Don't use tryWithFallback #2493
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Why not? - It's a hack - It can add a factor of two for a failed implicit search, which can add up - It swallows up useful info for the first implicit search which caused the fallback. The only test failing after removal was t2429.scala. That test was originally for an issue where scalac crashed. It involves some fairly exotic code over List[Nothing]'s. I think we can ignore it for now, and just add the type annotation to make it compile.
DarkDimius
approved these changes
May 23, 2017
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Why not?
which can add up
which caused the fallback.
The only test failing after removal was t2429.scala. That test
was originally for an issue where scalac crashed. It involves
some fairly exotic code over List[Nothing]'s. I think we can
ignore it for now, and just add the type annotation to make it
compile.
The commit also contains some improvements for implicit search diagnostics and a test that was used to find the issues. Originally the goal was to get better info out of -explain-implicits. That's still unfulfilled, but at least the search does not become weird anymore. Previously, instead of getting an "implicit not found" error we got a an ambiguous implicit because the fallback tried again with a wildcard expected type.