Merge pull request #1623 from paulp/merge-2.10.x

Merge 2.10.0-wip/.x into master

6 files changed, 91 insertions, 18 deletions

diff --git a/src/reflect/scala/reflect/internal/Definitions.scala b/src/reflect/scala/reflect/internal/Definitions.scala
index ed45010091..8e406b6f62 100644
--- a/src/reflect/scala/reflect/internal/Definitions.scala
+++ b/src/reflect/scala/reflect/internal/Definitions.scala
@@ -981,6 +981,7 @@ trait Definitions extends api.StandardDefinitions {
     lazy val BeanPropertyAttr           = requiredClass[scala.beans.BeanProperty]
     lazy val BooleanBeanPropertyAttr    = requiredClass[scala.beans.BooleanBeanProperty]
     lazy val CloneableAttr              = requiredClass[scala.annotation.cloneable]
+    lazy val CompileTimeOnlyAttr        = getClassIfDefined("scala.reflect.macros.compileTimeOnly")
     lazy val DeprecatedAttr             = requiredClass[scala.deprecated]
     lazy val DeprecatedNameAttr         = requiredClass[scala.deprecatedName]
     lazy val DeprecatedInheritanceAttr  = requiredClass[scala.deprecatedInheritance]
diff --git a/src/reflect/scala/reflect/internal/SymbolTable.scala b/src/reflect/scala/reflect/internal/SymbolTable.scala
index 68b5794b59..fb1bf9ed9d 100644
--- a/src/reflect/scala/reflect/internal/SymbolTable.scala
+++ b/src/reflect/scala/reflect/internal/SymbolTable.scala
@@ -6,6 +6,7 @@
 package scala.reflect
 package internal
 
+import scala.annotation.elidable
 import scala.collection.{ mutable, immutable }
 import util._
 
@@ -108,6 +109,11 @@ abstract class SymbolTable extends macros.Universe
     val global: SymbolTable.this.type = SymbolTable.this
   } with util.TraceSymbolActivity
 
+  /** Check that the executing thread is the compiler thread. No-op here,
+   *  overridden in interactive.Global. */
+  @elidable(elidable.WARNING)
+  def assertCorrectThread() {}
+
   /** Are we compiling for Java SE? */
   // def forJVM: Boolean
 
diff --git a/src/reflect/scala/reflect/internal/Symbols.scala b/src/reflect/scala/reflect/internal/Symbols.scala
index 30e5ecd643..0ad0275fba 100644
--- a/src/reflect/scala/reflect/internal/Symbols.scala
+++ b/src/reflect/scala/reflect/internal/Symbols.scala
@@ -740,6 +740,9 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
     def elisionLevel        = getAnnotation(ElidableMethodClass) flatMap { _.intArg(0) }
     def implicitNotFoundMsg = getAnnotation(ImplicitNotFoundClass) flatMap { _.stringArg(0) }
 
+    def isCompileTimeOnly       = hasAnnotation(CompileTimeOnlyAttr)
+    def compileTimeOnlyMessage  = getAnnotation(CompileTimeOnlyAttr) flatMap (_ stringArg 0)
+
     /** Is this symbol an accessor method for outer? */
     final def isOuterAccessor = {
       hasFlag(STABLE | ARTIFACT) &&
@@ -1259,6 +1262,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
         }
         val current = phase
         try {
+          assertCorrectThread()
           phase = phaseOf(infos.validFrom)
           tp.complete(this)
         } finally {
@@ -1329,6 +1333,7 @@ trait Symbols extends api.Symbols { self: SymbolTable =>
           infos = infos.prev
 
         if (validTo < curPeriod) {
+          assertCorrectThread()
           // adapt any infos that come from previous runs
           val current = phase
           try {
diff --git a/src/reflect/scala/reflect/internal/TreeInfo.scala b/src/reflect/scala/reflect/internal/TreeInfo.scala
index ddfc1f2af0..7ae7cf1821 100644
--- a/src/reflect/scala/reflect/internal/TreeInfo.scala
+++ b/src/reflect/scala/reflect/internal/TreeInfo.scala
@@ -287,6 +287,68 @@ abstract class TreeInfo {
     isSelfConstrCall(tree1) || isSuperConstrCall(tree1)
   }
 
