Don't allow 'var x: T' for objects that require initialization
This commit is contained in:
Zahary Karadjov
Andreas Rumpf
parent
7652aede41
commit
05a0ec4adb
4 changed files with 63 additions and 37 deletions
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@ -11,14 +11,6 @@
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# included from sem.nim
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type
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InitStatus = enum
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initUnknown
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initFull # All of the fields have been initialized
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initPartial # Some of the fields have been initialized
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initNone # None of the fields have been initialized
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initConflict # Fields from different branches have been initialized
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proc mergeInitStatus(existing: var InitStatus, newStatus: InitStatus) =
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case newStatus
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of initConflict:
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@ -136,12 +128,12 @@ proc fieldsPresentInInitExpr(c: PContext, fieldsRecList, initExpr: PNode): strin
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if result.len != 0: result.add ", "
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result.add field.sym.name.s.quoteStr
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proc missingMandatoryFields(c: PContext, fieldsRecList, initExpr: PNode,
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requiresFullInit = false): string =
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proc missingMandatoryFields(c: PContext, fieldsRecList: PNode,
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constrCtx: ObjConstrContext): string =
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for r in directFieldsInRecList(fieldsRecList):
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if requiresFullInit or sfRequiresInit in r.sym.flags or
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if constrCtx.requiresFullInit or sfRequiresInit in r.sym.flags or
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{tfNotNil, tfRequiresInit, tfHasRequiresInit} * r.sym.typ.flags != {}:
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let assignment = locateFieldInInitExpr(c, r.sym, initExpr)
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let assignment = locateFieldInInitExpr(c, r.sym, constrCtx.initExpr)
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if assignment == nil:
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if result.len == 0:
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result = r.sym.name.s
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@ -149,34 +141,35 @@ proc missingMandatoryFields(c: PContext, fieldsRecList, initExpr: PNode,
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result.add ", "
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result.add r.sym.name.s
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proc checkForMissingFields(c: PContext, recList, initExpr: PNode,
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requiresFullInit = false) =
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let missing = missingMandatoryFields(c, recList, initExpr, requiresFullInit)
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proc checkForMissingFields(c: PContext, recList: PNode,
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constrCtx: ObjConstrContext) =
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let missing = missingMandatoryFields(c, recList, constrCtx)
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if missing.len > 0:
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localError(c.config, initExpr.info, "fields not initialized: $1.", [missing])
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localError(c.config, constrCtx.initExpr.info,
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"The $1 type requires the following fields to be initialized: $2.",
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[constrCtx.typ.sym.name.s, missing])
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proc semConstructFields(c: PContext, recNode: PNode,
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initExpr: PNode, flags: TExprFlags,
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requiresFullInit = false): InitStatus =
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constrCtx: ObjConstrContext,
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flags: TExprFlags): InitStatus =
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result = initUnknown
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case recNode.kind
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of nkRecList:
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for field in recNode:
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let status = semConstructFields(c, field, initExpr,
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flags, requiresFullInit)
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let status = semConstructFields(c, field, constrCtx, flags)
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mergeInitStatus(result, status)
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of nkRecCase:
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template fieldsPresentInBranch(branchIdx: int): string =
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let branch = recNode[branchIdx]
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let fields = branch[^1]
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fieldsPresentInInitExpr(c, fields, initExpr)
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fieldsPresentInInitExpr(c, fields, constrCtx.initExpr)
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template checkMissingFields(branchNode: PNode) =
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if branchNode != nil:
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let fields = branchNode[^1]
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checkForMissingFields(c, fields, initExpr, requiresFullInit)
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checkForMissingFields(c, fields, constrCtx)
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let discriminator = recNode[0]
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internalAssert c.config, discriminator.kind == nkSym
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@ -184,14 +177,13 @@ proc semConstructFields(c: PContext, recNode: PNode,
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for i in 1..<recNode.len:
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let innerRecords = recNode[i][^1]
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let status = semConstructFields(c, innerRecords, initExpr,
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flags, requiresFullInit)
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let status = semConstructFields(c, innerRecords, constrCtx, flags)
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if status notin {initNone, initUnknown}:
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mergeInitStatus(result, status)
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if selectedBranch != -1:
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let prevFields = fieldsPresentInBranch(selectedBranch)
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let currentFields = fieldsPresentInBranch(i)
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localError(c.config, initExpr.info,
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localError(c.config, constrCtx.initExpr.info,
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("The fields '$1' and '$2' cannot be initialized together, " &
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"because they are from conflicting branches in the case object.") %
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[prevFields, currentFields])
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@ -202,7 +194,7 @@ proc semConstructFields(c: PContext, recNode: PNode,
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if selectedBranch != -1:
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template badDiscriminatorError =
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let fields = fieldsPresentInBranch(selectedBranch)
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localError(c.config, initExpr.info,
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localError(c.config, constrCtx.initExpr.info,
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("cannot prove that it's safe to initialize $1 with " &
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"the runtime value for the discriminator '$2' ") %
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[fields, discriminator.sym.name.s])
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@ -210,7 +202,7 @@ proc semConstructFields(c: PContext, recNode: PNode,
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template wrongBranchError(i) =
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let fields = fieldsPresentInBranch(i)
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localError(c.config, initExpr.info,
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localError(c.config, constrCtx.initExpr.info,
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"a case selecting discriminator '$1' with value '$2' " &
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"appears in the object construction, but the field(s) $3 " &
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"are in conflict with this value.",
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@ -226,7 +218,8 @@ proc semConstructFields(c: PContext, recNode: PNode,
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let flags = flags*{efAllowDestructor} + {efPreferStatic,
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efPreferNilResult}
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var discriminatorVal = semConstrField(c, flags,
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discriminator.sym, initExpr)
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discriminator.sym,
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constrCtx.initExpr)
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if discriminatorVal != nil:
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discriminatorVal = discriminatorVal.skipHidden
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if discriminatorVal.kind notin nkLiterals and (
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@ -295,13 +288,15 @@ proc semConstructFields(c: PContext, recNode: PNode,
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else:
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result = initNone
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let discriminatorVal = semConstrField(c, flags + {efPreferStatic},
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discriminator.sym, initExpr)
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discriminator.sym,
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constrCtx.initExpr)
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if discriminatorVal == nil:
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# None of the branches were explicitly selected by the user and no
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# value was given to the discrimator. We can assume that it will be
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# initialized to zero and this will select a particular branch as
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# a result:
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let matchedBranch = recNode.pickCaseBranch newIntLit(c.graph, initExpr.info, 0)
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let defaultValue = newIntLit(c.graph, constrCtx.initExpr.info, 0)
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let matchedBranch = recNode.pickCaseBranch defaultValue
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checkMissingFields matchedBranch
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else:
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result = initPartial
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@ -317,7 +312,7 @@ proc semConstructFields(c: PContext, recNode: PNode,
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of nkSym:
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let field = recNode.sym
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let e = semConstrField(c, flags, field, initExpr)
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let e = semConstrField(c, flags, field, constrCtx.initExpr)
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result = if e != nil: initFull else: initNone
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else:
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@ -328,17 +323,18 @@ proc semConstructType(c: PContext, initExpr: PNode,
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result = initUnknown
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var
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t = t
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requiresFullInit = tfRequiresInit in t.flags
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constrCtx = ObjConstrContext(typ: t, initExpr: initExpr,
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requiresFullInit: tfRequiresInit in t.flags)
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while true:
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let status = semConstructFields(c, t.n, initExpr,
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flags, requiresFullInit)
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let status = semConstructFields(c, t.n, constrCtx, flags)
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mergeInitStatus(result, status)
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if status in {initPartial, initNone, initUnknown}:
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checkForMissingFields c, t.n, initExpr, requiresFullInit
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checkForMissingFields c, t.n, constrCtx
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let base = t[0]
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if base == nil: break
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t = skipTypes(base, skipPtrs)
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requiresFullInit = requiresFullInit or tfRequiresInit in t.flags
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constrCtx.requiresFullInit = constrCtx.requiresFullInit or
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tfRequiresInit in t.flags
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proc semObjConstr(c: PContext, n: PNode, flags: TExprFlags): PNode =
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var t = semTypeNode(c, n[0], nil)
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