Merge pull request #1324 from Friendseeker/this-context-dependent

Avoid spurious recompilations when unrelated constructor with default argument changes

internal/compiler-bridge/src/main/scala/xsbt/ClassName.scala

@@ -58,6 +58,9 @@ trait ClassName extends Compat {
   protected def constructorNameAsString(cls: Symbol): String =
     cls.fullName(';') ++ ";init;"
 
+  protected def constructorNameAsString(cls: Symbol, index: String): String =
+    cls.fullName(';') ++ s";init;default;$index"
+
   /**
    * Mangle a JVM symbol name in a format better suited for internal uses by sbt.
    */

internal/compiler-bridge/src/main/scala/xsbt/ExtractAPI.scala

@@ -327,7 +327,7 @@ class ExtractAPI[GlobalType <: Global](
         case returnType =>
           val retType = processType(in, dropConst(returnType))
           xsbti.api.Def.of(
-            simpleName(s),
+            simpleNameForMethod(s),
             getAccess(s),
             getModifiers(s),
             annotations(in, s),
@@ -827,9 +827,22 @@ class ExtractAPI[GlobalType <: Global](
   }
 
   private def simpleName(s: Symbol): String = {
-    val n = s.unexpandedName
-    val n2 = if (n == nme.CONSTRUCTOR) constructorNameAsString(s.enclClass) else n.decode.toString
-    n2.trim
+    s.unexpandedName.decode.trim
+  }
+
+  private def simpleNameForMethod(s: Symbol): String = {
+    val name = s.unexpandedName
+    val untrimmedName = if (name == nme.CONSTRUCTOR)
+      constructorNameAsString(s.enclClass)
+    else {
+      val decoded = name.decode
+      val constructorWithDefaultArgument = "<init>\\$default\\$(\\d+)".r
+      decoded match {
+        case constructorWithDefaultArgument(index) => constructorNameAsString(s.enclClass, index)
+        case _                                     => decoded
+      }
+    }
+    untrimmedName.trim
   }
 
   private def staticAnnotations(annotations: List[AnnotationInfo]): List[AnnotationInfo] =

zinc/src/sbt-test/source-dependencies/constructors-unrelated-2/A.scala

@@ -0,0 +1,4 @@
+class A {
+  var z = B.z // introduce a member ref dependency to B
+  var c: C = new C(1)
+}

zinc/src/sbt-test/source-dependencies/constructors-unrelated-2/B.scala

@@ -0,0 +1,7 @@
+class B(val z: Int) {
+  def this(x: Int, y: Int = 2) = this(x + y)
+}
+
+object B {
+  val z = 1
+}

zinc/src/sbt-test/source-dependencies/constructors-unrelated-2/C.scala

@@ -0,0 +1,3 @@
+class C(z: String) {
+  def this(x: Int, y: Int = 2) = this("")
+}

zinc/src/sbt-test/source-dependencies/constructors-unrelated-2/changes/B.scala

@@ -0,0 +1,7 @@
+class B(val z: Int) {
+  def this(x: Int, y: String = "") = this(x + y.toInt)
+}
+
+object B {
+  val z = 1
+}

zinc/src/sbt-test/source-dependencies/constructors-unrelated-2/changes/C.scala

@@ -0,0 +1,3 @@
+class C(z: String) {
+  def this(x: Boolean, y: Int = 2) = this("")
+}

zinc/src/sbt-test/source-dependencies/constructors-unrelated-2/test

@@ -0,0 +1,8 @@
+> compile
+$ copy-file changes/B.scala B.scala
+# Second compilation round, there should be no third round (we don't need to recompile A.scala)
+> compile
+# Check that there were only two rounds of compilation
+> checkIterations 2
+$ copy-file changes/C.scala C.scala
+-> compile