From c9682121b6ed33fe67dad445ebc665d13b369bbb Mon Sep 17 00:00:00 2001
From: Som Snytt <som.snytt@gmail.com>
Date: Tue, 20 Sep 2016 23:42:38 -0700
Subject: SI-9839 Avoid crash in macro import selector pos

Ignore bad name pos.

Also delete unused val. Thanks, `-Ywarn-unused`!
---
 src/compiler/scala/tools/nsc/typechecker/Contexts.scala   | 10 ++++------
 test/files/neg/warn-unused-imports.check                  |  5 ++++-
 test/files/neg/warn-unused-imports/sample_1.scala         | 15 +++++++++++++++
 .../neg/warn-unused-imports/warn-unused-imports_2.scala   |  4 ++++
 4 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
index 7a3b8d2ab6..67168917e1 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
@@ -64,10 +64,8 @@ trait Contexts { self: Analyzer =>
     for (imps <- allImportInfos.remove(unit)) {
       for (imp <- imps.distinct.reverse) {
         val used = allUsedSelectors(imp)
-
-        imp.tree.selectors filterNot (s => isMaskImport(s) || used(s)) foreach { sel =>
-          reporter.warning(imp posOf sel, "Unused import")
-        }
+        for (sel <- imp.tree.selectors if !isMaskImport(sel) && !used(sel))
+          reporter.warning(imp.posOf(sel), "Unused import")
       }
       allUsedSelectors --= imps
     }
@@ -825,7 +823,6 @@ trait Contexts { self: Analyzer =>
     private def collectImplicitImports(imp: ImportInfo): List[ImplicitInfo] = {
       val qual = imp.qual
 
-      val qualSym = qual.tpe.typeSymbol
       val pre = qual.tpe
       def collect(sels: List[ImportSelector]): List[ImplicitInfo] = sels match {
         case List() =>
@@ -1412,7 +1409,8 @@ trait Contexts { self: Analyzer =>
 
   class ImportInfo(val tree: Import, val depth: Int) {
     def pos = tree.pos
-    def posOf(sel: ImportSelector) = tree.pos withPoint sel.namePos
+    def posOf(sel: ImportSelector) =
+      if (sel.namePos >= 0) tree.pos withPoint sel.namePos else tree.pos
 
     /** The prefix expression */
     def qual: Tree = tree.symbol.info match {
diff --git a/test/files/neg/warn-unused-imports.check b/test/files/neg/warn-unused-imports.check
index 0a53d7a9cd..29d73a6264 100644
--- a/test/files/neg/warn-unused-imports.check
+++ b/test/files/neg/warn-unused-imports.check
@@ -51,5 +51,8 @@ warn-unused-imports_2.scala:149: warning: Unused import
 warn-unused-imports_2.scala:150: warning: Unused import
     import p1.A                         // warn
               ^
-16 warnings found
+warn-unused-imports_2.scala:158: warning: Unused import
+  def x = Macro.f  // warn, not crash
+                ^
+17 warnings found
 one error found
diff --git a/test/files/neg/warn-unused-imports/sample_1.scala b/test/files/neg/warn-unused-imports/sample_1.scala
index d2f86239db..eea4d0eb4c 100644
--- a/test/files/neg/warn-unused-imports/sample_1.scala
+++ b/test/files/neg/warn-unused-imports/sample_1.scala
@@ -15,3 +15,18 @@ object Sample {
   def f(x: X) = ???
   def g(y: Y) = ???
 }
+
+import scala.language.experimental.macros
+import scala.reflect.macros.blackbox.Context
+ 
+object Macro {
+  def f: Int = macro fImpl
+  def fImpl(c: Context): c.Tree = {
+    import c.universe._
+ 
+    q"""
+     import scala.util.Random
+     42 // TODO randomize
+    """
+  }
+}
diff --git a/test/files/neg/warn-unused-imports/warn-unused-imports_2.scala b/test/files/neg/warn-unused-imports/warn-unused-imports_2.scala
index 56ad3393a1..58fe0131d9 100644
--- a/test/files/neg/warn-unused-imports/warn-unused-imports_2.scala
+++ b/test/files/neg/warn-unused-imports/warn-unused-imports_2.scala
@@ -153,3 +153,7 @@ trait Outsiders {
     //Future("abc".bippy)
   }
 }
+
+class MacroClient {
+  def x = Macro.f  // warn, not crash
+}
-- 
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