SI-5702 Pattern parser halts on star

In patterns, the parser halts when it sees stars.
This means it does not handle infix notation for a case class
named "*".  This patch uses lookahead to decide whether to parse
'_' '*' as a sequence pattern or as the start of infix.
(For both normal and error cases, the tokens are always consumed
immediately.) Error messages are improved for _* (as a help to learners)
and slightly improved recovery helps the parse continue.
The entry point for XML patterns is now distinct; otherwise,
the change is local to pattern3-simplepattern; the entry point
for simplepattern() is unchanged because it is commented
"hook for IDE."

16 files changed, 191 insertions, 26 deletions

diff --git a/test/files/neg/t1878-typer.check b/test/files/neg/t1878-typer.check
new file mode 100644
index 0000000000..e3a20d0be7
--- /dev/null
+++ b/test/files/neg/t1878-typer.check
@@ -0,0 +1,4 @@
+t1878-typer.scala:4: error: _* may only come last
+    case <p> { _* } </p> =>
+                ^
+one error found
diff --git a/test/files/neg/t1878-typer.scala b/test/files/neg/t1878-typer.scala
new file mode 100644
index 0000000000..1eb0cb7dff
--- /dev/null
+++ b/test/files/neg/t1878-typer.scala
@@ -0,0 +1,6 @@
+object Test extends App {
+  // illegal - bug #1764
+  null match {
+    case <p> { _* } </p> =>
+  }
+}
diff --git a/test/files/neg/t1878.check b/test/files/neg/t1878.check
index b47367e12c..ac2071c3d8 100644
--- a/test/files/neg/t1878.check
+++ b/test/files/neg/t1878.check
@@ -1,21 +1,7 @@
-t1878.scala:3: error: _* may only come last
+t1878.scala:3: error: bad use of _* (a sequence pattern must be the last pattern)
   val err1 = "" match { case Seq(f @ _*, ',') => f }
-                                 ^
-t1878.scala:3: error: scrutinee is incompatible with pattern type;
- found   : Seq[A]
- required: String
-  val err1 = "" match { case Seq(f @ _*, ',') => f }
-                                ^
-t1878.scala:3: error: not found: value f
-  val err1 = "" match { case Seq(f @ _*, ',') => f }
-                                                 ^
-t1878.scala:3: error: value _2 is not a member of object Seq
-  val err1 = "" match { case Seq(f @ _*, ',') => f }
-             ^
-t1878.scala:9: error: _* may only come last
+                                       ^
+t1878.scala:9: error: bad use of _* (a sequence pattern must be the last pattern)
   val List(List(_*, arg2), _) = List(List(1,2,3), List(4,5,6))
-                 ^
-t1878.scala:13: error: _* may only come last
-    case <p> { _* } </p> =>
-                ^
-6 errors found
+                  ^
+two errors found
diff --git a/test/files/neg/t1878.scala b/test/files/neg/t1878.scala
index 5278fbb7bd..99fee48a96 100644
--- a/test/files/neg/t1878.scala
+++ b/test/files/neg/t1878.scala
@@ -8,8 +8,10 @@ object Test extends App {
   // illegal
   val List(List(_*, arg2), _) = List(List(1,2,3), List(4,5,6))
   
+  /* see t1878-typer.scala
   // illegal - bug #1764
   null match {
     case <p> { _* } </p> =>
   }
+  */
 }
diff --git a/test/files/neg/t3189.check b/test/files/neg/t3189.check
new file mode 100644
index 0000000000..3913c526a2
--- /dev/null
+++ b/test/files/neg/t3189.check
@@ -0,0 +1,4 @@
+t3189.scala:2: error: use _* to match a sequence
+  val Array(a,b*) = ("": Any)
+                ^
+one error found
diff --git a/test/pending/neg/t3189.scala b/test/files/neg/t3189.scala
index 4ea4bb7581..4ea4bb7581 100644
--- a/test/pending/neg/t3189.scala
+++ b/test/files/neg/t3189.scala
diff --git a/test/files/neg/t5702-neg-bad-and-wild.check b/test/files/neg/t5702-neg-bad-and-wild.check
new file mode 100644
index 0000000000..eae81ad5f2
--- /dev/null
+++ b/test/files/neg/t5702-neg-bad-and-wild.check
@@ -0,0 +1,28 @@
+t5702-neg-bad-and-wild.scala:10: error: bad use of _* (a sequence pattern must be the last pattern)
+      case List(1, _*,) => // bad use of _* (a sequence pattern must be the last pattern)
+                     ^
+t5702-neg-bad-and-wild.scala:10: error: illegal start of simple pattern
