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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 used (or 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 '$1'"
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'"
errRecursiveDependencyIteratorX = "recursion is not supported in iterators: '$1'"
errPragmaOnlyInHeaderOfProcX = "pragmas are only allowed in the header of a proc; redefinition of $1"
errCannotAssignToGlobal = "cannot assign local to global variable"
proc implicitlyDiscardable(n: PNode): bool
proc hasEmpty(typ: PType): bool =
if typ.kind in {tySequence, tyArray, tySet}:
result = typ.elementType.kind == tyEmpty
elif typ.kind == tyTuple:
result = false
for s in typ.kids:
result = result or hasEmpty(s)
else:
result = false
proc semDiscard(c: PContext, n: PNode): PNode =
result = n
checkSonsLen(n, 1, c.config)
if n[0].kind != nkEmpty:
n[0] = semExprWithType(c, n[0])
let sonType = n[0].typ
let sonKind = n[0].kind
if isEmptyType(sonType) or hasEmpty(sonType) or
sonType.kind in {tyNone, tyTypeDesc} or
sonKind == nkTypeOfExpr:
localError(c.config, n.info, errInvalidDiscard)
if sonType.kind == tyProc and sonKind notin nkCallKinds:
# tyProc is disallowed to prevent ``discard foo`` to be valid, when ``discard foo()`` is meant.
localError(c.config, n.info, "illegal discard proc, did you mean: " & $n[0] & "()")
proc semBreakOrContinue(c: PContext, n: PNode): PNode =
result = n
checkSonsLen(n, 1, c.config)
if n[0].kind != nkEmpty:
if n.kind != nkContinueStmt:
var s: PSym = nil
case n[0].kind
of nkIdent: s = lookUp(c, n[0])
of nkSym: s = n[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[0] = x
suggestSym(c.graph, x.info, s, c.graph.usageSym)
onUse(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.nestedBlockCounter > 0 and n.kind == nkBreakStmt and not c.p.breakInLoop:
localError(c.config, n.info, warnUnnamedBreak)
elif (c.p.nestedLoopCounter <= 0) and ((c.p.nestedBlockCounter <= 0) or n.kind == nkContinueStmt):
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[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[0] = forceBool(c, semExprWithType(c, n[0], expectedType = getSysType(c.graph, n.info, tyBool)))
inc(c.p.nestedLoopCounter)
let oldBreakInLoop = c.p.breakInLoop
c.p.breakInLoop = true
n[1] = semStmt(c, n[1], flags)
c.p.breakInLoop = oldBreakInLoop
dec(c.p.nestedLoopCounter)
closeScope(c)
if n[1].typ == c.enforceVoidContext:
result.typ = c.enforceVoidContext
elif efInTypeof in flags:
result.typ = n[1].typ
elif implicitlyDiscardable(n[1]):
result[1].typ = c.enforceVoidContext
proc semProc(c: PContext, n: PNode): PNode
proc semExprBranch(c: PContext, n: PNode; flags: TExprFlags = {}; expectedType: PType = nil): PNode =
result = semExpr(c, n, flags, expectedType)
if result.typ != nil:
# XXX tyGenericInst here?
if result.typ.kind in {tyVar, tyLent}: result = newDeref(result)
proc semExprBranchScope(c: PContext, n: PNode; expectedType: PType = nil): PNode =
openScope(c)
result = semExprBranch(c, n, expectedType = expectedType)
closeScope(c)
const
skipForDiscardable = {nkStmtList, nkStmtListExpr,
nkOfBranch, nkElse, nkFinally, nkExceptBranch,
nkElifBranch, nkElifExpr, nkElseExpr, nkBlockStmt, nkBlockExpr,
nkHiddenStdConv, nkHiddenSubConv, nkHiddenDeref}
proc implicitlyDiscardable(n: PNode): bool =
# same traversal as endsInNoReturn
template checkBranch(branch) =
if not implicitlyDiscardable(branch):
return false
var it = n
# skip these beforehand, no special handling needed
while it.kind in skipForDiscardable and it.len > 0:
it = it.lastSon
case it.kind
of nkIfExpr, nkIfStmt:
for branch in it:
checkBranch:
if branch.len == 2:
branch[1]
elif branch.len == 1:
branch[0]
else:
raiseAssert "Malformed `if` statement during implicitlyDiscardable"
# all branches are discardable
result = true
of nkCaseStmt:
for i in 1 ..< it.len:
let branch = it[i]
checkBranch:
case branch.kind
of nkOfBranch:
branch[^1]
of nkElifBranch:
branch[1]
of nkElse:
branch[0]
else:
raiseAssert "Malformed `case` statement in implicitlyDiscardable"
# all branches are discardable
result = true
of nkTryStmt:
checkBranch(it[0])
for i in 1 ..< it.len:
let branch = it[i]
if branch.kind != nkFinally:
checkBranch(branch[^1])
# all branches are discardable
result = true
of nkCallKinds:
result = it[0].kind == nkSym and {sfDiscardable, sfNoReturn} * it[0].sym.flags != {}
of nkLastBlockStmts:
result = true
else:
result = false
proc endsInNoReturn(n: PNode, returningNode: var PNode; discardableCheck = false): bool =
## check if expr ends the block like raising or call of noreturn procs do
result = false # assume it does return
template checkBranch(branch) =
if not endsInNoReturn(branch, returningNode, discardableCheck):
# proved a branch returns
return false
var it = n
# skip these beforehand, no special handling needed
let skips = if discardableCheck: skipForDiscardable else: skipForDiscardable-{nkBlockExpr, nkBlockStmt}
while it.kind in skips and it.len > 0:
it = it.lastSon
case it.kind
of nkIfExpr, nkIfStmt:
var hasElse = false
for branch in it:
checkBranch:
if branch.len == 2:
branch[1]
elif branch.len == 1:
hasElse = true
branch[0]
else:
raiseAssert "Malformed `if` statement during endsInNoReturn"
# none of the branches returned
result = hasElse # Only truly a no-return when it's exhaustive
of nkCaseStmt:
let caseTyp = skipTypes(it[0].typ, abstractVar-{tyTypeDesc})
# semCase should already have checked for exhaustiveness in this case
# effectively the same as having an else
var hasElse = caseTyp.shouldCheckCaseCovered()
# actual noreturn checks
for i in 1 ..< it.len:
let branch = it[i]
checkBranch:
case branch.kind
of nkOfBranch:
branch[^1]
of nkElifBranch:
branch[1]
of nkElse:
hasElse = true
branch[0]
else:
raiseAssert "Malformed `case` statement in endsInNoReturn"
# Can only guarantee a noreturn if there is an else or it's exhaustive
result = hasElse
of nkTryStmt:
checkBranch(it[0])
var lastIndex = it.len - 1
if it[lastIndex].kind == nkFinally:
# if finally is noreturn, then the entire statement is noreturn
if endsInNoReturn(it[lastIndex][^1], returningNode, discardableCheck):
return true
dec lastIndex
for i in 1 .. lastIndex:
let branch = it[i]
checkBranch(branch[^1])
# none of the branches returned
result = true
of nkLastBlockStmts:
result = true
of nkCallKinds:
result = it[0].kind == nkSym and sfNoReturn in it[0].sym.flags
if not result:
returningNode = it
else:
result = false
returningNode = it
proc endsInNoReturn(n: PNode): bool =
var dummy: PNode = nil
result = endsInNoReturn(n, dummy)
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.transitionSonsKind(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 {tyTyped, tyVoid}:
if implicitlyDiscardable(result):
var n = newNodeI(nkDiscardStmt, result.info, 1)
n[0] = result
# notes that it doesn't transform nodes into discard statements
elif result.typ.kind != tyError and c.config.cmd != cmdInteractive:
if result.typ.kind == tyNone:
localError(c.config, result.info, "expression has no type: " &
renderTree(result, {renderNoComments}))
else:
# Ignore noreturn procs since they don't have a type
var n = result
if result.endsInNoReturn(n, discardableCheck = true):
return
var s = "expression '" & $n & "' is of type '" &
result.typ.typeToString & "' and has to be used (or discarded)"
if result.info.line != n.info.line or
result.info.fileIndex != n.info.fileIndex:
s.add "; start of expression here: " & c.config$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; expectedType: PType = nil): PNode =
result = n
var typ = commonTypeBegin
var expectedType = expectedType
var hasElse = false
for i in 0..<n.len:
var it = n[i]
if it.len == 2:
openScope(c)
it[0] = forceBool(c, semExprWithType(c, it[0], expectedType = getSysType(c.graph, n.info, tyBool)))
it[1] = semExprBranch(c, it[1], flags, expectedType)
typ = commonType(c, typ, it[1])
if not endsInNoReturn(it[1]):
expectedType = typ
closeScope(c)
elif it.len == 1:
hasElse = true
it[0] = semExprBranchScope(c, it[0], expectedType)
typ = commonType(c, typ, it[0])
if not endsInNoReturn(it[0]):
expectedType = typ
else: illFormedAst(it, c.config)
if isEmptyType(typ) or typ.kind in {tyNil, tyUntyped} or
(not hasElse and efInTypeof notin flags):
for it in n: discardCheck(c, it.lastSon, flags)
result.transitionSonsKind(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[j]):
it[j] = fitNode(c, typ, it[j], it[j].info)
result.transitionSonsKind(nkIfExpr)
result.typ = typ
proc semTry(c: PContext, n: PNode; flags: TExprFlags; expectedType: PType = nil): 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 isImported = false
if isImportedException(typ, c.config):
isImported = true
elif not isException(typ):
localError(c.config, typeNode.info, errExprCannotBeRaised)
elif not isDefectOrCatchableError(typ):
message(c.config, a.info, warnBareExcept, "catch a more precise Exception deriving from CatchableError or Defect.")
