new feature: --staticBoundChecks:on to enforce static array index checking (#10965)

compiler/astalgo.nim

@@ -182,6 +182,7 @@ proc getModule*(s: PSym): PSym =
   assert((result.kind == skModule) or (result.owner != result))
   while result != nil and result.kind != skModule: result = result.owner
 
+proc fromSystem*(op: PSym): bool {.inline.} = sfSystemModule in getModule(op).flags
 proc getSymFromList*(list: PNode, ident: PIdent, start: int = 0): PSym =
   for i in start..<list.len:
     if list[i].kind == nkSym:

compiler/commands.nim

@@ -297,6 +297,7 @@ proc testCompileOption*(conf: ConfigRef; switch: string, info: TLineInfo): bool
   of "boundchecks": result = contains(conf.options, optBoundsCheck)
   of "refchecks": result = contains(conf.options, optRefCheck)
   of "overflowchecks": result = contains(conf.options, optOverflowCheck)
+  of "staticboundchecks": result = contains(conf.options, optStaticBoundsCheck)
   of "stylechecks": result = contains(conf.options, optStyleCheck)
   of "linedir": result = contains(conf.options, optLineDir)
   of "assertions", "a": result = contains(conf.options, optAssert)
@@ -591,6 +592,7 @@ proc processSwitch*(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
   of "boundchecks": processOnOffSwitch(conf, {optBoundsCheck}, arg, pass, info)
   of "refchecks": processOnOffSwitch(conf, {optRefCheck}, arg, pass, info)
   of "overflowchecks": processOnOffSwitch(conf, {optOverflowCheck}, arg, pass, info)
+  of "staticboundchecks": processOnOffSwitch(conf, {optStaticBoundsCheck}, arg, pass, info)
   of "stylechecks": processOnOffSwitch(conf, {optStyleCheck}, arg, pass, info)
   of "linedir": processOnOffSwitch(conf, {optLineDir}, arg, pass, info)
   of "assertions", "a": processOnOffSwitch(conf, {optAssert}, arg, pass, info)

compiler/guards.nim

@@ -250,7 +250,6 @@ proc pred(n: PNode): PNode =
     result = n
 
 proc canon*(n: PNode; o: Operators): PNode =
-  # XXX for now only the new code in 'semparallel' uses this
   if n.safeLen >= 1:
     result = shallowCopy(n)
     for i in 0..<n.len:
@@ -275,7 +274,7 @@ proc canon*(n: PNode; o: Operators): PNode =
     result = negate(result[1], result[2], result, o)
   of someLen:
     result[0] = o.opLen.newSymNode
-  of someLt:
+  of someLt - {mLtF64}:
     # x < y  same as x <= y-1:
     let y = n[2].canon(o)
     let p = pred(y)
@@ -315,12 +314,12 @@ proc canon*(n: PNode; o: Operators): PNode =
         if plus != nil and not isLetLocation(x, true):
           result = buildCall(result[0].sym, plus, y[1])
       else: discard
-    elif x.isValue and y.getMagic in someAdd and y[2].isValue:
+    elif x.isValue and y.getMagic in someAdd and y[2].kind == x.kind:
       # 0 <= a.len + 3
       # -3 <= a.len
       result[1] = x |-| y[2]
       result[2] = y[1]
-    elif x.isValue and y.getMagic in someSub and y[2].isValue:
+    elif x.isValue and y.getMagic in someSub and y[2].kind == x.kind:
       # 0 <= a.len - 3
       # 3 <= a.len
       result[1] = x |+| y[2]
@@ -340,6 +339,8 @@ proc usefulFact(n: PNode; o: Operators): PNode =
       if isLetLocation(n[1], true) or isLetLocation(n[2], true):
         # XXX algebraic simplifications!  'i-1 < a.len' --> 'i < a.len+1'
         result = n
+      elif n[1].getMagic in someLen or n[2].getMagic in someLen:
+        result = n
   of someLe+someLt:
     if isLetLocation(n[1], true) or isLetLocation(n[2], true):
       # XXX algebraic simplifications!  'i-1 < a.len' --> 'i < a.len+1'
@@ -401,10 +402,20 @@ type
   TModel* = object
     s*: seq[PNode] # the "knowledge base"
     o*: Operators
+    beSmart*: bool
 
