fix: throw an error before assigning ErrorType when expanding constVa…

…lue (#21364) fixes #21359
scala · Sep 12, 2024 · e9d4831 · e9d4831
2 parents 4891858 + e66860b
commit e9d4831
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diff --git a/compiler/src/dotty/tools/dotc/inlines/Inlines.scala b/compiler/src/dotty/tools/dotc/inlines/Inlines.scala
@@ -429,6 +429,7 @@ object Inlines:
           val constVal = tryConstValue(tpe)
           if constVal.isEmpty then
             val msg = NotConstant("cannot take constValue", tpe)
+            report.error(msg, callTypeArgs.head.srcPos)
             ref(defn.Predef_undefined).withSpan(callTypeArgs.head.span).withType(ErrorType(msg))
           else
             constVal

diff --git a/tests/neg/i21359.scala b/tests/neg/i21359.scala
@@ -0,0 +1,6 @@
+import scala.compiletime.constValueTuple
+import scala.deriving.Mirror
+
+case class Hello(a: Int)
+val mirror = summon[Mirror.Of[Hello]]
+val test = constValueTuple[mirror.MirroredElemTypes] // error