Merge pull request #694 from retronym/ticket/4831-2

SI-4831 Fix ambiguous import detection for renamed imports.

4 files changed, 32 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 2a1af2755f..fec5063bd0 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -4575,17 +4575,17 @@ trait Typers extends Modes with Adaptations with Tags {
               qual = atPos(tree.pos.focusStart)(gen.mkAttributedQualifier(pre))
           } else {
             if (impSym.exists) {
-              var impSym1 = NoSymbol
+              var impSym1: Symbol = NoSymbol
               var imports1 = imports.tail
               def ambiguousImport() = {
-                if (!(imports.head.qual.tpe =:= imports1.head.qual.tpe))
+                if (!(imports.head.qual.tpe =:= imports1.head.qual.tpe && impSym == impSym1))
                   ambiguousError(
                     "it is imported twice in the same scope by\n"+imports.head +  "\nand "+imports1.head)
               }
               while (errorContainer == null && !imports1.isEmpty &&
                      (!imports.head.isExplicitImport(name) ||
                       imports1.head.depth == imports.head.depth)) {
-                var impSym1 = imports1.head.importedSymbol(name)
+                impSym1 = imports1.head.importedSymbol(name)
                 if (reallyExists(impSym1)) {
                   if (imports1.head.isExplicitImport(name)) {
                     if (imports.head.isExplicitImport(name) ||
diff --git a/test/files/neg/t4831.check b/test/files/neg/t4831.check
new file mode 100644
index 0000000000..3b8b836f05
--- /dev/null
+++ b/test/files/neg/t4831.check
@@ -0,0 +1,7 @@
+t4831.scala:10: error: reference to b is ambiguous;
+it is imported twice in the same scope by
+import O.b
+and import O.{a=>b}
+  println(b)
+          ^
+one error found
diff --git a/test/files/neg/t4831.scala b/test/files/neg/t4831.scala
new file mode 100644
index 0000000000..82346ec57d
--- /dev/null
+++ b/test/files/neg/t4831.scala
@@ -0,0 +1,11 @@
+object O {
+  val a = 0
+  val b = 1
+}
+
+import O.{a => b}
+import O.b
+
+object test {
+  println(b)
+}
diff --git a/test/files/pos/t4831.scala b/test/files/pos/t4831.scala
new file mode 100644
index 0000000000..48002106e6
--- /dev/null
+++ b/test/files/pos/t4831.scala
@@ -0,0 +1,11 @@
+object O {
+  val a = 0
+}
+
+
+object test {
+  val O1: O.type = O
+  val O2: O.type = O
+  import O1.a, O2.a
+  println(a)
+}