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semstmts.nim
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semstmts.nim
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#
#
# The Nim Compiler
# (c) Copyright 2013 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## this module does the semantic checking of statements
# included from sem.nim
var enforceVoidContext = PType(kind: tyStmt)
proc semDiscard(c: PContext, n: PNode): PNode =
result = n
checkSonsLen(n, 1)
if n.sons[0].kind != nkEmpty:
n.sons[0] = semExprWithType(c, n.sons[0])
if isEmptyType(n.sons[0].typ) or n.sons[0].typ.kind == tyNone:
localError(n.info, errInvalidDiscard)
proc semBreakOrContinue(c: PContext, n: PNode): PNode =
result = n
checkSonsLen(n, 1)
if n.sons[0].kind != nkEmpty:
if n.kind != nkContinueStmt:
var s: PSym
case n.sons[0].kind
of nkIdent: s = lookUp(c, n.sons[0])
of nkSym: s = n.sons[0].sym
else: illFormedAst(n)
s = getGenSym(c, s)
if s.kind == skLabel and s.owner.id == c.p.owner.id:
var x = newSymNode(s)
x.info = n.info
incl(s.flags, sfUsed)
n.sons[0] = x
suggestSym(x.info, s, c.graph.usageSym)
styleCheckUse(x.info, s)
else:
localError(n.info, errInvalidControlFlowX, s.name.s)
else:
localError(n.info, errGenerated, "'continue' cannot have a label")
elif (c.p.nestedLoopCounter <= 0) and (c.p.nestedBlockCounter <= 0):
localError(n.info, errInvalidControlFlowX,
renderTree(n, {renderNoComments}))
proc semAsm(con: PContext, n: PNode): PNode =
checkSonsLen(n, 2)
var marker = pragmaAsm(con, n.sons[0])
if marker == '\0': marker = '`' # default marker
result = semAsmOrEmit(con, n, marker)
proc semWhile(c: PContext, n: PNode): PNode =
result = n
checkSonsLen(n, 2)
openScope(c)
n.sons[0] = forceBool(c, semExprWithType(c, n.sons[0]))
inc(c.p.nestedLoopCounter)
n.sons[1] = semStmt(c, n.sons[1])
dec(c.p.nestedLoopCounter)
closeScope(c)
if n.sons[1].typ == enforceVoidContext:
result.typ = enforceVoidContext
proc toCover(t: PType): BiggestInt =
var t2 = skipTypes(t, abstractVarRange-{tyTypeDesc})
if t2.kind == tyEnum and enumHasHoles(t2):
result = sonsLen(t2.n)
else:
result = lengthOrd(skipTypes(t, abstractVar-{tyTypeDesc}))
when false:
proc performProcvarCheck(c: PContext, info: TLineInfo, s: PSym) =
## Checks that the given symbol is a proper procedure variable, meaning
## that it
var smoduleId = getModule(s).id
if sfProcvar notin s.flags and s.typ.callConv == ccDefault and
smoduleId != c.module.id:
block outer:
for module in c.friendModules:
if smoduleId == module.id:
break outer
localError(info, errXCannotBePassedToProcVar, s.name.s)
template semProcvarCheck(c: PContext, n: PNode) =
when false:
var n = n.skipConv
if n.kind in nkSymChoices:
for x in n:
if x.sym.kind in {skProc, skMethod, skConverter, skIterator}:
performProcvarCheck(c, n.info, x.sym)
elif n.kind == nkSym and n.sym.kind in {skProc, skMethod, skConverter,
skIterator}:
performProcvarCheck(c, n.info, n.sym)
proc semProc(c: PContext, n: PNode): PNode
include semdestruct
proc semDestructorCheck(c: PContext, n: PNode, flags: TExprFlags) {.inline.} =
when not newDestructors:
if efAllowDestructor notin flags and
n.kind in nkCallKinds+{nkObjConstr,nkBracket}:
if instantiateDestructor(c, n.typ) != nil:
localError(n.info, warnDestructor)
# This still breaks too many things:
when false:
if efDetermineType notin flags and n.typ.kind == tyTypeDesc and
c.p.owner.kind notin {skTemplate, skMacro}:
localError(n.info, errGenerated, "value expected, but got a type")
proc semExprBranch(c: PContext, n: PNode): PNode =
result = semExpr(c, n)
if result.typ != nil:
