fixes #17033 [backport:1.4] (#17061)

* fixes #17033 [backport:1.4]

* make test robust against stdlib gensym things

* cleanup assertions.nim to make topt_no_cursor easier to get right

compiler/varpartitions.nim

@@ -57,6 +57,7 @@ type
     ownsData,
     preventCursor,
     isReassigned,
+    isConditionallyReassigned,
     viewDoesMutate,
     viewBorrowsFromConst
 
@@ -98,6 +99,7 @@ type
     goals: set[Goal]
     unanalysableMutation: bool
     inAsgnSource, inConstructor, inNoSideEffectSection: int
+    inConditional, inLoop: int
     owner: PSym
     g: ModuleGraph
 
@@ -748,6 +750,13 @@ proc traverse(c: var Partitions; n: PNode) =
   else:
     for child in n: traverse(c, child)
 
+proc markAsReassigned(c: var Partitions; vid: int) {.inline.} =
+  c.s[vid].flags.incl isReassigned
+  if c.inConditional > 0 and c.inLoop > 0:
+    # bug #17033: live ranges with loops and conditionals are too
+    # complex for our current analysis, so we prevent the cursorfication.
+    c.s[vid].flags.incl isConditionallyReassigned
+
 proc computeLiveRanges(c: var Partitions; n: PNode) =
   # first pass: Compute live ranges for locals.
   # **Watch out!** We must traverse the tree like 'traverse' does
@@ -777,7 +786,7 @@ proc computeLiveRanges(c: var Partitions; n: PNode) =
         if n[1].kind == nkSym and (c.s[vid].reassignedTo == 0 or c.s[vid].reassignedTo == n[1].sym.id):
           c.s[vid].reassignedTo = n[1].sym.id
         else:
-          c.s[vid].flags.incl isReassigned
+          markAsReassigned(c, vid)
 
   of nkSym:
     dec c.abstractTime
@@ -804,7 +813,7 @@ proc computeLiveRanges(c: var Partitions; n: PNode) =
         if not paramType.isCompileTimeOnly and paramType.kind == tyVar:
           let vid = variableId(c, it.sym)
           if vid >= 0:
-            c.s[vid].flags.incl isReassigned
+            markAsReassigned(c, vid)
 
   of nkAddr, nkHiddenAddr:
     computeLiveRanges(c, n[0])
@@ -822,7 +831,13 @@ proc computeLiveRanges(c: var Partitions; n: PNode) =
     #   while cond:
     #     mutate(graph)
     #     connect(graph, cursorVar)
+    inc c.inLoop
     for child in n: computeLiveRanges(c, child)
+    inc c.inLoop
+  of nkElifBranch, nkElifExpr, nkElse, nkOfBranch:
+    inc c.inConditional
+    for child in n: computeLiveRanges(c, child)
+    dec c.inConditional
   else:
     for child in n: computeLiveRanges(c, child)
 
@@ -896,7 +911,8 @@ proc computeCursors*(s: PSym; n: PNode; g: ModuleGraph) =
   var par = computeGraphPartitions(s, n, g, {cursorInference})
   for i in 0 ..< par.s.len:
     let v = addr(par.s[i])
-    if v.flags * {ownsData, preventCursor} == {} and v.sym.kind notin {skParam, skResult} and
+    if v.flags * {ownsData, preventCursor, isConditionallyReassigned} == {} and
+        v.sym.kind notin {skParam, skResult} and
         v.sym.flags * {sfThread, sfGlobal} == {} and hasDestructor(v.sym.typ) and
         v.sym.typ.skipTypes({tyGenericInst, tyAlias}).kind != tyOwned:
       let rid = root(par, i)

lib/system/assertions.nim

@@ -86,13 +86,11 @@ template assert*(cond: untyped, msg = "") =
   ##
   ## No code will be generated for `assert` when passing `-d:danger` (implied by `--assertions:off`).
   ## See `command line switches <nimc.html#compiler-usage-commandminusline-switches>`_.
-  const expr = astToStr(cond)
+  assertImpl(cond, msg, astToStr(cond), compileOption("assertions"))
-  assertImpl(cond, msg, expr, compileOption("assertions"))
 
