Avoid infinite recursion when looking for import suggestions

Co-authored-by: Ondřej Lhoták <[email protected]>
Co-authored-by: Nguyen Pham <[email protected]>

Author: 3 people

compiler/src/dotty/tools/dotc/typer/ImportSuggestions.scala

@@ -97,6 +97,7 @@ trait ImportSuggestions:
           if refSym.is(JavaDefined) then Nil
           else nestedRoots(site)
       nested
+        .filter(mbr => mbr.asTerm != ref.termSymbol)
         .map(mbr => TermRef(ref, mbr.asTerm))
         .flatMap(rootsIn)
         .toList

tests/neg/22145.check

@@ -0,0 +1,4 @@
+-- [E008] Not Found Error: tests/neg/22145.scala:3:7 -------------------------------------------------------------------
+3 |  base.foo() // error
+  |  ^^^^^^^^
+  |  value foo is not a member of Collection

tests/neg/22145.scala

@@ -0,0 +1,6 @@
+trait Collection:
+  val base: Collection = ???
+  base.foo() // error
+
+  object O extends Collection:
+    def foo(): Int = ???

tests/neg/22145b.check

@@ -0,0 +1,36 @@
+-- [E008] Not Found Error: tests/neg/22145b.scala:13:19 ----------------------------------------------------------------
+13 |      require(base.isWithin(p, start, end), "position is out of bounds") // error
+   |              ^^^^^^^^^^^^^
+   |              value isWithin is not a member of Collection.this.Self
+-- [E008] Not Found Error: tests/neg/22145b.scala:26:59 ----------------------------------------------------------------
+26 |      def positionAfter(p: Position): Position = self.base.positionAfter(p) // error
+   |                                                 ^^^^^^^^^^^^^^^^^^^^^^^
+   |value positionAfter is not a member of Collection.this.Self.
+   |An extension method was tried, but could not be fully constructed:
+   |
+   |    this.positionAfter(self.base)
+   |
+   |    failed with:
+   |
+   |        Found:    (self.base : Collection.this.Self)
+   |        Required: Collection.given_is_Slice_Collection.Self²
+   |        
+   |        where:    Self  is a type in trait Collection
+   |                  Self² is a type in object given_is_Slice_Collection which is an alias of Collection.this.Slice
+   |        
+-- [E008] Not Found Error: tests/neg/22145b.scala:27:50 ----------------------------------------------------------------
+27 |      def apply(p: Position): Element = self.base.apply(p) // error
+   |                                        ^^^^^^^^^^^^^^^
+   |value apply is not a member of Collection.this.Self.
+   |An extension method was tried, but could not be fully constructed:
+   |
+   |    this.apply(self.base)
+   |
+   |    failed with:
+   |
+   |        Found:    (self.base : Collection.this.Self)
+   |        Required: Collection.given_is_Slice_Collection.Self²
+   |        
+   |        where:    Self  is a type in trait Collection
+   |                  Self² is a type in object given_is_Slice_Collection which is an alias of Collection.this.Slice
+   |        

tests/neg/22145b.scala

@@ -0,0 +1,38 @@
+import language.experimental.modularity
+
+trait Collection:
+  me =>
+
+  type Self
+  type Position
+  type Element
+
+  final class Slice(private[Collection] val base: Self, val start: Position, val end: Position):
+
+    final def apply(p: Position): Element =
+      require(base.isWithin(p, start, end), "position is out of bounds") // error
+      base.apply(p)
+
+  end Slice
+
+  given Slice is Collection:
+
+    type Position = me.Position
+    type Element = me.Element
+
+    extension (self: Self)
+      def start: Position = self.start
+      def end: Position = self.end
+      def positionAfter(p: Position): Position = self.base.positionAfter(p) // error
+      def apply(p: Position): Element = self.base.apply(p) // error
+
+  end given
+
+  extension (self: Self)
+
+    def start: Position
+    def end: Position
+    def positionAfter(p: Position): Position
+    def apply(p: Position): Element
+
+  end extension