if containsOrIncl(check, typ.id):
localError(c.config, typeNode.info, errExceptionAlreadyHandled)
typeNode = newNodeIT(nkType, typeNode.info, typ)
isImported
result = n
checkMinSonsLen(n, 2, c.config)
var typ = commonTypeBegin
var expectedType = expectedType
n[0] = semExprBranchScope(c, n[0], expectedType)
if not endsInNoReturn(n[0]):
typ = commonType(c, typ, n[0].typ)
expectedType = typ
var last = n.len - 1
var catchAllExcepts = 0
for i in 1..last:
let a = n[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] = move a[0].sons
if a.len == 2 and a[0].isInfixAs():
# support ``except Exception as ex: body``
let isImported = semExceptBranchType(a[0][1])
let symbol = newSymG(skLet, a[0][2], c)
symbol.typ = if isImported: a[0][1].typ
else: a[0][1].typ.toRef(c.idgen)
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
message(c.config, a.info, warnBareExcept,
"The bare except clause is deprecated; use `except CatchableError:` instead")
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 isNative, isImported: bool = false
for j in 0..<a.len-1:
let tmp = semExceptBranchType(a[j])
if tmp: isImported = true
else: isNative = true
if isNative and isImported:
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:
if a.kind != nkFinally:
a[^1] = semExprBranchScope(c, a[^1], expectedType)
typ = commonType(c, typ, a[^1])
if not endsInNoReturn(a[^1]):
expectedType = typ
else:
a[^1] = semExprBranchScope(c, a[^1])
dec last
closeScope(c)
if isEmptyType(typ) or typ.kind in {tyNil, tyUntyped}:
discardCheck(c, n[0], flags)
for i in 1..<n.len: discardCheck(c, n[i].lastSon, flags)
if typ == c.enforceVoidContext:
result.typ = c.enforceVoidContext
else:
if n.lastSon.kind == nkFinally: discardCheck(c, n.lastSon.lastSon, flags)
if not endsInNoReturn(n[0]):
n[0] = fitNode(c, typ, n[0], n[0].info)
for i in 1..last:
var it = n[i]
let j = it.len-1
if not endsInNoReturn(it[j]):
it[j] = fitNode(c, typ, it[j], it[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[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
if not floatRangeCheck(result.floatVal, typ):
localError(c.config, n.info, errFloatToString % [$result.floatVal, typeToString(typ)])
elif r1.kind == nkSym and typ.skipTypes(abstractRange).kind == tyCstring:
discard "keep nkHiddenStdConv for cstring conversions"
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 =
result = nil
for scope in localScopesFrom(c, c.currentScope.parent):
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[i], s): return true
result = n.kind == nkSym and n.sym.name.id == s.id
proc semIdentDef(c: PContext, n: PNode, kind: TSymKind, reportToNimsuggest = true): PSym =
if isTopLevel(c):
result = semIdentWithPragma(c, kind, n, {sfExported}, fromTopLevel = true)
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)
result.options = c.config.options
proc getLineInfo(n: PNode): TLineInfo =
case n.kind
of nkPostfix:
if len(n) > 1:
return getLineInfo(n[1])
of nkAccQuoted, nkPragmaExpr:
if len(n) > 0:
return getLineInfo(n[0])
else:
discard
result = n.info
let info = getLineInfo(n)
if reportToNimsuggest:
suggestSym(c.graph, info, result, c.graph.usageSym)
proc checkNilable(c: PContext; v: PSym) =
if {sfGlobal, sfImportc} * v.flags == {sfGlobal} and v.typ.requiresInit:
if v.astdef.isNil:
message(c.config, v.info, warnProveInit, v.name.s)