+      case List(1, _*,) => // bad use of _* (a sequence pattern must be the last pattern)
+                      ^
+t5702-neg-bad-and-wild.scala:12: error: illegal start of simple pattern
+      case List(1, _*3,) => // illegal start of simple pattern
+                       ^
+t5702-neg-bad-and-wild.scala:14: error: use _* to match a sequence
+      case List(1, x*) => // use _* to match a sequence
+                     ^
+t5702-neg-bad-and-wild.scala:15: error: trailing * is not a valid pattern
+      case List(x*, 1) => // trailing * is not a valid pattern
+                  ^
+t5702-neg-bad-and-wild.scala:16: error: trailing * is not a valid pattern
+      case (1, x*) => // trailing * is not a valid pattern
+                 ^
+t5702-neg-bad-and-wild.scala:17: error: bad use of _* (sequence pattern not allowed)
+      case (1, x@_*) => // bad use of _* (sequence pattern not allowed)
+                   ^
+t5702-neg-bad-and-wild.scala:23: error: bad use of _* (a sequence pattern must be the last pattern)
+    val K(ns @ _*, x) = k // bad use of _* (a sequence pattern must be the last pattern)
+                 ^
+t5702-neg-bad-and-wild.scala:24: error: bad use of _* (sequence pattern not allowed)
+    val (b, _ * ) = Pair(5,6) // bad use of _* (sequence pattern not allowed)
+                ^
+9 errors found
diff --git a/test/files/neg/t5702-neg-bad-and-wild.scala b/test/files/neg/t5702-neg-bad-and-wild.scala
new file mode 100644
index 0000000000..3833a002b1
--- /dev/null
+++ b/test/files/neg/t5702-neg-bad-and-wild.scala
@@ -0,0 +1,29 @@
+
+object Test {
+  case class K(i: Int)
+
+  def main(args: Array[String]) {
+    val k = new K(9)
+    val is = List(1,2,3)
+
+    is match {
+      case List(1, _*,) => // bad use of _* (a sequence pattern must be the last pattern)
+                           // illegal start of simple pattern
+      case List(1, _*3,) => // illegal start of simple pattern
+      //case List(1, _*3:) =>  // poor recovery by parens
+      case List(1, x*) => // use _* to match a sequence
+      case List(x*, 1) => // trailing * is not a valid pattern
+      case (1, x*) => // trailing * is not a valid pattern
+      case (1, x@_*) => // bad use of _* (sequence pattern not allowed)
+    }
+
+// good syntax, bad semantics, detected by typer
+//gowild.scala:14: error: star patterns must correspond with varargs parameters
+    val K(is @ _*) = k
+    val K(ns @ _*, x) = k // bad use of _* (a sequence pattern must be the last pattern)
+    val (b, _ * ) = Pair(5,6) // bad use of _* (sequence pattern not allowed)
+// no longer complains
+//bad-and-wild.scala:15: error: ')' expected but '}' found.
+  }
+}
+
diff --git a/test/files/neg/t5702-neg-bad-brace.check b/test/files/neg/t5702-neg-bad-brace.check
new file mode 100644
index 0000000000..503f7d95ed
--- /dev/null
+++ b/test/files/neg/t5702-neg-bad-brace.check
@@ -0,0 +1,10 @@
+t5702-neg-bad-brace.scala:14: error: Unmatched closing brace '}' ignored here
+      case List(1, _*} =>
+                     ^
+t5702-neg-bad-brace.scala:14: error: illegal start of simple pattern
+      case List(1, _*} =>
+                       ^
+t5702-neg-bad-brace.scala:15: error: ')' expected but '}' found.
+    }
+    ^
+three errors found
diff --git a/test/files/neg/t5702-neg-bad-brace.scala b/test/files/neg/t5702-neg-bad-brace.scala
new file mode 100644
index 0000000000..16a341cf8c
--- /dev/null
+++ b/test/files/neg/t5702-neg-bad-brace.scala
@@ -0,0 +1,17 @@
+
+object Test {
+
+  def main(args: Array[String]) {
+    val is = List(1,2,3)
+
+    is match {
+// the erroneous brace is ignored, so we can't halt on it.
+// maybe brace healing can detect overlapping unmatched (...}
+// In this case, the fix emits an extra error:
+// t5702-neg-bad-brace.scala:10: error: Unmatched closing brace '}' ignored here
+// t5702-neg-bad-brace.scala:10: error: illegal start of simple pattern (i.e., =>)
+// t5702-neg-bad-brace.scala:11: error: ')' expected but '}' found.