# XXX tyGenericInst here?
semProcvarCheck(c, result)
if result.typ.kind == tyVar: result = newDeref(result)
semDestructorCheck(c, result, {})
proc semExprBranchScope(c: PContext, n: PNode): PNode =
openScope(c)
result = semExprBranch(c, n)
closeScope(c)
const
skipForDiscardable = {nkIfStmt, nkIfExpr, nkCaseStmt, nkOfBranch,
nkElse, nkStmtListExpr, nkTryStmt, nkFinally, nkExceptBranch,
nkElifBranch, nkElifExpr, nkElseExpr, nkBlockStmt, nkBlockExpr}
proc implicitlyDiscardable(n: PNode): bool =
var n = n
while n.kind in skipForDiscardable: n = n.lastSon
result = isCallExpr(n) and n.sons[0].kind == nkSym and
sfDiscardable in n.sons[0].sym.flags
proc fixNilType(n: PNode) =
if isAtom(n):
if n.kind != nkNilLit and n.typ != nil:
localError(n.info, errDiscardValueX, n.typ.typeToString)
elif n.kind in {nkStmtList, nkStmtListExpr}:
n.kind = nkStmtList
for it in n: fixNilType(it)
n.typ = nil
proc discardCheck(c: PContext, result: PNode) =
if c.matchedConcept != nil: return
if result.typ != nil and result.typ.kind notin {tyStmt, tyVoid}:
if result.kind == nkNilLit:
result.typ = nil
message(result.info, warnNilStatement)
elif implicitlyDiscardable(result):
var n = result
result.typ = nil
while n.kind in skipForDiscardable:
n = n.lastSon
n.typ = nil
elif result.typ.kind != tyError and gCmd != cmdInteractive:
if result.typ.kind == tyNil:
fixNilType(result)
message(result.info, warnNilStatement)
else:
var n = result
while n.kind in skipForDiscardable: n = n.lastSon
var s = "expression '" & $n & "' is of type '" &
result.typ.typeToString & "' and has to be discarded"
if result.typ.kind == tyProc:
s.add "; for a function call use ()"
localError(n.info, s)
proc semIf(c: PContext, n: PNode): PNode =
result = n
var typ = commonTypeBegin
var hasElse = false
for i in countup(0, sonsLen(n) - 1):
var it = n.sons[i]
if it.len == 2:
when newScopeForIf: openScope(c)
it.sons[0] = forceBool(c, semExprWithType(c, it.sons[0]))
when not newScopeForIf: openScope(c)
it.sons[1] = semExprBranch(c, it.sons[1])
typ = commonType(typ, it.sons[1].typ)
closeScope(c)
elif it.len == 1:
hasElse = true
it.sons[0] = semExprBranchScope(c, it.sons[0])
typ = commonType(typ, it.sons[0].typ)
else: illFormedAst(it)
if isEmptyType(typ) or typ.kind == tyNil or not hasElse:
for it in n: discardCheck(c, it.lastSon)
result.kind = nkIfStmt
# propagate any enforced VoidContext:
if typ == enforceVoidContext: result.typ = enforceVoidContext
else:
for it in n:
let j = it.len-1
it.sons[j] = fitNode(c, typ, it.sons[j], it.sons[j].info)
result.kind = nkIfExpr
result.typ = typ
proc semCase(c: PContext, n: PNode): PNode =
result = n
checkMinSonsLen(n, 2)
openScope(c)
n.sons[0] = semExprWithType(c, n.sons[0])
var chckCovered = false
var covered: BiggestInt = 0
var typ = commonTypeBegin
var hasElse = false
let caseTyp = skipTypes(n.sons[0].typ, abstractVarRange-{tyTypeDesc})
case caseTyp.kind
of tyInt..tyInt64, tyChar, tyEnum, tyUInt..tyUInt32, tyBool:
chckCovered = true
of tyFloat..tyFloat128, tyString, tyError:
discard
else:
localError(n.info, errSelectorMustBeOfCertainTypes)
return
for i in countup(1, sonsLen(n) - 1):
var x = n.sons[i]
when defined(nimsuggest):
if gIdeCmd == ideSug and exactEquals(gTrackPos, x.info) and caseTyp.kind == tyEnum:
suggestEnum(c, x, caseTyp)
case x.kind
of nkOfBranch:
checkMinSonsLen(x, 2)
semCaseBranch(c, n, x, i, covered)
var last = sonsLen(x)-1
x.sons[last] = semExprBranchScope(c, x.sons[last])
typ = commonType(typ, x.sons[last].typ)
of nkElifBranch:
chckCovered = false
checkSonsLen(x, 2)
when newScopeForIf: openScope(c)
x.sons[0] = forceBool(c, semExprWithType(c, x.sons[0]))
when not newScopeForIf: openScope(c)
x.sons[1] = semExprBranch(c, x.sons[1])
typ = commonType(typ, x.sons[1].typ)
closeScope(c)
of nkElse:
chckCovered = false
checkSonsLen(x, 1)
x.sons[0] = semExprBranchScope(c, x.sons[0])
typ = commonType(typ, x.sons[0].typ)
hasElse = true
else:
illFormedAst(x)
if chckCovered:
if covered == toCover(n.sons[0].typ):
hasElse = true
else:
localError(n.info, errNotAllCasesCovered)
closeScope(c)
if isEmptyType(typ) or typ.kind == tyNil or not hasElse:
for i in 1..n.len-1: discardCheck(c, n.sons[i].lastSon)
# propagate any enforced VoidContext:
if typ == enforceVoidContext:
result.typ = enforceVoidContext
else:
for i in 1..n.len-1:
var it = n.sons[i]
let j = it.len-1
it.sons[j] = fitNode(c, typ, it.sons[j], it.sons[j].info)
result.typ = typ
proc semTry(c: PContext, n: PNode): PNode =
result = n
inc c.p.inTryStmt
checkMinSonsLen(n, 2)
var typ = commonTypeBegin
n.sons[0] = semExprBranchScope(c, n.sons[0])
typ = commonType(typ, n.sons[0].typ)
var check = initIntSet()
var last = sonsLen(n) - 1
for i in countup(1, last):
var a = n.sons[i]
checkMinSonsLen(a, 1)
var length = sonsLen(a)
openScope(c)
if a.kind == nkExceptBranch:
# so that ``except [a, b, c]`` is supported:
if length == 2 and a.sons[0].kind == nkBracket:
