'nil' as a statement is deprecated, use an empty 'discard' instead

2026-05-08 06:50:26 +00:00 · 2014-01-19 16:54:59 +01:00
parent cde9e5d644
commit 73c6efdf66
54 changed files with 170 additions and 170 deletions
--- a/compiler/aliases.nim
+++ b/compiler/aliases.nim
@@ -54,7 +54,7 @@ proc isPartOfAux(a, b: PType, marker: var TIntSet): TAnalysisResult =
    for i in countup(0, sonsLen(a) - 1): 
      result = isPartOfAux(a.sons[i], b, marker)
      if result == arYes: return 
-  else: nil
+  else: discard

 proc isPartOf(a, b: PType): TAnalysisResult = 
  ## checks iff 'a' can be part of 'b'. Iterates over VALUE types!
@@ -140,7 +140,7 @@ proc isPartOf*(a, b: PNode): TAnalysisResult =
      result = isPartOf(a[1], b[1])
    of nkObjUpConv, nkObjDownConv, nkCheckedFieldExpr:
      result = isPartOf(a[0], b[0])
-    else: nil
+    else: discard
    # Calls return a new location, so a default of ``arNo`` is fine.
  else:
    # go down recursively; this is quite demanding:
@@ -177,6 +177,6 @@ proc isPartOf*(a, b: PNode): TAnalysisResult =
        if isPartOf(a.typ, b.typ) != arNo:
          result = isPartOf(a[0], b)
          if result == arNo: result = arMaybe
-      else: nil
-    else: nil
+      else: discard
+    else: discard

--- a/compiler/ast.nim
+++ b/compiler/ast.nim
@@ -1257,7 +1257,7 @@ proc propagateToOwner*(owner, elem: PType) =
      owner.flags.incl tfNeedsInit
  
  if tfNeedsInit in elem.flags:
-    if owner.kind in HaveTheirOwnEmpty: nil
+    if owner.kind in HaveTheirOwnEmpty: discard
    else: owner.flags.incl tfNeedsInit
    
  if tfShared in elem.flags:
--- a/compiler/ccgcalls.nim
+++ b/compiler/ccgcalls.nim
@@ -73,7 +73,7 @@ proc isInCurrentFrame(p: BProc, n: PNode): bool =
    result = false
  of nkObjUpConv, nkObjDownConv, nkCheckedFieldExpr:
    result = isInCurrentFrame(p, n.sons[0])
-  else: nil
+  else: discard

 proc openArrayLoc(p: BProc, n: PNode): PRope =
  var a: TLoc
--- a/compiler/ccgexprs.nim
+++ b/compiler/ccgexprs.nim
@@ -202,7 +202,7 @@ proc asgnComplexity(n: PNode): int =
    of nkRecList:
      for t in items(n):
        result += asgnComplexity(t)
-    else: nil
+    else: discard

 proc optAsgnLoc(a: TLoc, t: PType, field: PRope): TLoc =
  result.k = locField
@@ -228,7 +228,7 @@ proc genOptAsgnObject(p: BProc, dest, src: TLoc, flags: TAssignmentFlags,
                     optAsgnLoc(src, field.typ, field.loc.r), flags)
  of nkRecList:
    for child in items(t): genOptAsgnObject(p, dest, src, flags, child)
-  else: nil
+  else: discard

 proc genGenericAsgn(p: BProc, dest, src: TLoc, flags: TAssignmentFlags) =
  # Consider: 
@@ -1901,7 +1901,7 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
  of nkClosure: genClosure(p, n, d)
  of nkMetaNode: expr(p, n.sons[0], d)

-  of nkEmpty:  nil
+  of nkEmpty: discard
  of nkWhileStmt: genWhileStmt(p, n)
  of nkVarSection, nkLetSection: genVarStmt(p, n)
  of nkConstSection: genConstStmt(p, n)
@@ -1931,7 +1931,7 @@ proc expr(p: BProc, n: PNode, d: var TLoc) =
  of nkCommentStmt, nkIteratorDef, nkIncludeStmt, 
     nkImportStmt, nkImportExceptStmt, nkExportStmt, nkExportExceptStmt, 
     nkFromStmt, nkTemplateDef, nkMacroDef: 
-    nil
+    discard
  of nkPragma: genPragma(p, n)
  of nkProcDef, nkMethodDef, nkConverterDef: 
    if (n.sons[genericParamsPos].kind == nkEmpty):
--- a/compiler/ccgmerge.nim
+++ b/compiler/ccgmerge.nim
@@ -285,7 +285,7 @@ proc readMergeSections(cfilename: string, m: var TMergeSections) =
  withCFile(cfilename):
    readKey(L, k)
    if k == "NIM_merge_INFO":   
-      nil
+      discard
    elif ^L.bufpos == '*' and ^(L.bufpos+1) == '/':
      inc(L.bufpos, 2)
      # read back into section
--- a/compiler/ccgtrav.nim
+++ b/compiler/ccgtrav.nim
@@ -83,7 +83,7 @@ proc genTraverseProc(c: var TTraversalClosure, accessor: PRope, typ: PType) =
    if typ.callConv == ccClosure:
      lineCg(p, cpsStmts, c.visitorFrmt, rfmt(nil, "$1.ClEnv", accessor))
  else:
-    nil
+    discard

 proc genTraverseProcSeq(c: var TTraversalClosure, accessor: PRope, typ: PType) =
  var p = c.p
--- a/compiler/ccgtypes.nim
+++ b/compiler/ccgtypes.nim
@@ -25,7 +25,7 @@ proc mangleField(name: string): string =
    of 'A'..'Z': 
      add(result, chr(ord(name[i]) - ord('A') + ord('a')))
    of '_': 
-      nil
+      discard
    of 'a'..'z', '0'..'9': 
      add(result, name[i])
    else: 
@@ -48,7 +48,7 @@ proc mangle(name: string): string =
    of 'A'..'Z': 
      add(result, chr(ord(name[i]) - ord('A') + ord('a')))
    of '_': 
-      nil
+      discard
    of 'a'..'z', '0'..'9': 
      add(result, name[i])
    else: 
--- a/compiler/cgen.nim
+++ b/compiler/cgen.nim
@@ -319,7 +319,7 @@ proc genObjectInit(p: BProc, section: TCProcSection, t: PType, a: TLoc,
                   takeAddr: bool) =
  case analyseObjectWithTypeField(t)
  of frNone:
-    nil
+    discard
  of frHeader:
    var r = rdLoc(a)
    if not takeAddr: r = ropef("(*$1)", [r])
@@ -832,7 +832,7 @@ proc genProcNoForward(m: BModule, prc: PSym) =
    discard cgsym(m, prc.name.s)
    return  
  genProcPrototype(m, prc)
-  if lfNoDecl in prc.loc.flags: nil
+  if lfNoDecl in prc.loc.flags: discard
  elif prc.typ.callConv == ccInline:
    # We add inline procs to the calling module to enable C based inlining.
    # This also means that a check with ``q.declaredThings`` is wrong, we need
--- a/compiler/cgmeth.nim
+++ b/compiler/cgmeth.nim
@@ -66,7 +66,7 @@ proc sameMethodBucket(a, b: PSym): bool =
    if sameType(aa, bb) or
        (aa.kind == tyObject) and (bb.kind == tyObject) and
        (inheritanceDiff(bb, aa) < 0):
-      nil
+      discard
    else:
      return
  result = true
--- a/compiler/depends.nim
+++ b/compiler/depends.nim
@@ -39,7 +39,7 @@ proc addDotDependency(c: PPassContext, n: PNode): PNode =
  of nkStmtList, nkBlockStmt, nkStmtListExpr, nkBlockExpr: 
    for i in countup(0, sonsLen(n) - 1): discard addDotDependency(c, n.sons[i])
  else: 
-    nil
+    discard

