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Don't allow 'var x: T' for objects that require initialization

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This commit is contained in:
Zahary Karadjov
2020-03-27 20:22:37 +02:00
committed by Andreas Rumpf
parent 7652aede41
commit 05a0ec4adb
4 changed files with 63 additions and 37 deletions
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18
compiler/sem.nim
View File

@@ -58,6 +58,24 @@ proc isArrayConstr(n: PNode): bool {.inline.} =
result = n.kind == nkBracket and
n.typ.skipTypes(abstractInst).kind == tyArray
type
ObjConstrContext = object
typ: PType # The constructed type
initExpr: PNode # The init expression (nkObjConstr)
requiresFullInit: bool # A `requiresInit` derived type will
# set this to true while visiting
# parent types.
InitStatus = enum # This indicates the result of object construction
initUnknown
initFull # All of the fields have been initialized
initPartial # Some of the fields have been initialized
initNone # None of the fields have been initialized
initConflict # Fields from different branches have been initialized
proc semConstructType(c: PContext, initExpr: PNode,
t: PType, flags: TExprFlags): InitStatus
template semIdeForTemplateOrGenericCheck(conf, n, requiresCheck) =
# we check quickly if the node is where the cursor is
when defined(nimsuggest):

68
compiler/semobjconstr.nim
View File

@@ -11,14 +11,6 @@
# included from sem.nim
type
InitStatus = enum
initUnknown
initFull # All of the fields have been initialized
initPartial # Some of the fields have been initialized
initNone # None of the fields have been initialized
initConflict # Fields from different branches have been initialized
proc mergeInitStatus(existing: var InitStatus, newStatus: InitStatus) =
case newStatus
of initConflict:
@@ -136,12 +128,12 @@ proc fieldsPresentInInitExpr(c: PContext, fieldsRecList, initExpr: PNode): strin
if result.len != 0: result.add ", "
result.add field.sym.name.s.quoteStr
proc missingMandatoryFields(c: PContext, fieldsRecList, initExpr: PNode,
requiresFullInit = false): string =
proc missingMandatoryFields(c: PContext, fieldsRecList: PNode,
constrCtx: ObjConstrContext): string =
for r in directFieldsInRecList(fieldsRecList):
if requiresFullInit or sfRequiresInit in r.sym.flags or
if constrCtx.requiresFullInit or sfRequiresInit in r.sym.flags or
{tfNotNil, tfRequiresInit, tfHasRequiresInit} * r.sym.typ.flags != {}:
let assignment = locateFieldInInitExpr(c, r.sym, initExpr)
let assignment = locateFieldInInitExpr(c, r.sym, constrCtx.initExpr)
if assignment == nil:
if result.len == 0:
result = r.sym.name.s
@@ -149,34 +141,35 @@ proc missingMandatoryFields(c: PContext, fieldsRecList, initExpr: PNode,
result.add ", "
result.add r.sym.name.s
proc checkForMissingFields(c: PContext, recList, initExpr: PNode,
requiresFullInit = false) =
let missing = missingMandatoryFields(c, recList, initExpr, requiresFullInit)
proc checkForMissingFields(c: PContext, recList: PNode,
constrCtx: ObjConstrContext) =
let missing = missingMandatoryFields(c, recList, constrCtx)
if missing.len > 0:
localError(c.config, initExpr.info, "fields not initialized: $1.", [missing])
localError(c.config, constrCtx.initExpr.info,
"The $1 type requires the following fields to be initialized: $2.",
[constrCtx.typ.sym.name.s, missing])
proc semConstructFields(c: PContext, recNode: PNode,
initExpr: PNode, flags: TExprFlags,
requiresFullInit = false): InitStatus =
constrCtx: ObjConstrContext,
flags: TExprFlags): InitStatus =
result = initUnknown
case recNode.kind
of nkRecList:
for field in recNode:
let status = semConstructFields(c, field, initExpr,
flags, requiresFullInit)
let status = semConstructFields(c, field, constrCtx, flags)
mergeInitStatus(result, status)
of nkRecCase:
template fieldsPresentInBranch(branchIdx: int): string =
let branch = recNode[branchIdx]
let fields = branch[^1]
fieldsPresentInInitExpr(c, fields, initExpr)
fieldsPresentInInitExpr(c, fields, constrCtx.initExpr)
template checkMissingFields(branchNode: PNode) =
if branchNode != nil:
let fields = branchNode[^1]
checkForMissingFields(c, fields, initExpr, requiresFullInit)
checkForMissingFields(c, fields, constrCtx)
let discriminator = recNode[0]
internalAssert c.config, discriminator.kind == nkSym
@@ -184,14 +177,13 @@ proc semConstructFields(c: PContext, recNode: PNode,
for i in 1..<recNode.len:
let innerRecords = recNode[i][^1]
let status = semConstructFields(c, innerRecords, initExpr,
flags, requiresFullInit)
let status = semConstructFields(c, innerRecords, constrCtx, flags)
if status notin {initNone, initUnknown}:
mergeInitStatus(result, status)
if selectedBranch != -1:
let prevFields = fieldsPresentInBranch(selectedBranch)
let currentFields = fieldsPresentInBranch(i)
localError(c.config, initExpr.info,
localError(c.config, constrCtx.initExpr.info,
("The fields '$1' and '$2' cannot be initialized together, " &
"because they are from conflicting branches in the case object.") %
[prevFields, currentFields])
@@ -202,7 +194,7 @@ proc semConstructFields(c: PContext, recNode: PNode,
if selectedBranch != -1:
template badDiscriminatorError =
let fields = fieldsPresentInBranch(selectedBranch)
localError(c.config, initExpr.info,
localError(c.config, constrCtx.initExpr.info,
("cannot prove that it's safe to initialize $1 with " &
"the runtime value for the discriminator '$2' ") %
[fields, discriminator.sym.name.s])
@@ -210,7 +202,7 @@ proc semConstructFields(c: PContext, recNode: PNode,
template wrongBranchError(i) =
let fields = fieldsPresentInBranch(i)
localError(c.config, initExpr.info,
localError(c.config, constrCtx.initExpr.info,
"a case selecting discriminator '$1' with value '$2' " &
"appears in the object construction, but the field(s) $3 " &
"are in conflict with this value.",
@@ -226,7 +218,8 @@ proc semConstructFields(c: PContext, recNode: PNode,
let flags = flags*{efAllowDestructor} + {efPreferStatic,
efPreferNilResult}
var discriminatorVal = semConstrField(c, flags,
discriminator.sym, initExpr)
discriminator.sym,
constrCtx.initExpr)
if discriminatorVal != nil:
discriminatorVal = discriminatorVal.skipHidden
if discriminatorVal.kind notin nkLiterals and (
@@ -295,13 +288,15 @@ proc semConstructFields(c: PContext, recNode: PNode,
else:
result = initNone
let discriminatorVal = semConstrField(c, flags + {efPreferStatic},
discriminator.sym, initExpr)
discriminator.sym,
constrCtx.initExpr)
if discriminatorVal == 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:
let matchedBranch = recNode.pickCaseBranch newIntLit(c.graph, initExpr.info, 0)
let defaultValue = newIntLit(c.graph, constrCtx.initExpr.info, 0)
let matchedBranch = recNode.pickCaseBranch defaultValue
checkMissingFields matchedBranch
else:
result = initPartial
@@ -317,7 +312,7 @@ proc semConstructFields(c: PContext, recNode: PNode,
of nkSym:
let field = recNode.sym
let e = semConstrField(c, flags, field, initExpr)
let e = semConstrField(c, flags, field, constrCtx.initExpr)
result = if e != nil: initFull else: initNone
else:
@@ -328,17 +323,18 @@ proc semConstructType(c: PContext, initExpr: PNode,
result = initUnknown
var
t = t
requiresFullInit = tfRequiresInit in t.flags
constrCtx = ObjConstrContext(typ: t, initExpr: initExpr,
requiresFullInit: tfRequiresInit in t.flags)
while true:
let status = semConstructFields(c, t.n, initExpr,
flags, requiresFullInit)
let status = semConstructFields(c, t.n, constrCtx, flags)
mergeInitStatus(result, status)
if status in {initPartial, initNone, initUnknown}:
checkForMissingFields c, t.n, initExpr, requiresFullInit
checkForMissingFields c, t.n, constrCtx
let base = t[0]
if base == nil: break
t = skipTypes(base, skipPtrs)
requiresFullInit = requiresFullInit or tfRequiresInit in t.flags
constrCtx.requiresFullInit = constrCtx.requiresFullInit or
tfRequiresInit in t.flags
proc semObjConstr(c: PContext, n: PNode, flags: TExprFlags): PNode =
var t = semTypeNode(c, n[0], nil)

