llvm/llvm-project

Create a check that warns about using %p printf specifier

Open

#43,453 opened on Nov 21, 2019

View on GitHub
 (11 comments) (0 reactions) (0 assignees)C++ (10,782 forks)batch import
bugzillaclang:static analyzerenhancementgood first issue

Repository metrics

Stars
 (26,378 stars)
PR merge metrics
 (Avg merge 1d 2h) (1,000 merged PRs in 30d)

Description
Bugzilla Link 44108
Version unspecified
OS Windows NT

Extended Description

Recently I ran into some surprising behavior surrounding the use of %p in a printf call. On Windows %p with a nullptr prints zeros, but on Linux %p with a nullptr prints "(nil)". This is surprising, but conforming to the standard which states (roughly) that the result of %p is implementation dependent.

Create a check that warns about the potential non-portable output when using %p in a printf or scanf specifier.

Contributor guide

Research direction
Study existing clang tidy checks for printf format strings, locate relevant code in the Clang source tree, implement a new check that warns when %p is used in printf/scanf, and add unit tests for various platforms.
Tech stack
cpp
Domain
backendtooling
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
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
C++Git
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50