rust-lang / rust-lang/rfcs

Support macro invocations in match branch position

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#2,654 4 comments 9 reactions 0 assignees View on GitHub

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A-control-flow A-macros A-patterns A-syntax T-lang
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Description

Sorry if there's already and issue for this, but I couldn't find one.

On many occasions I've wanted to use macros to generate match branches. eg.

match x {
    macro_which_outputs_some_branches!(),
    Foo::Bar => 23,
}

Is there a reason not to support this?

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First steps

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  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

The issue names no files, tests, or entry points to begin with. First clarify the proposed macro syntax and its parser and language-design implications; done would require an accepted design for supporting macro-generated match branches.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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