Fix #3480: Fix expanded name

compiler/src/dotty/tools/dotc/core/NameOps.scala

@@ -114,11 +114,12 @@ object NameOps {
       else name.toTermName.exclude(AvoidClashName)
     }
 
-    def expandedName(base: Symbol, kind: QualifiedNameKind = ExpandedName)(implicit ctx: Context): N = {
-      val prefix =
-        if (base.name.is(ExpandedName)) base.name else base.fullNameSeparated(ExpandPrefixName)
-      likeSpaced { kind(prefix.toTermName, name.toTermName) }
-    }
+    /** The expanded name.
+     *  This is the fully qualified name of `base` with `ExpandPrefixName` as separator,
+     *  followed by `kind` and the name.
+     */
+    def expandedName(base: Symbol, kind: QualifiedNameKind = ExpandedName)(implicit ctx: Context): N =
+      likeSpaced { base.fullNameSeparated(ExpandPrefixName, kind, name) }
 
     /** Revert the expanded name. */
     def unexpandedName: N = likeSpaced {

compiler/src/dotty/tools/dotc/core/SymDenotations.scala

@@ -391,18 +391,23 @@ object SymDenotations {
      *  Drops package objects. Represents each term in the owner chain by a simple `_$`.
      */
     def fullNameSeparated(kind: QualifiedNameKind)(implicit ctx: Context): Name =
-      if (symbol == NoSymbol ||
-          owner == NoSymbol ||
-          owner.isEffectiveRoot ||
-          kind == FlatName && owner.is(PackageClass)) name
+      maybeOwner.fullNameSeparated(kind, kind, name)
+
+    /** The encoded full path name of this denotation (separated by `prefixKind`),
+     *  followed by the separator implied by `kind` and the given `name`.
+     *  Drops package objects. Represents each term in the owner chain by a simple `_$`.
+     */
+     def fullNameSeparated(prefixKind: QualifiedNameKind, kind: QualifiedNameKind, name: Name)(implicit ctx: Context): Name =
+      if (symbol == NoSymbol || isEffectiveRoot || kind == FlatName && is(PackageClass))
+        name
       else {
         var filler = ""
-        var encl = owner
+        var encl = symbol
         while (!encl.isClass && !encl.isPackageObject) {
           encl = encl.owner
           filler += "_$"
         }
-        var prefix = encl.fullNameSeparated(kind)
+        var prefix = encl.fullNameSeparated(prefixKind)
         if (kind.separator == "$")
           // duplicate scalac's behavior: don't write a double '$$' for module class members.
           prefix = prefix.exclude(ModuleClassName)
@@ -412,10 +417,9 @@ object SymDenotations {
           case name: SimpleName => qualify(name)
           case name @ AnyQualifiedName(_, _) => qualify(name.mangled.toSimpleName)
         }
-        if (isType) fn.toTypeName else fn.toTermName
+        if (name.isType) fn.toTypeName else fn.toTermName
       }
 
-
     /** The encoded flat name of this denotation, where joined names are separated by `separator` characters. */
     def flatName(implicit ctx: Context): Name = fullNameSeparated(FlatName)
 

tests/pos/i3480.scala

@@ -0,0 +1,5 @@
+class Test {
+  def foo(x: PartialFunction[Int, Int]) = x(0)
+
+  foo({ case i => i})
+}

tests/run/i3006b.check

@@ -1,3 +1,3 @@
-Foo$$init$$$bar$1
-Foo$$init$$$bar$2
-Bar$$init$$$bar$1
+Foo$$_$bar$1
+Foo$$_$bar$2
+Bar$$_$bar$1