rust stdlib cfg-select pattern-matching release

Rust 1.95 stabilizes cfg_select and if-let guards

cfg_select! macro replaces cfg-if crate with compile-time config matching; if-let guards extend let chains into match expressions for pattern-based conditionals.

Summary

Eliminates external dependency for conditional compilation and reduces boilerplate in match expressions with combined pattern matching and guards. Workflow friction drops when config logic stays in stdlib.

Why it matters

Implementation verdict

cfg_select! replaces cfg-if; no dependencies required. if-let guards require no migration—opt-in syntax in existing match expressions. Ship now: both are stable and backward-compatible.

Sources

1.cfg_select! macro that acts roughly similar to a compile-time match on cfgs
2.This fulfills the same purpose as the popular cfg-if crate, although with a different syntax
3.Rust 1.95 brings that capability into match expressions, allowing for conditionals based on pattern matching
4.the compiler will not currently consider the patterns matched in if let guards as part of the exhaustiveness evaluation of the overall match

Dev Signal

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