diff options
Diffstat (limited to 'compiler/nilcheck.nim')
| -rw-r--r-- | compiler/nilcheck.nim | 188 |
1 files changed, 97 insertions, 91 deletions
diff --git a/compiler/nilcheck.nim b/compiler/nilcheck.nim index 23f403589..7e0efc34b 100644 --- a/compiler/nilcheck.nim +++ b/compiler/nilcheck.nim @@ -7,13 +7,16 @@ # distribution, for details about the copyright. # -import ast, renderer, intsets, tables, msgs, options, lineinfos, strformat, idents, treetab, hashes -import sequtils, strutils, std / sets +import ast, renderer, msgs, options, lineinfos, idents, treetab +import std/[intsets, tables, sequtils, strutils, sets, strformat, hashes] + +when defined(nimPreviewSlimSystem): + import std/assertions # IMPORTANT: notes not up to date, i'll update this comment again -# +# # notes: -# +# # Env: int => nilability # a = b # nilability a <- nilability b @@ -111,7 +114,7 @@ type Symbol = distinct int ## the index of an expression in the pre-indexed sequence of those - ExprIndex = distinct int16 + ExprIndex = distinct int16 ## the set index SetIndex = distinct int @@ -131,7 +134,7 @@ type ## the context for the checker: an instance for each procedure NilCheckerContext = ref object # abstractTime: AbstractTime - # partitions: Partitions + # partitions: Partitions # symbolGraphs: Table[Symbol, ] symbolIndices: Table[Symbol, ExprIndex] ## index for each symbol expressions: SeqOfDistinct[ExprIndex, PNode] ## a sequence of pre-indexed expressions @@ -306,6 +309,7 @@ proc symbol(n: PNode): Symbol = # echo "symbol ", n, " ", n.kind, " ", result.int func `$`(map: NilMap): string = + result = "" var now = map var stack: seq[NilMap] = @[] while not now.isNil: @@ -360,7 +364,7 @@ func `$`(a: Symbol): string = $(a.int) template isConstBracket(n: PNode): bool = - n.kind == nkBracketExpr and n[1].kind in nkLiterals + n.kind == nkBracketExpr and n[1].kind in nkLiterals proc index(ctx: NilCheckerContext, n: PNode): ExprIndex = # echo "n ", n, " ", n.kind @@ -373,7 +377,7 @@ proc index(ctx: NilCheckerContext, n: PNode): ExprIndex = #echo n.kind # internalError(ctx.config, n.info, "expected " & $a & " " & $n & " to have a index") return noExprIndex - # + # #ctx.symbolIndices[symbol(n)] @@ -384,7 +388,7 @@ proc aliasSet(ctx: NilCheckerContext, map: NilMap, index: ExprIndex): IntSet = result = map.sets[map.setIndices[index]] - + proc store(map: NilMap, ctx: NilCheckerContext, index: ExprIndex, value: Nilability, kind: TransitionKind, info: TLineInfo, node: PNode = nil) = if index == noExprIndex: return @@ -413,8 +417,8 @@ proc moveOut(ctx: NilCheckerContext, map: NilMap, target: PNode) = if targetSetIndex != noSetIndex: var targetSet = map.sets[targetSetIndex] if targetSet.len > 1: - var other: ExprIndex - + var other: ExprIndex = default(ExprIndex) + for element in targetSet: if element.ExprIndex != targetIndex: other = element.ExprIndex @@ -440,7 +444,7 @@ proc move(ctx: NilCheckerContext, map: NilMap, target: PNode, assigned: PNode) = #echo "move ", target, " ", assigned var targetIndex = ctx.index(target) var assignedIndex: ExprIndex - var targetSetIndex = map.setIndices[targetIndex] + var targetSetIndex = map.setIndices[targetIndex] var assignedSetIndex: SetIndex if assigned.kind == nkSym: assignedIndex = ctx.index(assigned) @@ -494,16 +498,16 @@ proc checkCall(n, ctx, map): Check = # check args and handle possible mutations var isNew = false - result.map = map + result = Check(map: map) for i, child in n: discard check(child, ctx, map) - + if i > 0: # var args make a new map with MaybeNil for our node # as it might have been mutated # TODO similar for normal refs and fields: find dependent exprs: brackets - - if child.kind == nkHiddenAddr and not child.typ.isNil and child.typ.kind == tyVar and child.typ[0].kind == tyRef: + + if child.kind == nkHiddenAddr and not child.typ.isNil and child.typ.kind == tyVar and child.typ.elementType.kind == tyRef: if not isNew: result.map = newNilMap(map) isNew = true @@ -526,7 +530,7 @@ proc checkCall(n, ctx, map): Check = isNew = true moveOutDependants(ctx, result.map, child) storeDependants(ctx, result.map, child, MaybeNil) - + if n[0].kind == nkSym and n[0].sym.magic == mNew: # new hidden deref? var value = if n[1].kind == nkHiddenDeref: n[1][0] else: n[1] @@ -552,13 +556,13 @@ template event(b: History): string = of TSafe: "it is safe here as it returns false for isNil" of TPotentialAlias: "it might be changed directly or through an alias" of TDependant: "it might be changed because its base might be changed" - + proc derefWarning(n, ctx, map; kind: Nilability) = ## a warning for potentially unsafe dereference if n.info in ctx.warningLocations: return ctx.warningLocations.incl(n.info) - var a: seq[History] + var a: seq[History] = @[] if n.kind == nkSym: a = history(map, ctx.index(n)) var res = "" @@ -587,14 +591,14 @@ proc handleNilability(check: Check; n, ctx, map) = else: when defined(nilDebugInfo): message(ctx.config, n.info, hintUser, "can deref " & $n) - + proc checkDeref(n, ctx, map): Check = ## check dereference: deref n should be ok only if n is Safe result = check(n[0], ctx, map) - + handleNilability(result, n[0], ctx, map) - + proc checkRefExpr(n, ctx; check: Check): Check = ## check ref expressions: TODO not sure when this happens result = check @@ -625,7 +629,7 @@ proc checkBracketExpr(n, ctx, map): Check = result = check(n[1], ctx, result.map) result = checkRefExpr(n, ctx, result) # echo n, " ", result.nilability - + template union(l: Nilability, r: Nilability): Nilability = ## unify two states @@ -654,7 +658,7 @@ proc findCommonParent(l: NilMap, r: NilMap): NilMap = result = l.parent while not result.isNil: var rparent = r.parent - while not rparent.isNil: + while not rparent.isNil: if result == rparent: return result rparent = rparent.parent @@ -666,17 +670,17 @@ proc union(ctx: NilCheckerContext, l: NilMap, r: NilMap): NilMap = ## what if they are from different parts of the same tree ## e.g. ## a -> b -> c - ## -> b1 + ## -> b1 ## common then? - ## + ## if l.isNil: return r elif r.isNil: return l - + let common = findCommonParent(l, r) result = newNilMap(common, ctx.expressions.len.int) - + for index, value in l: let h = history(r, index) let info = if h.len > 0: h[^1].info else: TLineInfo(line: 0) # assert h.len > 0 @@ -715,11 +719,11 @@ proc checkAsgn(target: PNode, assigned: PNode; ctx, map): Check = result = check(assigned, ctx, map) else: result = Check(nilability: typeNilability(target.typ), map: map) - + # we need to visit and check those, but we don't use the result for now # is it possible to somehow have another event happen here? discard check(target, ctx, map) - + if result.map.isNil: result.map = map if target.kind in {nkSym, nkDotExpr} or isConstBracket(target): @@ -738,8 +742,8 @@ proc checkAsgn(target: PNode, assigned: PNode; ctx, map): Check = if symbol(elementNode) in ctx.symbolIndices: var elementIndex = ctx.index(elementNode) result.map.store(ctx, elementIndex, value, TAssign, target.info, elementNode) - - + + proc checkReturn(n, ctx, map): Check = ## check return # return n same as result = n; return ? @@ -749,10 +753,11 @@ proc checkReturn(n, ctx, map): Check = proc checkIf(n, ctx, map): Check = ## check branches based on condition + result = default(Check) var mapIf: NilMap = map - + # first visit the condition - + # the structure is not If(Elif(Elif, Else), Else) # it