Refactorings on Names: forbid .name on Name and cleanups on the way (#4834)

* Simplify type of NameOps.specializedFor

The current type is inconsistent with other uses of likeSpaced. And mentioning
`name` in a return type would prevent making it private as in next commit.

* Stop accidental support for `.name` on Name

This is easy for `TermNameDecorator`, and last commit makes it easy for
`NameDecorator`.

* Avoid misleading `tree: Name`

This lets you think that `tree.name` is sensible tho it isn't, and for more than
an year (since ce333b1).

* Generalize Name.likeSpaced and hide the one from NameDecorator

* Rename NameOps.likeSpaced to prevent confusion

* Address review: Make likeSpaced* take Name, not PreName

Author: Blaisorblade

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

@@ -49,7 +49,7 @@ object NameOps {
     }
   }
 
-  implicit class NameDecorator[N <: Name](val name: N) extends AnyVal {
+  implicit class NameDecorator[N <: Name](private val name: N) extends AnyVal {
     import nme._
 
     def testSimple(f: SimpleName => Boolean): Boolean = name match {
@@ -58,8 +58,8 @@ object NameOps {
       case _ => false
     }
 
-    def likeSpaced(n: PreName): N =
-      (if (name.isTermName) n.toTermName else n.toTypeName).asInstanceOf[N]
+    private def likeSpacedN(n: Name): N =
+      name.likeSpaced(n).asInstanceOf[N]
 
     def isConstructorName = name == CONSTRUCTOR || name == TRAIT_CONSTRUCTOR
     def isStaticConstructorName = name == STATIC_CONSTRUCTOR
@@ -100,7 +100,7 @@ object NameOps {
      *  method needs to work on mangled as well as unmangled names because
      *  it is also called from the backend.
      */
-    def stripModuleClassSuffix: N = likeSpaced {
+    def stripModuleClassSuffix: N = likeSpacedN {
       val semName = name.toTermName match {
         case name: SimpleName if name.endsWith("$") => name.unmangleClassName
         case _ => name
@@ -109,7 +109,7 @@ object NameOps {
     }
 
     /** If flags is a ModuleClass but not a Package, add module class suffix */
-    def adjustIfModuleClass(flags: Flags.FlagSet): N = likeSpaced {
+    def adjustIfModuleClass(flags: Flags.FlagSet): N = likeSpacedN {
       if (flags is (ModuleClass, butNot = Package)) name.asTypeName.moduleClassName
       else name.toTermName.exclude(AvoidClashName)
     }
@@ -119,27 +119,27 @@ object NameOps {
      *  followed by `kind` and the name.
      */
     def expandedName(base: Symbol, kind: QualifiedNameKind = ExpandedName)(implicit ctx: Context): N =
-      likeSpaced { base.fullNameSeparated(ExpandPrefixName, kind, name) }
+      likeSpacedN { base.fullNameSeparated(ExpandPrefixName, kind, name) }
 
     /** Revert the expanded name. */
-    def unexpandedName: N = likeSpaced {
+    def unexpandedName: N = likeSpacedN {
       name.rewrite { case ExpandedName(_, unexp) => unexp }
     }
 
     /** Remove the variance from the name. */
-    def invariantName: N = likeSpaced {
+    def invariantName: N = likeSpacedN {
       name.rewrite { case VariantName(invariant, _) => invariant }
     }
 
-    def implClassName: N = likeSpaced(name ++ tpnme.IMPL_CLASS_SUFFIX)
+    def implClassName: N = likeSpacedN(name ++ tpnme.IMPL_CLASS_SUFFIX)
 
     def traitOfImplClassName: N = {
       val suffix = tpnme.IMPL_CLASS_SUFFIX.toString
       assert(name.endsWith(suffix), name)
-      likeSpaced(name.mapLast(_.dropRight(suffix.length)))
+      likeSpacedN(name.mapLast(_.dropRight(suffix.length)))
     }
 
-    def errorName: N = likeSpaced(name ++ nme.ERROR)
+    def errorName: N = likeSpacedN(name ++ nme.ERROR)
 
     /** Map variance value -1, +1 to 0, 1 */
     private def varianceToNat(v: Int) = (v + 1) / 2
@@ -150,7 +150,7 @@ object NameOps {
     /** Name with variance prefix: `+` for covariant, `-` for contravariant */
     def withVariance(v: Int): N = {
       val underlying = name.exclude(VariantName)
-      likeSpaced(
+      likeSpacedN(
           if (v == 0) underlying
           else VariantName(underlying.toTermName, varianceToNat(v)))
     }
@@ -160,7 +160,7 @@ object NameOps {
      */
     def variance = name.collect { case VariantName(_, n) => natToVariance(n) }.getOrElse(0)
 
