fixes #2420; negative indexing for slicing is obsolete (breaking change!)

4 files changed, 24 insertions, 22 deletions

diff --git a/compiler/semcall.nim b/compiler/semcall.nim
index 4309661f3..c48e761e3 100644
--- a/compiler/semcall.nim
+++ b/compiler/semcall.nim
@@ -201,7 +201,8 @@ proc resolveOverloads(c: PContext, n, orig: PNode,
 
     elif nfDotSetter in n.flags:
       internalAssert f.kind == nkIdent and n.sonsLen == 3
-      let calleeName = newStrNode(nkStrLit, f.ident.s[0.. -2]).withInfo(n.info)
+      let calleeName = newStrNode(nkStrLit,
+        f.ident.s[0..f.ident.s.len-2]).withInfo(n.info)
       let callOp = newIdentNode(getIdent".=", n.info)
       n.sons[0..1] = [callOp, n[1], calleeName]
       orig.sons[0..1] = [callOp, orig[1], calleeName]
diff --git a/compiler/semdestruct.nim b/compiler/semdestruct.nim
index bbc68ee87..aaab49a10 100644
--- a/compiler/semdestruct.nim
+++ b/compiler/semdestruct.nim
@@ -12,7 +12,7 @@
 # included from sem.nim
 
 # special marker values that indicates that we are
-# 1) AnalyzingDestructor: currently analyzing the type for destructor 
+# 1) AnalyzingDestructor: currently analyzing the type for destructor
 # generation (needed for recursive types)
 # 2) DestructorIsTrivial: completed the analysis before and determined
 # that the type has a trivial destructor
@@ -41,7 +41,7 @@ proc doDestructorStuff(c: PContext, s: PSym, n: PNode) =
     if t.kind != tyGenericBody:
       localError(n.info, errDestructorNotGenericEnough)
       return
-  
+
   t.destructor = s
   # automatically insert calls to base classes' destructors
   if n.sons[bodyPos].kind != nkEmpty:
@@ -71,17 +71,18 @@ proc destroyCase(c: PContext, n: PNode, holder: PNode): PNode =
   result.addSon(newNode(nkDotExpr, n.info, @[holder, n.sons[0]]))
   for i in countup(1, n.len - 1):
     # of A, B:
-    var caseBranch = newNode(n[i].kind, n[i].info, n[i].sons[0 .. -2])
-    
-    let stmt = destroyFieldOrFields(c, n[i].lastSon, holder)
+    let ni = n[i]
+    var caseBranch = newNode(ni.kind, ni.info, ni.sons[0..ni.len-2])
+
+    let stmt = destroyFieldOrFields(c, ni.lastSon, holder)
     if stmt == nil:
-      caseBranch.addSon(newNode(nkStmtList, n[i].info, @[]))
+      caseBranch.addSon(newNode(nkStmtList, ni.info, @[]))
     else:
       caseBranch.addSon(stmt)
       nonTrivialFields += stmt.len
-    
+
     result.addSon(caseBranch)
-  
+
   # maybe no fields were destroyed?
   if nonTrivialFields == 0:
     result = nil
@@ -107,7 +108,7 @@ proc destroyFieldOrFields(c: PContext, field: PNode, holder: PNode): PNode =
 proc generateDestructor(c: PContext, t: PType): PNode =
   ## generate a destructor for a user-defined object or tuple type
   ## returns nil if the destructor turns out to be trivial
-  
+
   # XXX: This may be true for some C-imported types such as
   # Tposix_spawnattr
   if t.n == nil or t.n.sons == nil: return
@@ -120,13 +121,13 @@ proc generateDestructor(c: PContext, t: PType): PNode =
 
 proc instantiateDestructor(c: PContext, typ: PType): PType =
   # returns nil if a variable of type `typ` doesn't require a
-  # destructor. Otherwise, returns the type, which holds the 
+  # destructor. Otherwise, returns the type, which holds the
   # destructor that must be used for the varialbe.
   # The destructor is either user-defined or automatically
   # generated by the compiler in a member-wise fashion.
   var t = skipTypes(typ, {tyConst, tyMutable}).skipGenericAlias
   let typeHoldingUserDefinition = if t.kind == tyGenericInst: t.base else: t
-  
+
   if typeHoldingUserDefinition.destructor != nil:
     # XXX: This is not entirely correct for recursive types, but we need
     # it temporarily to hide the "destroy is already defined" problem
@@ -135,7 +136,7 @@ proc instantiateDestructor(c: PContext, typ: PType): PType =
       return typeHoldingUserDefinition
     else:
       return nil
-  
+
   t = t.skipTypes({tyGenericInst})
   case t.kind
   of tySequence, tyArray, tyArrayConstr, tyOpenArray, tyVarargs:
@@ -200,16 +201,16 @@ proc insertDestructors(c: PContext,
       varId = varSection[j][0]
       varTyp = varId.sym.typ
       info = varId.info
-    
+
     if varTyp == nil or sfGlobal in varId.sym.flags: continue
     let destructableT = instantiateDestructor(c, varTyp)
-    
+
     if destructableT != nil:
       var tryStmt = newNodeI(nkTryStmt, info)
 
       if j < totalVars - 1:
         var remainingVars = newNodeI(varSection.kind, info)
-        remainingVars.sons = varSection.sons[(j+1)..(-1)]
+        remainingVars.sons = varSection.sons[(j+1)..varSection.len-1]
         let (outer, inner) = insertDestructors(c, remainingVars)
         if outer != nil:
           tryStmt.addSon(outer)
@@ -221,7 +222,7 @@ proc insertDestructors(c: PContext,
       else:
         result.inner = newNodeI(nkStmtList, info)
         tryStmt.addSon(result.inner)
-    
+
       tryStmt.addSon(
         newNode(nkFinally, info, @[
           semStmt(c, newNode(nkCall, info, @[
diff --git a/compiler/semmagic.nim b/compiler/semmagic.nim
index 56746ce26..de7700be6 100644
--- a/compiler/semmagic.nim
+++ b/compiler/semmagic.nim
@@ -167,10 +167,10 @@ proc magicsAfterOverloadResolution(c: PContext, n: PNode,
     result.typ = n[1].typ
   of mDotDot:
     result = n
-    # we only need to warnings here about negative indexing:
-    if isNegative(n.sons[1]) or (n.len > 2 and isNegative(n.sons[2])):
-      message(n.info, warnDeprecated,
-        "use '^' instead of '-'; negative indexing")
+    # disallow negative indexing for now:
+    if not c.p.bracketExpr.isNil:
+      if isNegative(n.sons[1]) or (n.len > 2 and isNegative(n.sons[2])):
+        localError(n.info, "use '^' instead of '-'; negative indexing is obsolete")
   of mRoof:
     # error correction:
     result = n.sons[1]
diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index ae0cbd84f..7263b21b9 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -1281,7 +1281,7 @@ proc semStmtList(c: PContext, n: PNode, flags: TExprFlags): PNode =
       var tryStmt = newNodeI(nkTryStmt, n.sons[i].info)
       var body = newNodeI(nkStmtList, n.sons[i].info)
       if i < n.sonsLen - 1:
-        body.sons = n.sons[(i+1)..(-1)]
+        body.sons = n.sons[(i+1)..n.len-1]
       tryStmt.addSon(body)
       tryStmt.addSon(deferPart)
       n.sons[i] = semTry(c, tryStmt)