a.sons[0..0] = a.sons[0].sons
length = a.sonsLen
# Iterate through each exception type in the except branch.
for j in countup(0, length-2):
var typeNode = a.sons[j] # e.g. `Exception`
var symbolNode: PNode = nil # e.g. `foobar`
# Handle the case where the `Exception as foobar` syntax is used.
if typeNode.isInfixAs():
typeNode = a.sons[j].sons[1]
symbolNode = a.sons[j].sons[2]
# Resolve the type ident into a PType.
var typ = semTypeNode(c, typeNode, nil).toObject()
if typ.kind != tyObject:
localError(a.sons[j].info, errExprCannotBeRaised)
let newTypeNode = newNodeI(nkType, typeNode.info)
newTypeNode.typ = typ
if symbolNode.isNil:
a.sons[j] = newTypeNode
else:
a.sons[j].sons[1] = newTypeNode
# Add the exception ident to the symbol table.
let symbol = newSymG(skLet, symbolNode, c)
symbol.typ = typ.toRef()
addDecl(c, symbol)
# Overwrite symbol in AST with the symbol in the symbol table.
let symNode = newNodeI(nkSym, typeNode.info)
symNode.sym = symbol
a.sons[j].sons[2] = symNode
if containsOrIncl(check, typ.id):
localError(a.sons[j].info, errExceptionAlreadyHandled)
elif a.kind != nkFinally:
illFormedAst(n)
# last child of an nkExcept/nkFinally branch is a statement:
a.sons[length-1] = semExprBranchScope(c, a.sons[length-1])
if a.kind != nkFinally: typ = commonType(typ, a.sons[length-1].typ)
else: dec last
closeScope(c)
dec c.p.inTryStmt
if isEmptyType(typ) or typ.kind == tyNil:
discardCheck(c, n.sons[0])
for i in 1..n.len-1: discardCheck(c, n.sons[i].lastSon)
if typ == enforceVoidContext:
result.typ = enforceVoidContext
else:
if n.lastSon.kind == nkFinally: discardCheck(c, n.lastSon.lastSon)
n.sons[0] = fitNode(c, typ, n.sons[0], n.sons[0].info)
for i in 1..last:
var it = n.sons[i]
let j = it.len-1
it.sons[j] = fitNode(c, typ, it.sons[j], it.sons[j].info)
result.typ = typ
proc fitRemoveHiddenConv(c: PContext, typ: PType, n: PNode): PNode =
result = fitNode(c, typ, n, n.info)
if result.kind in {nkHiddenStdConv, nkHiddenSubConv}:
let r1 = result.sons[1]
if r1.kind in {nkCharLit..nkUInt64Lit} and typ.skipTypes(abstractRange).kind in {tyFloat..tyFloat128}:
result = newFloatNode(nkFloatLit, BiggestFloat r1.intVal)
result.info = n.info
result.typ = typ
else:
changeType(r1, typ, check=true)
result = r1
elif not sameType(result.typ, typ):
changeType(result, typ, check=false)
proc findShadowedVar(c: PContext, v: PSym): PSym =
for scope in walkScopes(c.currentScope.parent):
if scope == c.topLevelScope: break
let shadowed = strTableGet(scope.symbols, v.name)
if shadowed != nil and shadowed.kind in skLocalVars:
return shadowed
proc identWithin(n: PNode, s: PIdent): bool =
for i in 0 .. n.safeLen-1:
if identWithin(n.sons[i], s): return true
result = n.kind == nkSym and n.sym.name.id == s.id
proc semIdentDef(c: PContext, n: PNode, kind: TSymKind): PSym =
if isTopLevel(c):
result = semIdentWithPragma(c, kind, n, {sfExported})
incl(result.flags, sfGlobal)
#if kind in {skVar, skLet}:
# echo "global variable here ", n.info, " ", result.name.s
else:
result = semIdentWithPragma(c, kind, n, {})
if result.owner.kind == skModule:
incl(result.flags, sfGlobal)
suggestSym(n.info, result, c.graph.usageSym)
styleCheckDef(result)
proc checkNilable(v: PSym) =
if {sfGlobal, sfImportC} * v.flags == {sfGlobal} and
{tfNotNil, tfNeedsInit} * v.typ.flags != {}:
if v.ast.isNil:
message(v.info, warnProveInit, v.name.s)
elif tfNotNil in v.typ.flags and tfNotNil notin v.ast.typ.flags:
message(v.info, warnProveInit, v.name.s)