 proc addFact*(m: var TModel, nn: PNode) =
   let n = usefulFact(nn, m.o)
-  if n != nil: m.s.add n
+  if n != nil:
+    if not m.beSmart:
+      m.s.add n
+    else:
+      let c = canon(n, m.o)
+      if c.getMagic == mAnd:
+        addFact(m, c[1])
+        addFact(m, c[2])
+      else:
+        m.s.add c
 
 proc addFactNeg*(m: var TModel, n: PNode) =
   let n = n.neg(m.o)
@@ -614,6 +625,9 @@ proc impliesGe(fact, x, c: PNode): TImplication =
 
 proc impliesLe(fact, x, c: PNode): TImplication =
   if not isLocation(x):
+    if c.isValue:
+      if leValue(x, x): return impYes
+      else: return impNo
     return impliesGe(fact, c, x)
   case fact[0].sym.magic
   of someEq:
@@ -799,7 +813,7 @@ proc ple(m: TModel; a, b: PNode): TImplication =
     if lastOrd(nil, a.typ) <= b.intVal: return impYes
   # 3 <= x   iff  low(x) <= 3
   if a.isValue and b.typ != nil and b.typ.isOrdinalType:
-    if firstOrd(nil, b.typ) <= a.intVal: return impYes
+    if a.intVal <= firstOrd(nil, b.typ): return impYes
 
   # x <= x
   if sameTree(a, b): return impYes
@@ -810,7 +824,11 @@ proc ple(m: TModel; a, b: PNode): TImplication =
 
   #   x <= y+c  if 0 <= c and x <= y
   #   x <= y+(-c)  if c <= 0  and y >= x
-  if b.getMagic in someAdd and zero() <=? b[2] and a <=? b[1]: return impYes
+  if b.getMagic in someAdd:
+    if zero() <=? b[2] and a <=? b[1]: return impYes
+    # x <= y-c  if x+c <= y
+    if b[2] <=? zero() and (canon(m.o.opSub.buildCall(a, b[2]), m.o) <=? b[1]):
+      return impYes
 
   #   x+c <= y  if c <= 0 and x <= y
   if a.getMagic in someAdd and a[2] <=? zero() and a[1] <=? b: return impYes
@@ -899,10 +917,13 @@ proc pleViaModelRec(m: var TModel; a, b: PNode): TImplication =
       # --> true  if  (len-100) <= (len-1)
       let x = fact[1]
       let y = fact[2]
-      if sameTree(x, a) and y.getMagic in someAdd and b.getMagic in someAdd and
-         sameTree(y[1], b[1]):
-        if ple(m, b[2], y[2]) == impYes:
-          return impYes
+      # x <= y.
+      # Question: x <= b? True iff y <= b.
+      if sameTree(x, a):
+        if ple(m, y, b) == impYes: return impYes
+        if y.getMagic in someAdd and b.getMagic in someAdd and sameTree(y[1], b[1]):
+          if ple(m, b[2], y[2]) == impYes:
+            return impYes
 
       # x <= y implies a <= b  if  a <= x and y <= b
       if ple(m, a, x) == impYes:
@@ -961,6 +982,10 @@ proc proveLe*(m: TModel; a, b: PNode): TImplication =
 proc addFactLe*(m: var TModel; a, b: PNode) =
   m.s.add canon(m.o.opLe.buildCall(a, b), m.o)
 
+proc addFactLt*(m: var TModel; a, b: PNode) =
+  let bb = m.o.opAdd.buildCall(b, minusOne())
+  addFactLe(m, a, bb)
+
 proc settype(n: PNode): PType =
   result = newType(tySet, n.typ.owner)
   addSonSkipIntLit(result, n.typ)

compiler/lineinfos.nim

@@ -36,7 +36,8 @@ type
     warnUnusedImportX,
     warnInheritFromException,
     warnEachIdentIsTuple,
-    warnProveInit, warnProveField, warnProveIndex, warnGcUnsafe, warnGcUnsafe2,
+    warnProveInit, warnProveField, warnProveIndex, 
+    warnStaticIndexCheck, warnGcUnsafe, warnGcUnsafe2,
     warnUninit, warnGcMem, warnDestructor, warnLockLevel, warnResultShadowed,
     warnInconsistentSpacing, warnCaseTransition, warnCycleCreated, warnUser,
     hintSuccess, hintSuccessX, hintCC,
@@ -87,6 +88,7 @@ const
     warnProveInit: "Cannot prove that '$1' is initialized. This will become a compile time error in the future.",
     warnProveField: "cannot prove that field '$1' is accessible",
     warnProveIndex: "cannot prove index '$1' is valid",
+    warnStaticIndexCheck: "$1",
     warnGcUnsafe: "not GC-safe: '$1'",
     warnGcUnsafe2: "$1",
     warnUninit: "'$1' might not have been initialized",
@@ -142,7 +144,8 @@ const
     "TypelessParam", "UseBase", "WriteToForeignHeap",
     "UnsafeCode", "UnusedImport", "InheritFromException",
     "EachIdentIsTuple",
-    "ProveInit", "ProveField", "ProveIndex", "GcUnsafe", "GcUnsafe2", "Uninit",
+    "ProveInit", "ProveField", "ProveIndex",
+    "IndexCheck", "GcUnsafe", "GcUnsafe2", "Uninit",
     "GcMem", "Destructor", "LockLevel", "ResultShadowed",
     "Spacing", "CaseTransition", "CycleCreated", "User"]
 