+      case List(1, _*} =>
+    }
+  }
+}
diff --git a/test/files/neg/t5702-neg-bad-xbrace.check b/test/files/neg/t5702-neg-bad-xbrace.check
new file mode 100644
index 0000000000..d88638aee9
--- /dev/null
+++ b/test/files/neg/t5702-neg-bad-xbrace.check
@@ -0,0 +1,7 @@
+t5702-neg-bad-xbrace.scala:19: error: bad brace or paren after _*
+          case <year>{_*)}</year> => y
+                        ^
+t5702-neg-bad-xbrace.scala:28: error: bad brace or paren after _*
+    val <top>{a, z@_*)}</top> = xml
+                     ^
+two errors found
diff --git a/test/files/neg/t5702-neg-bad-xbrace.scala b/test/files/neg/t5702-neg-bad-xbrace.scala
new file mode 100644
index 0000000000..64bbdb18be
--- /dev/null
+++ b/test/files/neg/t5702-neg-bad-xbrace.scala
@@ -0,0 +1,31 @@
+
+object Test {
+  def main(args: Array[String]) {
+    /* PiS example, minus a brace
+    val yearMade = 1965
+    val old =
+      <a>{ if (yearMade < 2000) <old>yearMade}</old>
+           else xml.NodeSeq.Empty } </a>
+    println(old)
+    */
+
+    // bad brace or paren after _*
+    // actually, we know it's a bad paren...
+    // we skip it because not in a context looking for rparen
+    val xyear = <year>1965</year>
+    val ancient =
+      <b>{
+        val when = xyear match {
+          case <year>{_*)}</year> => y
+          case _ => "2035"
+        }
+        <old>{when}</old>
+      }</b>
+    println(ancient)
+
+    val xml = <top><a>apple</a><b>boy</b><c>child</c></top>
+    // bad brace or paren after _*
+    val <top>{a, z@_*)}</top> = xml
+    println("A for "+ a +", ending with "+ z)
+  }
+}
diff --git a/test/files/neg/t5702-neg-ugly-xbrace.check b/test/files/neg/t5702-neg-ugly-xbrace.check
new file mode 100644
index 0000000000..7d80bbf6be
--- /dev/null
+++ b/test/files/neg/t5702-neg-ugly-xbrace.check
@@ -0,0 +1,19 @@
+t5702-neg-ugly-xbrace.scala:11: error: bad brace or paren after _*
+    val <top>{a, z@_*)</top> = xml
+                     ^
+t5702-neg-ugly-xbrace.scala:12: error: Missing closing brace `}' assumed here
+    println("A for "+ a +", ending with "+ z)
+    ^
+t5702-neg-ugly-xbrace.scala:13: error: in XML literal: in XML content, please use '}}' to express '}'
+  }
+  ^
+t5702-neg-ugly-xbrace.scala:11: error:  I encountered a '}' where I didn't expect one, maybe this tag isn't closed <top>
+    val <top>{a, z@_*)</top> = xml
+         ^
+t5702-neg-ugly-xbrace.scala:14: error: illegal start of simple pattern
+}
+^
+t5702-neg-ugly-xbrace.scala:14: error: '}' expected but eof found.
+}
+ ^
+6 errors found
diff --git a/test/files/neg/t5702-neg-ugly-xbrace.scala b/test/files/neg/t5702-neg-ugly-xbrace.scala
new file mode 100644
index 0000000000..0ff7bfa09d
--- /dev/null
+++ b/test/files/neg/t5702-neg-ugly-xbrace.scala
@@ -0,0 +1,14 @@
+
+object Test {
+  def main(args: Array[String]) {
+
+    val xml = <top><a>apple</a><b>boy</b><c>child</c></top>
+    // This is the more likely typo, and the uglier parse.
+    // We could turn it into a } if } does not follow (to
+    // avoid handing }} back to xml) but that is quite ad hoc.
+    // Assuming } for ) after _* would not be not outlandish.
+    // bad brace or paren after _*
+    val <top>{a, z@_*)</top> = xml
+    println("A for "+ a +", ending with "+ z)
+  }
+}
diff --git a/test/files/pos/t5702-pos-infix-star.scala b/test/files/pos/t5702-pos-infix-star.scala
new file mode 100644
index 0000000000..756bcdd8de
--- /dev/null
+++ b/test/files/pos/t5702-pos-infix-star.scala
@@ -0,0 +1,15 @@
+
+object Test {
+  case class *(a: Int, b: Int)
+  type Star = *
+  case class P(a: Int, b: Star) // alias still required
+
+  def main(args: Array[String]) {
+    val v = new *(6,7)
+    val x * y = v
+    printf("%d,%d\n",x,y)
+    val p = P(5, v)
+    val P(a, b * c) = p
+    printf("%d,%d,%d\n",a,b,c)
+  }
+}
diff --git a/test/pending/neg/t3189.check b/test/pending/neg/t3189.check
deleted file mode 100644
index 43dd0f29a0..0000000000
--- a/test/pending/neg/t3189.check
+++ /dev/null
@@ -1,7 +0,0 @@
-t3189.scala:2: error: illegal start of simple pattern
-  val Array(a,b*) = ("": Any)
-                ^
-t3189.scala:3: error: ')' expected but '}' found.
-}
-^
-two errors found