Fix false-positive by-name implicit warnings with -Wmacros
#10781
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lrytz
reviewed
May 21, 2024
| t match { | ||
| case Apply(coercion, _) if t.isInstanceOf[ApplyImplicitView] => | ||
| coercion.symbol.paramLists match { | ||
| case (p :: Nil) :: _ if p.isByNameParam => refchecksWarning(t.pos, s"Block result was adapted via implicit conversion (${coercion.symbol}) taking a by-name parameter", WarningCategory.LintBynameImplicit) |
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Suggested change
| case (p :: Nil) :: _ if p.isByNameParam => refchecksWarning(t.pos, s"Block result was adapted via implicit conversion (${coercion.symbol}) taking a by-name parameter", WarningCategory.LintBynameImplicit) | |
| case (p :: Nil) :: _ if p.isByNameParam => refchecksWarning(t.pos, s"Block result was adapted via implicit conversion (${coercion.symbol}) taking a by-name parameter; statements are not evaluated eagerly", WarningCategory.LintBynameImplicit) |
or something like that?
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Or just the opposite. This is the opposite where only the result expression is adapted. I'll upgrade both messages!
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I pushed messages for the two cases that are less cryptic. The OP confusing case is that if a block is converted, the conversion applies only to the result expression. This matters if the method parameter is by-name. The related confusing case is that if the method is overloaded, the conversion applies to the whole block, the opposite of the first case. |
-Wmacros
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Only warn about a block arg passed into the by-name param of an implicit method if it was an implicit view.
Fixes scala/bug#12072
This implements lrytz's suggestion on the ticket.
scala/bug#12072 (comment)
Confirmed that the Shapeless 2 solutions to the guide exercises now compile cleanly.
Since Shapeless is not relying on conversions, this PR ignores the ticket title as a red herring.