compiler/options.nim

@@ -26,7 +26,7 @@ type                          # please make sure we have under 32 options
   TOption* = enum             # **keep binary compatible**
     optNone, optObjCheck, optFieldCheck, optRangeCheck, optBoundsCheck,
     optOverflowCheck, optNilCheck, optRefCheck,
-    optNaNCheck, optInfCheck, optStyleCheck,
+    optNaNCheck, optInfCheck, optStaticBoundsCheck, optStyleCheck,
     optAssert, optLineDir, optWarns, optHints,
     optOptimizeSpeed, optOptimizeSize, optStackTrace, # stack tracing support
     optLineTrace,             # line tracing support (includes stack tracing)
@@ -320,7 +320,7 @@ const oldExperimentalFeatures* = {implicitDeref, dotOperators, callOperator, par
 const
   ChecksOptions* = {optObjCheck, optFieldCheck, optRangeCheck, optNilCheck,
     optOverflowCheck, optBoundsCheck, optAssert, optNaNCheck, optInfCheck,
-    optStyleCheck, optRefCheck}
+    optStyleCheck}
 
   DefaultOptions* = {optObjCheck, optFieldCheck, optRangeCheck,
     optBoundsCheck, optOverflowCheck, optAssert, optWarns, optRefCheck,

compiler/pragmas.nim

@@ -42,7 +42,8 @@ const
     wTags, wLocks, wGcSafe}
   exprPragmas* = {wLine, wLocks, wNoRewrite, wGcSafe, wNoSideEffect}
   stmtPragmas* = {wChecks, wObjChecks, wFieldChecks, wRangeChecks,
-    wBoundChecks, wOverflowChecks, wNilChecks, wStyleChecks, wAssertions,
+    wBoundChecks, wOverflowChecks, wNilChecks, wStaticBoundchecks, 
+    wStyleChecks, wAssertions,
     wWarnings, wHints,
     wLineDir, wStackTrace, wLineTrace, wOptimization, wHint, wWarning, wError,
     wFatal, wDefine, wUndef, wCompile, wLink, wLinksys, wPure, wPush, wPop,
@@ -344,6 +345,7 @@ proc pragmaToOptions(w: TSpecialWord): TOptions {.inline.} =
   of wFloatChecks: {optNaNCheck, optInfCheck}
   of wNanChecks: {optNaNCheck}
   of wInfChecks: {optInfCheck}
+  of wStaticBoundchecks: {optStaticBoundsCheck}
   of wStyleChecks: {optStyleCheck}
   of wAssertions: {optAssert}
   of wWarnings: {optWarns}
@@ -1027,7 +1029,8 @@ proc singlePragma(c: PContext, sym: PSym, n: PNode, i: var int,
       of wCodegenDecl: processCodegenDecl(c, it, sym)
       of wChecks, wObjChecks, wFieldChecks, wRangeChecks, wBoundChecks,
          wOverflowChecks, wNilChecks, wAssertions, wWarnings, wHints,
-         wLineDir, wOptimization, wStyleChecks, wCallconv, wDebugger, wProfiler,
+         wLineDir, wOptimization, wStaticBoundchecks, wStyleChecks, 
+         wCallconv, wDebugger, wProfiler,
          wFloatChecks, wNanChecks, wInfChecks, wPatterns, wTrMacros:
         processOption(c, it, c.config.options)
       of wStackTrace, wLineTrace:

compiler/semparallel.nim

@@ -23,7 +23,7 @@
 
 import
   ast, astalgo, idents, lowerings, magicsys, guards, sempass2, msgs,
-  renderer, types, modulegraphs, options, spawn
+  renderer, types, modulegraphs, options, spawn, lineinfos
 
