llvm/llvm-project

Create a check that warns about using %p printf specifier

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#43,453 opened on Nov 21, 2019

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bugzillaclang:static analyzerenhancementgood first issue

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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