scala/scala — pull request #548 by adriaanm (2012-05-14 11:52:39+00:00)
Title: suspend type vars in SubTypePair's equals

SubTypePair's equals method calls =:= on the involved types,
which mutates the TypeVars contained in them
this is undesirable since we're simply checking whether a subtype test is pending

in addition to making subtyping "more correct" for type vars,
it should avoid the stackoverflow that's been plaguing us
(https://groups.google.com/d/topic/scala-internals/2gHzNjtB4xA/discussion)

SubTypePair's equals method method is only called when subtype checking
hits a recursion threshold (subsametypeRecursions >= LogPendingSubTypesThreshold)

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https://raw.github.com/gist/2235522/1b198fadd1.buildlog certifies ant test-opt was run on 1b198fadd1