 from trees import getMagic
 from strutils import `%`
@@ -129,10 +129,12 @@ template `?`(x): untyped = x.renderTree
 proc checkLe(c: AnalysisCtx; a, b: PNode) =
   case proveLe(c.guards, a, b)
   of impUnknown:
-    localError(c.graph.config, a.info, "cannot prove: " & ?a & " <= " & ?b & " (bounds check)")
+    message(c.graph.config, a.info, warnStaticIndexCheck,
+      "cannot prove: " & ?a & " <= " & ?b)
   of impYes: discard
   of impNo:
-    localError(c.graph.config, a.info, "can prove: " & ?a & " > " & ?b & " (bounds check)")
+    message(c.graph.config, a.info, warnStaticIndexCheck,
+      "can prove: " & ?a & " > " & ?b)
 
 proc checkBounds(c: AnalysisCtx; arr, idx: PNode) =
   checkLe(c, lowBound(c.graph.config, arr), idx)
@@ -162,17 +164,17 @@ proc overlap(m: TModel; conf: ConfigRef; x,y,c,d: PNode) =
     case proveLe(m, x, d)
     of impNo: discard
     of impUnknown, impYes:
-      localError(conf, x.info,
+      message(conf, x.info, warnStaticIndexCheck,
         "cannot prove: $# > $#; required for ($#)..($#) disjoint from ($#)..($#)" %
             [?c, ?y, ?x, ?y, ?c, ?d])
   of impYes:
     case proveLe(m, x, d)
     of impUnknown:
-      localError(conf, x.info,
+      message(conf, x.info, warnStaticIndexCheck,
         "cannot prove: $# > $#; required for ($#)..($#) disjoint from ($#)..($#)" %
           [?x, ?d, ?x, ?y, ?c, ?d])
     of impYes:
-      localError(conf, x.info, "($#)..($#) not disjoint from ($#)..($#)" %
+      message(conf, x.info, warnStaticIndexCheck, "($#)..($#) not disjoint from ($#)..($#)" %
                 [?c, ?y, ?x, ?y, ?c, ?d])
     of impNo: discard
   of impNo: discard
@@ -261,8 +263,6 @@ proc min(a, b: PNode): PNode =
   elif a.intVal < b.intVal: result = a
   else: result = b
 
-proc fromSystem(op: PSym): bool = sfSystemModule in getModule(op).flags
-
 template pushSpawnId(c, body) {.dirty.} =
   inc c.spawns
   let oldSpawnId = c.currentSpawnId

compiler/sempass2.nim

@@ -75,6 +75,7 @@ type
     gcUnsafe, isRecursive, isTopLevel, hasSideEffect, inEnforcedGcSafe: bool
     inEnforcedNoSideEffects: bool
     maxLockLevel, currLockLevel: TLockLevel
+    currOptions: TOptions
     config: ConfigRef
     graph: ModuleGraph
     c: PContext
@@ -668,6 +669,32 @@ proc cstringCheck(tracked: PEffects; n: PNode) =
       a.typ.kind == tyString and a.kind notin {nkStrLit..nkTripleStrLit}):
     message(tracked.config, n.info, warnUnsafeCode, renderTree(n))
 
+proc checkLe(c: PEffects; a, b: PNode) =
+  case proveLe(c.guards, a, b)
+  of impUnknown:
+    #for g in c.guards.s:
+    #  if g != nil: echo "I Know ", g
+    message(c.config, a.info, warnStaticIndexCheck,
+      "cannot prove: " & $a & " <= " & $b)
+  of impYes:
+    discard
+  of impNo:
+    message(c.config, a.info, warnStaticIndexCheck,
+      "can prove: " & $a & " > " & $b)
+
+proc checkBounds(c: PEffects; arr, idx: PNode) =
+  checkLe(c, lowBound(c.config, arr), idx)
+  checkLe(c, idx, highBound(c.config, arr, c.guards.o))
+
+proc checkRange(c: PEffects; value: PNode; typ: PType) =
+  if typ.skipTypes(abstractInst - {tyRange}).kind == tyRange:
+    let lowBound = nkIntLit.newIntNode(firstOrd(c.config, typ))
+    lowBound.info = value.info
+    let highBound = nkIntLit.newIntNode(lastOrd(c.config, typ))
+    highBound.info = value.info
+    checkLe(c, lowBound, value)
+    checkLe(c, value, highBound)
+
 proc createTypeBoundOps(tracked: PEffects, typ: PType; info: TLineInfo) =
   createTypeBoundOps(tracked.graph, tracked.c, typ, info)
   if (typ != nil and tfHasAsgn in typ.flags) or
@@ -755,12 +782,17 @@ proc track(tracked: PEffects, n: PNode) =
           discard
         else:
           message(tracked.config, arg.info, warnProveInit, $arg)
+
       # check required for 'nim check':
       if n[1].typ.len > 0:
         createTypeBoundOps(tracked, n[1].typ.lastSon, n.info)
         createTypeBoundOps(tracked, n[1].typ, n.info)
         # new(x, finalizer): Problem: how to move finalizer into 'createTypeBoundOps'?
 
