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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
const
errNoSymbolToBorrowFromFound = "no symbol to borrow from found"
errDiscardValueX = "value of type '$1' has to be discarded"
errInvalidDiscard = "statement returns no value that can be discarded"
errInvalidControlFlowX = "invalid control flow: $1"
errSelectorMustBeOfCertainTypes = "selector must be of an ordinal type, float or string"
errExprCannotBeRaised = "only a 'ref object' can be raised"
errBreakOnlyInLoop = "'break' only allowed in loop construct"
errExceptionAlreadyHandled = "exception already handled"
errYieldNotAllowedHere = "'yield' only allowed in an iterator"
errYieldNotAllowedInTryStmt = "'yield' cannot be used within 'try' in a non-inlined iterator"
errInvalidNumberOfYieldExpr = "invalid number of 'yield' expressions"
errCannotReturnExpr = "current routine cannot return an expression"
errGenericLambdaNotAllowed = "A nested proc can have generic parameters only when " &
"it is used as an operand to another routine and the types " &
"of the generic paramers can be inferred from the expected signature."
errCannotInferTypeOfTheLiteral = "cannot infer the type of the $1"
errCannotInferReturnType = "cannot infer the return type of the proc"
errCannotInferStaticParam = "cannot infer the value of the static param '$1'"
errProcHasNoConcreteType = "'$1' doesn't have a concrete type, due to unspecified generic parameters."
errLetNeedsInit = "'let' symbol requires an initialization"
errThreadvarCannotInit = "a thread var cannot be initialized explicitly; this would only run for the main thread"
errImplOfXexpected = "implementation of '$1' expected"
errRecursiveDependencyX = "recursive dependency: '$1'"
errPragmaOnlyInHeaderOfProcX = "pragmas are only allowed in the header of a proc; redefinition of $1"
proc semDiscard(c: PContext, n: PNode): PNode =
result = n
checkSonsLen(n, 1, c.config)
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 or n.sons[0].kind == nkTypeOfExpr:
localError(c.config, n.info, errInvalidDiscard)
proc semBreakOrContinue(c: PContext, n: PNode): PNode =
result = n
checkSonsLen(n, 1, c.config)
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, c.config)
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(c.config, x.info, s, c.graph.usageSym)
styleCheckUse(x.info, s)
else:
localError(c.config, n.info, errInvalidControlFlowX % s.name.s)
else:
localError(c.config, n.info, errGenerated, "'continue' cannot have a label")
elif (c.p.nestedLoopCounter <= 0) and (c.p.nestedBlockCounter <= 0):
localError(c.config, n.info, errInvalidControlFlowX %
renderTree(n, {renderNoComments}))
proc semAsm(c: PContext, n: PNode): PNode =
checkSonsLen(n, 2, c.config)
var marker = pragmaAsm(c, n.sons[0])
if marker == '\0': marker = '`' # default marker
result = semAsmOrEmit(c, n, marker)
proc semWhile(c: PContext, n: PNode; flags: TExprFlags): PNode =
result = n
checkSonsLen(n, 2, c.config)
openScope(c)
n.sons[0] = forceBool(c, semExprWithType(c, n.sons[0]))
inc(c.p.nestedLoopCounter)
n.sons[1] = semStmt(c, n.sons[1], flags)
dec(c.p.nestedLoopCounter)
closeScope(c)
if n.sons[1].typ == c.enforceVoidContext:
result.typ = c.enforceVoidContext
elif efInTypeof in flags:
result.typ = n[1].typ
proc toCover(c: PContext, t: PType): BiggestInt =
let t2 = skipTypes(t, abstractVarRange-{tyTypeDesc})
if t2.kind == tyEnum and enumHasHoles(t2):
result = sonsLen(t2.n)
else:
result = lengthOrd(c.config, skipTypes(t, abstractVar-{tyTypeDesc}))
proc semProc(c: PContext, n: PNode): PNode
proc semExprBranch(c: PContext, n: PNode; flags: TExprFlags = {}): PNode =
result = semExpr(c, n, flags)
if result.typ != nil:
