add default field support for object in ARC/ORC

compiler/ast.nim

@@ -503,6 +503,7 @@ type
     nfLastRead  # this node is a last read
     nfFirstWrite# this node is a first write
     nfHasComment # node has a comment
+    nfUseDefaultField # node has a default value (object constructor)
 
   TNodeFlags* = set[TNodeFlag]
   TTypeFlag* = enum   # keep below 32 for efficiency reasons (now: 45)
@@ -705,7 +706,7 @@ type
     mInstantiationInfo, mGetTypeInfo, mGetTypeInfoV2,
     mNimvm, mIntDefine, mStrDefine, mBoolDefine, mRunnableExamples,
     mException, mBuiltinType, mSymOwner, mUncheckedArray, mGetImplTransf,
-    mSymIsInstantiationOf, mNodeId, mPrivateAccess
+    mSymIsInstantiationOf, mNodeId, mPrivateAccess, mZeroDefault
 
 
 # things that we can evaluate safely at compile time, even if not asked for it:

compiler/ccgexprs.nim

@@ -2436,7 +2436,7 @@ proc genMagicExpr(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
         p.module.s[cfsDynLibInit].addf("\t$1 = ($2) hcrGetProc($3, \"$1\");$n",
              [mangleDynLibProc(prc), getTypeDesc(p.module, prc.loc.t), getModuleDllPath(p.module, prc)])
     genCall(p, e, d)
-  of mDefault: genDefault(p, e, d)
+  of mDefault, mZeroDefault: genDefault(p, e, d)
   of mReset: genReset(p, e)
   of mEcho: genEcho(p, e[1].skipConv)
   of mArrToSeq: genArrToSeq(p, e, d)

compiler/jsgen.nim

@@ -2164,7 +2164,7 @@ proc genMagic(p: PProc, n: PNode, r: var TCompRes) =
   of mNewSeq: genNewSeq(p, n)
   of mNewSeqOfCap: unaryExpr(p, n, r, "", "[]")
   of mOf: genOf(p, n, r)
-  of mDefault: genDefault(p, n, r)
+  of mDefault, mZeroDefault: genDefault(p, n, r)
   of mReset, mWasMoved: genReset(p, n)
   of mEcho: genEcho(p, n, r)
   of mNLen..mNError, mSlurp, mStaticExec:
@@ -2274,7 +2274,7 @@ proc genObjConstr(p: PProc, n: PNode, r: var TCompRes) =
     gen(p, val, a)
     var f = it[0].sym
     if f.loc.r == nil: f.loc.r = mangleName(p.module, f)
-    fieldIDs.incl(lookupFieldAgain(n.typ, f).id)
+    fieldIDs.incl(lookupFieldAgain(n.typ.skipTypes({tyDistinct}), f).id)
 
     let typ = val.typ.skipTypes(abstractInst)
     if a.typ == etyBaseIndex:

compiler/nim.cfg

@@ -6,6 +6,7 @@ define:booting
 define:nimcore
 define:nimPreviewFloatRoundtrip
 define:nimPreviewSlimSystem
+define:nimPreviewRangeDefault
 
 #import:"$projectpath/testability"
 

compiler/parser.nim

@@ -1963,11 +1963,7 @@ proc parseObjectCase(p: var Parser): PNode =
   #|             | IND{=} objectBranches)
   result = newNodeP(nkRecCase, p)
   getTokNoInd(p)
-  var a = newNodeP(nkIdentDefs, p)
-  a.add(identWithPragma(p))
-  eat(p, tkColon)
-  a.add(parseTypeDesc(p))
-  a.add(p.emptyNode)
+  var a = parseIdentColonEquals(p, {withPragma})
   result.add(a)
   if p.tok.tokType == tkColon: getTok(p)
   flexComment(p, result)