+    elif a.kind == nkSym and a.sym.magic in {mArrGet, mArrPut} and
+        optStaticBoundsCheck in tracked.currOptions:
+      checkBounds(tracked, n[1], n[2])
+
     if a.kind == nkSym and a.sym.name.s.len > 0 and a.sym.name.s[0] == '=' and
           tracked.owner.kind != skMacro:
       let opKind = find(AttachedOpToStr, a.sym.name.s.normalize)
@@ -849,6 +881,28 @@ proc track(tracked: PEffects, n: PNode) =
   of nkForStmt, nkParForStmt:
     # we are very conservative here and assume the loop is never executed:
     let oldState = tracked.init.len
+
+    let oldFacts = tracked.guards.s.len
+    let iterCall = n[n.len-2]
+    if optStaticBoundsCheck in tracked.currOptions and iterCall.kind in nkCallKinds:
+      let op = iterCall[0]
+      if op.kind == nkSym and fromSystem(op.sym):
+        let iterVar = n[0]
+        case op.sym.name.s
+        of "..", "countup", "countdown":
+          let lower = iterCall[1]
+          let upper = iterCall[2]
+          # for i in 0..n   means  0 <= i and i <= n. Countdown is
+          # the same since only the iteration direction changes.
+          addFactLe(tracked.guards, lower, iterVar)
+          addFactLe(tracked.guards, iterVar, upper)
+        of "..<":
+          let lower = iterCall[1]
+          let upper = iterCall[2]
+          addFactLe(tracked.guards, lower, iterVar)
+          addFactLt(tracked.guards, iterVar, upper)
+        else: discard
+
     for i in 0..<n.len-2:
       let it = n[i]
       track(tracked, it)
@@ -858,7 +912,6 @@ proc track(tracked: PEffects, n: PNode) =
             createTypeBoundOps(tracked, x.typ, x.info)
         else:
           createTypeBoundOps(tracked, it.typ, it.info)
-    let iterCall = n[^2]
     let loopBody = n[^1]
     if tracked.owner.kind != skMacro and iterCall.safeLen > 1:
       # XXX this is a bit hacky:
@@ -867,6 +920,7 @@ proc track(tracked: PEffects, n: PNode) =
     track(tracked, iterCall)
     track(tracked, loopBody)
     setLen(tracked.init, oldState)
+    setLen(tracked.guards.s, oldFacts)
   of nkObjConstr:
     when false: track(tracked, n[0])
     let oldFacts = tracked.guards.s.len
@@ -932,18 +986,27 @@ proc track(tracked: PEffects, n: PNode) =
         # a better solution will come up eventually.
         if n[1].typ.kind != tyString:
           createTypeBoundOps(tracked, n[1].typ, n[1].info)
+      if optStaticBoundsCheck in tracked.currOptions:
+        checkRange(tracked, n[1], n.typ)
   of nkObjUpConv, nkObjDownConv, nkChckRange, nkChckRangeF, nkChckRange64:
     if n.len == 1:
       track(tracked, n[0])
       if tracked.owner.kind != skMacro:
         createTypeBoundOps(tracked, n.typ, n.info)
         createTypeBoundOps(tracked, n[0].typ, n[0].info)
+      if optStaticBoundsCheck in tracked.currOptions:
+        checkRange(tracked, n[0], n.typ)
   of nkBracket:
     for i in 0..<n.safeLen:
       track(tracked, n[i])
       checkForSink(tracked.config, tracked.owner, n[i])
     if tracked.owner.kind != skMacro:
       createTypeBoundOps(tracked, n.typ, n.info)
+  of nkBracketExpr:
+    if optStaticBoundsCheck in tracked.currOptions and n.len == 2:
+      if n[0].typ != nil and skipTypes(n[0].typ, abstractVar).kind != tyTuple:
+        checkBounds(tracked, n[0], n[1])
+    for i in 0 ..< n.len: track(tracked, n[i])
   else:
     for i in 0..<n.safeLen: track(tracked, n[i])
 
