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<title>rust/compiler/rustc_errors/src/codes.rs, branch 1.77.2</title>
<subtitle>https://github.com/rust-lang/rust
</subtitle>
<id>http://git.dreamy.place/mirrors/rust/atom?h=1.77.2</id>
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<updated>2024-01-28T20:41:41+00:00</updated>
<entry>
<title>Stop using `String` for error codes.</title>
<updated>2024-01-28T20:41:41+00:00</updated>
<author>
<name>Nicholas Nethercote</name>
<email>n.nethercote@gmail.com</email>
</author>
<published>2024-01-13T23:57:07+00:00</published>
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<id>urn:sha1:5d9dfbd08f38c2a9bc71d39de8f5c7776afe0f9e</id>
<content type='text'>
Error codes are integers, but `String` is used everywhere to represent
them. Gross!

This commit introduces `ErrCode`, an integral newtype for error codes,
replacing `String`. It also introduces a constant for every error code,
e.g. `E0123`, and removes the `error_code!` macro. The constants are
imported wherever used with `use rustc_errors::codes::*`.

With the old code, we have three different ways to specify an error code
at a use point:
```
error_code!(E0123)  // macro call

struct_span_code_err!(dcx, span, E0123, "msg");  // bare ident arg to macro call

\#[diag(name, code = "E0123")]  // string
struct Diag;
```

With the new code, they all use the `E0123` constant.
```
E0123  // constant

struct_span_code_err!(dcx, span, E0123, "msg");  // constant

\#[diag(name, code = E0123)]  // constant
struct Diag;
```

The commit also changes the structure of the error code definitions:
- `rustc_error_codes` now just defines a higher-order macro listing the
  used error codes and nothing else.
- Because that's now the only thing in the `rustc_error_codes` crate, I
  moved it into the `lib.rs` file and removed the `error_codes.rs` file.
- `rustc_errors` uses that macro to define everything, e.g. the error
  code constants and the `DIAGNOSTIC_TABLES`. This is in its new
  `codes.rs` file.
</content>
</entry>
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