LLVM Bug Life Cycle

Introduction - Achieving consistency in how we deal with bug reports

We aim to achieve a basic level of consistency in how reported bugs evolve from being reported, to being worked on, and finally getting closed out. The consistency helps reporters, developers and others to gain a better understanding of what a particular bug state actually means and what to expect might happen next.

At the same time, we aim to not over-specify the life cycle of bugs in the LLVM Bug Tracking System, as the overall goal is to make it easier to work with and understand the bug reports.

The main parts of the life cycle documented here are:

  1. Reporting

  2. Triaging

  3. Actively working on fixing

  4. Closing

Furthermore, some of the metadata in the bug tracker, such as what labels we use, needs to be maintained. See the following for details:

  1. Maintenance of metadata

Reporting bugs

See How to submit an LLVM bug report on further details on how to submit good bug reports.

You can apply labels to the bug to provide extra information to make the bug easier to discover, such as a label for the part of the project the bug pertains to.

Triaging bugs

Open bugs that have not been marked with the confirmed label are bugs that still need to be triaged. When triage is complete, the confirmed label should be added along with any other labels that help to classify the report, unless the issue is being closed.

The goal of triaging a bug is to make sure a newly reported bug ends up in a good, actionable state. Try to answer the following questions while triaging:

  • Is the reported behavior actually wrong?

    • E.g. does a miscompile example depend on undefined behavior?

  • Can you reproduce the bug from the details in the report?

    • If not, is there a reasonable explanation why it cannot be reproduced?

  • Is it related to an already reported bug?

  • Are the following fields filled in correctly?

    • Title

    • Description

    • Labels

  • When able to do so, please add the appropriate labels to classify the bug, such as the tool (clang, clang-format, clang-tidy, etc) or component (backend:<name>, compiler-rt:<name>, clang:<name>, etc).

  • If the issue is with a particular revision of the C or C++ standard, please add the appropriate language standard label (c++20, c99, etc).

  • Please don’t use both a general and a specific label. For example, bugs labeled c++17 shouldn’t also have c++, and bugs labeled clang:codegen shouldn’t also have clang.

  • Add the good first issue label if you think this would be a good bug to be fixed by someone new to LLVM. This label feeds into the landing page for new contributors.

  • If you are unsure of what a label is intended to be used for, please see the documentation for our labels.

Actively working on fixing bugs

Please remember to assign the bug to yourself if you’re actively working on fixing it and to unassign it when you’re no longer actively working on it. You unassign a bug by removing the person from the Assignees field.

Resolving/Closing bugs

Resolving bugs is good! Make sure to properly record the reason for resolving. Examples of reasons for resolving are:

  • If the issue has been resolved by a particular commit, close the issue with a brief comment mentioning which commit(s) fixed it. If you are authoring the fix yourself, your git commit message may include the phrase Fixes #<issue number> on a line by itself. GitHub recognizes such commit messages and will automatically close the specified issue with a reference to your commit.

  • If the reported behavior is not a bug, it is appropriate to close the issue with a comment explaining why you believe it is not a bug, and adding the invalid tag.

  • If the bug duplicates another issue, close it as a duplicate by adding the duplicate label with a comment pointing to the issue it duplicates.

  • If there is a sound reason for not fixing the issue (difficulty, ABI, open research questions, etc), add the wontfix label and a comment explaining why no changes are expected.

  • If there is a specific and plausible reason to think that a given bug is otherwise inapplicable or obsolete. One example is an open bug that doesn’t contain enough information to clearly understand the problem being reported (e.g. not reproducible). It is fine to close such a bug, adding with the worksforme label and leaving a comment to encourage the reporter to reopen the bug with more information if it’s still reproducible for them.

Maintenance of metadata

Project member with write access to the project can create new labels, but we discourage adding ad hoc labels because we want to control the proliferation of labels and avoid single-use labels. If you would like a new label added, please open an issue asking to create an issue label and add the infrastructure label to the issue. The request should include a description of what the label is for. Alternatively, you can ask for the label to be created on the #infrastructure channel on the LLVM Discord.