is # If(Elif, Elif, Else) @@ -762,10 +767,10 @@ proc checkIf(n, ctx, map): Check = # the state of the conditions: negating conditions before the current one var layerHistory = newNilMap(mapIf) # the state after branch effects - var afterLayer: NilMap + var afterLayer: NilMap = nil # the result nilability for expressions var nilability = Safe - + for branch in n.sons: var branchConditionLayer = newNilMap(layerHistory) var branchLayer: NilMap @@ -779,7 +784,7 @@ proc checkIf(n, ctx, map): Check = else: branchLayer = layerHistory code = branch - + let branchCheck = checkBranch(code, ctx, branchLayer) # handles nil afterLayer -> returns branchCheck.map afterLayer = ctx.union(afterLayer, branchCheck.map) @@ -796,7 +801,7 @@ proc checkIf(n, ctx, map): Check = result.map = ctx.union(layerHistory, afterLayer) result.nilability = Safe # no expr? else: - # similar to else: because otherwise we are jumping out of + # similar to else: because otherwise we are jumping out of # the branch, so no union with the mapIf (we dont continue if the condition was true) # here it also doesn't matter for the parent branch what happened in the branch, e.g. assigning to nil # as if we continue there, we haven't entered the branch probably @@ -820,8 +825,8 @@ proc checkFor(n, ctx, map): Check = # echo namedMapDebugInfo(ctx, map) var check2 = check(n.sons[2], ctx, m) var map2 = check2.map - - result.map = ctx.union(map0, m) + + result = Check(map: ctx.union(map0, m)) result.map = ctx.union(result.map, map2) result.nilability = Safe @@ -848,20 +853,21 @@ proc checkWhile(n, ctx, map): Check = var map1 = m.copyMap() var check2 = check(n.sons[1], ctx, m) var map2 = check2.map - - result.map = ctx.union(map0, map1) + + result = Check(map: ctx.union(map0, map1)) result.map = ctx.union(result.map, map2) result.nilability = Safe - + proc checkInfix(n, ctx, map): Check = ## check infix operators in condition ## a and b : map is based on a; next b ## a or b : map is an union of a and b's ## a == b : use checkCondition ## else: no change, just check args + result = default(Check) if n[0].kind == nkSym: - var mapL: NilMap - var mapR: NilMap + var mapL: NilMap = nil + var mapR: NilMap = nil if n[0].sym.magic notin {mAnd, mEqRef}: mapL = checkCondition(n[1], ctx, map, false, false) mapR = checkCondition(n[2], ctx, map, false, false) @@ -882,7 +888,7 @@ proc checkInfix(n, ctx, map): Check = result.map = checkCondition(n[2], ctx, map, false, false) elif $n[1] == "false": result.map = checkCondition(n[2], ctx, map, true, false) - + if result.map.isNil: result.map = map else: @@ -894,7 +900,7 @@ proc checkInfix(n, ctx, map): Check = proc checkIsNil(n, ctx, map; isElse: bool = false): Check = ## check isNil calls ## update the map depending on if it is not isNil or isNil - result.map = newNilMap(map) + result = Check(map: newNilMap(map)) let value = n[1] result.map.store(ctx, ctx.index(n[1]), if not isElse: Nil else: Safe, TArg, n.info, n) @@ -906,24 +912,24 @@ proc infix(ctx: NilCheckerContext, l: PNode, r: PNode, magic: TMagic): PNode = else: "" var cache = newIdentCache() - var op = newSym(skVar, cache.getIdent(name), nextId ctx.idgen, nil, r.info) + var op = newSym(skVar, cache.getIdent(name), ctx.idgen, nil, r.info) op.magic = magic result = nkInfix.newTree( newSymNode(op, r.info), l, r) - result.typ = newType(tyBool, nextId ctx.idgen, nil) + result.typ = newType(tyBool, ctx.idgen, nil) proc prefixNot(ctx: NilCheckerContext, node: PNode): PNode = var cache = newIdentCache() - var op = newSym(skVar, cache.getIdent("not"), nextId ctx.idgen, nil, node.info) + var op = newSym(skVar, cache.getIdent("not"), ctx.idgen, nil, node.info) op.magic = mNot