 proc generateDot(project: string) = 
  writeRope(ropef("digraph $1 {$n$2}$n", [
--- a/compiler/docgen2.nim
+++ b/compiler/docgen2.nim
@@ -27,7 +27,7 @@ proc close(p: PPassContext, n: PNode): PNode =
    try:
      generateIndex(g.doc)
    except EIO:
-      nil
+      discard

 proc processNode(c: PPassContext, n: PNode): PNode = 
  result = n
@@ -46,4 +46,4 @@ proc myOpen(module: PSym): PPassContext =
 const docgen2Pass* = makePass(open = myOpen, process = processNode, close = close)

 proc finishDoc2Pass*(project: string) = 
-  nil
+  discard
--- a/compiler/filter_tmpl.nim
+++ b/compiler/filter_tmpl.nim
@@ -55,7 +55,7 @@ proc scanPar(p: var TTmplParser, d: int) =
    of ']': dec(p.bracket)
    of '{': inc(p.curly)
    of '}': dec(p.curly)
-    else: nil
+    else: discard
    inc(i)

 proc withInExpr(p: TTmplParser): bool {.inline.} = 
--- a/compiler/guards.nim
+++ b/compiler/guards.nim
@@ -439,7 +439,7 @@ proc impliesLe(fact, x, c: PNode): TImplication =
        if leValue(c, fact.sons[1].pred): result = impNo

  of mNot, mOr, mAnd: internalError(x.info, "impliesLe")
-  else: nil
+  else: discard

 proc impliesLt(fact, x, c: PNode): TImplication =
  # x < 3  same as x <= 2:
--- a/compiler/hlo.nim
+++ b/compiler/hlo.nim
@@ -81,7 +81,7 @@ proc hlo(c: PContext, n: PNode): PNode =
    else:
      # perform type checking, so that the replacement still fits:
      if isEmptyType(n.typ) and isEmptyType(result.typ):
-        nil
+        discard
      else:
        result = fitNode(c, n.typ, result)
      # optimization has been applied so check again:
--- a/compiler/jsgen.nim
+++ b/compiler/jsgen.nim
@@ -143,7 +143,7 @@ proc mangle(name: string): string =
    of 'A'..'Z': 
      add(result, chr(ord(name[i]) - ord('A') + ord('a')))
    of '_': 
-      nil
+      discard
    of 'a'..'z', '0'..'9': 
      add(result, name[i])
    else: add(result, 'X' & toHex(ord(name[i]), 2))
@@ -996,10 +996,10 @@ proc genSym(p: PProc, n: PNode, r: var TCompRes) =
    r.res = s.loc.r
    if lfNoDecl in s.loc.flags or s.magic != mNone or
       {sfImportc, sfInfixCall} * s.flags != {}:
-      nil
+      discard
    elif s.kind == skMethod and s.getBody.kind == nkEmpty:
      # we cannot produce code for the dispatcher yet:
-      nil
+      discard
    elif sfForward in s.flags:
      p.g.forwarded.add(s)
    elif not p.g.generatedSyms.containsOrIncl(s.id):
@@ -1336,10 +1336,10 @@ proc genMagic(p: PProc, n: PNode, r: var TCompRes) =
    else:
      unaryExpr(p, n, r, "", "($1.length-1)")
  of mInc:
-    if not (optOverflowCheck in p.options): binaryExpr(p, n, r, "", "$1 += $2")
+    if optOverflowCheck notin p.options: binaryExpr(p, n, r, "", "$1 += $2")
    else: binaryExpr(p, n, r, "addInt", "$1 = addInt($1, $2)")
  of ast.mDec:
-    if not (optOverflowCheck in p.options): binaryExpr(p, n, r, "", "$1 -= $2")
+    if optOverflowCheck notin p.options: binaryExpr(p, n, r, "", "$1 -= $2")
    else: binaryExpr(p, n, r, "subInt", "$1 = subInt($1, $2)")
  of mSetLengthStr: binaryExpr(p, n, r, "", "$1.length = ($2)-1")
  of mSetLengthSeq: binaryExpr(p, n, r, "", "$1.length = $2")
@@ -1544,7 +1544,7 @@ proc gen(p: PProc, n: PNode, r: var TCompRes) =
    r.res = toRope(n.intVal)
  of nkNilLit:
    if isEmptyType(n.typ):
-      nil
+      discard
    elif mapType(n.typ) == etyBaseIndex:
      r.typ = etyBaseIndex
      r.address = toRope"null" | toRope"nil"
@@ -1592,12 +1592,12 @@ proc gen(p: PProc, n: PNode, r: var TCompRes) =
  of nkChckRange: genRangeChck(p, n, r, "chckRange")
  of nkStringToCString: convStrToCStr(p, n, r)
  of nkCStringToString: convCStrToStr(p, n, r)
-  of nkEmpty: nil
+  of nkEmpty: discard
  of nkLambdaKinds: 
    let s = n.sons[namePos].sym
    discard mangleName(s)
    r.res = s.loc.r
-    if lfNoDecl in s.loc.flags or s.magic != mNone: nil
+    if lfNoDecl in s.loc.flags or s.magic != mNone: discard
    elif not p.g.generatedSyms.containsOrIncl(s.id):
      app(p.locals, genProc(p, s))
  of nkMetaNode: gen(p, n.sons[0], r)
@@ -1614,7 +1614,7 @@ proc gen(p: PProc, n: PNode, r: var TCompRes) =
  of nkIfStmt, nkIfExpr: genIf(p, n, r)
  of nkWhileStmt: genWhileStmt(p, n)
  of nkVarSection, nkLetSection: genVarStmt(p, n)
-  of nkConstSection: nil
+  of nkConstSection: discard
  of nkForStmt, nkParForStmt: 
    internalError(n.info, "for statement not eliminated")
  of nkCaseStmt: 
@@ -1633,7 +1633,7 @@ proc gen(p: PProc, n: PNode, r: var TCompRes) =
  of nkRaiseStmt: genRaiseStmt(p, n)
  of nkTypeSection, nkCommentStmt, nkIteratorDef, nkIncludeStmt, 
     nkImportStmt, nkImportExceptStmt, nkExportStmt, nkExportExceptStmt, 
-     nkFromStmt, nkTemplateDef, nkMacroDef, nkPragma: nil
+     nkFromStmt, nkTemplateDef, nkMacroDef, nkPragma: discard
  of nkProcDef, nkMethodDef, nkConverterDef:
    var s = n.sons[namePos].sym
    if {sfExportc, sfCompilerProc} * s.flags == {sfExportc}:
--- a/compiler/lambdalifting.nim
+++ b/compiler/lambdalifting.nim
@@ -1,7 +1,7 @@
 #
 #
 #           The Nimrod Compiler
-#        (c) Copyright 2013 Andreas Rumpf
+#        (c) Copyright 2014 Andreas Rumpf
 #
 #    See the file "copying.txt", included in this
 #    distribution, for details about the copyright.
@@ -275,7 +275,7 @@ proc captureVar(o: POuterContext, i: PInnerContext, local: PSym,
  addCapturedVar(it, local)
  if it == e:
    # common case: local directly in current environment:
-    nil
+    discard
  else:
    # it's in some upper environment:
    access = indirectAccess(access, addDep(e, it, i.fn), info)
@@ -314,7 +314,7 @@ proc gatherVars(o: POuterContext, i: PInnerContext, n: PNode) =
      if o.currentEnv != env:
        discard addDep(o.currentEnv, env, i.fn)
        internalError(n.info, "too complex environment handling required")
-  of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: nil
+  of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: discard
  else:
    for k in countup(0, sonsLen(n) - 1): 
      gatherVars(o, i, n.sons[k])
@@ -351,7 +351,7 @@ proc makeClosure(prc, env: PSym, info: TLineInfo): PNode =

