diff --git a/compiler/ccgthreadvars.nim b/compiler/ccgthreadvars.nim
index 7ef084ba8..7ef084ba8 100644..100755
--- a/compiler/ccgthreadvars.nim
+++ b/compiler/ccgthreadvars.nim
diff --git a/compiler/lookups.nim b/compiler/lookups.nim
index d72ec1555..a2cb434a0 100755
--- a/compiler/lookups.nim
+++ b/compiler/lookups.nim
@@ -52,12 +52,12 @@ proc CloseScope*(tab: var TSymTab) =
   if (tab.tos > len(tab.stack)): InternalError("CloseScope")
   var it: TTabIter
   var s = InitTabIter(it, tab.stack[tab.tos-1])
-  while s != nil: 
+  while s != nil:
     if sfForward in s.flags: 
       LocalError(s.info, errImplOfXexpected, getSymRepr(s))
-    elif ({sfUsed, sfInInterface} * s.flags == {}) and
-        (optHints in s.options): # BUGFIX: check options in s!
-      if not (s.kind in {skForVar, skParam, skMethod, skUnknown}): 
+    elif {sfUsed, sfInInterface} * s.flags == {} and optHints in s.options: 
+      # BUGFIX: check options in s!
+      if s.kind notin {skForVar, skParam, skMethod, skUnknown, skGenericParam}:
         Message(s.info, hintXDeclaredButNotUsed, getSymRepr(s))
     s = NextIter(it, tab.stack[tab.tos-1])
   astalgo.rawCloseScope(tab)
diff --git a/compiler/msgs.nim b/compiler/msgs.nim
index f6ec4729a..b2ead1d9e 100755
--- a/compiler/msgs.nim
+++ b/compiler/msgs.nim
@@ -522,6 +522,7 @@ proc rawMessage*(msg: TMsgKind, args: openarray[string]) =
   of warnMin..warnMax: 
     if not (optWarns in gOptions): return 
     if not (msg in gNotes): return 
+    writeContext(unknownLineInfo())
     frmt = rawWarningFormat
     inc(gWarnCounter)
   of hintMin..hintMax: 
@@ -552,6 +553,7 @@ proc liMessage(info: TLineInfo, msg: TMsgKind, arg: string,
     lastError = info
   of warnMin..warnMax: 
     ignoreMsg = optWarns notin gOptions or msg notin gNotes
+    if not ignoreMsg: writeContext(info)
     frmt = posWarningFormat
     inc(gWarnCounter)
   of hintMin..hintMax: 
diff --git a/compiler/nversion.nim b/compiler/nversion.nim
index 8fb436f11..45b804d40 100755
--- a/compiler/nversion.nim
+++ b/compiler/nversion.nim
@@ -1,7 +1,7 @@
 #
 #
 #           The Nimrod Compiler
-#        (c) Copyright 2010 Andreas Rumpf
+#        (c) Copyright 2011 Andreas Rumpf
 #
 #    See the file "copying.txt", included in this
 #    distribution, for details about the copyright.
@@ -15,6 +15,6 @@ const
   defaultAsmMarkerSymbol* = '!'
   VersionMajor* = 0
   VersionMinor* = 8
-  VersionPatch* = 11
+  VersionPatch* = 12
   VersionAsString* = $VersionMajor & "." & $VersionMinor & "." & $VersionPatch
 
diff --git a/compiler/seminst.nim b/compiler/seminst.nim
index c398f1ca2..2db8289f2 100755
--- a/compiler/seminst.nim
+++ b/compiler/seminst.nim
@@ -19,6 +19,8 @@ proc instantiateGenericParamList(c: PContext, n: PNode, pt: TIdTable) =
     var q = a.sym
     if not (q.typ.kind in {tyTypeDesc, tyGenericParam}): continue 
     var s = newSym(skType, q.name, getCurrOwner())
+    s.info = q.info
+    incl(s.flags, sfUsed)
     var t = PType(IdTableGet(pt, q.typ))
     if t == nil: 
       LocalError(a.info, errCannotInstantiateX, s.name.s)
diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index 4a80bb783..61709ad48 100755
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -205,7 +205,7 @@ proc semIdentDef(c: PContext, n: PNode, kind: TSymKind): PSym =
     incl(result.flags, sfGlobal)
   else: 
     result = semIdentWithPragma(c, kind, n, {})
-  
+    
 proc semVar(c: PContext, n: PNode): PNode = 
   var b: PNode
   result = copyNode(n)
diff --git a/compiler/semthreads.nim b/compiler/semthreads.nim
index bff8823b2..b6bdc9e60 100644..100755
--- a/compiler/semthreads.nim
+++ b/compiler/semthreads.nim
@@ -112,7 +112,7 @@ proc analyseSym(c: PProcCtx, n: PNode): TThreadOwner =
     if sfGlobal in v.flags:
       if sfThreadVar in v.flags: 
         result = toMine 
-      elif containsTyRef(v.typ):
+      elif containsGarbageCollectedRef(v.typ):
         result = toTheirs
   of skTemp, skForVar: result = toNil
   of skConst: result = toMine
@@ -126,7 +126,8 @@ proc analyseSym(c: PProcCtx, n: PNode): TThreadOwner =
 