elif tfNotNil in v.typ.flags and not v.astdef.typ.isNil and tfNotNil notin v.astdef.typ.flags:
message(c.config, v.info, warnProveInit, v.name.s)
#include liftdestructors
proc addToVarSection(c: PContext; result: var PNode; n: PNode) =
if result.kind != nkStmtList:
result = makeStmtList(result)
result.add n
proc addToVarSection(c: PContext; result: var PNode; orig, identDefs: PNode) =
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.id == ord(wUnderscore):
v.flags.incl(sfGenSym)
result = true
else:
result = false
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 0..<n.len:
var a = n[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)
if a[^2].kind != nkEmpty:
let typ = semTypeNode(c, a[^2], nil)
for j in 0..<a.len-2:
let v = semIdentDef(c, a[j], skParam)
styleCheckDef(c, v)
onDef(a[j].info, v)
v.typ = typ
strTableIncl(c.signatures, v)
else:
localError(c.config, a.info, "'using' section must have a type")
var def: PNode
if a[^1].kind != nkEmpty:
localError(c.config, a.info, "'using' sections cannot contain assignments")
proc hasUnresolvedParams(n: PNode; flags: TExprFlags): bool =
result = tfUnresolved in n.typ.flags
when false:
case n.kind
of nkSym:
result = isGenericRoutineStrict(n.sym)
of nkSymChoices:
for ch in n:
if hasUnresolvedParams(ch, flags):
return true
result = false
else:
result = false
if efOperand in flags:
if tfUnresolved notin n.typ.flags:
result = false
proc makeDeref(n: PNode): PNode =
var t = n.typ
if t.kind in tyUserTypeClasses and t.isResolvedUserTypeClass:
t = t.last
t = skipTypes(t, {tyGenericInst, tyAlias, tySink, tyOwned})
result = n
if t.kind in {tyVar, tyLent}:
result = newNodeIT(nkHiddenDeref, n.info, t.elementType)
result.add n
t = skipTypes(t.elementType, {tyGenericInst, tyAlias, tySink, tyOwned})
while t.kind in {tyPtr, tyRef}:
var a = result
let baseTyp = t.elementType
result = newNodeIT(nkHiddenDeref, n.info, baseTyp)
result.add a
t = skipTypes(baseTyp, {tyGenericInst, tyAlias, tySink, tyOwned})
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), c.idgen, obj.sym, n[1].info)
field.typ = skipIntLit(typ, c.idgen)
field.position = obj.n.len
obj.n.add newSymNode(field)
n[0] = makeDeref x
n[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, preferDesc) &
"; new type is: " & typeToString(typ, preferDesc))
v.typ = typ
proc isPossibleMacroPragma(c: PContext, it: PNode, key: PNode): bool =
# make sure it's not a normal pragma, and calls an identifier
# considerQuotedIdent below will fail on non-identifiers
result = whichPragma(it) == wInvalid and key.kind in nkIdentKinds
if result:
# make sure it's not a user pragma
let ident = considerQuotedIdent(c, key)
result = strTableGet(c.userPragmas, ident) == nil
if result:
# make sure it's not a custom pragma
var amb = false
let sym = searchInScopes(c, ident, amb)
result = sym == nil or sfCustomPragma notin sym.flags
proc copyExcept(n: PNode, i: int): PNode =
result = copyNode(n)
for j in 0..<n.len:
if j != i: result.add(n[j])
proc semVarMacroPragma(c: PContext, a: PNode, n: PNode): PNode =
# Mirrored with semProcAnnotation
result = nil
# a, b {.prag.}: int = 3 not allowed
const lhsPos = 0
if a.len == 3 and a[lhsPos].kind == nkPragmaExpr:
var b = a[lhsPos]
const
namePos = 0
pragmaPos = 1
let pragmas = b[pragmaPos]
for i in 0 ..< pragmas.len:
let it = pragmas[i]