 proc transformInnerProc(o: POuterContext, i: PInnerContext, n: PNode): PNode =
  case n.kind
-  of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: nil
+  of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: discard
  of nkSym:
    let s = n.sym
    if s == i.fn: 
@@ -371,7 +371,7 @@ proc transformInnerProc(o: POuterContext, i: PInnerContext, n: PNode): PNode =
  of nkProcDef, nkMethodDef, nkConverterDef, nkMacroDef, nkTemplateDef,
     nkIteratorDef:
    # don't recurse here:
-    nil
+    discard
  else:
    for j in countup(0, sonsLen(n) - 1):
      let x = transformInnerProc(o, i, n.sons[j])
@@ -386,7 +386,7 @@ proc searchForInnerProcs(o: POuterContext, n: PNode) =
  if n == nil: return
  case n.kind
  of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: 
-    nil
+    discard
  of nkSym:
    if isInnerProc(n.sym, o.fn) and not containsOrIncl(o.processed, n.sym.id):
      var inner = newInnerContext(n.sym)
@@ -422,7 +422,7 @@ proc searchForInnerProcs(o: POuterContext, n: PNode) =
    # counts, not the block where it is captured!
    for i in countup(0, sonsLen(n) - 1):
      var it = n.sons[i]
-      if it.kind == nkCommentStmt: nil
+      if it.kind == nkCommentStmt: discard
      elif it.kind == nkIdentDefs:
        var L = sonsLen(it)
        if it.sons[0].kind != nkSym: internalError(it.info, "transformOuter")
@@ -441,7 +441,7 @@ proc searchForInnerProcs(o: POuterContext, n: PNode) =
     nkIteratorDef:
    # don't recurse here:
    # XXX recurse here and setup 'up' pointers
-    nil
+    discard
  else:
    for i in countup(0, sonsLen(n) - 1):
      searchForInnerProcs(o, n.sons[i])
@@ -500,7 +500,7 @@ proc generateClosureCreation(o: POuterContext, scope: PEnv): PNode =
 proc transformOuterProc(o: POuterContext, n: PNode): PNode =
  if n == nil: return nil
  case n.kind
-  of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: nil
+  of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: discard
  of nkSym:
    var local = n.sym
    var closure = PEnv(idTableGet(o.lambdasToEnv, local))
@@ -540,7 +540,7 @@ proc transformOuterProc(o: POuterContext, n: PNode): PNode =
  of nkProcDef, nkMethodDef, nkConverterDef, nkMacroDef, nkTemplateDef, 
     nkIteratorDef: 
    # don't recurse here:
-    nil
+    discard
  of nkHiddenStdConv, nkHiddenSubConv, nkConv:
    let x = transformOuterProc(o, n.sons[1])
    if x != nil: n.sons[1] = x
@@ -625,7 +625,7 @@ proc transfIterBody(c: var TIterContext, n: PNode): PNode =
    if interestingIterVar(s) and c.iter.id == s.owner.id:
      if not containsOrIncl(c.capturedVars, s.id): addField(c.tup, s)
      result = indirectAccess(newSymNode(c.closureParam), s, n.info)
-  of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: nil
+  of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit: discard
  of nkYieldStmt:
    inc c.state.typ.n.sons[1].intVal
    let stateNo = c.state.typ.n.sons[1].intVal
--- a/compiler/lexer.nim
+++ b/compiler/lexer.nim
@@ -434,7 +434,7 @@ proc handleHexChar(L: var TLexer, xi: var int) =
  of 'A'..'F': 
    xi = (xi shl 4) or (ord(L.buf[L.bufpos]) - ord('A') + 10)
    inc(L.bufpos)
-  else: nil
+  else: discard

 proc handleDecChars(L: var TLexer, xi: var int) = 
  while L.buf[L.bufpos] in {'0'..'9'}: 
--- a/compiler/lookups.nim
+++ b/compiler/lookups.nim
@@ -286,7 +286,7 @@ proc initOverloadIter*(o: var TOverloadIter, c: PContext, n: PNode): PSym =
    o.symChoiceIndex = 1
    o.inSymChoice = initIntSet()
    incl(o.inSymChoice, result.id)
-  else: nil
+  else: discard
  if result != nil and result.kind == skStub: loadStub(result)

 proc lastOverloadScope*(o: TOverloadIter): int =
--- a/compiler/msgs.nim
+++ b/compiler/msgs.nim
@@ -113,7 +113,7 @@ type
    warnDifferentHeaps, warnWriteToForeignHeap, warnImplicitClosure,
    warnEachIdentIsTuple, warnShadowIdent, 
    warnProveInit, warnProveField, warnProveIndex,
-    warnUninit, warnUser,
+    warnUninit, warnGcMem, warnUser,
    hintSuccess, hintSuccessX,
    hintLineTooLong, hintXDeclaredButNotUsed, hintConvToBaseNotNeeded,
    hintConvFromXtoItselfNotNeeded, hintExprAlwaysX, hintQuitCalled,
@@ -370,6 +370,7 @@ const
    warnProveField: "cannot prove that field '$1' is accessible [ProveField]",
    warnProveIndex: "cannot prove index '$1' is valid [ProveIndex]",
    warnUninit: "'$1' might not have been initialized [Uninit]",
+    warnGcMem: "'$1' uses GC'ed memory [GcMem]",
    warnUser: "$1 [User]", 
    hintSuccess: "operation successful [Success]", 
    hintSuccessX: "operation successful ($# lines compiled; $# sec total; $#) [SuccessX]", 
@@ -389,7 +390,7 @@ const
    hintUser: "$1 [User]"]

 const
-  WarningsToStr*: array[0..23, string] = ["CannotOpenFile", "OctalEscape", 
+  WarningsToStr*: array[0..24, string] = ["CannotOpenFile", "OctalEscape", 
    "XIsNeverRead", "XmightNotBeenInit",
    "Deprecated", "ConfigDeprecated",
    "SmallLshouldNotBeUsed", "UnknownMagic", 
@@ -397,7 +398,7 @@ const
    "CommentXIgnored", "NilStmt",
    "AnalysisLoophole", "DifferentHeaps", "WriteToForeignHeap",
    "ImplicitClosure", "EachIdentIsTuple", "ShadowIdent", 
-    "ProveInit", "ProveField", "ProveIndex", "Uninit", "User"]
+    "ProveInit", "ProveField", "ProveIndex", "Uninit", "GcMem", "User"]

