This is a tracking issue for the feature gate #![feature(slice_patterns)] covering the following RFCs:

• "Finalize syntax for slice patterns with subslices" (RFC: Finalize syntax for slice patterns with subslices rfcs#2359),
• "Make .. a pattern syntactically" (Mini-RFC: Make .. a pattern syntactically rfcs#2707),
• "Array pattern adjustments" (RFC: Array pattern adjustments rfcs#495).

For the old tracking issue see #23121.

Steps:

• Implement the changes in RFC: Finalize syntax for slice patterns with subslices rfcs#2359 and Mini-RFC: Make .. a pattern syntactically rfcs#2707
  (cc @rust-lang/compiler -- can anyone write up mentoring instructions?)
• Adjust documentation (see instructions on rustc-guide)
  • Reference documentation is tracked in Document subslice patterns reference#739.
  • Rustc-guide documentation is tracked in Document slice patterns rustc-dev-guide#563.
  • Book documentation in the book is tracked in Document subslice patterns book#2225.
• Stabilization PR (Stabilize #![feature(slice_patterns)] in 1.42.0 #67712)

Unresolved questions:

None thus far.