groovy / groovy/groovy-eclipse

Fix type inferencing for withTraits expression

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enhancement
Dominant language
Java
Stars
681
Forks
197
PR merge metrics
No merged PRs in 30d

Description

Consider the following:

trait Filtering {
  StringBuilder append(String str) {
    def subst = str.replace('o', '')
    super.append(subst)
  }
  String toString() {
    super.toString()
  }
}

def sb = new StringBuilder().withTraits(Filtering)
sb.append('Groovy')
println sb.toString()

"sb" infers as Object, "append" shows as unknown (underlined) and "toString" infers to Object.toString(). Is it possible to infer that typeof(sb) is Filtering from the source?

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the withTraits example in the issue and inspect how Eclipse Groovy Development Tools infers the type of sb. Trace the handling of the withTraits expression and verify that sb, append, and toString resolve to the trait-aware type rather than Object.

Written by the indexing model from the issue text.

Assessment

Tech stack
groovy
Domain
devtools
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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