let key = if it.kind in nkPragmaCallKinds and it.len >= 1: it[0] else: it
trySuggestPragmas(c, key)
if isPossibleMacroPragma(c, it, key):
# we transform ``var p {.m, rest.}`` into ``m(do: var p {.rest.})`` and
# let the semantic checker deal with it:
var x = newNodeI(nkCall, key.info)
x.add(key)
if it.kind in nkPragmaCallKinds and it.len > 1:
# pass pragma arguments to the macro too:
for i in 1..<it.len:
x.add(it[i])
# Drop the pragma from the list, this prevents getting caught in endless
# recursion when the nkCall is semanticized
let oldExpr = a[lhsPos]
let newPragmas = copyExcept(pragmas, i)
if newPragmas.kind != nkEmpty and newPragmas.len == 0:
a[lhsPos] = oldExpr[namePos]
else:
a[lhsPos] = copyNode(oldExpr)
a[lhsPos].add(oldExpr[namePos])
a[lhsPos].add(newPragmas)
var unarySection = newNodeI(n.kind, a.info)
unarySection.add(a)
x.add(unarySection)
# recursion assures that this works for multiple macro annotations too:
var r = semOverloadedCall(c, x, x, {skMacro, skTemplate}, {efNoUndeclared})
if r == nil:
# Restore the old list of pragmas since we couldn't process this
a[lhsPos] = oldExpr
# No matching macro was found but there's always the possibility this may
# be a .pragma. template instead
continue
doAssert r[0].kind == nkSym
let m = r[0].sym
case m.kind
of skMacro: result = semMacroExpr(c, r, r, m, {})
of skTemplate: result = semTemplateExpr(c, r, m, {})
else:
a[lhsPos] = oldExpr
continue
doAssert result != nil
return result
template isLocalSym(sym: PSym): bool =
sym.kind in {skVar, skLet, skParam} and not
({sfGlobal, sfPure} * sym.flags != {} or
sym.typ.kind == tyTypeDesc or
sfCompileTime in sym.flags) or
sym.kind in {skProc, skFunc, skIterator} and
sfGlobal notin sym.flags
template isLocalVarSym(n: PNode): bool =
n.kind == nkSym and isLocalSym(n.sym)
proc usesLocalVar(n: PNode): bool =
result = false
for z in 1 ..< n.len:
if n[z].isLocalVarSym:
return true
elif n[z].kind in nkCallKinds:
if usesLocalVar(n[z]):
return true
proc globalVarInitCheck(c: PContext, n: PNode) =
if n.isLocalVarSym or n.kind in nkCallKinds and usesLocalVar(n):
localError(c.config, n.info, errCannotAssignToGlobal)
const
errTupleUnpackingTupleExpected = "tuple expected for tuple unpacking, but got '$1'"
errTupleUnpackingDifferentLengths = "tuple with $1 elements expected, but got '$2' with $3 elements"
proc makeVarTupleSection(c: PContext, n, a, def: PNode, typ: PType, symkind: TSymKind, origResult: var PNode): PNode =
## expand tuple unpacking assignments into new var/let/const section
##
## mirrored with semexprs.makeTupleAssignments
if typ.kind != tyTuple:
localError(c.config, a.info, errTupleUnpackingTupleExpected %
[typeToString(typ, preferDesc)])
elif a.len-2 != typ.len:
localError(c.config, a.info, errTupleUnpackingDifferentLengths %
[$(a.len-2), typeToString(typ, preferDesc), $typ.len])
var
tempNode: PNode = nil
lastDef: PNode
let defkind = if symkind == skConst: nkConstDef else: nkIdentDefs
# temporary not needed if not const and RHS is tuple literal
# const breaks with seqs without temporary
let useTemp = def.kind notin {nkPar, nkTupleConstr} or symkind == skConst
if useTemp:
# use same symkind for compatibility with original section
let temp = newSym(symkind, getIdent(c.cache, "tmpTuple"), c.idgen, getCurrOwner(c), n.info)
temp.typ = typ
temp.flags.incl(sfGenSym)
