_1 extends string>(): void; // should be M
};

Root cause

In pseudotypenodebuilder.go, the loop that serializes object-literal elements used defer cleanup() to pop the per-element nodebuilder scope:

for _, e := range elements {
    if e.Kind != pseudochecker.PseudoObjectElementKindPropertyAssignment {
        cleanup := b.enterNewScope(...)
        defer cleanup() // runs at function return, not loop end
    }
    ...
}

Because defer fires at function return rather than loop-iteration end, per-element scopes were nested instead of sibling. The second method's enterNewScope ran inside the first's scope, so foo's M was still in the inherited typeParameterNamesByText set and the de-duplicator renamed bar's M to M_1.

Changes

• internal/checker/pseudotypenodebuilder.go — Hoist cleanup to a loop-scoped variable and invoke it explicitly at the end of each iteration (after newProp is appended), so sibling element scopes are properly siblings.
• New test — testdata/tests/cases/compiler/declarationEmitObjectLiteralMethodGenericNoSuffix.ts covers the issue's repro plus shared-T methods and multi-type-parameter methods.
• Baseline update — declarationEmitConstObjectLiteralGenericMethod1.d.ts previously baked in the buggy T_1 output; now emits T.

[jakebailey]

Yikes, oops

[Copilot]

Pull request overview

Fixes a declaration-emit bug in the pseudo type-node builder where per-object-literal-element scopes were accidentally nested (due to defer inside a loop), causing unnecessary _N suffixing of generic type parameter names across sibling object-literal methods in emitted .d.ts.

Changes:

• Correct scope cleanup in pseudoTypeToNode for object-literal elements by invoking the per-element cleanup at the end of each loop iteration (instead of deferring until function return).
• Add a new compiler test covering sibling object-literal generic methods (including shared type parameter names and multi-type-parameter methods).
• Update an existing baseline to reflect the corrected emitted generic parameter name (removing the spurious suffix).

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
internal/checker/pseudotypenodebuilder.go	Fix per-element scope cleanup so sibling object-literal members don’t share type-parameter name de-duplication state.
testdata/tests/cases/compiler/declarationEmitObjectLiteralMethodGenericNoSuffix.ts	New repro test for object-literal sibling generic methods emitting without _N suffix.
testdata/baselines/reference/compiler/declarationEmitObjectLiteralMethodGenericNoSuffix.types	New baseline for the added test (types output).
testdata/baselines/reference/compiler/declarationEmitObjectLiteralMethodGenericNoSuffix.symbols	New baseline for the added test (symbols output).
testdata/baselines/reference/compiler/declarationEmitObjectLiteralMethodGenericNoSuffix.js	New baseline for the added test (JS + .d.ts output).
testdata/baselines/reference/compiler/declarationEmitConstObjectLiteralGenericMethod1.js	Baseline update reflecting corrected .d.ts output (T instead of T_1).