  HintsToStr*: array[0..15, string] = ["Success", "SuccessX", "LineTooLong", 
    "XDeclaredButNotUsed", "ConvToBaseNotNeeded", "ConvFromXtoItselfNotNeeded", 
@@ -856,6 +857,5 @@ ropes.errorHandler = proc (err: TRopesError, msg: string, useWarning: bool) =
  of rTokenTooLong:
    internalError("ropes: token too long: " & msg)
  of rCannotOpenFile:
-    rawMessage(if useWarning: warnCannotOpenFile else: errCannotOpenFile,
-               msg)
- 
+    rawMessage(if useWarning: warnCannotOpenFile else: errCannotOpenFile, msg)
+
--- a/compiler/nimconf.nim
+++ b/compiler/nimconf.nim
@@ -101,11 +101,11 @@ proc jumpToDirective(L: var TLexer, tok: var TToken, dest: TJumpDest) =
          break 
        if nestedIfs > 0: dec(nestedIfs)
      else: 
-        nil
+        discard
      ppGetTok(L, tok)
-    elif tok.tokType == tkEof: 
+    elif tok.tokType == tkEof:
      lexMessage(L, errTokenExpected, "@end")
-    else: 
+    else:
      ppGetTok(L, tok)
  
 proc parseDirective(L: var TLexer, tok: var TToken) = 
--- a/compiler/nimrod.nimrod.cfg
+++ b/compiler/nimrod.nimrod.cfg
@@ -16,3 +16,5 @@ import:testability
@if windows:
  cincludes: "$lib/wrappers/libffi/common"
@end
+
+cs:partial
--- a/compiler/parser.nim
+++ b/compiler/parser.nim
@@ -1817,7 +1817,7 @@ proc parseStmt(p: var TParser): PNode =
    withInd(p):
      while true:
        if p.tok.indent == p.currInd:
-          nil
+          discard
        elif p.tok.tokType == tkSemiColon:
          getTok(p)
          if p.tok.indent < 0 or p.tok.indent == p.currInd: discard
--- a/compiler/passaux.nim
+++ b/compiler/passaux.nim
@@ -41,7 +41,7 @@ proc cleanUp(c: PPassContext, n: PNode): PNode =
      if sfDeadCodeElim notin getModule(s).flags and not astNeeded(s): 
        s.ast.sons[bodyPos] = ast.emptyNode # free the memory
  else: 
-    nil
+    discard

 const cleanupPass* = makePass(process = cleanUp, close = cleanUp)

--- a/compiler/patterns.nim
+++ b/compiler/patterns.nim
@@ -40,7 +40,7 @@ proc canonKind(n: PNode): TNodeKind =
  of nkCallKinds: result = nkCall
  of nkStrLit..nkTripleStrLit: result = nkStrLit
  of nkFastAsgn: result = nkAsgn
-  else: nil
+  else: discard

 proc sameKinds(a, b: PNode): bool {.inline.} =
  result = a.kind == b.kind or a.canonKind == b.canonKind
@@ -267,7 +267,7 @@ proc applyRule*(c: PContext, s: PSym, n: PNode): PNode =
      var rs = result.sons[i]
      let param = params.sons[i].sym
      case whichAlias(param)
-      of aqNone: nil
+      of aqNone: discard
      of aqShouldAlias:
        # it suffices that it aliases for sure with *some* other param:
        var ok = false
--- a/compiler/procfind.nim
+++ b/compiler/procfind.nim
@@ -60,7 +60,7 @@ proc searchForProcOld*(c: PContext, scope: PScope, fn: PSym): PSym =
          localError(fn.info, errNotOverloadable, fn.name.s)
          return
        of paramsNotEqual:
-          nil
+          discard
      result = nextIdentIter(it, scope.symbols)

 proc searchForProcNew(c: PContext, scope: PScope, fn: PSym): PSym =
--- a/compiler/renderer.nim
+++ b/compiler/renderer.nim
@@ -236,7 +236,7 @@ proc containsNL(s: string): bool =
    of '\x0D', '\x0A': 
      return true
    else: 
-      nil
+      discard
  result = false

 proc pushCom(g: var TSrcGen, n: PNode) = 
@@ -487,7 +487,7 @@ proc hasCom(n: PNode): bool =
  result = false
  if n.comment != nil: return true
  case n.kind
-  of nkEmpty..nkNilLit: nil
+  of nkEmpty..nkNilLit: discard
  else: 
    for i in countup(0, sonsLen(n) - 1): 
      if hasCom(n.sons[i]): return true
@@ -769,7 +769,7 @@ proc gsub(g: var TSrcGen, n: PNode, c: TContext) =
  if n.comment != nil: pushCom(g, n)
  case n.kind                 # atoms:
  of nkTripleStrLit: putRawStr(g, tkTripleStrLit, n.strVal)
-  of nkEmpty: nil
+  of nkEmpty: discard
  of nkType: put(g, tkInvalid, atom(n))
  of nkSym, nkIdent: gident(g, n)
  of nkIntLit: put(g, tkIntLit, atom(n))
@@ -1273,7 +1273,7 @@ proc renderModule(n: PNode, filename: string,
    case n.sons[i].kind
    of nkTypeSection, nkConstSection, nkVarSection, nkLetSection,
       nkCommentStmt: putNL(g)
-    else: nil
+    else: discard
  gcoms(g)
  if optStdout in gGlobalOptions:
    write(stdout, g.buf)
--- a/compiler/rodread.nim
+++ b/compiler/rodread.nim
@@ -539,7 +539,7 @@ proc cmdChangeTriggersRecompilation(old, new: TCommands): bool =
  of cmdNone, cmdDoc, cmdInterpret, cmdPretty, cmdGenDepend, cmdDump,
      cmdCheck, cmdParse, cmdScan, cmdIdeTools, cmdDef, 
      cmdRst2html, cmdRst2tex, cmdInteractive, cmdRun:
-    nil
+    discard
  # else: trigger recompilation:
  result = true
  
--- a/compiler/rodwrite.nim
+++ b/compiler/rodwrite.nim
@@ -573,7 +573,7 @@ proc process(c: PPassContext, n: PNode): PNode =
  of nkPragma: 
    addStmt(w, n)
  else: 
-    nil
+    discard

 proc myOpen(module: PSym): PPassContext =
  if module.id < 0: internalError("rodwrite: module ID not set")
--- a/compiler/semcall.nim
+++ b/compiler/semcall.nim
@@ -71,7 +71,7 @@ proc pickBestCandidate(c: PContext, headSymbol: PNode,
          var cmp = cmpCandidates(best, z)
          if cmp < 0: best = z   # x is better than the best so far
          elif cmp == 0: alt = z # x is as good as the best so far
-          else: nil
+          else: discard
    sym = nextOverloadIter(o, c, headSymbol)

 proc notFoundError*(c: PContext, n: PNode, errors: seq[string]) =
--- a/compiler/semexprs.nim
+++ b/compiler/semexprs.nim
@@ -168,7 +168,7 @@ proc checkConvertible(c: PContext, castDest, src: PType): TConvStatus =
      if not compareTypes(castDest, src, dcEqIgnoreDistinct):
        result = convNotLegal
    else:
-      nil
+      discard

 proc isCastable(dst, src: PType): bool = 
  #const
@@ -204,7 +204,7 @@ proc semConv(c: PContext, n: PNode): PNode =
  if not isSymChoice(op):
    let status = checkConvertible(c, result.typ, op.typ)
    case status
-    of convOK: nil
+    of convOK: discard
    of convNotNeedeed:
      message(n.info, hintConvFromXtoItselfNotNeeded, result.typ.typeToString)
    of convNotLegal:
@@ -397,7 +397,7 @@ proc changeType(n: PNode, newType: PType, check: bool) =
  of nkPar: 
    if newType.kind != tyTuple: 
      internalError(n.info, "changeType: no tuple type for constructor")
-    elif newType.n == nil: nil
+    elif newType.n == nil: discard
    elif sonsLen(n) > 0 and n.sons[0].kind == nkExprColonExpr: 
      for i in countup(0, sonsLen(n) - 1): 
        var m = n.sons[i].sons[0]
@@ -423,7 +423,7 @@ proc changeType(n: PNode, newType: PType, check: bool) =
      if value < firstOrd(newType) or value > lastOrd(newType):
        localError(n.info, errGenerated, "cannot convert " & $value &
                                         " to " & typeToString(newType))
-  else: nil
+  else: discard
  n.typ = newType

 proc arrayConstrType(c: PContext, n: PNode): PType = 
@@ -513,7 +513,7 @@ proc fixAbstractType(c: PContext, n: PNode) =
      # an implicitly constructed array (passed to an open array):
      n.sons[i] = semArrayConstr(c, it, {})
    else: 
-      nil
+      discard
      #if (it.typ == nil): 
      #  InternalError(it.info, "fixAbstractType: " & renderTree(it))  
  