6
compiler/semstmts.nim
View File

@@ -614,7 +614,11 @@ proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
if tup.kind == tyTuple: setVarType(c, v, tup[j])
else: v.typ = tup
b[j] = newSymNode(v)
checkNilable(c, v)
if def.kind == nkEmpty:
if v.typ.kind in {tyObject, tyTuple}:
discard semConstructType(c, newNodeI(nkObjConstr, v.info), v.typ, {})
else:
checkNilable(c, v)
if sfCompileTime in v.flags:
var x = newNodeI(result.kind, v.info)
x.add result[i]

8
tests/constructors/tinvalid_construction.nim
View File

@@ -125,10 +125,14 @@ accept PartialRequiresInit(a: 10, b: "x")
accept PartialRequiresInit(a: 20)
reject PartialRequiresInit(b: "x")
reject PartialRequiresInit()
reject:
var obj: PartialRequiresInit
accept FullRequiresInit(a: 10, b: 20)
reject FullRequiresInit(a: 10)
reject FullRequiresInit(b: 20)
reject:
var obj: FullRequiresInit
accept FullRequiresInitWithParent(a: notNilRef, b: notNilRef, c: notNilRef, e: 10, d: 20)
accept FullRequiresInitWithParent(a: notNilRef, b: notNilRef, c: nil, e: 10, d: 20)
@@ -136,9 +140,13 @@ reject FullRequiresInitWithParent(a: notNilRef, b: nil, c: nil, e: 10, d: 20) #
reject FullRequiresInitWithParent(a: notNilRef, b: notNilRef, e: 10, d: 20) # c should not be missing
reject FullRequiresInitWithParent(a: notNilRef, b: notNilRef, c: nil, e: 10) # d should not be missing
reject FullRequiresInitWithParent()
reject:
var obj: FullRequiresInitWithParent
# this will be accepted, because the false outer branch will be taken and the inner A branch
accept TNestedChoices()
accept:
var obj: TNestedChoices
# but if we supply a run-time value for the inner branch, the compiler won't be able to prove
# that the notnil field was initialized