Skip var when target type inference widens a generic argument#1103
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`List<I> x = singletonList(c)` where `c` is a `C extends I` keeps the LST type as `List<I>` via target type inference. Converting to `var x = List.of(c)` drops the target context, so javac re-infers `List<C>` and downstream usages expecting `List<I>` fail to compile. Detect the widening by comparing each argument's type to its resolved parameter type: when the parameter is a bare class (not parameterized) that is a strict supertype of the argument, target inference widened a `<T>` substitution, and switching to `var` would narrow it back.
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Summary
List<I> x = singletonList(c)wherecis aC extends Ikeeps the LST type asList<I>via target type inference, but converting tovar x = List.of(c)makes javac re-inferList<C>— breaking any downstream usage that requires the declared supertype.UseVarForGenericMethodInvocationsnow detects this by checking each argument against its resolved parameter type: when the parameter is a bare (non-parameterized) class that is a strict supertype of the argument, target inference widened a<T>substitution and the conversion is skipped.Test plan
declaredSupertypeWidensTypeArgumentinUseVarForGenericMethodInvocationsTestorg.openrewrite.java.migrate.lang.var.*pass