golang/go

cmd/vet: reject flag.Parse during func init

Open

#33,190 opened on Jul 19, 2019

View on GitHub
 (4 comments) (12 reactions) (0 assignees)Go (19,008 forks)batch import
AnalysisNeedsFixearly-in-cyclehelp wanted

Repository metrics

Stars
 (133,883 stars)
PR merge metrics
 (No merged PRs in 30d)

Description

In #31859, @cespare suggested rejecting flag.Parse during func init, which is always incorrect (other packages not yet initialized may want to define flags).

We could add a special runtime hook of some kind to allow flag to see whether main.main has started, but that would be unfortunate. There also may be lots of code in the wild that does parse flags during init and kind of works out OK, and if it's working well enough we don't want to break it unnecessarily.

A vet check, on by default during go test, seems like the perfect compromise to me.

Contributor guide

Research direction
Implement a new go vet check that detects calls to flag.Parse inside init functions. This can be done by adding an analyzer in the go/analysis package that inspects function declarations and looks for flag.Parse calls within init functions. Then register it in go vet's list of analyzers.
Tech stack
go
Domain
backend
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Gogo vet
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65