@@ -677,7 +677,7 @@ proc semOverloadedCallAnalyseEffects(c: PContext, n: PNode, nOrig: PNode,
      return
    let callee = result.sons[0].sym
    case callee.kind
-    of skMacro, skTemplate: nil
+    of skMacro, skTemplate: discard
    else:
      if (callee.kind == skIterator) and (callee.id == c.p.owner.id): 
        localError(n.info, errRecursiveDependencyX, callee.name.s)
@@ -1098,7 +1098,7 @@ proc takeImplicitAddr(c: PContext, n: PNode): PNode =
  of nkHiddenDeref, nkDerefExpr: return n.sons[0]
  of nkBracketExpr:
    if len(n) == 1: return n.sons[0]
-  else: nil
+  else: discard
  var valid = isAssignable(c, n)
  if valid != arLValue:
    if valid == arLocalLValue:
@@ -1207,7 +1207,7 @@ proc semProcBody(c: PContext, n: PNode): PNode =
    # transform ``expr`` to ``result = expr``, but not if the expr is already
    # ``result``:
    if result.kind == nkSym and result.sym == c.p.resultSym:
-      nil
+      discard
    elif result.kind == nkNilLit:
      # or ImplicitlyDiscardable(result):
      # new semantic: 'result = x' triggers the void context
@@ -1244,7 +1244,7 @@ proc semYieldVarResult(c: PContext, n: PNode, restype: PType) =
          a.sons[i] = takeImplicitAddr(c, a.sons[i])
        else:
          localError(n.sons[0].info, errXExpected, "tuple constructor")
-  else: nil
+  else: discard
  
 proc semYield(c: PContext, n: PNode): PNode =
  result = n
@@ -1472,7 +1472,7 @@ proc tryExpr(c: PContext, n: PNode,
    result = semExpr(c, n, flags)
    if msgs.gErrorCounter != oldErrorCount: result = nil
  except ERecoverableError:
-    nil
+    discard
  # undo symbol table changes (as far as it's possible):
  c.generics = oldGenerics
  c.inGenericContext = oldInGenericContext
@@ -1590,9 +1590,9 @@ proc semSetConstr(c: PContext, n: PNode): PNode =
          typ = skipTypes(n.sons[i].typ, {tyGenericInst, tyVar, tyOrdinal})
    if not isOrdinalType(typ):
      localError(n.info, errOrdinalTypeExpected)
-      typ = makeRangeType(c, 0, MaxSetElements - 1, n.info)
+      typ = makeRangeType(c, 0, MaxSetElements-1, n.info)
    elif lengthOrd(typ) > MaxSetElements: 
-      typ = makeRangeType(c, 0, MaxSetElements - 1, n.info)
+      typ = makeRangeType(c, 0, MaxSetElements-1, n.info)
    addSonSkipIntLit(result.typ, typ)
    for i in countup(0, sonsLen(n) - 1): 
      var m: PNode
@@ -1629,27 +1629,27 @@ proc semTableConstr(c: PContext, n: PNode): PNode =
  if lastKey != n.len: illFormedAst(n)
  result = semExpr(c, result)

-type 
-  TParKind = enum 
+type
+  TParKind = enum
    paNone, paSingle, paTupleFields, paTuplePositions

-proc checkPar(n: PNode): TParKind = 
+proc checkPar(n: PNode): TParKind =
  var length = sonsLen(n)
  if length == 0: 
    result = paTuplePositions # ()
  elif length == 1: 
    result = paSingle         # (expr)
-  else: 
+  else:
    if n.sons[0].kind == nkExprColonExpr: result = paTupleFields
    else: result = paTuplePositions
-    for i in countup(0, length - 1): 
-      if result == paTupleFields: 
+    for i in countup(0, length - 1):
+      if result == paTupleFields:
        if (n.sons[i].kind != nkExprColonExpr) or
-            not (n.sons[i].sons[0].kind in {nkSym, nkIdent}): 
+            not (n.sons[i].sons[0].kind in {nkSym, nkIdent}):
          localError(n.sons[i].info, errNamedExprExpected)
          return paNone
-      else: 
-        if n.sons[i].kind == nkExprColonExpr: 
+      else:
+        if n.sons[i].kind == nkExprColonExpr:
          localError(n.sons[i].info, errNamedExprNotAllowed)
          return paNone

@@ -1659,8 +1659,7 @@ proc semTupleFieldsConstr(c: PContext, n: PNode, flags: TExprFlags): PNode =
  typ.n = newNodeI(nkRecList, n.info) # nkIdentDefs
  var ids = initIntSet()
  for i in countup(0, sonsLen(n) - 1):
-    if (n.sons[i].kind != nkExprColonExpr) or
-        not (n.sons[i].sons[0].kind in {nkSym, nkIdent}):
+    if n[i].kind != nkExprColonExpr or n[i][0].kind notin {nkSym, nkIdent}:
      illFormedAst(n.sons[i])
    var id: PIdent
    if n.sons[i].sons[0].kind == nkIdent: id = n.sons[i].sons[0].ident
--- a/compiler/semfold.nim
+++ b/compiler/semfold.nim
@@ -222,7 +222,7 @@ proc getIntervalType*(m: TMagic, n: PNode): PType =
    commutativeOp(min)
  of mMaxI, mMaxI64:
    commutativeOp(max)
-  else: nil
+  else: discard
  
 discard """
  mShlI, mShlI64,
@@ -546,7 +546,7 @@ proc foldArrayAccess(m: PSym, n: PNode): PNode =
    if (idx >= 0) and (idx < len(x.strVal)): 
      result.intVal = ord(x.strVal[int(idx)])
    elif idx == len(x.strVal): 
-      nil
+      discard
    else: 
      localError(n.info, errIndexOutOfBounds)
  else: discard
--- a/compiler/semmagic.nim
+++ b/compiler/semmagic.nim
@@ -53,7 +53,7 @@ proc semTypeTraits(c: PContext, n: PNode): PNode =
  if t.sonsLen > 0:
    # This is either a type known to sem or a typedesc
    # param to a regular proc (again, known at instantiation)
-    result = evalTypeTrait(n[0], t, GetCurrOwner())
+    result = evalTypeTrait(n[0], t, getCurrOwner())
  else:
    # a typedesc variable, pass unmodified to evals
    result = n
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -136,6 +136,7 @@ proc discardCheck(c: PContext, result: PNode) =
  if result.typ != nil and result.typ.kind notin {tyStmt, tyEmpty}:
    if result.kind == nkNilLit:
      result.typ = nil
+      message(result.info, warnNilStatement)
    elif implicitlyDiscardable(result):
      var n = result
      result.typ = nil
@@ -145,10 +146,11 @@ proc discardCheck(c: PContext, result: PNode) =
    elif c.inTypeClass > 0 and result.typ.kind == tyBool:
      let verdict = semConstExpr(c, result)
      if verdict.intVal == 0:
-        localError(result.info, "type class predicate failed.")
+        localError(result.info, "type class predicate failed")
    elif result.typ.kind != tyError and gCmd != cmdInteractive:
      if result.typ.kind == tyNil:
        fixNilType(result)
+        message(result.info, warnNilStatement)
      else:
        var n = result
        while n.kind in skipForDiscardable: n = n.lastSon
@@ -996,7 +998,7 @@ proc semProcAux(c: PContext, n: PNode, kind: TSymKind,
  if proto == nil: 
    s.typ.callConv = lastOptionEntry(c).defaultCC
    # add it here, so that recursive procs are possible:
-    if sfGenSym in s.flags: nil
+    if sfGenSym in s.flags: discard
    elif kind in OverloadableSyms:
      if not typeIsDetermined:
        addInterfaceOverloadableSymAt(c, s.scope, s)
@@ -1252,9 +1254,9 @@ proc semStmtList(c: PContext, n: PNode): PNode =
      of LastBlockStmts: 
        for j in countup(i + 1, length - 1): 
          case n.sons[j].kind
-          of nkPragma, nkCommentStmt, nkNilLit, nkEmpty: nil
+          of nkPragma, nkCommentStmt, nkNilLit, nkEmpty: discard
          else: localError(n.sons[j].info, errStmtInvalidAfterReturn)
-      else: nil
+      else: discard
  if result.len == 1:
    result = result.sons[0]
  when false:
--- a/compiler/semtypes.nim
+++ b/compiler/semtypes.nim
@@ -537,7 +537,7 @@ proc semRecordNodeAux(c: PContext, n: PNode, check: var TIntSet, pos: var int,
      if a.kind == nkEmpty: addSon(father, newSymNode(f))
      else: addSon(a, newSymNode(f))
    if a.kind != nkEmpty: addSon(father, a)
-  of nkEmpty: nil
+  of nkEmpty: discard
  else: illFormedAst(n)
  
