not nil: progress (#1095)

Author: Araq

src/hexer/duplifier.nim

@@ -680,7 +680,7 @@ proc trNewobj(c: var Context; n: var Cursor; e: Expects; kind: ExprKind) =
 
   let baseType = refType.firstSon
   var refTypeCopy = refType
-  let typeKey = takeMangle(refTypeCopy, c.lifter.bits)
+  let typeKey = takeMangle(refTypeCopy, Frontend, c.lifter.bits)
   let typeSym = pool.syms.getOrIncl(typeKey & GeneratedTypeSuffix)
 
   copyIntoKind c.dest, CastX, info:

src/hexer/lifter.nim

@@ -188,7 +188,7 @@ proc requestLifting(c: var LiftingCtx; op: AttachedOp; t: TypeCursor): SymId =
     if result != SymId(0):
       return result
 
-  let key = mangle(t, c.bits)
+  let key = mangle(t, Frontend, c.bits)
   result = c.structuralTypeToHook[op].getOrDefault(key)
   if result == SymId(0):
     let name = generateHookName(c, op, key)

src/hexer/nifcgen.nim

@@ -330,7 +330,7 @@ proc trAsNamedType(c: var EContext; n: var Cursor) =
   let info = n.info
   var body = n
   let k = body.typeKind
-  let key = takeMangle(n, c.bits)
+  let key = takeMangle(n, Backend, c.bits)
 
   var val = c.newTypes.getOrDefault(key)
   if val == SymId(0):

src/nimony/contracts.nim

@@ -40,6 +40,7 @@ type
     directlyInitialized: HashSet[SymId]
     startInstr: Cursor
     errors: TokenBuf
+    procCanRaise: bool
 
 proc buildErr(c: var Context; info: PackedLineInfo; msg: string) =
   when defined(debug):
@@ -273,7 +274,10 @@ proc wantNotNil(c: var Context; n: Cursor) =
     else:
       let r = analysableRoot(c, n)
       if r == NoSymId:
-        buildErr c, n.info, "cannot analyze expression is not nil: " & asNimCode(n)
+        if n.exprKind == NewobjX and c.procCanRaise:
+          discard "fine, nil value is mapped to OOM by the compiler"
+        else:
+          buildErr c, n.info, "cannot analyze expression is not nil: " & asNimCode(n)
       else:
         let fact = inferle.isNotNil(VarId r)
         if implies(c.facts, fact):
@@ -630,6 +634,10 @@ proc addAsgnFact(c: var Context; fact: LeXplusC) =
     c.facts.add fact
     c.facts.add fact.geXplusC
 
+proc cannotBeNil(c: var Context; n: Cursor): bool {.inline.} =
+  let t = getType(c.typeCache, n)
+  result = markedAs(t, NotnilU)
+
 proc analyseAsgn(c: var Context; pc: var Cursor) =
   inc pc # skip asgn instruction
   let expected = getType(c.typeCache, pc)
@@ -645,6 +653,7 @@ proc analyseAsgn(c: var Context; pc: var Cursor) =
     # after `x = 4` we know two facts: `x >= 4` and `x <= 4`
     inc pc
     checkNilMatch c, pc, expected
+    let rhs = pc
     if rightHandSide(c, pc, fact):
       if fact.a == fact.b:
         variableChangedByDiff(c.facts, fact.a, fact.c)
@@ -653,6 +662,10 @@ proc analyseAsgn(c: var Context; pc: var Cursor) =
         addAsgnFact c, fact
     else:
       invalidateFactsAbout(c.facts, fact.a)
+
+    if (rhs.exprKind == NewobjX and c.procCanRaise) or cannotBeNil(c, rhs):
+      # we know: x != nil after the assignment:
+      c.facts.add isNotNil(fact.a)
   else:
     analyseExpr c, pc
     checkNilMatch c, pc, expected
@@ -861,10 +874,14 @@ proc checkContracts(c: var Context; n: Cursor) =
   #echo "CF IS ", codeListing(c.cf)
 
   c.startInstr = readonlyCursorAt(c.cf, 0)
+  c.procCanRaise = false
   var body = c.startInstr
   if body.stmtKind in {ProcS, FuncS, IteratorS, ConverterS, MethodS, MacroS}:
     inc body
-    for i in 0 ..< BodyPos: skip body
+    for i in 0 ..< BodyPos:
+      if i == ProcPragmasPos:
+        c.procCanRaise = hasPragma(body, RaisesP)
+      skip body
 
   var current = BasicBlockIdx(cursorToPosition(c.cf, body))
   var bbs = computeBasicBlocks(c.cf, current.int)

src/nimony/sem.nim

@@ -3285,7 +3285,15 @@ proc semLocalTypeImpl(c: var SemContext; n: var Cursor; context: TypeDeclContext
         c.dest.addDotToken()
       else:
         takeTree c, n
-    of PtrT, RefT, MutT, OutT, LentT, SinkT, NotT, UarrayT,
+    of PtrT, RefT:
+      if tryTypeClass(c, n):
+        return
+      takeToken c, n
+      semLocalTypeImpl c, n, InLocalDecl
+      if n.kind != ParRi:
+        takeTree c, n # notnil, nil
+      takeParRi c, n
+    of MutT, OutT, LentT, SinkT, NotT, UarrayT,
        StaticT, TypedescT:
       if tryTypeClass(c, n):
         return

src/nimony/typekeys.nim

@@ -9,7 +9,11 @@ include nifprelude
 import ".." / nimony / nimony_model
 import treemangler
 
