Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

x/tools/go/analysis/passes/ctrlflow: encode more knowledge about standard library in ctrlflow analyzer #497

Open
wants to merge 1 commit into
base: master
Choose a base branch
from

Conversation

yuxincs
Copy link

@yuxincs yuxincs commented Jun 5, 2024

ctrlflow Analyzer has a list of intrinsic no-return functions such as "syscall.Exit" but not higher-level standard library
functions like "os.Exit". It relies on actually analyzing those functions (which internally will call the intrinsic no-return
functions), and then exporting the knowledge as "noReturn" facts for downstream analyses.

However, as is noted in "analysis" framework documentation
(https://pkg.go.dev/golang.org/x/tools/go/analysis#hdr-Modular_analysis_with_Facts):

"Some driver implementations (such as those based on Bazel and Blaze) do not currently apply analyzers to packages
of the standard library. Therefore, for best results, analyzer authors should not rely on analysis facts being available for
standard packages."

From our testing with Bazel (nogo), this still seems to be true (May 2024), since rules_go
(https://github.com/bazelbuild/rules_go) compiles the standard library via "go install", where analyzers are not applied,
and hence won't export the "noReturn" facts. This would have cascading effects since "os.Exit" not being marked as
no-return will lead to user-defined functions like

func HandleError(err error) {
SendLog(err)
os.Exit(1)
}

as well as its further wrappers not being marked as no-return. Then, the blocks containing calls to them would still have
successors (incorrectly).

Following the recommendations from the documentation ("analyzer authors should not rely on analysis facts being
available"), this PR encodes more higher-level functions from the standard library as no-return.

@gopherbot
Copy link
Contributor

This PR (HEAD: 98bebae) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/tools/+/590497.

Important tips:

  • Don't comment on this PR. All discussion takes place in Gerrit.
  • You need a Gmail or other Google account to log in to Gerrit.
  • To change your code in response to feedback:
    • Push a new commit to the branch used by your GitHub PR.
    • A new "patch set" will then appear in Gerrit.
    • Respond to each comment by marking as Done in Gerrit if implemented as suggested. You can alternatively write a reply.
    • Critical: you must click the blue Reply button near the top to publish your Gerrit responses.
    • Multiple commits in the PR will be squashed by GerritBot.
  • The title and description of the GitHub PR are used to construct the final commit message.
    • Edit these as needed via the GitHub web interface (not via Gerrit or git).
    • You should word wrap the PR description at ~76 characters unless you need longer lines (e.g., for tables or URLs).
  • See the Sending a change via GitHub and Reviews sections of the Contribution Guide as well as the FAQ for details.

@gopherbot
Copy link
Contributor

Message from Gopher Robot:

Patch Set 1:

(1 comment)


Please don’t reply on this GitHub thread. Visit golang.org/cl/590497.
After addressing review feedback, remember to publish your drafts!

@yuxincs yuxincs changed the title Encode more knowledge about standard library in ctrlflow analyzer x/tools/go/analysis/passes/ctrlflow: encode more knowledge about standard library in ctrlflow analyzer Jun 5, 2024
@gopherbot
Copy link
Contributor

Message from Gopher Robot:

Patch Set 1:

Congratulations on opening your first change. Thank you for your contribution!

Next steps:
A maintainer will review your change and provide feedback. See
https://go.dev/doc/contribute#review for more info and tips to get your
patch through code review.

Most changes in the Go project go through a few rounds of revision. This can be
surprising to people new to the project. The careful, iterative review process
is our way of helping mentor contributors and ensuring that their contributions
have a lasting impact.


Please don’t reply on this GitHub thread. Visit golang.org/cl/590497.
After addressing review feedback, remember to publish your drafts!

@gopherbot
Copy link
Contributor

Message from Yuxin Wang:

Patch Set 2:

(1 comment)


Please don’t reply on this GitHub thread. Visit golang.org/cl/590497.
After addressing review feedback, remember to publish your drafts!

@gopherbot
Copy link
Contributor

Message from Tim King:

Patch Set 3:

(6 comments)


Please don’t reply on this GitHub thread. Visit golang.org/cl/590497.
After addressing review feedback, remember to publish your drafts!

@gopherbot
Copy link
Contributor

Message from Lasse Folger:

Patch Set 3:

(1 comment)


Please don’t reply on this GitHub thread. Visit golang.org/cl/590497.
After addressing review feedback, remember to publish your drafts!

@gopherbot
Copy link
Contributor

Message from Tim King:

Patch Set 3:

(1 comment)


Please don’t reply on this GitHub thread. Visit golang.org/cl/590497.
After addressing review feedback, remember to publish your drafts!

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

Successfully merging this pull request may close these issues.

2 participants