# XXX tyGenericInst here?
if result.typ.kind in {tyVar, tyLent}: result = newDeref(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,
nkHiddenStdConv, nkHiddenDeref}
proc implicitlyDiscardable(n: PNode): bool =
var n = n
while n.kind in skipForDiscardable: n = n.lastSon
result = n.kind == nkRaiseStmt or
(isCallExpr(n) and n.sons[0].kind == nkSym and
sfDiscardable in n.sons[0].sym.flags)
proc fixNilType(c: PContext; n: PNode) =
if isAtom(n):
if n.kind != nkNilLit and n.typ != nil:
localError(c.config, n.info, errDiscardValueX % n.typ.typeToString)
elif n.kind in {nkStmtList, nkStmtListExpr}:
n.kind = nkStmtList
for it in n: fixNilType(c, it)
n.typ = nil
proc discardCheck(c: PContext, result: PNode, flags: TExprFlags) =
if c.matchedConcept != nil or efInTypeof in flags: return
if result.typ != nil and result.typ.kind notin {tyStmt, tyVoid}:
if implicitlyDiscardable(result):
var n = newNodeI(nkDiscardStmt, result.info, 1)
n[0] = result
elif result.typ.kind != tyError and c.config.cmd != cmdInteractive:
var n = result
while n.kind in skipForDiscardable: n = n.lastSon
var s = "expression '" & $n & "' is of type '" &
result.typ.typeToString & "' and has to be discarded"
if result.info.line != n.info.line or
result.info.fileIndex != n.info.fileIndex:
s.add "; start of expression here: " & c.config$result.info
if result.typ.kind == tyProc:
s.add "; for a function call use ()"
localError(c.config, n.info, s)
proc semIf(c: PContext, n: PNode; flags: TExprFlags): 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:
openScope(c)
it.sons[0] = forceBool(c, semExprWithType(c, it.sons[0]))
it.sons[1] = semExprBranch(c, it.sons[1])
typ = commonType(typ, it.sons[1])
closeScope(c)
elif it.len == 1:
hasElse = true
it.sons[0] = semExprBranchScope(c, it.sons[0])
typ = commonType(typ, it.sons[0])
else: illFormedAst(it, c.config)
if isEmptyType(typ) or typ.kind in {tyNil, tyExpr} or
(not hasElse and efInTypeof notin flags):
for it in n: discardCheck(c, it.lastSon, flags)
result.kind = nkIfStmt
# propagate any enforced VoidContext:
if typ == c.enforceVoidContext: result.typ = c.enforceVoidContext
else:
for it in n:
let j = it.len-1
if not endsInNoReturn(it.sons[j]):
it.sons[j] = fitNode(c, typ, it.sons[j], it.sons[j].info)
result.kind = nkIfExpr
result.typ = typ
proc semTry(c: PContext, n: PNode; flags: TExprFlags): PNode =
var check = initIntSet()
template semExceptBranchType(typeNode: PNode): bool =
# returns true if exception type is imported type
let typ = semTypeNode(c, typeNode, nil).toObject()
var is_imported = false
if isImportedException(typ, c.config):
is_imported = true
elif not isException(typ):
localError(c.config, typeNode.info, errExprCannotBeRaised)
if containsOrIncl(check, typ.id):
localError(c.config, typeNode.info, errExceptionAlreadyHandled)
typeNode = newNodeIT(nkType, typeNode.info, typ)
is_imported
result = n
inc c.p.inTryStmt
checkMinSonsLen(n, 2, c.config)
var typ = commonTypeBegin
n[0] = semExprBranchScope(c, n[0])
typ = commonType(typ, n[0].typ)
var last = sonsLen(n) - 1
var catchAllExcepts = 0
for i in countup(1, last):
let a = n.sons[i]
checkMinSonsLen(a, 1, c.config)
openScope(c)
if a.kind == nkExceptBranch:
if a.len == 2 and a[0].kind == nkBracket:
# rewrite ``except [a, b, c]: body`` -> ```except a, b, c: body```
a.sons[0..0] = a[0].sons
if a.len == 2 and a[0].isInfixAs():
# support ``except Exception as ex: body``
let is_imported = semExceptBranchType(a[0][1])
let symbol = newSymG(skLet, a[0][2], c)
symbol.typ = if is_imported: a[0][1].typ
else: a[0][1].typ.toRef()
addDecl(c, symbol)