-    def freshened(implicit ctx: Context): N = likeSpaced {
+    def freshened(implicit ctx: Context): N = likeSpacedN {
       name.toTermName match {
         case ModuleClassName(original) => ModuleClassName(original.freshened)
         case name => UniqueName.fresh(name)
@@ -233,12 +233,12 @@ object NameOps {
       case nme.clone_ => nme.clone_
     }
 
-    def specializedFor(classTargs: List[Types.Type], classTargsNames: List[Name], methodTargs: List[Types.Type], methodTarsNames: List[Name])(implicit ctx: Context): name.ThisName = {
+    def specializedFor(classTargs: List[Types.Type], classTargsNames: List[Name], methodTargs: List[Types.Type], methodTarsNames: List[Name])(implicit ctx: Context): N = {
 
       val methodTags: Seq[Name] = (methodTargs zip methodTarsNames).sortBy(_._2).map(x => defn.typeTag(x._1))
       val classTags: Seq[Name] = (classTargs zip classTargsNames).sortBy(_._2).map(x => defn.typeTag(x._1))
 
-      name.likeSpaced(name ++ nme.specializedTypeNames.prefix ++
+      likeSpacedN(name ++ nme.specializedTypeNames.prefix ++
         methodTags.fold(nme.EMPTY)(_ ++ _) ++ nme.specializedTypeNames.separator ++
         classTags.fold(nme.EMPTY)(_ ++ _) ++ nme.specializedTypeNames.suffix)
     }
@@ -249,11 +249,11 @@ object NameOps {
     def unmangleClassName: N = name.toTermName match {
       case name: SimpleName
       if name.endsWith(str.MODULE_SUFFIX) && !nme.falseModuleClassNames.contains(name) =>
-        likeSpaced(name.dropRight(str.MODULE_SUFFIX.length).moduleClassName)
+        likeSpacedN(name.dropRight(str.MODULE_SUFFIX.length).moduleClassName)
       case _ => name
     }
 
-    def unmangle(kind: NameKind): N = likeSpaced {
+    def unmangle(kind: NameKind): N = likeSpacedN {
       name rewrite {
         case unmangled: SimpleName =>
           kind.unmangle(unmangled)
@@ -271,7 +271,7 @@ object NameOps {
     }
   }
 
-  implicit class TermNameDecorator(val name: TermName) extends AnyVal {
+  implicit class TermNameDecorator(private val name: TermName) extends AnyVal {
     import nme._
 
     def setterName: TermName = name.exclude(FieldName) ++ str.SETTER_SUFFIX

compiler/src/dotty/tools/dotc/reporting/diagnostic/messages.scala

@@ -1260,26 +1260,26 @@ object messages {
            |""".stripMargin
   }
 
-  case class OverloadedOrRecursiveMethodNeedsResultType(tree: Names.TermName)(implicit ctx: Context)
+  case class OverloadedOrRecursiveMethodNeedsResultType(method: Names.TermName)(implicit ctx: Context)
   extends Message(OverloadedOrRecursiveMethodNeedsResultTypeID) {
     val kind = "Syntax"
-    val msg = hl"""overloaded or recursive method ${tree} needs return type"""
+    val msg = hl"""overloaded or recursive method ${method} needs return type"""
     val explanation =
-      hl"""Case 1: ${tree} is overloaded
-          |If there are multiple methods named `${tree.name}` and at least one definition of
+      hl"""Case 1: ${method} is overloaded
+          |If there are multiple methods named `${method}` and at least one definition of
           |it calls another, you need to specify the calling method's return type.
           |
-          |Case 2: ${tree} is recursive
-          |If `${tree.name}` calls itself on any path, you need to specify its return type.
+          |Case 2: ${method} is recursive
+          |If `${method}` calls itself on any path, you need to specify its return type.
           |""".stripMargin
   }
 
-  case class RecursiveValueNeedsResultType(tree: Names.TermName)(implicit ctx: Context)
+  case class RecursiveValueNeedsResultType(value: Names.TermName)(implicit ctx: Context)
   extends Message(RecursiveValueNeedsResultTypeID) {
     val kind = "Syntax"
-    val msg = hl"""recursive value ${tree.name} needs type"""
+    val msg = hl"""recursive value ${value} needs type"""
     val explanation =
-      hl"""The definition of `${tree.name}` is recursive and you need to specify its type.
+      hl"""The definition of `${value}` is recursive and you need to specify its type.
           |""".stripMargin
   }