compiler/sem.nim

@@ -42,6 +42,7 @@ proc semOpAux(c: PContext, n: PNode)
 proc semParamList(c: PContext, n, genericParams: PNode, s: PSym)
 proc addParams(c: PContext, n: PNode, kind: TSymKind)
 proc maybeAddResult(c: PContext, s: PSym, n: PNode)
+proc addDefaultFieldForResult(c: PContext, n: PNode, t: PType)
 proc tryExpr(c: PContext, n: PNode, flags: TExprFlags = {}): PNode
 proc activate(c: PContext, n: PNode)
 proc semQuoteAst(c: PContext, n: PNode): PNode
@@ -535,6 +536,127 @@ proc setGenericParamsMisc(c: PContext; n: PNode) =
   else:
     n[miscPos][1] = orig
 
+proc caseBranchMatchesExpr(branch, matched: PNode): bool =
+  for i in 0 ..< branch.len-1:
+    if branch[i].kind == nkRange:
+      if overlap(branch[i], matched): return true
+    elif exprStructuralEquivalent(branch[i], matched):
+      return true
+
+proc pickCaseBranchIndex(caseExpr, matched: PNode): int =
+  let endsWithElse = caseExpr[^1].kind == nkElse
+  for i in 1..<caseExpr.len - endsWithElse.int:
+    if caseExpr[i].caseBranchMatchesExpr(matched):
+      return i
+  if endsWithElse:
+    return caseExpr.len - 1
+
+proc defaultFieldsForTheUninitialized(c: PContext, recNode: PNode): seq[PNode]
+proc defaultNodeField(c: PContext, a: PNode): PNode
+proc defaultNodeField(c: PContext, a: PNode, aTyp: PType): PNode
+
+const defaultFieldsSkipTypes = {tyGenericInst, tyAlias, tySink, tyDistinct}
+
+proc defaultFieldsForTuple(c: PContext, recNode: PNode, hasDefault: var bool): seq[PNode] =
+  case recNode.kind
+  of nkRecList:
+    for field in recNode:
+      result.add defaultFieldsForTuple(c, field, hasDefault)
+  of nkSym:
+    let field = recNode.sym
+    let recType = recNode.typ.skipTypes(defaultFieldsSkipTypes)
+    if field.ast != nil: #Try to use default value
+      hasDefault = true
+      result.add newTree(nkExprColonExpr, recNode, field.ast)
+    else:
+      if recType.kind in {tyObject, tyArray, tyTuple}:
+        let asgnExpr = defaultNodeField(c, recNode, recNode.typ)
+        if asgnExpr != nil:
+          hasDefault = true
+          asgnExpr.flags.incl nfUseDefaultField
+          result.add newTree(nkExprColonExpr, recNode, asgnExpr)
+          return
+
+      let asgnType = newType(tyTypeDesc, nextTypeId(c.idgen), recType.owner)
+      rawAddSon(asgnType, recType)
+      let asgnExpr = newTree(nkCall,
+                      newSymNode(getSysMagic(c.graph, recNode.info, "zeroDefault", mZeroDefault)),
+                      newNodeIT(nkType, recNode.info, asgnType)
+                    )
+      asgnExpr.flags.incl nfUseDefaultField
+      asgnExpr.typ = recType
+      result.add newTree(nkExprColonExpr, recNode, asgnExpr)
+  else:
+    doAssert false
+
+proc defaultFieldsForTheUninitialized(c: PContext, recNode: PNode): seq[PNode] =
+  case recNode.kind
+  of nkRecList:
+    for field in recNode:
+      result.add defaultFieldsForTheUninitialized(c, field)
+  of nkRecCase:
+    let discriminator = recNode[0]
+    var selectedBranch: int
+    let defaultValue = discriminator.sym.ast
+    if defaultValue == nil:
+      # None of the branches were explicitly selected by the user and no value
+      # was given to the discrimator. We can assume that it will be initialized
+      # to zero and this will select a particular branch as a result:
+      selectedBranch = recNode.pickCaseBranchIndex newIntNode(nkIntLit#[c.graph]#, 0)
+    else: # Try to use default value
+      selectedBranch = recNode.pickCaseBranchIndex defaultValue
+      result.add newTree(nkExprColonExpr, discriminator, defaultValue)
+    result.add defaultFieldsForTheUninitialized(c, recNode[selectedBranch][^1])
+  of nkSym:
+    let field = recNode.sym
+    let recType = recNode.typ.skipTypes(defaultFieldsSkipTypes)
+    if field.ast != nil: #Try to use default value
+      result.add newTree(nkExprColonExpr, recNode, field.ast)
+    elif recType.kind in {tyObject, tyArray, tyTuple}:
+      let asgnExpr = defaultNodeField(c, recNode, recNode.typ)
+      if asgnExpr != nil:
+        asgnExpr.flags.incl nfUseDefaultField
+        result.add newTree(nkExprColonExpr, recNode, asgnExpr)
+  else:
+    doAssert false
+
+proc defaultNodeField(c: PContext, a: PNode, aTyp: PType): PNode =
+  let aTypSkip = aTyp.skipTypes(defaultFieldsSkipTypes)
+  if aTypSkip.kind == tyObject:
+    let child = defaultFieldsForTheUninitialized(c, aTyp.skipTypes(defaultFieldsSkipTypes).n)
+    if child.len > 0:
+      let aTypSkipDistinct = aTyp.skipTypes({tyDistinct})
+      var asgnExpr = newTree(nkObjConstr, newNodeIT(nkType, a.info, aTypSkipDistinct))
+      asgnExpr.typ = aTypSkipDistinct
+      asgnExpr.sons.add child
+      result = semExpr(c, asgnExpr)
+      if aTyp.kind == tyDistinct:
+        result = newTree(nkConv, newNodeIT(nkType, a.info, aTyp), result)
+        result.typ = aTyp
+  elif aTypSkip.kind == tyArray:
+    let child = defaultNodeField(c, a, aTypSkip[1])
+
+    if child != nil:
+      let node = newNode(nkIntLit)
+      node.intVal = toInt64(lengthOrd(c.graph.config, aTypSkip))
+      result = semExpr(c, newTree(nkCall, newSymNode(getSysSym(c.graph, a.info, "arrayWith"), a.info),
+              semExprWithType(c, child),
+              node
+                ))
+      result.typ = aTyp
+  elif aTypSkip.kind == tyTuple:
+    var hasDefault = false
+    if aTypSkip.n != nil:
+      let children = defaultFieldsForTuple(c, aTypSkip.n, hasDefault)
+      if hasDefault and children.len > 0:
+        result = newNodeI(nkTupleConstr, a.info)
+        result.typ = aTyp
+        result.sons.add children
+        result = semExpr(c, result)
+
+proc defaultNodeField(c: PContext, a: PNode): PNode =
+  result = defaultNodeField(c, a, a.typ)
+
 include semtempl, semgnrc, semstmts, semexprs
 