+  /**
+   * Does this tree represent an irrefutable pattern match
+   * in the position `for { <tree> <- expr }` based only
+   * on information at the `parser` phase? To qualify, there
+   * may be no subtree that will be interpreted as a
+   * Stable Identifier Pattern.
+   *
+   * For instance:
+   *
+   * {{{
+   * foo @ (bar, (baz, quux))
+   * }}}
+   *
+   * is a variable pattern; if the structure matches,
+   * then the remainder is inevitable.
+   *
+   * The following are not variable patterns.
+   *
+   * {{{
+   *   foo @ (bar, (`baz`, quux)) // back quoted ident, not at top level
+   *   foo @ (bar, Quux)          // UpperCase ident, not at top level
+   * }}}
+   *
+   * If the pattern is a simple identifier, it is always
+   * a variable pattern. For example, the following
+   * introduce new bindings:
+   *
+   * {{{
+   * for { X <- xs } yield X
+   * for { `backquoted` <- xs } yield `backquoted`
+   * }}}
+   *
+   * Note that this differs from a case clause:
+   *
+   * {{{
+   *   object X
+   *   scrut match {
+   *      case X =>  // case _ if scrut == X
+   *   }
+   * }}}
+   *
+   * Background: [[https://groups.google.com/d/msg/scala-internals/qwa_XOw_7Ks/IktkeTBYqg0J]]
+   *
+   */
+  def isVarPatternDeep(tree: Tree): Boolean = {
+    def isVarPatternDeep0(tree: Tree): Boolean = {
+      tree match {
+        case Bind(name, pat)  => isVarPatternDeep0(pat)
+        case Ident(name)      => isVarPattern(tree)
+        case Apply(sel, args) =>
+          (    isReferenceToScalaMember(sel, TupleClass(args.size).name.toTermName)
+            && (args forall isVarPatternDeep0)
+            )
+        case _                => false
+      }
+    }
+    tree match {
+      case Ident(name) => true
+      case _           => isVarPatternDeep0(tree)
+    }
+  }
+
   /** Is tree a variable pattern? */
   def isVarPattern(pat: Tree): Boolean = pat match {
     case x: Ident           => !x.isBackquoted && nme.isVariableName(x.name)
@@ -372,24 +434,6 @@ abstract class TreeInfo {
     case _                                       => false
   }
 
-  /** Is this tree comprised of nothing but identifiers,
-   *  but possibly in bindings or tuples? For instance
-   *
-   *    foo @ (bar, (baz, quux))
-   *
-   *  is a variable pattern; if the structure matches,
-   *  then the remainder is inevitable.
-   */
-  def isVariablePattern(tree: Tree): Boolean = tree match {
-    case Bind(name, pat)  => isVariablePattern(pat)
-    case Ident(name)      => true
-    case Apply(sel, args) =>
-      (    isReferenceToScalaMember(sel, TupleClass(args.size).name.toTermName)
-        && (args forall isVariablePattern)
-      )
-    case _ => false
-  }
-
   /** Is this argument node of the form <expr> : _* ?
    */
   def isWildcardStarArg(tree: Tree): Boolean = tree match {
diff --git a/src/reflect/scala/reflect/internal/Types.scala b/src/reflect/scala/reflect/internal/Types.scala
index 02cdac4046..42a9d9e456 100644
--- a/src/reflect/scala/reflect/internal/Types.scala
+++ b/src/reflect/scala/reflect/internal/Types.scala
@@ -143,6 +143,7 @@ trait Types extends api.Types { self: SymbolTable =>
     /** Undo all changes to constraints to type variables upto `limit`. */
     //OPT this method is public so we can do `manual inlining`
     def undoTo(limit: UndoPairs) {
+      assertCorrectThread()
       while ((log ne limit) && log.nonEmpty) {
         val (tv, constr) = log.head
         tv.constr = constr
diff --git a/src/reflect/scala/reflect/macros/compileTimeOnly.scala b/src/reflect/scala/reflect/macros/compileTimeOnly.scala
new file mode 100644
index 0000000000..5a3a352a53
--- /dev/null
+++ b/src/reflect/scala/reflect/macros/compileTimeOnly.scala
@@ -0,0 +1,16 @@
+package scala.reflect
+package macros
+
+import scala.annotation.meta._
+
+/**
+ * An annotation that designates a member should not be referred to after
+ * type checking (which includes macro expansion); it must only be used in
+ * the arguments of some other macro that will eliminate it from the AST.
+ *
+ * @param  message the error message to print during compilation if a reference remains
+ *                 after type checking
+ * @since  2.10.1
+ */
+@getter @setter @beanGetter @beanSetter
+final class compileTimeOnly(message: String) extends scala.annotation.StaticAnnotation