tree 938807989fc06604c34778a763b976947a20a04b
parent 794e22862c9fed17cdb8d4f3d650851c667bc78e
parent 8c93798e9f80d6d6ed9a2ab4b01af06a8fea23b7
author bors <bors@rust-lang.org> 1548010898 +0000
committer bors <bors@rust-lang.org> 1548010898 +0000

Auto merge of #56884 - euclio:codeblock-diagnostics, r=QuietMisdreavus

rustdoc: overhaul code block lexing errors

Fixes #53919.

This PR moves the reporting of code block lexing errors from rendering time to an early pass, so we can use the compiler's error reporting mechanisms. This dramatically improves the diagnostics in this situation: we now de-emphasize the lexing errors as a note under a warning that has a span and suggestion instead of just emitting errors at the top level.

Additionally, this PR generalizes the markdown -> source span calculation function, which should allow other rustdoc warnings to use better spans in the future.

Last, the PR makes sure that the code block is always emitted in the docs, even if it fails to highlight correctly.

Of note:
- The new pass unfortunately adds another pass over the docs to gather the doc blocks for syntax-checking. I wonder if this could be combined with the pass that looks for testable blocks? I'm not familiar with that code, so I don't know how feasible that is.
- `pulldown_cmark` doesn't make it easy to find the spans of the code blocks, so the code that calculates the spans is a little nasty. It works for all the test cases I threw at it, but I wouldn't be surprised if an edge case would break it. Should have a thorough review.
- This PR worsens the state of #56885, since those certain fatal lexing errors are now emitted before docs get generated at all.