result = nkPrefix.newTree( newSymNode(op, node.info), node) - result.typ = newType(tyBool, nextId ctx.idgen, nil) + result.typ = newType(tyBool, ctx.idgen, nil) proc infixEq(ctx: NilCheckerContext, l: PNode, r: PNode): PNode = infix(ctx, l, r, mEqRef) @@ -942,9 +948,9 @@ proc checkCase(n, ctx, map): Check = # c2 # also a == true is a , a == false is not a let base = n[0] - result.map = map.copyMap() + result = Check(map: map.copyMap()) result.nilability = Safe - var a: PNode + var a: PNode = nil for child in n: case child.kind: of nkOfBranch: @@ -1016,7 +1022,7 @@ proc checkTry(n, ctx, map): Check = let tryCheck = check(n[0], ctx, currentMap) newMap = ctx.union(currentMap, tryCheck.map) canRaise = n[0].canRaise - + var afterTryMap = newMap for a, branch in n: if a > 0: @@ -1026,7 +1032,7 @@ proc checkTry(n, ctx, map): Check = let childCheck = check(branch[0], ctx, newMap) newMap = ctx.union(newMap, childCheck.map) hasFinally = true - of nkExceptBranch: + of nkExceptBranch: if canRaise: let childCheck = check(branch[^1], ctx, newMap) newMap = ctx.union(newMap, childCheck.map) @@ -1069,7 +1075,7 @@ proc reverse(kind: TransitionKind): TransitionKind = of TNil: TSafe of TSafe: TNil of TPotentialAlias: TPotentialAlias - else: + else: kind # raise newException(ValueError, "expected TNil or TSafe") @@ -1079,41 +1085,41 @@ proc reverseDirect(map: NilMap): NilMap = # because conditions should've stored their changes there # b: Safe (not b.isNil) # b: Parent Parent - # b: Nil (b.isNil) + # b: Nil (b.isNil) # layer block # [ Parent ] [ Parent ] - # if -> if state + # if -> if state # layer -> reverse # older older0 new # older new # [ b Nil ] [ Parent ] # elif # [ b Nil, c Nil] [ Parent ] - # + # - # if b.isNil: + # if b.isNil: # # [ b Safe] # c = A() # Safe - # elif not b.isNil: + # elif not b.isNil: # # [ b Safe ] + [b Nil] MaybeNil Unreachable # # Unreachable defer can't deref b, it is unreachable # discard # else: - # b + # b + - -# if +# if # if: we just pass the map with a new layer for its block # elif: we just pass the original map but with a new layer is the reverse of the previous popped layer (?) - # elif: + # elif: # else: we just pass the original map but with a new layer which is initialized as the reverse of the # top layer of else # else: - # + # # [ b MaybeNil ] [b Parent] [b Parent] [b Safe] [b Nil] [] # Safe # c == 1 @@ -1181,7 +1187,7 @@ proc checkResult(n, ctx, map) = of Unreachable: message(ctx.config, n.info, warnStrictNotNil, "return value is unreachable") of Safe, Parent: - discard + discard proc checkBranch(n: PNode, ctx: NilCheckerContext, map: NilMap): Check = result = check(n, ctx, map) @@ -1191,7 +1197,7 @@ proc checkBranch(n: PNode, ctx: NilCheckerContext, map: NilMap): Check = proc check(n: PNode, ctx: NilCheckerContext, map: NilMap): Check = assert not map.isNil - + # echo "check n ", n, " ", n.kind # echo "map ", namedMapDebugInfo(ctx, map) case n.kind: @@ -1214,12 +1220,12 @@ proc check(n: PNode, ctx: NilCheckerContext, map: NilMap): Check = result = check(n.sons[1], ctx, map) of nkStmtList, nkStmtListExpr, nkChckRangeF, nkChckRange64, nkChckRange, nkBracket, nkCurly, nkPar, nkTupleConstr, nkClosure, nkObjConstr, nkElse: - result.map = map + result = Check(map: map) if n.kind in {nkObjConstr, nkTupleConstr}: # TODO deeper nested elements? # A(field: B()) # - # field: Safe -> - var elements: seq[(PNode, Nilability)] + # field: Safe -> + var elements: seq[(PNode, Nilability)] = @[] for i, child in n: result = check(child, ctx, result.map) if i > 0: @@ -1230,7 +1236,7 @@ proc check(n: PNode, ctx: NilCheckerContext, map: NilMap): Check = else: for child in n: result = check(child, ctx, result.map) - + of