 proc addInheritedFieldsAux(c: PContext, check: var TIntSet, pos: var int, 
@@ -615,7 +615,7 @@ proc addParamOrResult(c: PContext, param: PSym, kind: TSymKind) =
 let typedescId = getIdent"typedesc"

 template shouldHaveMeta(t) =
-  InternalAssert tfHasMeta in t.flags
+  internalAssert tfHasMeta in t.flags
  # result.lastSon.flags.incl tfHasMeta

 proc liftParamType(c: PContext, procKind: TSymKind, genericParams: PNode,
@@ -745,7 +745,7 @@ proc liftParamType(c: PContext, procKind: TSymKind, genericParams: PNode,
      else:
        result = addImplicitGeneric(newTypeS(tyAnything, c))
 
-  else: nil
+  else: discard

  # result = liftingWalk(paramType)

@@ -939,7 +939,7 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
  result = nil
  if gCmd == cmdIdeTools: suggestExpr(c, n)
  case n.kind
-  of nkEmpty: nil
+  of nkEmpty: discard
  of nkTypeOfExpr:
    # for ``type(countup(1,3))``, see ``tests/ttoseq``.
    checkSonsLen(n, 1)
@@ -977,7 +977,7 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
            result = freshType(result, prev)
            result.flags.incl(tfNotNil)
          else:
-            LocalError(n.info, errGenerated, "invalid type")
+            localError(n.info, errGenerated, "invalid type")
        of 2:
          let negated = semTypeNode(c, n.sons[1], prev)
          result = makeNotType(c, negated)
@@ -1137,7 +1137,7 @@ proc processMagicType(c: PContext, m: PSym) =
  of mSet: setMagicType(m, tySet, 0) 
  of mSeq: setMagicType(m, tySequence, 0)
  of mOrdinal: setMagicType(m, tyOrdinal, 0)
-  of mPNimrodNode: nil
+  of mPNimrodNode: discard
  else: localError(m.info, errTypeExpected)
  
 proc semGenericConstraints(c: PContext, x: PType): PType =
--- a/compiler/semtypinst.nim
+++ b/compiler/semtypinst.nim
@@ -22,7 +22,7 @@ proc checkPartialConstructedType(info: TLineInfo, t: PType) =

 proc checkConstructedType*(info: TLineInfo, typ: PType) =
  var t = typ.skipTypes({tyDistinct})
-  if t.kind in tyTypeClasses: nil
+  if t.kind in tyTypeClasses: discard
  elif tfAcyclic in t.flags and skipTypes(t, abstractInst).kind != tyObject: 
    localError(info, errInvalidPragmaX, "acyclic")
  elif t.kind == tyVar and t.sons[0].kind == tyVar: 
@@ -364,7 +364,7 @@ proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType): PType =
  of tyGenericInst:
    result = instCopyType(cl, t)
    for i in 1 .. <result.sonsLen:
-      result.sons[i] = ReplaceTypeVarsT(cl, result.sons[i])
+      result.sons[i] = replaceTypeVarsT(cl, result.sons[i])
    propagateToOwner(result, result.lastSon)
  
  else:
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -381,7 +381,7 @@ proc procTypeRel(c: var TCandidate, f, a: PType): TTypeRelation =
    when useEffectSystem:
      if not compatibleEffects(f, a): return isNone
  of tyNil: result = f.allowsNil
-  else: nil
+  else: discard

 proc typeRangeRel(f, a: PType): TTypeRelation {.noinline.} =
  let
@@ -477,7 +477,7 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
  of tyAnything:
    return if f.kind == tyAnything: isGeneric
           else: isNone
-  else: nil
+  else: discard

  case f.kind
  of tyEnum:
@@ -530,7 +530,7 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
      result = typeRel(c, f.sons[1], a.sons[1])
      if result < isGeneric: result = isNone
      elif lengthOrd(fRange) != lengthOrd(a): result = isNone
-    else: nil
+    else: discard
  of tyOpenArray, tyVarargs:
    case a.kind
    of tyOpenArray, tyVarargs:
@@ -551,7 +551,7 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
        result = isConvertible
      elif typeRel(c, base(f), a.sons[0]) >= isGeneric: 
        result = isConvertible
-    else: nil
+    else: discard
  of tySequence:
    case a.kind
    of tySequence:
@@ -563,7 +563,7 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
        elif tfNotNil in f.flags and tfNotNil notin a.flags:
          result = isNilConversion
    of tyNil: result = f.allowsNil
-    else: nil
+    else: discard
  of tyOrdinal:
    if isOrdinalType(a):
      var x = if a.kind == tyOrdinal: a.sons[0] else: a
@@ -607,7 +607,7 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
      elif tfNotNil in f.flags and tfNotNil notin a.flags:
        result = isNilConversion
    of tyNil: result = f.allowsNil
-    else: nil
+    else: discard
  of tyRef: 
    case a.kind
    of tyRef:
@@ -616,7 +616,7 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
      elif tfNotNil in f.flags and tfNotNil notin a.flags:
        result = isNilConversion
    of tyNil: result = f.allowsNil
-    else: nil
+    else: discard
  of tyProc:
    result = procTypeRel(c, f, a)
    if result != isNone and tfNotNil in f.flags and tfNotNil notin a.flags:
@@ -632,7 +632,7 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
    of tyProc:
      if a.callConv != ccClosure: result = isConvertible
    of tyPtr, tyCString: result = isConvertible
-    else: nil
+    else: discard
  of tyString: 
    case a.kind
    of tyString: 
@@ -641,7 +641,7 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
      else:
        result = isEqual
    of tyNil: result = f.allowsNil
-    else: nil
+    else: discard
  of tyCString:
    # conversion from string to cstring is automatic:
    case a.kind
@@ -659,7 +659,7 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
          (skipTypes(a.sons[0], {tyRange}).kind in {tyInt..tyInt64}) and
          (a.sons[1].kind == tyChar): 
        result = isConvertible
-    else: nil
+    else: discard

  of tyEmpty:
    if a.kind == tyEmpty: result = isEqual
@@ -691,7 +691,7 @@ proc typeRel(c: var TCandidate, f, aOrig: PType, doBind = true): TTypeRelation =
    if x.kind == tyGenericInvokation or f.sons[0].kind != tyGenericBody:
      #InternalError("typeRel: tyGenericInvokation -> tyGenericInvokation")
      # simply no match for now:
-      nil
+      discard
    elif x.kind == tyGenericInst and 
          (f.sons[0] == x.sons[0]) and
          (sonsLen(x) - 1 == sonsLen(f)):
@@ -947,10 +947,10 @@ proc matchUserTypeClass*(c: PContext, m: var TCandidate,
    if e == nil: return nil

