Add diagnostic for private identifiers in destructuring patterns

[Spencer Young (youngspe)]

Fixes #35942

This tripped me up when I tried to do something like this, thinking it was valid syntax:

const { #foo: foo } = this;

This change adds a diagnostic: Private identifiers cannot be used in destructuring patterns. and a baseline test for it.

This is my first contribution to the compiler, so hopefully I'm not missing anything here (for example, is there a special process for adding diagnostics?)

[Copilot]

Pull request overview

Adds a compiler diagnostic for private identifiers used in object binding patterns.

Changes:

• Adds diagnostic TS18064 and checker validation.
• Adds a conformance test and generated baselines.

Reviewed changes

Copilot reviewed 7 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tsc/internal/checker/checker.go	Reports the diagnostic for binding elements.
tsc/internal/diagnostics/diagnosticMessages.json	Defines TS18064.
tsc/internal/diagnostics/diagnostics_generated.go	Adds generated diagnostic mappings.
tsc/testdata/tests/cases/conformance/classes/members/privateNames/privateNamesNotAllowedAsBindingPatterns.ts	Adds the compiler test case.
tsc/testdata/baselines/reference/conformance/privateNamesNotAllowedAsBindingPatterns.errors.txt	Captures the expected diagnostic.
tsc/testdata/baselines/reference/conformance/privateNamesNotAllowedAsBindingPatterns.js	Captures emitted JavaScript.
tsc/testdata/baselines/reference/conformance/privateNamesNotAllowedAsBindingPatterns.symbols	Captures symbol information.
tsc/testdata/baselines/reference/conformance/privateNamesNotAllowedAsBindingPatterns.types	Captures inferred types.

Files not reviewed (1)

• tsc/internal/diagnostics/diagnostics_generated.go: Generated file

[Copilot]

Pull request overview

Copilot reviewed 7 out of 8 changed files in this pull request and generated no new comments.

Files not reviewed (1)

• tsc/internal/diagnostics/diagnostics_generated.go: Generated file