From ced74110348d550c3870ac76ef067b151e97b237 Mon Sep 17 00:00:00 2001
From: Eugene Burmako <xeno.by@gmail.com>
Date: Thu, 13 Dec 2012 00:46:06 +0100
Subject: [PATCH] the scanner is now less eager about deprecations

When healing braces it isn't very useful to report deprecation warnings,
especially since this process is just simple context-free skimming, which
can't know about what positions can accept what identifiers.

Backport from https://github.com/scala/scala/pull/1807.
Original commit is https://github.com/scala/scala/commit/e5d34d70499504e085ddf957c1c818ffb63f4e8d.
---
 .../scala/tools/nsc/ast/parser/Scanners.scala     | 11 ++++++++++-
 .../neg/macro-false-deprecation-warning.check     |  4 ++++
 .../neg/macro-false-deprecation-warning.flags     |  1 +
 .../Impls_Macros_1.scala                          | 15 +++++++++++++++
 4 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 test/files/neg/macro-false-deprecation-warning.check
 create mode 100644 test/files/neg/macro-false-deprecation-warning.flags
 create mode 100644 test/files/neg/macro-false-deprecation-warning/Impls_Macros_1.scala

diff --git a/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala b/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
index 4f564c5d0b79..00d4d57b3464 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Scanners.scala
@@ -113,6 +113,11 @@ trait Scanners extends ScannersCommon {
       cbuf.append(c)
     }
 
+    /** Determines whether this scanner should emit identifier deprecation warnings,
+     *  e.g. when seeing `macro` or `then`, which are planned to become keywords in future versions of Scala.
+     */
+    protected def emitIdentifierDeprecationWarnings = true
+
     /** Clear buffer and set name and token */
     private def finishNamed(idtoken: Int = IDENTIFIER) {
       name = newTermName(cbuf.toString)
@@ -122,7 +127,7 @@ trait Scanners extends ScannersCommon {
         val idx = name.start - kwOffset
         if (idx >= 0 && idx < kwArray.length) {
           token = kwArray(idx)
-          if (token == IDENTIFIER && allowIdent != name)
+          if (token == IDENTIFIER && allowIdent != name && emitIdentifierDeprecationWarnings)
             deprecationWarning(name+" is now a reserved word; usage as an identifier is deprecated")
         }
       }
@@ -1488,6 +1493,10 @@ trait Scanners extends ScannersCommon {
     def improves(patches1: List[BracePatch]): Boolean =
       imbalanceMeasure > new ParensAnalyzer(unit, patches1).imbalanceMeasure
 
+    // don't emit deprecation warnings about identifiers like `macro` or `then`
+    // when skimming through the source file trying to heal braces
+    override def emitIdentifierDeprecationWarnings = false
+
     override def error(offset: Int, msg: String) {}
   }
 }
diff --git a/test/files/neg/macro-false-deprecation-warning.check b/test/files/neg/macro-false-deprecation-warning.check
new file mode 100644
index 000000000000..7d56505ec440
--- /dev/null
+++ b/test/files/neg/macro-false-deprecation-warning.check
@@ -0,0 +1,4 @@
+Impls_Macros_1.scala:5: error: illegal start of simple expression
+}
+^
+one error found
diff --git a/test/files/neg/macro-false-deprecation-warning.flags b/test/files/neg/macro-false-deprecation-warning.flags
new file mode 100644
index 000000000000..cd66464f2f63
--- /dev/null
+++ b/test/files/neg/macro-false-deprecation-warning.flags
@@ -0,0 +1 @@
+-language:experimental.macros
\ No newline at end of file
diff --git a/test/files/neg/macro-false-deprecation-warning/Impls_Macros_1.scala b/test/files/neg/macro-false-deprecation-warning/Impls_Macros_1.scala
new file mode 100644
index 000000000000..6dc2ea114b99
--- /dev/null
+++ b/test/files/neg/macro-false-deprecation-warning/Impls_Macros_1.scala
@@ -0,0 +1,15 @@
+import scala.reflect.macros.Context
+
+object Helper {
+  def unapplySeq[T](x: List[T]): Option[Seq[T]] =
+}
+
+object Macros {
+  def impl[T: c.WeakTypeTag](c: Context)(x: c.Expr[List[T]]) = {
+    c.universe.reify(Helper.unapplySeq(x.splice))
+  }
+
+  object UnapplyMacro {
+    def unapplySeq[T](x: List[T]): Option[Seq[T]] = macro impl[T]
+  }
+}