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C# printer: nine unit-test samples that Roslyn rejects #185
Description
The C# printer's unit tests now have Roslyn judge every sample (CommonJavaToCSharp.translate, CSharpCheck on tools/csharp-check -serve). On the first run, 9 of 131 samples do not compile. Each test sets compile = false with a pointer here until its printer bug is fixed; this issue closes when none is left.
TestJavaToCSharpStructure.conditionalVars:var node = c ? new IndexedExists<A, B>() : new UnindexedExists<A, string>()— CS0173, C# finds no common type for a conditional of two sibling classes; Java's is the common supertype (declare it, or cast one branch).TestJavaToCSharpStructure.innerClasses:Upcoming : IJavaIterator<long>withlong? Next()— CS0738, the boxedLong next()must override aslong, as it does for a top-level class.TestJavaToCSharpStructure.localClasses: a local class that captures (Adder) is referenced but not printed anywhere — CS0246.TestJavaToCSharpStructure.longTypeArguments: a cast through a wildcard printed asobject— CS0030 (the wildcard family).TestJavaToCSharpStructure.suppliers:sealed class Defaults<R> where R : Defaults<R>— CS0701, a class that is a type parameter's bound cannot besealed.TestJavaToCSharpStructure.tryWithResources:System.gc()unmapped (GC.Collect()).TestJavaToCSharpStructure.wildcardInterfaces: the wildcard interfaceIImpacterand the companionstatic class IImpacterofIImpacter<G>clash — CS0102.TestJavaToCSharpBcl.navigation: three errors in one sample:T[] ToArray<T>(T[] a) => items.ToArray()(CS0029,E[]toT[]),!Contains(v) && items.Add(v)whereAddisvoidon aHashSet-backedICollection(CS0019), andc.All(...)on the non-genericICollection(CS1061).TestJavaToCSharpFacts.inheritedFamilyAndStructswas the test's own fault (a package-private method implementing an interface method is not Java either) and is fixed.
Activity
bnaudts commentedon Nov 5, 2026
Harness: maddi
c8d0727fc. Fixes:e65b4878d(sealed bound, boxed override as the supertype's argument prints, self-bounded companion merged,AddReturning/ToArray(a)/ContainsAll,System.gc).Still opted out, all the wildcard design rather than single fixes:
conditionalVars: a conditional whose common type C# cannot write (a wildcard, an intersection) staysvar(CS0173). No message is reported for it yet either.longTypeArguments: a cast through a wildcard printed asobject(CS0030).wildcardInterfaces: now compiles its declarations, but a self-bounded wildcard interface declares no member mentioning the parameter, soimpacter.Impacts()onIImpacteris CS1061.localClassesis by design (LOCAL_CLASS: a capturing local class is not translated) and no longer counted here.bnaudts commentedon Nov 5, 2026
Corpus check of the fixes (maddi
cd0126f96): langchain4j 192 → 172 errors (the sealed bound), fernflower and the nullable warnings unchanged. Timefold 596 → 641 errors and 1330 → 1321 compiling files: mergingWeightedScoreImpacter's andConstraintMatchSupplier's companions into their wildcard interfaces removed the duplicate declarations (CS0101/CS0538), behind which Roslyn had hidden the errors of their twelve clients — the ImpactHandlers and ScoreInliners callImpactScorethrough the wildcard interface, which cannot declare a member mentioningScore_. Those files compiled before only because Roslyn gives up on an error type. Recorded in the ratchets with that note; the wildcard design is where they get fixed.toArray(new T[0])first went through the compatToArray(a)and inferred the wildcard'sobject; it is LINQ'sToArray()again for any created array (cd0126f96).C# unit tests: Roslyn judges every sample (tools/csharp-check -serve …
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