Currently, the output of `rustc --explain foo` displays the raw markdown in a
pager. This is acceptable, but using actual formatting makes it easier to
understand.
This patch consists of three major components:
1. A markdown parser. This is an extremely simple non-backtracking recursive
implementation that requires normalization of the final token stream
2. A utility to write the token stream to an output buffer
3. Configuration within rustc_driver_impl to invoke this combination for
`--explain`. Like the current implementation, it first attempts to print to
a pager with a fallback colorized terminal, and standard print as a last
resort.
If color is disabled, or if the output does not support it, or if printing
with color fails, it will write the raw markdown (which matches current
behavior).
Pagers known to support color are: `less` (with `-r`), `bat` (aka `catbat`),
and `delta`.
The markdown parser does not support the entire markdown specification, but
should support the following with reasonable accuracy:
- Headings, including formatting
- Comments
- Code, inline and fenced block (no indented block)
- Strong, emphasis, and strikethrough formatted text
- Links, anchor, inline, and reference-style
- Horizontal rules
- Unordered and ordered list items, including formatting
This parser and writer should be reusable by other systems if ever needed.
Fluent, with all the icu4x it brings in, takes quite some time to
compile. `fluent_messages!` is only needed in further downstream rustc
crates, but is blocking more upstream crates like `rustc_index`. By
splitting it out, we allow `rustc_macros` to be compiled earlier, which
speeds up `x check compiler` by about 5 seconds (and even more after the
needless dependency on `serde_json` is removed from
`rustc_data_structures`).
Use `IsTerminal` in place of `atty`
In any crate that can use nightly features, use `IsTerminal` rather than
`atty`:
- Use `IsTerminal` in `rustc_errors`
- Use `IsTerminal` in `rustc_driver`
- Use `IsTerminal` in `rustc_log`
- Use `IsTerminal` in `librustdoc`
- ... when creating diagnostics in rustc_metadata
- use the error_code! macro
- pass macro output to diag.code()
- use fluent from within manual implementation of SessionDiagnostic
- emit the untested errors in case they occur in the wild
- stop panicking in the probably-not-dead code, add fixme to write test
`MultiSpan` contains labels, which are more complicated with the
introduction of diagnostic translation and will use types from
`rustc_errors` - however, `rustc_errors` depends on `rustc_span` so
`rustc_span` cannot use types like `DiagnosticMessage` without
dependency cycles. Introduce a new `rustc_error_messages` crate that can
contain `DiagnosticMessage` and `MultiSpan`.
Signed-off-by: David Wood <david.wood@huawei.com>
Since RFC 3052 soft deprecated the authors field anyway, hiding it from
crates.io, docs.rs, and making Cargo not add it by default, and it is
not generally up to date/useful information, we should remove it from
crates in this repo.
