ddunbar
commented
7 years ago We now have an implementation of the core delta debugging algorithm already in SwiftPM:
https://github.com/apple/swift-package-manager/pull/1036
As a starter bug, this requires:
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Learning about the behavior of existing tools like this (see description), and why they are useful
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Figuring out how to invoke add a new tool to SwiftPM (e.g., {swift package minimize}).
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Creating a model of what kinds of reductions to try to perform. Something simple like starting with each individual source line in the entire package would be a reasonable place to start.
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Writing the logic to invoke the delta debugging algorithm with these reductions and then invoke the test predicate – this involves copying the source to a staging area, performing the modification, and then checking that the test predicate (i.e. shell script) passes or not.
I think this is a good starter bug because it is a potentially high-value feature that is purely additive and doesn't require significant design discussion (beyond the software engineering level).
belkadan
Additional Detail from JIRA
| | | |------------------|-----------------| |Votes | 0 | |Component/s | Package Manager | |Labels | Bug, StarterBug | |Assignee | None | |Priority | Medium | md5: 83f2d1d181b16d93390c4b88e07dd5ffIssue Description:
SwiftPM should have a feature to automatically minimize a package to the smallest package to pass some test predicate (supplied by a shell script, for example).
This is invaluable tool for getting high quality / actionable bug reports for compiler crashes, build failures, etc. from developers who may not otherwise be able to share their source code.
Similar tools in this space are:
C-Reduce: https://embed.cs.utah.edu/creduce/
Delta: http://delta.tigris.org
Bugpoint: http://llvm.org/docs/Bugpoint.html
and we know from experience that these tools can be very powerful at efficiently reducing even very large test inputs to small test cases.