-proc mangleImpl(b: var Mangler; c: var Cursor) =
+type
+  MangleMode* = enum
+    Backend, Frontend
+
+proc mangleImpl(b: var Mangler; c: var Cursor; mm: MangleMode) =
   var nested = 0
   while true:
     case c.kind
@@ -20,13 +24,13 @@ proc mangleImpl(b: var Mangler; c: var Cursor) =
         skip c # name
         skip c # export marker
         skip c # pragmas
-        mangleImpl b, c # type is interesting
+        mangleImpl b, c, mm # type is interesting
         skip c # value
         inc c # ParRi
       elif tag == "array":
         b.addTree tag
         inc c
-        mangleImpl b, c # type is interesting
+        mangleImpl b, c, mm # type is interesting
         if c.kind == ParLe and c.typeKind == RangetypeT:
           inc c # RangeT
           skip c # type is irrelevant, we care about the length
@@ -39,7 +43,7 @@ proc mangleImpl(b: var Mangler; c: var Cursor) =
           inc c # ParRi
           b.addIntLit(last - first + 1)
         else:
-          mangleImpl b, c
+          mangleImpl b, c, mm
         inc nested
       elif tag == "tuple":
         b.addTree(tag)
@@ -48,10 +52,10 @@ proc mangleImpl(b: var Mangler; c: var Cursor) =
           if c.substructureKind == KvU:
             inc c
             skip c # name
-            mangleImpl b, c # type is interesting
+            mangleImpl b, c, mm # type is interesting
             inc c # ParRi
           else:
-            mangleImpl b, c
+            mangleImpl b, c, mm
         b.endTree()
         inc c # ParRi
       elif tag == "u" or tag == "i" or tag == "f":
@@ -66,6 +70,15 @@ proc mangleImpl(b: var Mangler; c: var Cursor) =
           b.addIntLit(bits)
         inc c
         inc nested
+      elif mm == Backend and tag in ["ref", "ptr"]:
+        b.addTree(tag)
+        inc c
+        mangleImpl b, c, mm
+        if c.kind != ParRi:
+          skip c
+        assert c.kind == ParRi
+        b.endTree()
+        inc c
       else:
         b.addTree(tag)
         inc nested
@@ -109,15 +122,15 @@ proc mangleImpl(b: var Mangler; c: var Cursor) =
       inc c
     if nested == 0: break
 
-proc takeMangle*(c: var Cursor; bits = -1): string =
+proc takeMangle*(c: var Cursor; mm: MangleMode; bits = -1): string =
   var b = createMangler(30, bits)
-  mangleImpl b, c
+  mangleImpl b, c, mm
   result = b.extract()
 
-proc mangle*(c: Cursor; bits = -1): string =
+proc mangle*(c: Cursor; mm: MangleMode; bits = -1): string =
   var c = c
-  takeMangle c, bits
+  takeMangle c, mm, bits
 
-proc mangle*(b: var Mangler; c: Cursor) =
+proc mangle*(b: var Mangler; c: Cursor; mm: MangleMode) =
   var c = c
-  mangleImpl b, c
+  mangleImpl b, c, mm

src/nimony/vtables_frontend.nim

@@ -68,10 +68,10 @@ proc methodKey*(name: string; a: Cursor): string =
   var b = createMangler(60)
   while a.kind != ParRi:
     let pa = takeLocal(a, SkipFinalParRi)
-    mangle b, pa.typ
+    mangle b, pa.typ, Frontend
   inc a
   # also add return type:
-  mangle b, a
+  mangle b, a, Frontend
   skip a
   let (callConv, hasRaises) = processPragmas(a)
   result = name & ":" & b.extract() & ":" & $callConv & ":" & hasRaises

tests/nimony/notnil/tnew_raises.nim

@@ -0,0 +1,18 @@
+
+import std / syncio
+
+type
+  Myref = ref object
+    x: int
+
+proc p(): Myref not nil {.raises.} = Myref(x: 5)
+
+proc hah {.raises.} =
+  var r: Myref not nil
+  r = p()
+  echo r[].x
+
+try:
+  hah()
+except:
+  echo "god riddance"

tests/nimony/notnil/tnew_raises.output

@@ -0,0 +1 @@
+5

tests/nimony/notnil/tnilref.nim

@@ -0,0 +1,26 @@
+
+import std / syncio
+
+type
+  Myref = ref object
+    x: int
+
+proc p(): Myref not nil {.raises.} = Myref(x: 5)
+
+proc hah2 {.raises.} =
+  var r: nil Myref
+  r = p()
+  echo r[].x
+
+proc other =
+  var r: nil Myref = nil
+  if r != nil:
+    echo r[].x
+  else:
+    echo "is nil"
+
+try:
+  hah2()
+  other()
+except:
+  echo "god riddance"