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Fix #7839: Improve error message for implicit parameters #8960

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Merged
merged 1 commit into from
May 13, 2020
Merged

Fix #7839: Improve error message for implicit parameters #8960

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6 changes: 3 additions & 3 deletions compiler/src/dotty/tools/dotc/transform/Splicer.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -160,12 +160,12 @@ object Splicer {
// OK

case _ =>
val extra = if tree.span.isZeroExtent then ": " + tree.show else ""
ctx.error(
"""Malformed macro parameter
s"""Malformed macro parameter$extra
|
|Parameters may be:
|Parameters may only be:
| * Quoted parameters or fields
| * References to inline parameters
| * Literal values of primitive types
|""".stripMargin, tree.sourcePos)
}
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8 changes: 8 additions & 0 deletions tests/neg-macros/i7839.check
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@@ -0,0 +1,8 @@
-- Error: tests/neg-macros/i7839.scala:4:18 ----------------------------------------------------------------------------
4 | ${ transformImpl } // error
| ^
| Malformed macro parameter: dummyImplicit
|
| Parameters may only be:
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Why does it resolve DummyImplicit at all if it is neither of the two cases below?

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This is a static check that happens after typechecking. We do not modify in any way the typing of expressions within top level splices, we only restrict it based terms that can be interpreted when evaluating the macro.

| * Quoted parameters or fields
| * Literal values of primitive types
6 changes: 6 additions & 0 deletions tests/neg-macros/i7839.scala
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@@ -0,0 +1,6 @@
import scala.quoted._

inline def transform(using dummyImplicit: DummyImplicit): Unit =
${ transformImpl } // error

def transformImpl(using dummyImplicit: DummyImplicit)(using QuoteContext): Expr[Unit] = ???