nkDotExpr: result = checkDotExpr(n, ctx, map) of nkDerefExpr, nkHiddenDeref: @@ -1239,12 +1245,12 @@ proc check(n: PNode, ctx: NilCheckerContext, map: NilMap): Check = result = check(n.sons[0], ctx, map) of nkIfStmt, nkIfExpr: result = checkIf(n, ctx, map) - of nkAsgn: + of nkAsgn, nkFastAsgn, nkSinkAsgn: result = checkAsgn(n[0], n[1], ctx, map) - of nkVarSection: - result.map = map + of nkVarSection, nkLetSection: + result = Check(map: map) for child in n: - result = checkAsgn(child[0], child[2], ctx, result.map) + result = checkAsgn(child[0].skipPragmaExpr, child[2], ctx, result.map) of nkForStmt: result = checkFor(n, ctx, map) of nkCaseStmt: @@ -1260,32 +1266,32 @@ proc check(n: PNode, ctx: NilCheckerContext, map: NilMap): Check = of nkNone..pred(nkSym), succ(nkSym)..nkNilLit, nkTypeSection, nkProcDef, nkConverterDef, nkMethodDef, nkIteratorDef, nkMacroDef, nkTemplateDef, nkLambda, nkDo, nkFuncDef, nkConstSection, nkConstDef, nkIncludeStmt, nkImportStmt, - nkExportStmt, nkPragma, nkCommentStmt, nkBreakState, nkTypeOfExpr: - + nkExportStmt, nkPragma, nkCommentStmt, nkBreakState, + nkTypeOfExpr, nkMixinStmt, nkBindStmt: + discard "don't follow this : same as varpartitions" result = Check(nilability: Nil, map: map) else: var elementMap = map.copyMap() - var elementCheck: Check - elementCheck.map = elementMap + var elementCheck = Check(map: elementMap) for element in n: elementCheck = check(element, ctx, elementCheck.map) result = Check(nilability: Nil, map: elementCheck.map) - - + + proc typeNilability(typ: PType): Nilability = assert not typ.isNil # echo "typeNilability ", $typ.flags, " ", $typ.kind result = if tfNotNil in typ.flags: Safe - elif typ.kind in {tyRef, tyCString, tyPtr, tyPointer}: - # + elif typ.kind in {tyRef, tyCstring, tyPtr, tyPointer}: + # # tyVar ? tyVarargs ? tySink ? tyLent ? - # TODO spec? tests? + # TODO spec? tests? MaybeNil else: Safe @@ -1329,7 +1335,7 @@ proc preVisit(ctx: NilCheckerContext, s: PSym, body: PNode, conf: ConfigRef) = ctx.symbolIndices = {resultId: resultExprIndex}.toTable() var cache = newIdentCache() ctx.expressions = SeqOfDistinct[ExprIndex, PNode](@[newIdentNode(cache.getIdent("result"), s.ast.info)]) - var emptySet: IntSet # set[ExprIndex] + var emptySet: IntSet = initIntSet() # set[ExprIndex] ctx.dependants = SeqOfDistinct[ExprIndex, IntSet](@[emptySet]) for i, arg in s.typ.n.sons: if i > 0: @@ -1354,15 +1360,15 @@ proc checkNil*(s: PSym; body: PNode; conf: ConfigRef, idgen: IdGenerator) = var context = NilCheckerContext(config: conf, idgen: idgen) context.preVisit(s, body, conf) var map = newNilMap(nil, context.symbolIndices.len) - + for i, child in s.typ.n.sons: if i > 0: if child.kind != nkSym: continue map.store(context, context.index(child), typeNilability(child.typ), TArg, child.info, child) - map.store(context, resultExprIndex, if not s.typ[0].isNil and s.typ[0].kind == tyRef: Nil else: Safe, TResult, s.ast.info) - + map.store(context, resultExprIndex, if not s.typ.returnType.isNil and s.typ.returnType.kind == tyRef: Nil else: Safe, TResult, s.ast.info) + # echo "checking ", s.name.s, " ", filename let res = check(body, context, map) @@ -1374,8 +1380,8 @@ proc checkNil*(s: PSym; body: PNode; conf: ConfigRef, idgen: IdGenerator) = res.map.store(context, resultExprIndex, Safe, TAssign, s.ast.info) # TODO check for nilability result - # (ANotNil, BNotNil) : + # (ANotNil, BNotNil) : # do we check on asgn nilability at all? - if not s.typ[0].isNil and s.typ[0].kind == tyRef and tfNotNil in s.typ[0].flags: + if not s.typ.returnType.isNil and s.typ.returnType.kind == tyRef and tfNotNil in s.typ.returnType.flags: checkResult(s.ast, context, res.map) |