 template doAssert*(cond: untyped, msg = "") =
   ## Similar to `assert <#assert.t,untyped,string>`_ but is always turned on regardless of `--assertions`.
-  const expr = astToStr(cond)
+  assertImpl(cond, msg, astToStr(cond), true)
-  assertImpl(cond, msg, expr, true)
 
 template onFailedAssert*(msg, code: untyped): untyped {.dirty.} =
   ## Sets an assertion failure handler that will intercept any assert

tests/arc/topt_no_cursor.nim

@@ -3,8 +3,12 @@ discard """
 doing shady stuff...
 3
 6
-(@[1], @[2])'''
+(@[1], @[2])
-  cmd: '''nim c --gc:arc --expandArc:newTarget --expandArc:delete --expandArc:p1 --expandArc:tt --hint:Performance:off $file'''
+192.168.0.1
+192.168.0.1
+192.168.0.1
+192.168.0.1'''
+  cmd: '''nim c --gc:arc --expandArc:newTarget --expandArc:delete --expandArc:p1 --expandArc:tt --hint:Performance:off --assertions:off --expandArc:extractConfig $file'''
   nimout: '''--expandArc: newTarget
 
 var
@@ -78,6 +82,31 @@ try:
 finally:
   `=destroy`(:tmpD_2)
   `=destroy_1`(a)
+-- end of expandArc ------------------------
+--expandArc: extractConfig
+
+var lan_ip
+try:
+  lan_ip = ""
+  block :tmp:
+    var line
+    var i = 0
+    let L = len(txt)
+    block :tmp_1:
+      while i < L:
+        var splitted
+        try:
+          line = txt[i]
+          splitted = split(line, " ", -1)
+          if splitted[0] == "opt":
+            `=copy`(lan_ip, splitted[1])
+          echo [lan_ip]
+          echo [splitted[1]]
+          inc(i, 1)
+        finally:
+          `=destroy`(splitted)
+finally:
+  `=destroy_1`(lan_ip)
 -- end of expandArc ------------------------'''
 """
 
@@ -194,3 +223,56 @@ proc plus(input: string) =
   (rvalue, rnext) = rresult
 
 plus("123;")
+
+func substrEq(s: string, pos: int, substr: string): bool =
+  var i = 0
+  var length = substr.len
+  while i < length and pos+i < s.len and s[pos+i] == substr[i]:
+    inc i
+  return i == length
+
+template stringHasSep(s: string, index: int, sep: string): bool =
+  s.substrEq(index, sep)
+
+template splitCommon(s, sep, maxsplit, sepLen) =
+  var last = 0
+  var splits = maxsplit
+
+  while last <= len(s):
+    var first = last
+    while last < len(s) and not stringHasSep(s, last, sep):
+      inc(last)
+    if splits == 0: last = len(s)
+    yield substr(s, first, last-1)
+    if splits == 0: break
+    dec(splits)
+    inc(last, sepLen)
+
+iterator split(s: string, sep: string, maxsplit = -1): string =
+  splitCommon(s, sep, maxsplit, sep.len)
+
+template accResult(iter: untyped) =
+  result = @[]
+  for x in iter: add(result, x)
+
+func split*(s: string, sep: string, maxsplit = -1): seq[string] =
+  accResult(split(s, sep, maxsplit))
+
+
+let txt = @["opt 192.168.0.1", "static_lease 192.168.0.1"]
+
+# bug #17033
+
+proc extractConfig() =
+  var lan_ip = ""
+
+  for line in txt:
+    let splitted = line.split(" ")
+    if splitted[0] == "opt":
+      lan_ip = splitted[1] # "borrow" is conditional and inside a loop.
+      # Not good enough...
+      # we need a flag that live-ranges are disjoint
+    echo lan_ip
+    echo splitted[1] # Without this line everything works
+
+extractConfig()