lastDef = newNodeI(defkind, a.info)
newSons(lastDef, 3)
lastDef[0] = newSymNode(temp)
# NOTE: at the moment this is always ast.emptyNode, see parser.nim
lastDef[1] = a[^2]
lastDef[2] = def
temp.ast = lastDef
addToVarSection(c, origResult, n, lastDef)
tempNode = newSymNode(temp)
result = newNodeI(n.kind, a.info)
for j in 0..<a.len-2:
let name = a[j]
if useTemp and name.kind == nkIdent and name.ident.id == ord(wUnderscore):
# skip _ assignments if we are using a temp as they are already evaluated
continue
if name.kind == nkVarTuple:
# nested tuple
lastDef = newNodeI(nkVarTuple, name.info)
newSons(lastDef, name.len)
for k in 0..<name.len-2:
lastDef[k] = name[k]
else:
lastDef = newNodeI(defkind, name.info)
newSons(lastDef, 3)
lastDef[0] = name
lastDef[^2] = c.graph.emptyNode
if useTemp:
lastDef[^1] = newTupleAccessRaw(tempNode, j)
else:
var val = def[j]
if val.kind == nkExprColonExpr: val = val[1]
lastDef[^1] = val
result.add(lastDef)
proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
var b: PNode
result = copyNode(n)
# transform var x, y = 12 into var x = 12; var y = 12
# bug #18104; transformation should be finished before templates expansion
# TODO: move warnings for tuple here
var transformed = copyNode(n)
for i in 0..<n.len:
var a = n[i]
if a.kind == nkIdentDefs and a.len > 3 and a[^1].kind != nkEmpty:
for j in 0..<a.len-2:
var b = newNodeI(nkIdentDefs, a.info)
b.add a[j]
b.add a[^2]
b.add copyTree(a[^1])
transformed.add b
else:
transformed.add a
let n = transformed
for i in 0..<n.len:
var a = n[i]
if c.config.cmd == cmdIdeTools: suggestStmt(c, a)
if a.kind == nkCommentStmt: continue
if a.kind notin {nkIdentDefs, nkVarTuple}: illFormedAst(a, c.config)
checkMinSonsLen(a, 3, c.config)
b = semVarMacroPragma(c, a, n)
if b != nil:
addToVarSection(c, result, b)
continue
var hasUserSpecifiedType = false
var typ: PType = nil
if a[^2].kind != nkEmpty:
typ = semTypeNode(c, a[^2], nil)
hasUserSpecifiedType = true
var typFlags: TTypeAllowedFlags = {}
var def: PNode = c.graph.emptyNode
if a[^1].kind != nkEmpty:
def = semExprWithType(c, a[^1], {efTypeAllowed}, typ)
if def.kind == nkSym and def.sym.kind in {skTemplate, skMacro}:
typFlags.incl taIsTemplateOrMacro
elif def.typ.kind == tyTypeDesc and c.p.owner.kind != skMacro:
typFlags.incl taProcContextIsNotMacro
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 = fitNodeConsiderViewType(c, typ, def, def.info)
#changeType(def.skipConv, typ, check=true)
else:
typ = def.typ.skipTypes({tyStatic, tySink}).skipIntLit(c.idgen)
if typ.kind in tyUserTypeClasses and typ.isResolvedUserTypeClass:
typ = typ.last
if hasEmpty(typ):
localError(c.config, def.info, errCannotInferTypeOfTheLiteral % typ.kind.toHumanStr)
elif typ.kind == tyProc and def.kind == nkSym and isGenericRoutine(def.sym.ast):
let owner = typ.owner
let err =
# consistent error message with evaltempl/semMacroExpr
if owner != nil and owner.kind in {skTemplate, skMacro}:
errMissingGenericParamsForTemplate % def.renderTree
else:
errProcHasNoConcreteType % def.renderTree
localError(c.config, def.info, err)
when false:
# XXX This typing rule is neither documented nor complete enough to
# justify it. Instead use the newer 'unowned x' until we figured out
# a more general solution.
if symkind == skVar and typ.kind == tyOwned and def.kind notin nkCallKinds:
# special type inference rule: 'var it = ownedPointer' is turned
# into an unowned pointer.
typ = typ.lastSon
# this can only happen for errornous var statements:
if typ == nil: continue
if c.matchedConcept != nil:
typFlags.incl taConcept
typeAllowedCheck(c, a.info, typ, symkind, typFlags)
var tup = skipTypes(typ, {tyGenericInst, tyAlias, tySink})
if a.kind == nkVarTuple:
# generate new section from tuple unpacking and embed it into this one
let assignments = makeVarTupleSection(c, n, a, def, tup, symkind, result)
let resSection = semVarOrLet(c, assignments, symkind)
for resDef in resSection:
addToVarSection(c, result, n, resDef)
else:
if tup.kind == tyTuple and def.kind in {nkPar, nkTupleConstr} and
a.len > 3:
# var a, b = (1, 2)
message(c.config, a.info, warnEachIdentIsTuple)
for j in 0..<a.len-2:
if a[j].kind == nkDotExpr:
fillPartialObject(c, a[j], typ)
addToVarSection(c, result, n, a)
continue
var v = semIdentDef(c, a[j], symkind, false)
when defined(nimsuggest):
v.hasUserSpecifiedType = hasUserSpecifiedType
styleCheckDef(c, v)
onDef(a[j].info, v)
if sfGenSym notin v.flags:
if not isDiscardUnderscore(v): addInterfaceDecl(c, v)
else:
if v.owner == nil: v.owner = c.p.owner
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)
if def.kind != nkEmpty:
if sfThread in v.flags: localError(c.config, def.info, errThreadvarCannotInit)
setVarType(c, v, typ)
# this is needed for the evaluation pass, guard checking
# and custom pragmas:
b = newNodeI(nkIdentDefs, a.info)
if importantComments(c.config):
# keep documentation information:
b.comment = a.comment
# postfix not generated here (to generate, get rid of it in transf)
if a[j].kind == nkPragmaExpr:
var p = newNodeI(nkPragmaExpr, a.info)
p.add newSymNode(v)
p.add a[j][1]
b.add p
else:
b.add newSymNode(v)
# keep type desc for doc generator
b.add a[^2]
b.add copyTree(def)
addToVarSection(c, result, n, b)
v.ast = b
if def.kind == nkEmpty:
let actualType = v.typ.skipTypes({tyGenericInst, tyAlias,
tyUserTypeClassInst})
if actualType.kind in {tyObject, tyDistinct} and
actualType.requiresInit:
defaultConstructionError(c, v.typ, v.info)
else:
checkNilable(c, v)
# allow let to not be initialised if imported from C:
if v.kind == skLet and sfImportc notin v.flags and (strictDefs notin c.features or not isLocalSym(v)):
localError(c.config, a.info, errLetNeedsInit)
if sfCompileTime in v.flags:
var x = newNodeI(result.kind, v.info)
x.add result[i]
vm.setupCompileTimeVar(c.module, c.idgen, c.graph, x)
if v.flags * {sfGlobal, sfThread} == {sfGlobal}:
message(c.config, v.info, hintGlobalVar)
if {sfGlobal, sfPure} <= v.flags:
globalVarInitCheck(c, def)
suggestSym(c.graph, v.info, v, c.graph.usageSym)
proc semConst(c: PContext, n: PNode): PNode =
result = copyNode(n)
inc c.inStaticContext
var b: PNode
for i in 0..<n.len:
var a = n[i]
if c.config.cmd == cmdIdeTools: suggestStmt(c, a)
if a.kind == nkCommentStmt: continue
if a.kind notin {nkConstDef, nkVarTuple}: illFormedAst(a, c.config)
checkMinSonsLen(a, 3, c.config)
b = semVarMacroPragma(c, a, n)
if b != nil:
addToVarSection(c, result, b)
continue
var hasUserSpecifiedType = false
var typ: PType = nil
if a[^2].kind != nkEmpty:
typ = semTypeNode(c, a[^2], nil)
hasUserSpecifiedType = true
var typFlags: TTypeAllowedFlags = {}
# don't evaluate here since the type compatibility check below may add a converter
var def = semExprWithType(c, a[^1], {efTypeAllowed}, typ)
if def.kind == nkSym and def.sym.kind in {skTemplate, skMacro}:
typFlags.incl taIsTemplateOrMacro
elif def.typ.kind == tyTypeDesc and c.p.owner.kind != skMacro:
typFlags.incl taProcContextIsNotMacro
# check type compatibility between def.typ and typ:
if typ != nil:
if typ.isMetaType:
def = inferWithMetatype(c, typ, def)
typ = def.typ
else:
def = fitRemoveHiddenConv(c, typ, def)
else:
typ = def.typ
# evaluate the node