typetools / typetools/checker-framework
Signedness Checker support for bit patterns
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- Java
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Description
Some values are not arithmetic quantities, but are manipulated as a pattern of bits.
An example is the return value of Double.doubleToLongBits. Another example is a value used as a bitset.
The task is to add a new qualifier to the Signedness Checker to represent such values. It could be named @BitPattern or the like.
This type qualifier is a subtype of @UnknownSignedness and a supertype of @SignednessBottom, but is unrelated to all other type qualifiers.
All bitwise operators and shifts are permitted. All arithmetic operators are forbidden.
This will replace https://github.com/typetools/checker-framework/pull/3210 and https://github.com/typetools/jdk/pull/43; see them for examples of where annotations are needed in the JDK.
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 reviewing the Signedness Checker implementation and the examples in checker-framework#3210 and typetools/jdk#43, which the issue identifies as replacements. Define the new qualifier's hierarchy and operator rules, then verify that the needed JDK annotations are covered and the checker tests pass.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- java
- Domain
- compilers, devtools
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100