 proc addCodeForGenerics(c: PContext, n: PNode) =

compiler/semexprs.nim

@@ -900,8 +900,6 @@ proc semOverloadedCallAnalyseEffects(c: PContext, n: PNode, nOrig: PNode,
           rawAddSon(typ, result.typ)
           result.typ = typ
 
-proc semObjConstr(c: PContext, n: PNode, flags: TExprFlags): PNode
-
 proc resolveIndirectCall(c: PContext; n, nOrig: PNode;
                          t: PType): TCandidate =
   initCandidate(c, result, t)
@@ -2397,6 +2395,12 @@ proc semMagic(c: PContext, n: PNode, s: PSym, flags: TExprFlags): PNode =
   of mSizeOf:
     markUsed(c, n.info, s)
     result = semSizeof(c, setMs(n, s))
+  of mDefault:
+    result = semDirectOp(c, n, flags)
+    let typ = result[^1].typ.skipTypes({tyTypeDesc})
+    let defaultExpr = defaultNodeField(c, result[^1], typ)
+    if defaultExpr != nil:
+      result = defaultExpr
   else:
     result = semDirectOp(c, n, flags)
 

compiler/seminst.nim

@@ -151,6 +151,8 @@ proc instantiateBody(c: PContext, n, params: PNode, result, orig: PSym) =
       # As body is a sym to the borrowed proc.
       b = semProcBody(c, b)
     result.ast[bodyPos] = hloBody(c, b)
+    if orig.kind notin {skMacro, skTemplate} and orig.magic == mNone and sfNoInit notin orig.flags:
+      addDefaultFieldForResult(c, n, orig.typ[0])
     excl(result.flags, sfForward)
     trackProc(c, result, result.ast[bodyPos])
     dec c.inGenericInst

compiler/semmagic.nim

@@ -10,6 +10,8 @@
 # This include file implements the semantic checking for magics.
 # included from sem.nim
 
+proc semObjConstr(c: PContext, n: PNode, flags: TExprFlags): PNode
+
 proc semAddrArg(c: PContext; n: PNode): PNode =
   let x = semExprWithType(c, n)
   if x.kind == nkSym:
@@ -454,6 +456,23 @@ proc semPrivateAccess(c: PContext, n: PNode): PNode =
   c.currentScope.allowPrivateAccess.add t.sym
   result = newNodeIT(nkEmpty, n.info, getSysType(c.graph, n.info, tyVoid))
 
+proc addDefaultFieldForNew(c: PContext, n: PNode): PNode =
+  result = n
+  let typ = result[1].typ # new(x)
+  if typ.skipTypes({tyGenericInst, tyAlias, tySink}).kind == tyRef and typ.skipTypes({tyGenericInst, tyAlias, tySink})[0].kind == tyObject:
+    var asgnExpr = newTree(nkObjConstr, newNodeIT(nkType, result[1].info, typ))
+    asgnExpr.typ = typ
+    var t = typ.skipTypes({tyGenericInst, tyAlias, tySink})[0]
+    while true:
+      asgnExpr.sons.add defaultFieldsForTheUninitialized(c, t.n)
+      let base = t[0]
+      if base == nil:
+        break
+      t = skipTypes(base, skipPtrs)
+
+    if asgnExpr.sons.len > 1:
+      result = newTree(nkAsgn, result[1], asgnExpr)
+
 proc magicsAfterOverloadResolution(c: PContext, n: PNode,
                                    flags: TExprFlags): PNode =
   ## This is the preferred code point to implement magics.
@@ -512,6 +531,8 @@ proc magicsAfterOverloadResolution(c: PContext, n: PNode,
       result = n
     else:
       result = plugin(c, n)
+  of mNew:
+    result = addDefaultFieldForNew(c, n)
   of mNewFinalize:
     # Make sure the finalizer procedure refers to a procedure
     if n[^1].kind == nkSym and n[^1].sym.kind notin {skProc, skFunc}:
@@ -536,7 +557,7 @@ proc magicsAfterOverloadResolution(c: PContext, n: PNode,
           discard "already turned this one into a finalizer"
         else:
           bindTypeHook(c, turnFinalizerIntoDestructor(c, fin, n.info), n, attachedDestructor)
-    result = n
+    result = addDefaultFieldForNew(c, n)
   of mDestroy:
     result = n
     let t = n[1].typ.skipTypes(abstractVar)
@@ -562,7 +583,7 @@ proc magicsAfterOverloadResolution(c: PContext, n: PNode,
                                            tyAlias, tyUserTypeClassInst})
     if seqType.kind == tySequence and seqType.base.requiresInit:
       message(c.config, n.info, warnUnsafeSetLen, typeToString(seqType.base))
-  of mDefault:
+  of mDefault, mZeroDefault:
     result = n
     c.config.internalAssert result[1].typ.kind == tyTypeDesc
     let constructed = result[1].typ.base