# Overwrite symbol in AST with the symbol in the symbol table.
a[0][2] = newSymNode(symbol, a[0][2].info)
elif a.len == 1:
# count number of ``except: body`` blocks
inc catchAllExcepts
else:
# support ``except KeyError, ValueError, ... : body``
if catchAllExcepts > 0:
# if ``except: body`` already encountered,
# cannot be followed by a ``except KeyError, ... : body`` block
inc catchAllExcepts
var is_native, is_imported: bool
for j in 0..a.len-2:
let tmp = semExceptBranchType(a[j])
if tmp: is_imported = true
else: is_native = true
if is_native and is_imported:
localError(c.config, a[0].info, "Mix of imported and native exception types is not allowed in one except branch")
elif a.kind == nkFinally:
if i != n.len-1:
localError(c.config, a.info, "Only one finally is allowed after all other branches")
else:
illFormedAst(n, c.config)
if catchAllExcepts > 1:
# if number of ``except: body`` blocks is greater than 1
# or more specific exception follows a general except block, it is invalid
localError(c.config, a.info, "Only one general except clause is allowed after more specific exceptions")
# last child of an nkExcept/nkFinally branch is a statement:
a[^1] = semExprBranchScope(c, a[^1])
if a.kind != nkFinally: typ = commonType(typ, a[^1])
else: dec last
closeScope(c)
dec c.p.inTryStmt
if isEmptyType(typ) or typ.kind in {tyNil, tyExpr}:
discardCheck(c, n.sons[0], flags)
for i in 1..n.len-1: discardCheck(c, n.sons[i].lastSon, flags)
if typ == c.enforceVoidContext:
result.typ = c.enforceVoidContext
else:
if n.lastSon.kind == nkFinally: discardCheck(c, n.lastSon.lastSon, flags)
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(c, r1, typ, check=true)
result = r1
elif not sameType(result.typ, typ):
changeType(c, 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(c.config, n.info, result, c.graph.usageSym)
styleCheckDef(c.config, result)
proc checkNilable(c: PContext; v: PSym) =
if {sfGlobal, sfImportC} * v.flags == {sfGlobal} and
{tfNotNil, tfNeedsInit} * v.typ.flags != {}:
if v.ast.isNil:
message(c.config, v.info, warnProveInit, v.name.s)
elif tfNotNil in v.typ.flags and tfNotNil notin v.ast.typ.flags:
message(c.config, v.info, warnProveInit, v.name.s)
include semasgn
proc addToVarSection(c: PContext; result: PNode; orig, identDefs: PNode) =
let L = identDefs.len
let value = identDefs[L-1]
if result.kind == nkStmtList:
let o = copyNode(orig)
o.add identDefs
result.add o
else:
result.add identDefs
proc isDiscardUnderscore(v: PSym): bool =
if v.name.s == "_":
v.flags.incl(sfGenSym)
result = true
proc semUsing(c: PContext; n: PNode): PNode =
result = c.graph.emptyNode
if not isTopLevel(c): localError(c.config, n.info, errXOnlyAtModuleScope % "using")
for i in countup(0, sonsLen(n)-1):
var a = n.sons[i]
if c.config.cmd == cmdIdeTools: suggestStmt(c, a)
if a.kind == nkCommentStmt: continue
if a.kind notin {nkIdentDefs, nkVarTuple, nkConstDef}: illFormedAst(a, c.config)
checkMinSonsLen(a, 3, c.config)
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(c.config, a.info, "'using' section must have a type")
var def: PNode
if a.sons[length-1].kind != nkEmpty:
localError(c.config, 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 = n.typ
if t.kind in tyUserTypeClasses and t.isResolvedUserTypeClass:
t = t.lastSon
t = skipTypes(t, {tyGenericInst, tyAlias, tySink})
result = n
if t.kind in {tyVar, tyLent}:
result = newNodeIT(nkHiddenDeref, n.info, t.sons[0])
addSon(result, n)
t = skipTypes(t.sons[0], {tyGenericInst, tyAlias, tySink})
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, tySink})
proc fillPartialObject(c: PContext; n: PNode; typ: PType) =
if n.len == 2:
let x = semExprWithType(c, n[0])
let y = considerQuotedIdent(c, n[1])
let obj = x.typ.skipTypes(abstractPtrs)
if obj.kind == tyObject and tfPartial in obj.flags:
let field = newSym(skField, getIdent(c.cache, 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(c.config, n.info, "implicit object field construction " &
