SI-9383 Improved unused import warning

Previously, implicit search would mark every import
it touched as a lookup.

Instead, let subsequent type check perform the lookup.

1 files changed, 19 insertions, 19 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
index 7c931600e5..0cacca055f 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
@@ -24,7 +24,8 @@ trait Contexts { self: Analyzer =>
 
   object NoContext
     extends Context(EmptyTree, NoSymbol, EmptyScope, NoCompilationUnit,
-                    null) { // We can't pass the uninitialized `this`. Instead, we treat null specially in `Context#outer`
+      // We can't pass the uninitialized `this`. Instead, we treat null specially in `Context#outer`
+                    null) {
     enclClass  = this
     enclMethod = this
 
@@ -48,12 +49,11 @@ trait Contexts { self: Analyzer =>
   def ambiguousDefnAndImport(owner: Symbol, imp: ImportInfo) =
     LookupAmbiguous(s"it is both defined in $owner and imported subsequently by \n$imp")
 
-  private lazy val startContext = {
-    NoContext.make(
+  private lazy val startContext = NoContext.make(
     Template(List(), noSelfType, List()) setSymbol global.NoSymbol setType global.NoType,
     rootMirror.RootClass,
-    rootMirror.RootClass.info.decls)
-  }
+    rootMirror.RootClass.info.decls
+  )
 
   private lazy val allUsedSelectors =
     mutable.Map[ImportInfo, Set[ImportSelector]]() withDefaultValue Set()
@@ -947,10 +947,10 @@ trait Contexts { self: Analyzer =>
      *  if any such symbol is accessible from this context.
      */
     def importedAccessibleSymbol(imp: ImportInfo, name: Name): Symbol =
-      importedAccessibleSymbol(imp, name, requireExplicit = false)
+      importedAccessibleSymbol(imp, name, requireExplicit = false, record = false)
 
-    private def importedAccessibleSymbol(imp: ImportInfo, name: Name, requireExplicit: Boolean): Symbol =
-      imp.importedSymbol(name, requireExplicit) filter (s => isAccessible(s, imp.qual.tpe, superAccess = false))
+    private def importedAccessibleSymbol(imp: ImportInfo, name: Name, requireExplicit: Boolean, record: Boolean): Symbol =
+      imp.importedSymbol(name, requireExplicit, record) filter (s => isAccessible(s, imp.qual.tpe, superAccess = false))
 
     private def requiresQualifier(s: Symbol) = (
          s.owner.isClass
@@ -1057,7 +1057,7 @@ trait Contexts { self: Analyzer =>
       def imp2Explicit   = imp2 isExplicitImport name
 
       def lookupImport(imp: ImportInfo, requireExplicit: Boolean) =
-        importedAccessibleSymbol(imp, name, requireExplicit) filter qualifies
+        importedAccessibleSymbol(imp, name, requireExplicit, record = true) filter qualifies
 
       // Java: A single-type-import declaration d in a compilation unit c of package p
       // that imports a type named n shadows, throughout c, the declarations of:
@@ -1353,7 +1353,6 @@ trait Contexts { self: Analyzer =>
     protected def handleError(pos: Position, msg: String): Unit = onTreeCheckerError(pos, msg)
   }
 
-
   class ImportInfo(val tree: Import, val depth: Int) {
     def pos = tree.pos
     def posOf(sel: ImportSelector) = tree.pos withPoint sel.namePos
@@ -1369,19 +1368,20 @@ trait Contexts { self: Analyzer =>
     def isExplicitImport(name: Name): Boolean =
       tree.selectors exists (_.rename == name.toTermName)
 
-    /** The symbol with name `name` imported from import clause `tree`.
-     */
-    def importedSymbol(name: Name): Symbol = importedSymbol(name, requireExplicit = false)
+    /** The symbol with name `name` imported from import clause `tree`. */
+    def importedSymbol(name: Name): Symbol = importedSymbol(name, requireExplicit = false, record = true)
 
-    private def recordUsage(sel: ImportSelector, result: Symbol) {
-      def posstr = pos.source.file.name + ":" + posOf(sel).line
-      def resstr = if (tree.symbol.hasCompleteInfo) s"(qual=$qual, $result)" else s"(expr=${tree.expr}, ${result.fullLocationString})"
-      debuglog(s"In $this at $posstr, selector '${selectorString(sel)}' resolved to $resstr")
+    private def recordUsage(sel: ImportSelector, result: Symbol): Unit = {
+      debuglog(s"In $this at ${ pos.source.file.name }:${ posOf(sel).line }, selector '${ selectorString(sel)
+        }' resolved to ${
+          if (tree.symbol.hasCompleteInfo) s"(qual=$qual, $result)"
+          else s"(expr=${tree.expr}, ${result.fullLocationString})"
+        }")
       allUsedSelectors(this) += sel
     }
 
     /** If requireExplicit is true, wildcard imports are not considered. */
-    def importedSymbol(name: Name, requireExplicit: Boolean): Symbol = {
+    def importedSymbol(name: Name, requireExplicit: Boolean, record: Boolean): Symbol = {
       var result: Symbol = NoSymbol
       var renamed = false
       var selectors = tree.selectors
@@ -1398,7 +1398,7 @@ trait Contexts { self: Analyzer =>
         if (result == NoSymbol)
           selectors = selectors.tail
       }
-      if (settings.warnUnusedImport && selectors.nonEmpty && result != NoSymbol && pos != NoPosition)
+      if (record && settings.warnUnusedImport && selectors.nonEmpty && result != NoSymbol && pos != NoPosition)
         recordUsage(current, result)
 
       // Harden against the fallout from bugs like SI-6745