 proc lvalueSym(n: PNode): PNode =
   result = n
-  while result.kind in {nkDotExpr, nkBracketExpr, nkDerefExpr, nkHiddenDeref}:
+  while result.kind in {nkDotExpr, nkCheckedFieldExpr,
+                        nkBracketExpr, nkDerefExpr, nkHiddenDeref}:
     result = result.sons[0]
 
 proc writeAccess(c: PProcCtx, n: PNode, owner: TThreadOwner) =
@@ -138,7 +139,18 @@ proc writeAccess(c: PProcCtx, n: PNode, owner: TThreadOwner) =
     var lastOwner = analyseSym(c, a)
     case lastOwner
     of toNil:
-      c.mapping[v.id] = owner # fine, toNil can be overwritten
+      # fine, toNil can be overwritten
+      var newOwner: TThreadOwner
+      if sfGlobal in v.flags:
+        newOwner = owner
+      elif containsTyRef(v.typ):
+        # ``var local = gNode`` --> ok, but ``local`` is theirs! 
+        newOwner = owner
+      else:
+        # ``var local = gString`` --> string copy: ``local`` is mine! 
+        newOwner = toMine
+        # XXX BUG what if the tuple contains both ``tyRef`` and ``tyString``?
+      c.mapping[v.id] = newOwner
     of toVoid, toUndefined: InternalError(n.info, "writeAccess")
     of toTheirs: Message(n.info, warnWriteToForeignHeap)
     of toMine:
@@ -146,7 +158,7 @@ proc writeAccess(c: PProcCtx, n: PNode, owner: TThreadOwner) =
         Message(n.info, warnDifferentHeaps)
   else:
     # we could not backtrack to a concrete symbol, but that's fine:
-    var lastOwner = analyseSym(c, n)
+    var lastOwner = analyse(c, n)
     case lastOwner
     of toNil: nil # fine, toNil can be overwritten
     of toVoid, toUndefined: InternalError(n.info, "writeAccess")
@@ -178,7 +190,7 @@ proc analyseCall(c: PProcCtx, n: PNode): TThreadOwner =
     pushInfoContext(n.info)
     result = analyse(newCtx, prc.ast.sons[codePos])
     if prc.ast.sons[codePos].kind == nkEmpty and 
-       {sfNoSideEffect, sfThread} * prc.flags == {}:
+       {sfNoSideEffect, sfThread, sfImportc} * prc.flags == {}:
       Message(n.info, warnAnalysisLoophole, renderTree(n))
     if prc.typ.sons[0] != nil:
       if prc.ast.len > resultPos:
@@ -228,7 +240,7 @@ template aggregateOwner(result, ana: expr) =
   var a = ana # eval once
   if result != a:
     if result == toNil: result = a
-    else: Message(n.info, warnDifferentHeaps)
+    elif a != toNil: Message(n.info, warnDifferentHeaps)
 
 proc analyseArgs(c: PProcCtx, n: PNode, start = 1) =
   for i in start..n.len-1: discard analyse(c, n[i])
@@ -241,7 +253,14 @@ proc analyseOp(c: PProcCtx, n: PNode): TThreadOwner =
   else:
     var prc = n[0].sym
     case prc.magic
-    of mNone: result = analyseCall(c, n)
+    of mNone: 
+      if sfSystemModule in prc.owner.flags:
+        # System module proc does no harm :-)
+        analyseArgs(c, n)
+        if prc.typ.sons[0] == nil: result = toVoid
+        else: result = toNil
+      else:
+        result = analyseCall(c, n)
     of mNew, mNewFinalize, mNewSeq, mSetLengthStr, mSetLengthSeq,
         mAppendSeqElem, mReset, mAppendStrCh, mAppendStrStr:
       writeAccess(c, n[1], toMine)
@@ -260,8 +279,7 @@ proc analyseOp(c: PProcCtx, n: PNode): TThreadOwner =
       analyseArgs(c, n)
       result = toMine
     else:
-      # don't recurse, but check args; NOTE: This is essential that
-      # ``mCreateThread`` is handled here to avoid the recursion
+      # don't recurse, but check args:
       analyseArgs(c, n)
       if prc.typ.sons[0] == nil: result = toVoid
       else: result = toNil