    case e.kind
-    of nkReturnStmt: nil
-    of nkTypeSection: nil
-    of nkConstDef: nil
-    else: nil
+    of nkReturnStmt: discard
+    of nkTypeSection: discard
+    of nkConstDef: discard
+    else: discard
  
  result = arg
  put(m.bindings, f, a)
@@ -976,7 +976,7 @@ proc paramTypesMatchAux(m: var TCandidate, f, argType: PType,
 
  var
    r: TTypeRelation
-    a = if c.InTypeClass > 0: argType.skipTypes({tyTypeDesc})
+    a = if c.inTypeClass > 0: argType.skipTypes({tyTypeDesc})
        else: argType
 
  case fMaybeStatic.kind
--- a/compiler/suggest.nim
+++ b/compiler/suggest.nim
@@ -103,7 +103,7 @@ proc suggestObject(c: PContext, n: PNode, outputs: var int) =
      suggestObject(c, n.sons[0], outputs)
      for i in countup(1, L-1): suggestObject(c, lastSon(n.sons[i]), outputs)
  of nkSym: suggestField(c, n.sym, outputs)
-  else: nil
+  else: discard

 proc nameFits(c: PContext, s: PSym, n: PNode): bool = 
  var op = n.sons[0]
--- a/compiler/transf.nim
+++ b/compiler/transf.nim
@@ -193,7 +193,7 @@ proc transformConstSection(c: PTransf, v: PNode): PTransNode =

 proc hasContinue(n: PNode): bool = 
  case n.kind
-  of nkEmpty..nkNilLit, nkForStmt, nkParForStmt, nkWhileStmt: nil
+  of nkEmpty..nkNilLit, nkForStmt, nkParForStmt, nkWhileStmt: discard
  of nkContinueStmt: result = true
  else: 
    for i in countup(0, sonsLen(n) - 1): 
@@ -536,7 +536,7 @@ proc getMergeOp(n: PNode): PSym =
    if (n.sons[0].kind == nkSym) and (n.sons[0].sym.kind == skProc) and
        (sfMerge in n.sons[0].sym.flags): 
      result = n.sons[0].sym
-  else: nil
+  else: discard

 proc flattenTreeAux(d, a: PNode, op: PSym) = 
  var op2 = getMergeOp(a)
--- a/compiler/types.nim
+++ b/compiler/types.nim
@@ -345,7 +345,7 @@ proc canFormAcycleAux(marker: var TIntSet, typ: PType, startId: int): bool =
    #  # damn inheritance may introduce cycles:
    #  result = true
  of tyProc: result = typ.callConv == ccClosure
-  else: nil
+  else: discard

 proc canFormAcycle(typ: PType): bool =
  var marker = initIntSet()
@@ -432,10 +432,10 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
    if t.len == 0: result = "typedesc"
    else: result = "typedesc[" & typeToString(t.sons[0]) & "]"
  of tyStatic:
-    InternalAssert t.len > 0
+    internalAssert t.len > 0
    result = "static[" & typeToString(t.sons[0]) & "]"
  of tyTypeClass:
-    InternalAssert t.sym != nil and t.sym.owner != nil
+    internalAssert t.sym != nil and t.sym.owner != nil
    return t.sym.owner.name.s
  of tyBuiltInTypeClass:
    return "TypeClass"
@@ -446,7 +446,7 @@ proc typeToString(typ: PType, prefer: TPreferedDesc = preferName): string =
  of tyNot:
    result = "not " & typeToString(t.sons[0])
  of tyExpr:
-    InternalAssert t.len == 0
+    internalAssert t.len == 0
    result = "expr"
  of tyFromExpr:
    result = renderTree(t.n)
--- a/doc/manual.txt
+++ b/doc/manual.txt
@@ -1333,7 +1333,7 @@ Examples:
    # has default calling convention
    echo "x: ", mouseX, " y: ", mouseY
  
-  proc setOnMouseMove(mouseMoveEvent: TOnMouseMove) = nil
+  proc setOnMouseMove(mouseMoveEvent: TOnMouseMove) = discard
  
  # ok, 'onMouseMove' has the default calling convention, which is compatible
  # to 'closure':
--- a/doc/tut1.txt
+++ b/doc/tut1.txt
@@ -324,12 +324,12 @@ the compiler that for every other value nothing should be done:
  case n
  of 0..2, 4..7: echo("The number is in the set: {0, 1, 2, 4, 5, 6, 7}")
  of 3, 8: echo("The number is 3 or 8")
-  else: nil
+  else: discard

-The ``nil`` statement is a *do nothing* statement. The compiler knows that a
-case statement with an else part cannot fail and thus the error disappears. Note
-that it is impossible to cover all possible string values: that is why there is
-no such check for string cases.
+The empty ``discard`` statement is a *do nothing* statement. The compiler knows
+that a case statement with an else part cannot fail and thus the error 
+disappears. Note that it is impossible to cover all possible string values: 
+that is why there is no such check for string cases.

 In general the case statement is used for subrange types or enumerations where
 it is of great help that the compiler checks that you covered any possible
--- a/doc/tut2.txt
+++ b/doc/tut2.txt
@@ -614,7 +614,7 @@ simple proc for logging:

 .. code-block:: nimrod
  const
-    debug = True
+    debug = true

  proc log(msg: string) {.inline.} =
    if debug: stdout.writeln(msg)
@@ -631,7 +631,7 @@ Turning the ``log`` proc into a template solves this problem:

 .. code-block:: nimrod
  const
-    debug = True
+    debug = true

  template log(msg: string) =
    if debug: stdout.writeln(msg)
@@ -674,16 +674,15 @@ via a special ``:`` syntax:

  template withFile(f: expr, filename: string, mode: TFileMode,
                    body: stmt): stmt {.immediate.} =
-    block:
-      let fn = filename
-      var f: TFile
-      if open(f, fn, mode):
-        try:
-          body
-        finally:
-          close(f)
-      else:
-        quit("cannot open: " & fn)
+    let fn = filename
+    var f: TFile
+    if open(f, fn, mode):
+      try:
+        body
+      finally:
+        close(f)
+    else:
+      quit("cannot open: " & fn)
      
  withFile(txt, "ttempl3.txt", fmWrite):
    txt.writeln("line 1")
@@ -784,7 +783,7 @@ regular expressions:
  macro case_token(n: stmt): stmt =
    # creates a lexical analyzer from regular expressions
    # ... (implementation is an exercise for the reader :-)
-    nil
+    discard

  case_token: # this colon tells the parser it is a macro statement
  of r"[A-Za-z_]+[A-Za-z_0-9]*":
--- a/lib/packages/docutils/highlite.nim
+++ b/lib/packages/docutils/highlite.nim
@@ -73,7 +73,7 @@ proc initGeneralTokenizer*(g: var TGeneralTokenizer, buf: string) =
  g.pos = pos

 proc deinitGeneralTokenizer*(g: var TGeneralTokenizer) = 
-  nil
+  discard

 proc nimGetKeyword(id: string): TTokenClass = 
  for k in nimrodKeywords:
@@ -102,7 +102,7 @@ proc nimNumberPostfix(g: var TGeneralTokenizer, position: int): int =
      if g.buf[pos] in {'0'..'9'}: inc(pos)
      if g.buf[pos] in {'0'..'9'}: inc(pos)
    else: 
-      nil
+      discard
  result = pos

