From ca7bbcfb178c5a0c697a3cdd543e38f37b79f737 Mon Sep 17 00:00:00 2001
From: Som Snytt <som.snytt@gmail.com>
Date: Thu, 8 Dec 2016 14:03:05 -0800
Subject: SI-8704 Error on bad implicit sections

Instead of aborting when a class def has extra
parameter section, take all parameter sections
and sanity check the use of leading implicit
to indicate an implicit parameter section.
---
 .../scala/tools/nsc/ast/parser/Parsers.scala       | 32 +++++++++++++---------
 1 file changed, 19 insertions(+), 13 deletions(-)

(limited to 'src/compiler/scala/tools/nsc/ast/parser/Parsers.scala')

diff --git a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
index a511d753c1..45c177f5b9 100644
--- a/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
+++ b/src/compiler/scala/tools/nsc/ast/parser/Parsers.scala
@@ -2236,22 +2236,24 @@ self =>
      *  }}}
      */
     def paramClauses(owner: Name, contextBounds: List[Tree], ofCaseClass: Boolean): List[List[ValDef]] = {
-      var implicitmod = 0
-      var caseParam = ofCaseClass
-      val vds = new ListBuffer[List[ValDef]]
+      var implicitSection = -1
+      var implicitOffset  = -1
+      var warnAt          = -1
+      var caseParam       = ofCaseClass
+      val vds   = new ListBuffer[List[ValDef]]
       val start = in.offset
-      def paramClause(): List[ValDef] = {
-        if (in.token == RPAREN)
-          return Nil
-
-        if (in.token == IMPLICIT) {
-          in.nextToken()
-          implicitmod = Flags.IMPLICIT
-        }
-        commaSeparated(param(owner, implicitmod, caseParam  ))
+      def paramClause(): List[ValDef] = if (in.token == RPAREN) Nil else {
+        val implicitmod = 
+          if (in.token == IMPLICIT) {
+            if (implicitOffset == -1) { implicitOffset = in.offset ; implicitSection = vds.length }
+            else if (warnAt == -1) warnAt = in.offset
+            in.nextToken()
+            Flags.IMPLICIT
+          } else 0
+        commaSeparated(param(owner, implicitmod, caseParam))
       }
       newLineOptWhenFollowedBy(LPAREN)
-      while (implicitmod == 0 && in.token == LPAREN) {
+      while (in.token == LPAREN) {
         in.nextToken()
         vds += paramClause()
         accept(RPAREN)
@@ -2266,6 +2268,10 @@ self =>
           syntaxError(in.lastOffset, s"case classes must have a non-implicit parameter list; try 'case class ${
                                          owner.encoded}()${ vds.map(vs => "(...)").mkString }'")
       }
+      if (implicitSection != -1 && implicitSection != vds.length - 1)
+        syntaxError(implicitOffset, "an implicit parameter section must be last")
+      if (warnAt != -1)
+        syntaxError(warnAt, "multiple implicit parameter sections are not allowed")
       val result = vds.toList
       if (owner == nme.CONSTRUCTOR && (result.isEmpty || (result.head take 1 exists (_.mods.isImplicit)))) {
         in.token match {
-- 
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