include semasgn
proc addToVarSection(c: PContext; result: var PNode; orig, identDefs: PNode) =
# consider this:
# var
# x = 0
# withOverloadedAssignment = foo()
# y = use(withOverloadedAssignment)
# We need to split this into a statement list with multiple 'var' sections
# in order for this transformation to be correct.
let L = identDefs.len
let value = identDefs[L-1]
if value.typ != nil and tfHasAsgn in value.typ.flags and c.p.owner.kind != skFunc:
# the spec says we need to rewrite 'var x = T()' to 'var x: T; x = T()':
identDefs.sons[L-1] = emptyNode
if result.kind != nkStmtList:
let oldResult = result
oldResult.add identDefs
result = newNodeI(nkStmtList, result.info)
result.add oldResult
else:
let o = copyNode(orig)
o.add identDefs
result.add o
for i in 0 .. L-3:
result.add overloadedAsgn(c, identDefs[i], value)
elif result.kind == nkStmtList:
let o = copyNode(orig)
o.add identDefs
result.add o
else:
result.add identDefs
proc addDefer(c: PContext; result: var PNode; s: PSym) =
let deferDestructorCall = createDestructorCall(c, s)
if deferDestructorCall != nil:
if result.kind != nkStmtList:
let oldResult = result
result = newNodeI(nkStmtList, result.info)
result.add oldResult
result.add deferDestructorCall
proc isDiscardUnderscore(v: PSym): bool =
if v.name.s == "_":
v.flags.incl(sfGenSym)
result = true
proc semUsing(c: PContext; n: PNode): PNode =
result = ast.emptyNode
if not isTopLevel(c): localError(n.info, errXOnlyAtModuleScope, "using")
for i in countup(0, sonsLen(n)-1):
var a = n.sons[i]
if gCmd == cmdIdeTools: suggestStmt(c, a)
if a.kind == nkCommentStmt: continue
if a.kind notin {nkIdentDefs, nkVarTuple, nkConstDef}: illFormedAst(a)
checkMinSonsLen(a, 3)
var length = sonsLen(a)
if a.sons[length-2].kind != nkEmpty:
let typ = semTypeNode(c, a.sons[length-2], nil)
for j in countup(0, length-3):
let v = semIdentDef(c, a.sons[j], skParam)
v.typ = typ
strTableIncl(c.signatures, v)
else:
localError(a.info, "'using' section must have a type")
var def: PNode
if a.sons[length-1].kind != nkEmpty:
localError(a.info, "'using' sections cannot contain assignments")
proc hasEmpty(typ: PType): bool =
if typ.kind in {tySequence, tyArray, tySet}:
result = typ.lastSon.kind == tyEmpty
elif typ.kind == tyTuple:
for s in typ.sons:
result = result or hasEmpty(s)
proc makeDeref(n: PNode): PNode =
var t = skipTypes(n.typ, {tyGenericInst, tyAlias})
if t.kind in tyUserTypeClasses and t.isResolvedUserTypeClass:
t = t.lastSon
result = n
if t.kind == tyVar:
result = newNodeIT(nkHiddenDeref, n.info, t.sons[0])
addSon(result, n)
t = skipTypes(t.sons[0], {tyGenericInst, tyAlias})
while t.kind in {tyPtr, tyRef}:
var a = result
let baseTyp = t.lastSon
result = newNodeIT(nkHiddenDeref, n.info, baseTyp)
addSon(result, a)
t = skipTypes(baseTyp, {tyGenericInst, tyAlias})
proc fillPartialObject(c: PContext; n: PNode; typ: PType) =
if n.len == 2:
let x = semExprWithType(c, n[0])
let y = considerQuotedIdent(n[1])
let obj = x.typ.skipTypes(abstractPtrs)
if obj.kind == tyObject and tfPartial in obj.flags:
let field = newSym(skField, getIdent(y.s), obj.sym, n[1].info)
field.typ = skipIntLit(typ)
field.position = sonsLen(obj.n)
addSon(obj.n, newSymNode(field))
n.sons[0] = makeDeref x
n.sons[1] = newSymNode(field)
n.typ = field.typ
else:
localError(n.info, "implicit object field construction " &
"requires a .partial object, but got " & typeToString(obj))
else:
localError(n.info, "nkDotNode requires 2 children")
proc setVarType(v: PSym, typ: PType) =
if v.typ != nil and not sameTypeOrNil(v.typ, typ):
localError(v.info, "inconsistent typing for reintroduced symbol '" &
v.name.s & "': previous type was: " & typeToString(v.typ) &
"; new type is: " & typeToString(typ))
v.typ = typ
proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
var b: PNode
result = copyNode(n)
var hasCompileTime = false
for i in countup(0, sonsLen(n)-1):
var a = n.sons[i]
if gCmd == cmdIdeTools: suggestStmt(c, a)
if a.kind == nkCommentStmt: continue
if a.kind notin {nkIdentDefs, nkVarTuple, nkConstDef}: illFormedAst(a)
checkMinSonsLen(a, 3)
var length = sonsLen(a)
var typ: PType
if a.sons[length-2].kind != nkEmpty:
typ = semTypeNode(c, a.sons[length-2], nil)
else:
typ = nil
var def: PNode = ast.emptyNode
if a.sons[length-1].kind != nkEmpty:
def = semExprWithType(c, a.sons[length-1], {efAllowDestructor})
if def.typ.kind == tyTypeDesc and c.p.owner.kind != skMacro:
# prevent the all too common 'var x = int' bug:
localError(def.info, "'typedesc' metatype is not valid here; typed '=' instead of ':'?")
