Tracking issue for cfg_match · Issue #115585 · rust-lang/rust (original) (raw)

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Description

Provides a native way to easily manage multiple conditional flags without having to rewrite each clause multiple times.

Public API

cfg_match! { unix => { fn foo() { /* unix specific functionality / } } target_pointer_width = "32" => { fn foo() { / non-unix, 32-bit functionality / } } _ => { fn foo() { / fallback implementation */ } } }

Steps / History

• Implementation (Add the cfg_match! macro #115416)
• Final comment period
• Stabilization PR

Unresolved Questions

• What should the final syntax be? A match-like syntax feels more natural in the sense that each macro fragment resembles an arm.
• Should the macro be supported directly by a language feature?
• What should the feature name be? cfg_match conflicts with the already existing cfg_match crate.
• How can we support usage in both expression-position and item position?
• Support trailing commas to have similar grammar as match statements.

References

• https://crates.io/crates/cfg-match
• https://crates.io/crates/cfg-if
• Tracking issue for cfg_if #59442
• https://internals.rust-lang.org/t/is-cfg-if-going-to-be-pulled-into-std/13316