SAM conversion can be disabled using `-Xsource:2.11`

For completeness, `-Xsource:2.11 -Xexperimental` does enable it.

7 files changed, 15 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index ba6a9e20ea..35cfc644ab 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -2752,6 +2752,8 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
     def inferSamType(fun: Tree, pt: Type, mode: Mode): SAMFunction = {
       val sam =
         if (fun.isInstanceOf[Function] && !isFunctionType(pt)) {
+          // TODO: can we ensure there's always a SAMFunction attachment, instead of looking up the sam again???
+          // seems like overloading complicates things?
           val sam = samOf(pt)
           if (samMatchesFunctionBasedOnArity(sam, fun.asInstanceOf[Function].vparams)) sam
           else NoSymbol
diff --git a/src/reflect/scala/reflect/internal/Definitions.scala b/src/reflect/scala/reflect/internal/Definitions.scala
index 28f6afee39..72c56def80 100644
--- a/src/reflect/scala/reflect/internal/Definitions.scala
+++ b/src/reflect/scala/reflect/internal/Definitions.scala
@@ -829,13 +829,15 @@ trait Definitions extends api.StandardDefinitions {
       (sym eq PartialFunctionClass) || (sym eq AbstractPartialFunctionClass)
     }
 
+    private[this] val doSam = settings.isScala212 || (settings.isScala211 && settings.Xexperimental)
+
     /** The single abstract method declared by type `tp` (or `NoSymbol` if it cannot be found).
      *
      * The method must be monomorphic and have exactly one parameter list.
      * The class defining the method is a supertype of `tp` that
      * has a public no-arg primary constructor.
      */
-    def samOf(tp: Type): Symbol = {
+    def samOf(tp: Type): Symbol = if (!doSam) NoSymbol else {
       // look at erased type because we (only) care about what ends up in bytecode
       // (e.g., an alias type or intersection type is fine as long as the intersection dominator compiles to an interface)
       val tpSym = erasure.javaErasure(tp).typeSymbol
diff --git a/src/reflect/scala/reflect/internal/settings/MutableSettings.scala b/src/reflect/scala/reflect/internal/settings/MutableSettings.scala
index 38893d8db3..e75b3dff3d 100644
--- a/src/reflect/scala/reflect/internal/settings/MutableSettings.scala
+++ b/src/reflect/scala/reflect/internal/settings/MutableSettings.scala
@@ -58,6 +58,7 @@ abstract class MutableSettings extends AbsSettings {
   def maxClassfileName: IntSetting
 
   def isScala211: Boolean
+  def isScala212: Boolean
 }
 
 object MutableSettings {
diff --git a/src/reflect/scala/reflect/runtime/Settings.scala b/src/reflect/scala/reflect/runtime/Settings.scala
index 27d574b1de..b1d7fde1b4 100644
--- a/src/reflect/scala/reflect/runtime/Settings.scala
+++ b/src/reflect/scala/reflect/runtime/Settings.scala
@@ -51,4 +51,5 @@ private[reflect] class Settings extends MutableSettings {
   val Yrecursion        = new IntSetting(0)
   val maxClassfileName  = new IntSetting(255)
   def isScala211        = true
+  def isScala212        = true
 }
diff --git a/test/files/neg/sammy_disabled.check b/test/files/neg/sammy_disabled.check
new file mode 100644
index 0000000000..66db9dd5f2
--- /dev/null
+++ b/test/files/neg/sammy_disabled.check
@@ -0,0 +1,4 @@
+sammy_disabled.scala:3: error: missing parameter type
+class C { val f: F = x => "a" }
+                     ^
+one error found
diff --git a/test/files/neg/sammy_disabled.flags b/test/files/neg/sammy_disabled.flags
new file mode 100644
index 0000000000..cf42e9f940
--- /dev/null
+++ b/test/files/neg/sammy_disabled.flags
@@ -0,0 +1 @@
+-Xsource:2.11
diff --git a/test/files/neg/sammy_disabled.scala b/test/files/neg/sammy_disabled.scala
new file mode 100644
index 0000000000..12000a3e12
--- /dev/null
+++ b/test/files/neg/sammy_disabled.scala
@@ -0,0 +1,3 @@
+trait F { def apply(x: Int): String }
+
+class C { val f: F = x => "a" }