 proc nimNumber(g: var TGeneralTokenizer, position: int): int = 
--- a/lib/packages/docutils/rst.nim
+++ b/lib/packages/docutils/rst.nim
@@ -535,7 +535,7 @@ proc match(p: TRstParser, start: int, expr: string): bool =
        case p.tok[j].symbol[0]
        of 'a'..'z', 'A'..'Z': result = len(p.tok[j].symbol) == 1
        of '0'..'9': result = allCharsInSet(p.tok[j].symbol, {'0'..'9'})
-        else: nil
+        else: discard
    else: 
      var c = expr[i]
      var length = 0
@@ -640,7 +640,7 @@ proc parseUrl(p: var TRstParser, father: PRstNode) =
    var n = newRstNode(rnStandaloneHyperlink)
    while true: 
      case p.tok[p.idx].kind
-      of tkWord, tkAdornment, tkOther: nil
+      of tkWord, tkAdornment, tkOther: discard
      of tkPunct: 
        if p.tok[p.idx+1].kind notin {tkWord, tkAdornment, tkOther, tkPunct}:
          break
@@ -806,7 +806,7 @@ proc parseInline(p: var TRstParser, father: PRstNode) =
        return
    add(father, newLeaf(p))
    inc(p.idx)
-  else: nil
+  else: discard
  
 proc getDirective(p: var TRstParser): string = 
  if p.tok[p.idx].kind == tkWhite and p.tok[p.idx+1].kind == tkWord: 
@@ -1339,7 +1339,7 @@ proc parseSection(p: var TRstParser, result: PRstNode) =
    of rnDirective: a = parseDotDot(p)
    of rnEnumList: a = parseEnumList(p)
    of rnLeaf: rstMessage(p, meNewSectionExpected)
-    of rnParagraph: nil
+    of rnParagraph: discard
    of rnDefList: a = parseDefinitionList(p)
    of rnFieldList: 
      if p.idx > 0: dec(p.idx)
@@ -1351,7 +1351,7 @@ proc parseSection(p: var TRstParser, result: PRstNode) =
    of rnOptionList: a = parseOptionList(p)
    else:
      #InternalError("rst.parseSection()")
-      nil
+      discard
    if a == nil and k != rnDirective: 
      a = newRstNode(rnParagraph)
      parseParagraph(p, a)
@@ -1624,7 +1624,7 @@ proc resolveSubs(p: var TRstParser, n: PRstNode): PRstNode =
      add(result, n)
      add(result, y)
  of rnLeaf: 
-    nil
+    discard
  of rnContents: 
    p.hasToc = true
  else: 
--- a/lib/packages/docutils/rstgen.nim
+++ b/lib/packages/docutils/rstgen.nim
@@ -165,7 +165,7 @@ proc nextSplitPoint*(s: string, start: int): int =
    of 'a'..'z': 
      if result + 1 < len(s) + 0: 
        if s[result + 1] in {'A'..'Z'}: return 
-    else: nil
+    else: discard
    inc(result)
  dec(result)                 # last valid index
  
--- a/lib/pure/json.nim
+++ b/lib/pure/json.nim
@@ -626,7 +626,7 @@ proc len*(n: PJsonNode): int =
  case n.kind
  of JArray: result = n.elems.len
  of JObject: result = n.fields.len
-  else: nil
+  else: discard

 proc `[]`*(node: PJsonNode, name: string): PJsonNode =
  ## Gets a field from a `JObject`. Returns nil if the key is not found.
@@ -646,6 +646,7 @@ proc hasKey*(node: PJsonNode, key: string): bool =
  assert(node.kind == JObject)
  for k, item in items(node.fields):
    if k == key: return true
+
 proc existsKey*(node: PJsonNode, key: string): bool {.deprecated.} = node.hasKey(key)
  ## Deprecated for `hasKey`

--- a/lib/pure/osproc.nim
+++ b/lib/pure/osproc.nim
@@ -329,7 +329,7 @@ when defined(Windows) and not defined(useNimRtl):
      handle: THandle
      atTheEnd: bool

-  proc hsClose(s: PStream) = nil # nothing to do here
+  proc hsClose(s: PStream) = discard # nothing to do here
  proc hsAtEnd(s: PStream): bool = return PFileHandleStream(s).atTheEnd

  proc hsReadData(s: PStream, buffer: pointer, bufLen: int): int =
--- a/lib/pure/parseutils.nim
+++ b/lib/pure/parseutils.nim
@@ -370,7 +370,7 @@ iterator interpolatedFragments*(s: string): tuple[kind: TInterpolatedKind,
          of '\0':
            raise newException(EInvalidValue, 
              "Expected closing '}': " & s[i..s.len])
-          else: nil
+          else: discard
          inc j
        inc i, 2 # skip ${
        kind = ikExpr
--- a/lib/pure/sockets.nim
+++ b/lib/pure/sockets.nim
@@ -1523,7 +1523,7 @@ proc skip*(socket: TSocket) {.tags: [FReadIO], deprecated.} =
  ## **Deprecated since version 0.9.2**: This function is not safe for use.
  const bufSize = 1000
  var buf = alloc(bufSize)
-  while recv(socket, buf, bufSize) == bufSize: nil
+  while recv(socket, buf, bufSize) == bufSize: discard
  dealloc(buf)

 proc skip*(socket: TSocket, size: int, timeout = -1) =
--- a/lib/pure/streams.nim
+++ b/lib/pure/streams.nim
@@ -281,7 +281,7 @@ proc newFileStream*(filename: string, mode: TFileMode): PFileStream =


 when true:
-  nil
+  discard
 else:
  type
    TFileHandle* = cint ## Operating system file handle
--- a/lib/pure/strutils.nim
+++ b/lib/pure/strutils.nim
@@ -304,7 +304,7 @@ proc countLines*(s: string): int {.noSideEffect,
      if s[i+1] == '\l': inc i
      inc result
    of '\l': inc result
-    else: nil
+    else: discard
    inc i

 proc split*(s: string, seps: set[char] = Whitespace): seq[string] {.
--- a/lib/pure/times.nim
+++ b/lib/pure/times.nim
@@ -698,7 +698,7 @@ proc format*(info: TTimeInfo, f: string): string =
      of "ZZZ":
        result.add(info.tzname)
      of "":
-        nil # Do nothing.
+        discard
      else:
        raise newException(EInvalidValue, "Invalid format string: " & currentF)
      
--- a/lib/system/gc.nim
+++ b/lib/system/gc.nim
@@ -1029,11 +1029,7 @@ when not defined(useNimRtl):
        dec(gch.recGcLock)

  proc GC_setStrategy(strategy: TGC_Strategy) =
-    case strategy
-    of gcThroughput: nil
-    of gcResponsiveness: nil
-    of gcOptimizeSpace: nil
-    of gcOptimizeTime: nil
+    discard

  proc GC_enableMarkAndSweep() =
    gch.cycleThreshold = InitialCycleThreshold
--- a/web/news.txt
+++ b/web/news.txt
@@ -3,7 +3,7 @@ News
 ====


-2013-XX-XX Version 0.9.4 released
+2014-XX-XX Version 0.9.4 released
 =================================


@@ -37,6 +37,7 @@ Changes affecting backwards compatibility
  passed to shell, instead of just adding double quotes.
 - ``macros.dumpTree`` and ``macros.dumpLisp`` have been made ``immediate``,
  ``dumpTreeImm`` and ``dumpLispImm`` are now deprecated.
+- The ``nil`` statement has been deprecated, use an empty ``discard`` instead.


 Compiler Additions
@@ -68,7 +69,7 @@ Language Additions
  fields at compile-time.
 - The overload resolution now supports ``static[T]`` params that must be
  evaluatable at compile-time.
- Support for user-defined type classes have been added.
+- Support for user-defined type classes has been added.


 Tools improvements