"requires a .partial object, but got " & typeToString(obj))
else:
localError(c.config, n.info, "nkDotNode requires 2 children")
proc setVarType(c: PContext; v: PSym, typ: PType) =
if v.typ != nil and not sameTypeOrNil(v.typ, typ):
localError(c.config, 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 c.config.cmd == cmdIdeTools: suggestStmt(c, a)
if a.kind == nkCommentStmt: continue
if a.kind notin {nkIdentDefs, nkVarTuple, nkConstDef}: illFormedAst(a, c.config)
checkMinSonsLen(a, 3, c.config)
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 = c.graph.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(c.config, 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 = def.typ.skipTypes({tyStatic}).skipIntLit
if typ.kind in tyUserTypeClasses and typ.isResolvedUserTypeClass:
typ = typ.lastSon
if hasEmpty(typ):
localError(c.config, def.info, errCannotInferTypeOfTheLiteral %
($typ.kind).substr(2).toLowerAscii)
elif typ.kind == tyProc and tfUnresolved in typ.flags:
localError(c.config, def.info, errProcHasNoConcreteType % def.renderTree)
else:
if symkind == skLet: localError(c.config, a.info, errLetNeedsInit)
# this can only happen for errornous var statements:
if typ == nil: continue
typeAllowedCheck(c.config, a.info, typ, symkind, if c.matchedConcept != nil: {taConcept} else: {})
liftTypeBoundOps(c, typ, a.info)
var tup = skipTypes(typ, {tyGenericInst, tyAlias, tySink})
if a.kind == nkVarTuple:
if tup.kind != tyTuple:
localError(c.config, a.info, errXExpected, "tuple")
elif length-2 != sonsLen(tup):
localError(c.config, a.info, errWrongNumberOfVariables)
b = newNodeI(nkVarTuple, a.info)
newSons(b, length)
# keep type desc for doc generator
# NOTE: at the moment this is always ast.emptyNode, see parser.nim
b.sons[length-2] = a.sons[length-2]
b.sons[length-1] = def
addToVarSection(c, result, n, b)
elif tup.kind == tyTuple and def.kind in {nkPar, nkTupleConstr} and
a.kind == nkIdentDefs and a.len > 3:
message(c.config, 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(c.config, a.info, warnResultShadowed)
# a shadowed variable is an error unless it appears on the right
# side of the '=':
if warnShadowIdent in c.config.notes and not identWithin(def, v.name):
message(c.config, 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(c.config, def.info, errThreadvarCannotInit)
setVarType(c, v, typ)
b = newNodeI(nkIdentDefs, a.info)
if importantComments(c.config):
# keep documentation information:
b.comment = a.comment
addSon(b, newSymNode(v))
# keep type desc for doc generator
addSon(b, a.sons[length-2])
addSon(b, copyTree(def))
addToVarSection(c, result, n, b)
else:
if def.kind in {nkPar, nkTupleConstr}: v.ast = def[j]
# bug #7663, for 'nim check' this can be a non-tuple:
if tup.kind == tyTuple: setVarType(c, v, tup.sons[j])
else: v.typ = tup
b.sons[j] = newSymNode(v)
checkNilable(c, v)
if sfCompileTime in v.flags: hasCompileTime = true
if v.flags * {sfGlobal, sfThread} == {sfGlobal}:
message(c.config, v.info, hintGlobalVar)
if hasCompileTime:
vm.setupCompileTimeVar(c.module, c.graph, result)
# handled by the VM codegen:
#c.graph.recordStmt(c.graph, c.module, 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 c.config.cmd == cmdIdeTools: suggestStmt(c, a)
if a.kind == nkCommentStmt: continue
if a.kind != nkConstDef: illFormedAst(a, c.config)
checkSonsLen(a, 3, c.config)
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(c.config, 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(c.config, a.sons[2].info, errConstExprExpected)
continue
if typeAllowed(typ, skConst) != nil and def.kind != nkNilLit:
localError(c.config, a.info, "invalid type for const: " & typeToString(typ))
continue
setVarType(c, 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(c.config): 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 c.config.notes:
let shadowed = findShadowedVar(c, v)
if shadowed != nil:
# XXX should we do this here?
#shadowed.flags.incl(sfShadowed)
message(c.config, 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(c.config, result)
if n.kind == nkPragmaExpr:
pragma(c, result, n.sons[1], forVarPragmas)
proc semForVars(c: PContext, n: PNode; flags: TExprFlags): PNode =
result = n
var length = sonsLen(n)
let iterBase = n.sons[length-2].typ
var iter = skipTypes(iterBase, {tyGenericInst, tyAlias, tySink})
# 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(c.config, n.info, errWrongNumberOfVariables)
elif length-2 != sonsLen(iter):
localError(c.config, 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)
openScope(c)
n.sons[length-1] = semExprBranch(c, n.sons[length-1], flags)
if efInTypeof notin flags:
discardCheck(c, n.sons[length-1], flags)
closeScope(c)
dec(c.p.nestedLoopCounter)
proc implicitIterator(c: PContext, it: string, arg: PNode): PNode =
result = newNodeI(nkCall, arg.info)
result.add(newIdentNode(getIdent(c.cache, it), arg.info))
if arg.typ != nil and arg.typ.kind in {tyVar, tyLent}:
result.add newDeref(arg)
else:
result.add arg
result = semExprNoDeref(c, result, {efWantIterator})
proc isTrivalStmtExpr(n: PNode): bool =
for i in 0 .. n.len-2:
if n[i].kind notin {nkEmpty, nkCommentStmt}:
return false
result = true
proc handleStmtMacro(c: PContext; n, selector: PNode; magicType: string): PNode =
if selector.kind in nkCallKinds:
# we transform
# n := for a, b, c in m(x, y, z): Y
# to
# m(n)
let maType = magicsys.getCompilerProc(c.graph, magicType)
if maType == nil: return
let headSymbol = selector[0]
var o: TOverloadIter
var match: PSym = nil
var symx = initOverloadIter(o, c, headSymbol)
while symx != nil:
if symx.kind in {skTemplate, skMacro}:
if symx.typ.len == 2 and symx.typ[1] == maType.typ:
if match == nil:
match = symx
else:
localError(c.config, n.info, errAmbiguousCallXYZ % [
getProcHeader(c.config, match),
getProcHeader(c.config, symx), $selector])
symx = nextOverloadIter(o, c, headSymbol)
if match == nil: return
var callExpr = newNodeI(nkCall, n.info)
callExpr.add newSymNode(match)
callExpr.add n
case match.kind
of skMacro: result = semMacroExpr(c, callExpr, callExpr, match, {})
of skTemplate: result = semTemplateExpr(c, callExpr, match, {})
else: result = nil
proc handleForLoopMacro(c: PContext; n: PNode): PNode =
result = handleStmtMacro(c, n, n[^2], "ForLoopStmt")
