848e78550c
This commit implements documentation generation of the nomicon, the book, the style guide, and the standalone docs. New steps were added for each one as well as appropriate makefile targets for each one as well.
76 lines
3.7 KiB
Markdown
76 lines
3.7 KiB
Markdown
% Rustc UX guidelines
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Don't forget the user. Whether human or another program, such as an IDE, a
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good user experience with the compiler goes a long way into making developer
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lives better. We don't want users to be baffled by compiler output or
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learn arcane patterns to compile their program.
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## Error, Warning, Help, Note Messages
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When the compiler detects a problem, it can emit either an error, warning,
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note, or help message.
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An `error` is emitted when the compiler detects a problem that makes it unable
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to compile the program, either because the program is invalid or the
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programmer has decided to make a specific `warning` into an error.
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A `warning` is emitted when the compiler detects something odd about a
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program. For instance, dead code and unused `Result` values.
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A `help` is emitted following either an `error` or `warning` giving extra
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information to the user about how to solve their problem.
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A `note` is for identifying additional circumstances and parts of the code
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that lead to a warning or error. For example, the borrow checker will note any
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previous conflicting borrows.
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* Write in plain simple English. If your message, when shown on a – possibly
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small – screen (which hasn't been cleaned for a while), cannot be understood
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by a normal programmer, who just came out of bed after a night partying, it's
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too complex.
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* `Errors` and `Warnings` should not suggest how to fix the problem. A `Help`
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message should be emitted instead.
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* `Error`, `Warning`, `Note`, and `Help` messages start with a lowercase
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letter and do not end with punctuation.
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* Error messages should be succinct. Users will see these error messages many
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times, and more verbose descriptions can be viewed with the `--explain` flag.
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That said, don't make it so terse that it's hard to understand.
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* The word "illegal" is illegal. Prefer "invalid" or a more specific word
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instead.
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* Errors should document the span of code where they occur – the `span_..`
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methods allow to easily do this. Also `note` other spans that have contributed
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to the error if the span isn't too large.
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* When emitting a message with span, try to reduce the span to the smallest
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amount possible that still signifies the issue
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* Try not to emit multiple error messages for the same error. This may require
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detecting duplicates.
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* When the compiler has too little information for a specific error message,
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lobby for annotations for library code that allow adding more. For example see
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`#[on_unimplemented]`. Use these annotations when available!
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* Keep in mind that Rust's learning curve is rather steep, and that the
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compiler messages are an important learning tool.
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## Error Explanations
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Error explanations are long form descriptions of error messages provided with
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the compiler. They are accessible via the `--explain` flag. Each explanation
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comes with an example of how to trigger it and advice on how to fix it.
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* All of them are accessible [online](https://github.com/rust-lang/rust/blob/master/src/librustc/diagnostics.rs).
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* Explanations have full markdown support. Use it, especially to highlight
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code with backticks.
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* When talking about the compiler, call it `the compiler`, not `Rust` or
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`rustc`.
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## Compiler Flags
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* Flags should be orthogonal to each other. For example, if we'd have a
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json-emitting variant of multiple actions `foo` and `bar`, an additional
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--json flag is better than adding `--foo-json` and `--bar-json`.
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* Always give options a long descriptive name, if only for better
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understandable compiler scripts.
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* The `--verbose` flag is for adding verbose information to `rustc` output
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when not compiling a program. For example, using it with the `--version` flag
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gives information about the hashes of the code.
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* Experimental flags and options must be guarded behind the `-Z unstable-options` flag.
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