def.typ = errorType(c)
if typ != nil:
if typ.isMetaType:
def = inferWithMetatype(c, typ, def)
typ = def.typ
else:
# BUGFIX: ``fitNode`` is needed here!
# check type compatibility between def.typ and typ
def = fitNode(c, typ, def, def.info)
#changeType(def.skipConv, typ, check=true)
else:
typ = skipIntLit(def.typ)
if typ.kind in tyUserTypeClasses and typ.isResolvedUserTypeClass:
typ = typ.lastSon
if hasEmpty(typ):
localError(def.info, errCannotInferTypeOfTheLiteral,
($typ.kind).substr(2).toLowerAscii)
elif typ.kind == tyProc and tfUnresolved in typ.flags:
localError(def.info, errProcHasNoConcreteType, def.renderTree)
else:
if symkind == skLet: localError(a.info, errLetNeedsInit)
# this can only happen for errornous var statements:
if typ == nil: continue
typeAllowedCheck(a.info, typ, symkind)
var tup = skipTypes(typ, {tyGenericInst, tyAlias})
if a.kind == nkVarTuple:
if tup.kind != tyTuple:
localError(a.info, errXExpected, "tuple")
elif length-2 != sonsLen(tup):
localError(a.info, errWrongNumberOfVariables)
else:
b = newNodeI(nkVarTuple, a.info)
newSons(b, length)
b.sons[length-2] = a.sons[length-2] # keep type desc for doc generator
b.sons[length-1] = def
addToVarSection(c, result, n, b)
elif tup.kind == tyTuple and def.kind == nkPar and
a.kind == nkIdentDefs and a.len > 3:
message(a.info, warnEachIdentIsTuple)
for j in countup(0, length-3):
if a[j].kind == nkDotExpr:
fillPartialObject(c, a[j],
if a.kind != nkVarTuple: typ else: tup.sons[j])
addToVarSection(c, result, n, a)
continue
var v = semIdentDef(c, a.sons[j], symkind)
if sfGenSym notin v.flags and not isDiscardUnderscore(v):
addInterfaceDecl(c, v)
when oKeepVariableNames:
if c.inUnrolledContext > 0: v.flags.incl(sfShadowed)
else:
let shadowed = findShadowedVar(c, v)
if shadowed != nil:
shadowed.flags.incl(sfShadowed)
if shadowed.kind == skResult and sfGenSym notin v.flags:
message(a.info, warnResultShadowed)
# a shadowed variable is an error unless it appears on the right
# side of the '=':
if warnShadowIdent in gNotes and not identWithin(def, v.name):
message(a.info, warnShadowIdent, v.name.s)
if a.kind != nkVarTuple:
if def.kind != nkEmpty:
# this is needed for the evaluation pass and for the guard checking:
v.ast = def
if sfThread in v.flags: localError(def.info, errThreadvarCannotInit)
setVarType(v, typ)
b = newNodeI(nkIdentDefs, a.info)
if importantComments():
# keep documentation information:
b.comment = a.comment
addSon(b, newSymNode(v))
addSon(b, a.sons[length-2]) # keep type desc for doc generator
addSon(b, copyTree(def))
addToVarSection(c, result, n, b)
else:
if def.kind == nkPar: v.ast = def[j]
setVarType(v, tup.sons[j])
b.sons[j] = newSymNode(v)
when not newDestructors: addDefer(c, result, v)
checkNilable(v)
if sfCompileTime in v.flags: hasCompileTime = true
if hasCompileTime: vm.setupCompileTimeVar(c.module, c.cache, result)
proc semConst(c: PContext, n: PNode): PNode =
result = copyNode(n)
for i in countup(0, sonsLen(n) - 1):
var a = n.sons[i]
if gCmd == cmdIdeTools: suggestStmt(c, a)
if a.kind == nkCommentStmt: continue
if (a.kind != nkConstDef): illFormedAst(a)
checkSonsLen(a, 3)
var v = semIdentDef(c, a.sons[0], skConst)
var typ: PType = nil
if a.sons[1].kind != nkEmpty: typ = semTypeNode(c, a.sons[1], nil)
var def = semConstExpr(c, a.sons[2])
if def == nil:
localError(a.sons[2].info, errConstExprExpected)
continue
# check type compatibility between def.typ and typ:
if typ != nil:
def = fitRemoveHiddenConv(c, typ, def)
else:
typ = def.typ
if typ == nil:
localError(a.sons[2].info, errConstExprExpected)
continue
if typeAllowed(typ, skConst) != nil and def.kind != nkNilLit:
localError(a.info, "invalid type for const: " & typeToString(typ))
continue
setVarType(v, typ)
v.ast = def # no need to copy
if sfGenSym notin v.flags: addInterfaceDecl(c, v)
var b = newNodeI(nkConstDef, a.info)
if importantComments(): b.comment = a.comment
addSon(b, newSymNode(v))
addSon(b, a.sons[1])
addSon(b, copyTree(def))
addSon(result, b)
include semfields
proc addForVarDecl(c: PContext, v: PSym) =
if warnShadowIdent in gNotes:
let shadowed = findShadowedVar(c, v)
if shadowed != nil:
# XXX should we do this here?
#shadowed.flags.incl(sfShadowed)
message(v.info, warnShadowIdent, v.name.s)
addDecl(c, v)
proc symForVar(c: PContext, n: PNode): PSym =
let m = if n.kind == nkPragmaExpr: n.sons[0] else: n
result = newSymG(skForVar, m, c)
styleCheckDef(result)
proc semForVars(c: PContext, n: PNode): PNode =
result = n
var length = sonsLen(n)
let iterBase = n.sons[length-2].typ
var iter = skipTypes(iterBase, {tyGenericInst, tyAlias})
# length == 3 means that there is one for loop variable
# and thus no tuple unpacking:
if iter.kind != tyTuple or length == 3:
if length == 3:
var v = symForVar(c, n.sons[0])
if getCurrOwner(c).kind == skModule: incl(v.flags, sfGlobal)
# BUGFIX: don't use `iter` here as that would strip away
# the ``tyGenericInst``! See ``tests/compile/tgeneric.nim``
# for an example:
v.typ = iterBase
n.sons[0] = newSymNode(v)
if sfGenSym notin v.flags: addForVarDecl(c, v)
else:
localError(n.info, errWrongNumberOfVariables)
elif length-2 != sonsLen(iter):
localError(n.info, errWrongNumberOfVariables)
else:
for i in countup(0, length - 3):
var v = symForVar(c, n.sons[i])
if getCurrOwner(c).kind == skModule: incl(v.flags, sfGlobal)
v.typ = iter.sons[i]
n.sons[i] = newSymNode(v)
if sfGenSym notin v.flags and not isDiscardUnderscore(v):
addForVarDecl(c, v)
inc(c.p.nestedLoopCounter)
n.sons[length-1] = semStmt(c, n.sons[length-1])
dec(c.p.nestedLoopCounter)
proc implicitIterator(c: PContext, it: string, arg: PNode): PNode =
result = newNodeI(nkCall, arg.info)
result.add(newIdentNode(it.getIdent, arg.info))
if arg.typ != nil and arg.typ.kind == tyVar:
result.add newDeref(arg)
else:
result.add arg
result = semExprNoDeref(c, result, {efWantIterator})
proc semFor(c: PContext, n: PNode): PNode =
result = n
checkMinSonsLen(n, 3)
var length = sonsLen(n)
openScope(c)
n.sons[length-2] = semExprNoDeref(c, n.sons[length-2], {efWantIterator})
var call = n.sons[length-2]
let isCallExpr = call.kind in nkCallKinds
if isCallExpr and call[0].kind == nkSym and
call[0].sym.magic in {mFields, mFieldPairs, mOmpParFor}:
if call.sons[0].sym.magic == mOmpParFor:
result = semForVars(c, n)
result.kind = nkParForStmt
else:
result = semForFields(c, n, call.sons[0].sym.magic)
elif isCallExpr and call.sons[0].typ.callConv == ccClosure and
tfIterator in call.sons[0].typ.flags:
# first class iterator:
result = semForVars(c, n)
elif not isCallExpr or call.sons[0].kind != nkSym or
call.sons[0].sym.kind != skIterator:
if length == 3:
n.sons[length-2] = implicitIterator(c, "items", n.sons[length-2])
elif length == 4:
n.sons[length-2] = implicitIterator(c, "pairs", n.sons[length-2])
else:
localError(n.sons[length-2].info, errIteratorExpected)
result = semForVars(c, n)
else:
result = semForVars(c, n)
# propagate any enforced VoidContext:
if n.sons[length-1].typ == enforceVoidContext:
result.typ = enforceVoidContext
closeScope(c)
proc semRaise(c: PContext, n: PNode): PNode =
result = n
checkSonsLen(n, 1)
if n.sons[0].kind != nkEmpty:
n.sons[0] = semExprWithType(c, n.sons[0])
var typ = n.sons[0].typ
if typ.kind != tyRef or typ.lastSon.kind != tyObject:
localError(n.info, errExprCannotBeRaised)