@@ -1028,6 +1091,8 @@ proc initEffects(g: ModuleGraph; effects: PNode; s: PSym; t: var TEffects; c: PC
   t.init = @[]
   t.guards.s = @[]
   t.guards.o = initOperators(g)
+  t.currOptions = g.config.options + s.options
+  t.guards.beSmart = optStaticBoundsCheck in t.currOptions
   t.locked = @[]
   t.graph = g
   t.config = g.config

compiler/trees.nim

@@ -74,6 +74,7 @@ proc sameTree*(a, b: PNode): bool =
         result = true
 
 proc getMagic*(op: PNode): TMagic =
+  if op == nil: return mNone
   case op.kind
   of nkCallKinds:
     case op[0].kind

compiler/types.nim

@@ -716,7 +716,7 @@ proc firstOrd*(conf: ConfigRef; t: PType): Int128 =
   of tyOrdinal:
     if t.len > 0: result = firstOrd(conf, lastSon(t))
     else: internalError(conf, "invalid kind for firstOrd(" & $t.kind & ')')
-  of tyUncheckedArray:
+  of tyUncheckedArray, tyCString:
     result = Zero
   else:
     internalError(conf, "invalid kind for firstOrd(" & $t.kind & ')')

compiler/wordrecg.nim

@@ -50,7 +50,7 @@ type
     wNimcall, wStdcall, wCdecl, wSafecall, wSyscall, wInline, wNoInline,
     wFastcall, wClosure, wNoconv, wOn, wOff, wChecks, wRangeChecks,
     wBoundChecks, wOverflowChecks, wNilChecks,
-    wFloatChecks, wNanChecks, wInfChecks, wStyleChecks,
+    wFloatChecks, wNanChecks, wInfChecks, wStyleChecks, wStaticBoundchecks,
     wNonReloadable, wExecuteOnReload,
     wAssertions, wPatterns, wTrMacros, wSinkInference, wWarnings,
     wHints, wOptimization, wRaises, wWrites, wReads, wSize, wEffects, wTags,
@@ -137,7 +137,7 @@ const
     "cdecl", "safecall", "syscall", "inline", "noinline", "fastcall", "closure",
     "noconv", "on", "off", "checks", "rangechecks", "boundchecks",
     "overflowchecks", "nilchecks",
-    "floatchecks", "nanchecks", "infchecks", "stylechecks",
+    "floatchecks", "nanchecks", "infchecks", "stylechecks", "staticboundchecks",
     "nonreloadable", "executeonreload",
 
     "assertions", "patterns", "trmacros", "sinkinference", "warnings", "hints",

tests/arc/timportedobj.nim

@@ -1,14 +1,14 @@
-discard """
-  cmd: "nim c --gc:arc $file"
-  action: "compile"
-"""
-
-# bug #13269
-
-import posix
-proc foo*() =
-  var last = newSeq[Stat]()
-  var next = last
-  for i in 0..3:
-    last = next
-foo()
+discard """
+  cmd: "nim c --gc:arc $file"
+  action: "compile"
+"""
+
+# bug #13269
+
+import posix
+proc foo*() =
+  var last = newSeq[Stat]()
+  var next = last
+  for i in 0..3:
+    last = next
+foo()

tests/notnil/tnotnil4.nim

@@ -10,8 +10,9 @@ proc check(a: TObj not nil) =
 proc doit() =
    var x : array[0..1, TObj]
 
-   if x[0] != nil:
-      check(x[0])
+   let y = x[0]
+   if y != nil:
+      check(y)
 
 doit()
 

tests/parallel/tinvalid_array_bounds.nim

@@ -1,6 +1,6 @@
 discard """
-  errormsg: "can prove: i + 1 > 30"
-  line: 21
+  errormsg: "cannot prove (i)..(i) disjoint from (i + 1)..(i + 1)"
+  line: 20
 """
 
 import threadpool

tests/parallel/tuseafterdef.nim

@@ -1,6 +1,7 @@
 discard """
   errormsg: "(k)..(k) not disjoint from (k)..(k)"
   line: 23
+  action: compile
 """
 
 # bug #1597

tests/tools/second.nim

@@ -1,3 +1,3 @@
-import tables
-
-let dataEx* = {1: 2, 3: 4}.toTable
+import tables
+
+let dataEx* = {1: 2, 3: 4}.toTable