proc handleCaseStmtMacro(c: PContext; n: PNode): PNode =
# n[0] has been sem'checked and has a type. We use this to resolve
# 'match(n[0])' but then we pass 'n' to the 'match' macro. This seems to
# be the best solution.
var toResolve = newNodeI(nkCall, n.info)
toResolve.add newIdentNode(getIdent(c.cache, "match"), n.info)
toResolve.add n[0]
var errors: CandidateErrors
var r = resolveOverloads(c, toResolve, toResolve, {skTemplate, skMacro}, {},
errors, false)
if r.state == csMatch:
var match = r.calleeSym
markUsed(c.config, n[0].info, match, c.graph.usageSym)
styleCheckUse(n[0].info, match)
# but pass 'n' to the 'match' macro, not 'n[0]':
r.call.sons[1] = n
let toExpand = semResolvedCall(c, r, r.call, {})
case match.kind
of skMacro: result = semMacroExpr(c, toExpand, toExpand, match, {})
of skTemplate: result = semTemplateExpr(c, toExpand, match, {})
else: result = nil
# this would be the perfectly consistent solution with 'for loop macros',
# but it kinda sucks for pattern matching as the matcher is not attached to
# a type then:
when false:
result = handleStmtMacro(c, n, n[0], "CaseStmt")
proc semFor(c: PContext, n: PNode; flags: TExprFlags): PNode =
checkMinSonsLen(n, 3, c.config)
var length = sonsLen(n)
if forLoopMacros in c.features:
result = handleForLoopMacro(c, n)
if result != nil: return result
openScope(c)
result = n
n.sons[length-2] = semExprNoDeref(c, n.sons[length-2], {efWantIterator})
var call = n.sons[length-2]
if call.kind == nkStmtListExpr and isTrivalStmtExpr(call):
call = call.lastSon
n.sons[length-2] = call
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, flags)
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, flags)
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(c.config, n.sons[length-2].info, "iterator within for loop context expected")
result = semForVars(c, n, flags)
else:
result = semForVars(c, n, flags)
# propagate any enforced VoidContext:
if n.sons[length-1].typ == c.enforceVoidContext:
result.typ = c.enforceVoidContext
elif efInTypeof in flags:
result.typ = result.lastSon.typ
closeScope(c)
proc semCase(c: PContext, n: PNode; flags: TExprFlags): PNode =
result = n
checkMinSonsLen(n, 2, c.config)
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:
if caseStmtMacros in c.features:
result = handleCaseStmtMacro(c, n)
if result != nil: return result
localError(c.config, n.info, errSelectorMustBeOfCertainTypes)
return
for i in countup(1, sonsLen(n) - 1):
var x = n.sons[i]
when defined(nimsuggest):
if c.config.ideCmd == ideSug and exactEquals(c.config.m.trackPos, x.info) and caseTyp.kind == tyEnum:
suggestEnum(c, x, caseTyp)
case x.kind
of nkOfBranch:
checkMinSonsLen(x, 2, c.config)
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])
of nkElifBranch:
chckCovered = false
checkSonsLen(x, 2, c.config)
openScope(c)
x.sons[0] = forceBool(c, semExprWithType(c, x.sons[0]))
x.sons[1] = semExprBranch(c, x.sons[1])
typ = commonType(typ, x.sons[1])
closeScope(c)
of nkElse:
chckCovered = false
checkSonsLen(x, 1, c.config)
x.sons[0] = semExprBranchScope(c, x.sons[0])
typ = commonType(typ, x.sons[0])
hasElse = true
else:
illFormedAst(x, c.config)
if chckCovered:
if covered == toCover(c, n.sons[0].typ):
hasElse = true
else:
localError(c.config, n.info, "not all cases are covered")
closeScope(c)
if isEmptyType(typ) or typ.kind in {tyNil, tyExpr} or
(not hasElse and efInTypeof notin flags):
for i in 1..n.len-1: discardCheck(c, n.sons[i].lastSon, flags)
# propagate any enforced VoidContext:
if typ == c.enforceVoidContext:
result.typ = c.enforceVoidContext
else:
for i in 1..n.len-1:
var it = n.sons[i]
let j = it.len-1
if not endsInNoReturn(it.sons[j]):
it.sons[j] = fitNode(c, typ, it.sons[j], it.sons[j].info)
result.typ = typ
proc semRaise(c: PContext, n: PNode): PNode =
result = n
checkSonsLen(n, 1, c.config)
