fixes #584

compiler/guards.nim

@@ -9,7 +9,7 @@
 
 ## This module implements the 'implies' relation for guards.
 
-import ast, astalgo, msgs, magicsys, nimsets, trees, types, renderer
+import ast, astalgo, msgs, magicsys, nimsets, trees, types, renderer, idents
 
 const
   someEq = {mEqI, mEqI64, mEqF64, mEqEnum, mEqCh, mEqB, mEqRef, mEqProc,
@@ -69,9 +69,23 @@ proc isLetLocation(m: PNode, isApprox: bool): bool =
 
 proc interestingCaseExpr*(m: PNode): bool = isLetLocation(m, true)
 
-proc swapArgs(fact: PNode, newOp: string, m: TMagic): PNode =
+proc getMagicOp(name: string, m: TMagic): PSym =
+  result = newSym(skProc, getIdent(name), nil, unknownLineInfo())
+  result.magic = m
+
+let
+  opLe = getMagicOp("<=", mLeI)
+  opLt = getMagicOp("<", mLtI)
+  opAnd = getMagicOp("and", mAnd)
+  opOr = getMagicOp("or", mOr)
+  opNot = getMagicOp("not", mNot)
+  opIsNil = getMagicOp("isnil", mIsNil)
+  opContains = getMagicOp("contains", mInSet)
+  opEq = getMagicOp("==", mEqI)
+
+proc swapArgs(fact: PNode, newOp: PSym): PNode =
   result = newNodeI(nkCall, fact.info, 3)
-  result.sons[0] = newSymNode(getSysMagic(newOp, m))
+  result.sons[0] = newSymNode(newOp)
   result.sons[1] = fact.sons[2]
   result.sons[2] = fact.sons[1]
 
@@ -82,9 +96,9 @@ proc neg(n: PNode): PNode =
     result = n.sons[1]
   of someLt:
     # not (a < b)  ==  a >= b  ==  b <= a
-    result = swapArgs(n, "<=", mLeI)
+    result = swapArgs(n, opLe)
   of someLe:
-    result = swapArgs(n, "<", mLtI)
+    result = swapArgs(n, opLt)
   of mInSet:
     if n.sons[1].kind != nkCurly: return nil
     let t = n.sons[2].typ.skipTypes(abstractInst)
@@ -110,7 +124,7 @@ proc neg(n: PNode): PNode =
       b = n.sons[2].neg
     if a != nil and b != nil:
       result = newNodeI(nkCall, n.info, 3)
-      result.sons[0] = newSymNode(getSysMagic("and", mAnd))
+      result.sons[0] = newSymNode(opAnd)
       result.sons[1] = a
       result.sons[2] = b
     elif a != nil:
@@ -120,12 +134,12 @@ proc neg(n: PNode): PNode =
   else:
     # leave  not (a == 4)  as it is
     result = newNodeI(nkCall, n.info, 2)
-    result.sons[0] = newSymNode(getSysMagic("not", mNot))
+    result.sons[0] = newSymNode(opNot)
     result.sons[1] = n
 
 proc buildIsNil(arg: PNode): PNode =
   result = newNodeI(nkCall, arg.info, 2)
-  result.sons[0] = newSymNode(getSysMagic("isNil", mIsNil))
+  result.sons[0] = newSymNode(opIsNil)
   result.sons[1] = arg
 
 proc usefulFact(n: PNode): PNode =
@@ -154,7 +168,7 @@ proc usefulFact(n: PNode): PNode =
       b = usefulFact(n.sons[2])
     if a != nil and b != nil:
       result = newNodeI(nkCall, n.info, 3)
-      result.sons[0] = newSymNode(getSysMagic("and", mAnd))
+      result.sons[0] = newSymNode(opAnd)
       result.sons[1] = a
       result.sons[2] = b
     elif a != nil:
@@ -177,7 +191,7 @@ proc usefulFact(n: PNode): PNode =
       b = usefulFact(n.sons[2]).neg
     if a != nil and b != nil:
       result = newNodeI(nkCall, n.info, 3)
-      result.sons[0] = newSymNode(getSysMagic("and", mAnd))
+      result.sons[0] = newSymNode(opAnd)
       result.sons[1] = a
       result.sons[2] = b
       result = result.neg
@@ -520,7 +534,7 @@ proc buildOf(it, loc: PNode): PNode =
   s.typ = settype(loc)
   for i in 0..it.len-2: s.sons[i] = it.sons[i]
   result = newNodeI(nkCall, it.info, 3)
-  result.sons[0] = newSymNode(getSysMagic("contains", mInSet))
+  result.sons[0] = newSymNode(opContains)
   result.sons[1] = s
   result.sons[2] = loc
 
@@ -532,20 +546,20 @@ proc buildElse(n: PNode): PNode =
     for j in 0..branch.len-2:
       s.add(branch.sons[j])
   result = newNodeI(nkCall, n.info, 3)
-  result.sons[0] = newSymNode(getSysMagic("contains", mInSet))
+  result.sons[0] = newSymNode(opContains)
   result.sons[1] = s
   result.sons[2] = n.sons[0]
 
 proc addDiscriminantFact*(m: var TModel, n: PNode) =
   var fact = newNodeI(nkCall, n.info, 3)
-  fact.sons[0] = newSymNode(getSysMagic("==", mEqI))
+  fact.sons[0] = newSymNode(opEq)
   fact.sons[1] = n.sons[0]
   fact.sons[2] = n.sons[1]
   m.add fact
 
 proc addAsgnFact*(m: var TModel, key, value: PNode) =
   var fact = newNodeI(nkCall, key.info, 3)
-  fact.sons[0] = newSymNode(getSysMagic("==", mEqI))
+  fact.sons[0] = newSymNode(opEq)
   fact.sons[1] = key
   fact.sons[2] = value
   m.add fact

compiler/sempass2.nim

@@ -84,10 +84,10 @@ proc initVar(a: PEffects, n: PNode) =
 proc initVarViaNew(a: PEffects, n: PNode) =
   if n.kind != nkSym: return
   let s = n.sym
-  if {tfNeedsInit, tfNotNil} * s.typ.flags == {tfNotNil}:
+  if {tfNeedsInit, tfNotNil} * s.typ.flags <= {tfNotNil}:
     # 'x' is not nil, but that doesn't mean it's not nil children
     # are initialized:
-    initVarViaNew(a, n)
+    initVar(a, n)
 
 proc useVar(a: PEffects, n: PNode) =
   let s = n.sym
@@ -466,8 +466,7 @@ proc track(tracked: PEffects, n: PNode) =
         mergeEffects(tracked, effectList.sons[exceptionEffects], n)
         mergeTags(tracked, effectList.sons[tagEffects], n)
     for i in 1 .. <len(n): trackOperand(tracked, n.sons[i], paramType(op, i))
-    if a.kind == nkSym and a.sym.magic in {mNew, mNewFinalize, 
-                                           mNewSeq, mShallowCopy}:
+    if a.kind == nkSym and a.sym.magic in {mNew, mNewFinalize, mNewSeq}:
       # may not look like an assignment, but it is:
       initVarViaNew(tracked, n.sons[1])
     for i in 0 .. <safeLen(n):
@@ -581,22 +580,26 @@ proc setEffectsForProcType*(t: PType, n: PNode) =
     if not isNil(tagsSpec):
       effects.sons[tagEffects] = tagsSpec
 
+proc initEffects(effects: PNode; s: PSym; t: var TEffects) =
+  newSeq(effects.sons, effectListLen)
+  effects.sons[exceptionEffects] = newNodeI(nkArgList, s.info)
+  effects.sons[tagEffects] = newNodeI(nkArgList, s.info)
+  
+  t.exc = effects.sons[exceptionEffects]
+  t.tags = effects.sons[tagEffects]
+  t.owner = s
+  t.init = @[]
+  t.guards = @[]
+  
 proc trackProc*(s: PSym, body: PNode) =
   var effects = s.typ.n.sons[0]
   internalAssert effects.kind == nkEffectList
   # effects already computed?
   if sfForward in s.flags: return
   if effects.len == effectListLen: return
-  newSeq(effects.sons, effectListLen)
-  effects.sons[exceptionEffects] = newNodeI(nkArgList, body.info)
-  effects.sons[tagEffects] = newNodeI(nkArgList, body.info)
   
   var t: TEffects
-  t.exc = effects.sons[exceptionEffects]
-  t.tags = effects.sons[tagEffects]
-  t.owner = s
-  t.init = @[]
-  t.guards = @[]
+  initEffects(effects, s, t)
   track(t, body)
   
   if not isEmptyType(s.typ.sons[0]) and tfNeedsInit in s.typ.sons[0].flags and
@@ -619,3 +622,9 @@ proc trackProc*(s: PSym, body: PNode) =
     # after the check, use the formal spec:
     effects.sons[tagEffects] = tagsSpec
     
+proc trackTopLevelStmt*(module: PSym; n: PNode) =
+  var effects = newNode(nkEffectList, n.info)
+  var t: TEffects
+  initEffects(effects, module, t)
+
+  track(t, n)

compiler/transf.nim

@@ -754,6 +754,7 @@ proc transformStmt*(module: PSym, n: PNode): PNode =
     result = processTransf(c, n, module)
     result = liftLambdasForTopLevel(module, result)
     incl(result.flags, nfTransf)
+    when useEffectSystem: trackTopLevelStmt(module, result)
 
 proc transformExpr*(module: PSym, n: PNode): PNode =
   if nfTransf in n.flags:

tests/effects/teffects6.nim

@@ -4,7 +4,7 @@ type
   PMenuItem = ref object
 
 proc createMenuItem*(menu: PMenu, label: string, 
-                     action: proc (i: PMenuItem, p: pointer) {.cdecl.}) = nil
+                    action: proc (i: PMenuItem, p: pointer) {.cdecl.}) = discard
 
 var s: PMenu
 createMenuItem(s, "Go to definition...",

tests/notnil/tnotnil3.nim

@@ -0,0 +1,35 @@
+discard """
+  errormsg: "cannot prove 'variable' is not nil"
+  line: 31
+"""
+
+# bug #584
+# Testprogram for 'not nil' check
+
+const testWithResult = true
+
+type
+  A = object
+  B = object
+  C = object
+    a: ref A
+    b: ref B
+
+
+proc testNotNil(c: ref C not nil) =
+  discard
+
+
+when testWithResult:
+  proc testNotNilOnResult(): ref C =
+    new(result)
+    #result.testNotNil() # Here 'not nil' can't be proved
+
+
+var variable: ref C
+new(variable)
+variable.testNotNil() # Here 'not nil' is proved
+
+when testWithResult:
+  discard testNotNilOnResult()
+