Avoid underflow in render_source_line #47677
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
While testing #47655 I was able to make the compiler panic when it's compiled with debug assertions: ```shell > rustc /dev/null --crate-type proc-macro error: internal compiler error: unexpected panic note: the compiler unexpectedly panicked. this is a bug. note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports note: rustc 1.25.0-dev running on x86_64-apple-darwin note: run with `RUST_BACKTRACE=1` for a backtrace thread 'rustc' panicked at 'attempt to subtract with overflow', librustc_errors/emitter.rs:287:49 ``` Without debug assertions the following warning is emitted: ```shell > rustc /dev/null --crate-type proc-macro warning: unused variable: `registrar` --> /dev/null:0:1 | | = note: #[warn(unused_variables)] on by default = note: to avoid this warning, consider using `_registrar` instead ``` The panic is due to the unused variable warning being spanned to `/dev/null:0:1`. When `render_source_line` subtracts 1 from the line number to look up the source line it panics due to underflow. Without debug assertions this would wrap and cause us to return a blank string instead. Fix by explicitly testing for 0 and exiting early. I'm unsure how to automatically test this now that #46655 has been approved.
|
Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @pnkfelix (or someone else) soon. If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes. Please see the contribution instructions for more information. |
|
Thanks for the PR! We’ll periodically check in on it to make sure that @pnkfelix or someone else from the team reviews it soon. |
kennytm
added
the
S-waiting-on-review
kennytm
added
the
T-compiler
|
Review ping for you @pnkfelix! Also cc @rust-lang/compiler if anyone want to step in. |
|
@bors r+ rollup |
|
📌 Commit c6377f8 has been approved by |
kennytm
added
S-waiting-on-bors
kennytm
added a commit
to kennytm/rust
that referenced
this pull request
Jan 31, 2018
…source-line, r=estebank Avoid underflow in render_source_line While testing rust-lang#47655 I was able to make the compiler panic when it's compiled with debug assertions: ```shell > rustc /dev/null --crate-type proc-macro error: internal compiler error: unexpected panic note: the compiler unexpectedly panicked. this is a bug. note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports note: rustc 1.25.0-dev running on x86_64-apple-darwin note: run with `RUST_BACKTRACE=1` for a backtrace thread 'rustc' panicked at 'attempt to subtract with overflow', librustc_errors/emitter.rs:287:49 ``` Without debug assertions the following warning is emitted: ```shell > rustc /dev/null --crate-type proc-macro warning: unused variable: `registrar` --> /dev/null:0:1 | | = note: #[warn(unused_variables)] on by default = note: to avoid this warning, consider using `_registrar` instead ``` The panic is due to the unused variable warning being spanned to `/dev/null:0:1`. When `render_source_line` subtracts 1 from the line number to look up the source line it panics due to underflow. Without debug assertions this would wrap and cause us to return a blank string instead. Fix by explicitly testing for 0 and exiting early. I'm unsure how to automatically test this now that rust-lang#46655 has been approved.
bors
added a commit
that referenced
this pull request
Jan 31, 2018
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
While testing #47655 I was able to make the compiler panic when it's compiled with debug assertions:
Without debug assertions the following warning is emitted:
The panic is due to the unused variable warning being spanned to
/dev/null:0:1. Whenrender_source_linesubtracts 1 from the line number to look up the source line it panics due to underflow. Without debug assertions this would wrap and cause us to return a blank string instead.Fix by explicitly testing for 0 and exiting early. I'm unsure how to automatically test this now that #46655 has been approved.