if n[0].kind != nkEmpty:
n[0] = semExprWithType(c, n[0])
var typ = n[0].typ
if not isImportedException(typ, c.config):
typ = typ.skipTypes({tyAlias, tyGenericInst})
if typ.kind != tyRef:
localError(c.config, n.info, errExprCannotBeRaised)
if not isException(typ.lastSon):
localError(c.config, n.info, "raised object of type $1 does not inherit from Exception",
[typeToString(typ)])
proc addGenericParamListToScope(c: PContext, n: PNode) =
if n.kind != nkGenericParams: illFormedAst(n, c.config)
for i in countup(0, sonsLen(n)-1):
var a = n.sons[i]
if a.kind == nkSym: addDecl(c, a.sym)
else: illFormedAst(a, c.config)
proc typeSectionTypeName(c: PContext; n: PNode): PNode =
if n.kind == nkPragmaExpr:
if n.len == 0: illFormedAst(n, c.config)
result = n.sons[0]
else:
result = n
if result.kind != nkSym: illFormedAst(n, c.config)
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 c.config.cmd == cmdIdeTools:
inc c.inTypeContext
suggestStmt(c, a)
dec c.inTypeContext
if a.kind == nkCommentStmt: continue
if a.kind != nkTypeDef: illFormedAst(a, c.config)
checkSonsLen(a, 3, c.config)
let name = a.sons[0]
var s: PSym
if name.kind == nkDotExpr and a[2].kind == nkObjectTy:
let pkgName = considerQuotedIdent(c, name[0])
let typName = considerQuotedIdent(c, name[1])
let pkg = c.graph.packageSyms.strTableGet(pkgName)
if pkg.isNil or pkg.kind != skPackage:
localError(c.config, name.info, "unknown package name: " & pkgName.s)
else:
let typsym = pkg.tab.strTableGet(typName)
if typsym.isNil:
s = semIdentDef(c, name[1], skType)
s.typ = newTypeS(tyObject, c)
s.typ.sym = s
s.flags.incl sfForward
pkg.tab.strTableAdd s
addInterfaceDecl(c, s)
elif typsym.kind == skType and sfForward in typsym.flags:
s = typsym
addInterfaceDecl(c, s)
else:
localError(c.config, name.info, typsym.name.s & " is not a type that can be forwarded")
s = typsym
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)
if sfForward in s.flags:
# check if the symbol already exists:
let pkg = c.module.owner
if not isTopLevel(c) or pkg.isNil:
localError(c.config, name.info, "only top level types in a package can be 'package'")
else:
let typsym = pkg.tab.strTableGet(s.name)
if typsym != nil:
if sfForward notin typsym.flags or sfNoForward notin typsym.flags:
typeCompleted(typsym)
typsym.info = s.info
else:
localError(c.config, name.info, "cannot complete type '" & s.name.s & "' twice; " &
"previous type completion was here: " & c.config$typsym.info)
s = typsym
# add it here, so that recursive types are possible:
if sfGenSym notin s.flags: addInterfaceDecl(c, s)
if name.kind == nkPragmaExpr:
a.sons[0].sons[0] = newSymNode(s)
else:
a.sons[0] = newSymNode(s)
proc checkCovariantParamsUsages(c: PContext; genericType: PType) =
var body = genericType[^1]
proc traverseSubTypes(c: PContext; t: PType): bool =
template error(msg) = localError(c.config, 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(c, field.typ)
of tyArray:
return traverseSubTypes(c, t[1])
of tyProc:
for subType in t.sons:
if subType != nil:
subresult traverseSubTypes(c, subType)
if result:
error("non-invariant type param used in a proc type: " & $t)
of tySequence:
return traverseSubTypes(c, 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(c, 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(c, fieldType)
of tyPtr, tyRef, tyVar, tyLent:
if t.base.kind == tyGenericParam: return true
return traverseSubTypes(c, t.base)
of tyDistinct, tyAlias, tySink:
return traverseSubTypes(c, t.lastSon)
of tyGenericInst:
internalAssert c.config, false
else:
discard
discard traverseSubTypes(c, 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, c.config)
checkSonsLen(a, 3, c.config)
let name = typeSectionTypeName(c, a.sons[0])
var s = name.sym
if s.magic == mNone and a.sons[2].kind == nkEmpty:
localError(c.config, 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: