openrewrite / openrewrite/rewrite-static-analysis
Unused assignments should be removed
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- Dominant language
- Java
- Stars
- 62
- Forks
- 112
- Avg merge
- 1d 19h
- Merged PRs (30d)
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Description
see: https://rules.sonarsource.com/java/tag/unused/RSPEC-1854
A dead store happens when a local variable is assigned a value that is not read by any subsequent instruction. Calculating or retrieving a value only to then overwrite it or throw it away, could indicate a serious error in the code. Even if it’s not an error, it is at best a waste of resources. Therefore all calculated values should be used.
Note, that this problem, "dead code analysis", among others, is one of the posterchild problems solved by representing the tree as a Control Flow Graph.
See also: https://www.cs.utexas.edu/~pingali/CS380C/2020/lectures/CFG.pdf
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reading the linked SonarSource RSPEC-1854 rule and the referenced control-flow-graph lecture. Then inspect this repository’s existing static-analysis recipes to determine the intended entry point and tests; done means unused local assignments are identified and removed without affecting values that are subsequently read.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- java
- Domain
- devtools
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 30/100