proc addGenericParamListToScope(c: PContext, n: PNode) =
if n.kind != nkGenericParams: illFormedAst(n)
for i in countup(0, sonsLen(n)-1):
var a = n.sons[i]
if a.kind == nkSym: addDecl(c, a.sym)
else: illFormedAst(a)
proc typeSectionLeftSidePass(c: PContext, n: PNode) =
# process the symbols on the left side for the whole type section, before
# we even look at the type definitions on the right
for i in countup(0, sonsLen(n) - 1):
var a = n.sons[i]
when defined(nimsuggest):
if gCmd == cmdIdeTools:
inc c.inTypeContext
suggestStmt(c, a)
dec c.inTypeContext
if a.kind == nkCommentStmt: continue
if a.kind != nkTypeDef: illFormedAst(a)
checkSonsLen(a, 3)
let name = a.sons[0]
var s: PSym
if name.kind == nkDotExpr:
s = qualifiedLookUp(c, name, {checkUndeclared, checkModule})
if s.kind != skType or
s.typ.skipTypes(abstractPtrs).kind != tyObject or
tfPartial notin s.typ.skipTypes(abstractPtrs).flags:
localError(name.info, "only .partial objects can be extended")
else:
s = semIdentDef(c, name, skType)
s.typ = newTypeS(tyForward, c)
s.typ.sym = s # process pragmas:
if name.kind == nkPragmaExpr:
pragma(c, s, name.sons[1], typePragmas)
# add it here, so that recursive types are possible:
if sfGenSym notin s.flags: addInterfaceDecl(c, s)
a.sons[0] = newSymNode(s)
proc checkCovariantParamsUsages(genericType: PType) =
var body = genericType{-1}
proc traverseSubTypes(t: PType): bool =
template error(msg) = localError(genericType.sym.info, msg)
result = false
template subresult(r) =
let sub = r
result = result or sub
case t.kind
of tyGenericParam:
t.flags.incl tfWeakCovariant
return true
of tyObject:
for field in t.n:
subresult traverseSubTypes(field.typ)
of tyArray:
return traverseSubTypes(t[1])
of tyProc:
for subType in t.sons:
if subType != nil:
subresult traverseSubTypes(subType)
if result:
error("non-invariant type param used in a proc type: " & $t)
of tySequence:
return traverseSubTypes(t[0])
of tyGenericInvocation:
let targetBody = t[0]
for i in 1 .. <t.len:
let param = t[i]
if param.kind == tyGenericParam:
if tfCovariant in param.flags:
let formalFlags = targetBody[i-1].flags
if tfCovariant notin formalFlags:
error("covariant param '" & param.sym.name.s &
"' used in a non-covariant position")
elif tfWeakCovariant in formalFlags:
param.flags.incl tfWeakCovariant
result = true
elif tfContravariant in param.flags:
let formalParam = targetBody[i-1].sym
if tfContravariant notin formalParam.typ.flags:
error("contravariant param '" & param.sym.name.s &
"' used in a non-contravariant position")
result = true
else:
subresult traverseSubTypes(param)
of tyAnd, tyOr, tyNot, tyStatic, tyBuiltInTypeClass, tyCompositeTypeClass:
error("non-invariant type parameters cannot be used with types such '" & $t & "'")
of tyUserTypeClass, tyUserTypeClassInst:
error("non-invariant type parameters are not supported in concepts")
of tyTuple:
for fieldType in t.sons:
subresult traverseSubTypes(fieldType)
of tyPtr, tyRef, tyVar:
if t.base.kind == tyGenericParam: return true
return traverseSubTypes(t.base)
of tyDistinct, tyAlias:
return traverseSubTypes(t.lastSon)
of tyGenericInst:
internalAssert false
else:
discard
discard traverseSubTypes(body)
proc typeSectionRightSidePass(c: PContext, n: PNode) =
for i in countup(0, sonsLen(n) - 1):
var a = n.sons[i]
if a.kind == nkCommentStmt: continue
if (a.kind != nkTypeDef): illFormedAst(a)
checkSonsLen(a, 3)
let name = a.sons[0]
if (name.kind != nkSym): illFormedAst(a)
var s = name.sym
if s.magic == mNone and a.sons[2].kind == nkEmpty:
localError(a.info, errImplOfXexpected, s.name.s)
if s.magic != mNone: processMagicType(c, s)
if a.sons[1].kind != nkEmpty:
