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Merge pull request #1859 from retronym/ticket/6912

SI-6912 Avoid a typer cycle in overload resolution.
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2 parents 9ea0a20 + 7a23562 commit 5d65772762072aa950a488c666673dc248b01d6d @paulp paulp committed Jan 13, 2013
Showing with 20 additions and 0 deletions.
  1. +7 −0 src/compiler/scala/tools/nsc/typechecker/Infer.scala
  2. +4 −0 test/files/neg/t6912.check
  3. +9 −0 test/files/neg/t6912.scala
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7 src/compiler/scala/tools/nsc/typechecker/Infer.scala
@@ -1512,6 +1512,13 @@ trait Infer extends Checkable {
} else if (!competing.isEmpty) {
if (noAlternatives) NoBestExprAlternativeError(tree, pt, isSecondTry)
else if (!pt.isErroneous) AmbiguousExprAlternativeError(tree, pre, best, competing.head, pt, isSecondTry)
+ else {
+ // SI-6912 Don't give up and leave an OverloadedType on the tree.
+ // Originally I wrote this as `if (secondTry) ... `, but `tryTwice` won't attempt the second try
+ // unless an error is issued. We're not issuing an error, in the assumption that it would be
+ // spurious in light of the erroneous expected type
+ setError(tree)
+ }
} else {
// val applicable = alts1 filter (alt =>
// global.typer.infer.isWeaklyCompatible(pre.memberType(alt), pt))
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4 test/files/neg/t6912.check
@@ -0,0 +1,4 @@
+t6912.scala:8: error: not found: type Xxxx
+ def test[T]: Xxxx = Foo1[T]
+ ^
+one error found
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9 test/files/neg/t6912.scala
@@ -0,0 +1,9 @@
+object Foo1 {
+ def apply[T](a: Int = 0): Nothing = sys.error("")
+ def apply[T](z: String = ""): Nothing = sys.error("")
+}
+
+object Test {
+ // Triggered a cycle in Typers#adapt
+ def test[T]: Xxxx = Foo1[T]
+}

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