# We have a generic type declaration here. In generic types,
# symbol lookup needs to be done here.
openScope(c)
pushOwner(c, s)
if s.magic == mNone: s.typ.kind = tyGenericBody
# XXX for generic type aliases this is not correct! We need the
# underlying Id really:
#
# type
# TGObj[T] = object
# TAlias[T] = TGObj[T]
#
s.typ.n = semGenericParamList(c, a.sons[1], s.typ)
a.sons[1] = s.typ.n
s.typ.size = -1 # could not be computed properly
# we fill it out later. For magic generics like 'seq', it won't be filled
# so we use tyNone instead of nil to not crash for strange conversions
# like: mydata.seq
rawAddSon(s.typ, newTypeS(tyNone, c))
s.ast = a
inc c.inGenericContext
var body = semTypeNode(c, a.sons[2], nil)
dec c.inGenericContext
if body != nil:
body.sym = s
body.size = -1 # could not be computed properly
s.typ.sons[sonsLen(s.typ) - 1] = body
if tfCovariant in s.typ.flags:
checkCovariantParamsUsages(s.typ)
# XXX: This is a temporary limitation:
# The codegen currently produces various failures with
# generic imported types that have fields, but we need
# the fields specified in order to detect weak covariance.
# The proper solution is to teach the codegen how to handle
# such types, because this would offer various interesting
# possibilities such as instantiating C++ generic types with
# garbage collected Nim types.
if sfImportc in s.flags:
var body = s.typ.lastSon
if body.kind == tyObject:
# erases all declared fields
body.n.sons = nil
popOwner(c)
closeScope(c)
elif a.sons[2].kind != nkEmpty:
# process the type's body:
pushOwner(c, s)
var t = semTypeNode(c, a.sons[2], s.typ)
if s.typ == nil:
s.typ = t
elif t != s.typ and (s.typ == nil or s.typ.kind != tyAlias):
# this can happen for e.g. tcan_alias_specialised_generic:
assignType(s.typ, t)
#debug s.typ
s.ast = a
popOwner(c)
let aa = a.sons[2]
if aa.kind in {nkRefTy, nkPtrTy} and aa.len == 1 and
aa.sons[0].kind == nkObjectTy:
# give anonymous object a dummy symbol:
var st = s.typ
if st.kind == tyGenericBody: st = st.lastSon
internalAssert st.kind in {tyPtr, tyRef}
internalAssert st.lastSon.sym == nil
incl st.flags, tfRefsAnonObj
let obj = newSym(skType, getIdent(s.name.s & ":ObjectType"),
getCurrOwner(c), s.info)
obj.typ = st.lastSon
st.lastSon.sym = obj
proc checkForMetaFields(n: PNode) =
template checkMeta(t) =
if t != nil and t.isMetaType and tfGenericTypeParam notin t.flags:
localError(n.info, errTIsNotAConcreteType, t.typeToString)
if n.isNil: return
case n.kind
of nkRecList, nkRecCase:
for s in n: checkForMetaFields(s)
of nkOfBranch, nkElse:
checkForMetaFields(n.lastSon)
of nkSym:
let t = n.sym.typ
case t.kind
of tySequence, tySet, tyArray, tyOpenArray, tyVar, tyPtr, tyRef,
tyProc, tyGenericInvocation, tyGenericInst, tyAlias:
let start = ord(t.kind in {tyGenericInvocation, tyGenericInst})
for i in start .. <t.sons.len:
checkMeta(t.sons[i])
else:
checkMeta(t)
else:
internalAssert false
proc typeSectionFinalPass(c: PContext, n: PNode) =
for i in countup(0, sonsLen(n) - 1):
var a = n.sons[i]
if a.kind == nkCommentStmt: continue
if a.sons[0].kind != nkSym: illFormedAst(a)
var s = a.sons[0].sym
# compute the type's size and check for illegal recursions:
if a.sons[1].kind == nkEmpty:
var x = a[2]
while x.kind in {nkStmtList, nkStmtListExpr} and x.len > 0:
x = x.lastSon
if x.kind notin {nkObjectTy, nkDistinctTy, nkEnumTy, nkEmpty} and
s.typ.kind notin {tyObject, tyEnum}:
# type aliases are hard:
var t = semTypeNode(c, x, nil)
assert t != nil
if s.typ != nil and s.typ.kind != tyAlias:
if t.kind in {tyProc, tyGenericInst} and not t.isMetaType: