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Field checks for everybody (#8957)

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* Field checks for JS backend

* Clean nkCall nodes with no arguments

Generating a nkEmpty in place of no arguments makes no sense form the
AST point of view and also trips up the VM codegen.

* Field checks for VM backend

* Test case for #6612

This patchset fixes #6612

* Add test case for LHS double evaluation

* Prevent LHS double-eval for JS backend

* Prevent double evaluation in VM backend
This commit is contained in:
LemonBoy 2018-10-09 19:54:12 +02:00 • committed by Andreas Rumpf
commit ee14ace5d3
10 changed files with 223 additions and 43 deletions
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53
compiler/jsgen.nim
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@ -986,13 +986,50 @@ proc genFieldAccess(p: PProc, n: PNode, r: var TCompRes) =
proc genAddr(p: PProc, n: PNode, r: var TCompRes)
proc genCheckedFieldAddr(p: PProc, n: PNode, r: var TCompRes) =
let m = if n.kind == nkHiddenAddr: n.sons[0] else: n
internalAssert p.config, m.kind == nkCheckedFieldExpr
genAddr(p, m, r) # XXX
proc genCheckedFieldOp(p: PProc, n: PNode, addrTyp: PType, r: var TCompRes) =
internalAssert p.config, n.kind == nkCheckedFieldExpr
# nkDotExpr to access the requested field
let accessExpr = n[0]
# nkCall to check if the discriminant is valid
var checkExpr = n[1]
proc genCheckedFieldAccess(p: PProc, n: PNode, r: var TCompRes) =
genFieldAccess(p, n.sons[0], r) # XXX
let negCheck = checkExpr[0].sym.magic == mNot
if negCheck:
checkExpr = checkExpr[^1]
# Field symbol
var field = accessExpr[1].sym
internalAssert p.config, field.kind == skField
if field.loc.r == nil: field.loc.r = mangleName(p.module, field)
# Discriminant symbol
let disc = checkExpr[2].sym
internalAssert p.config, disc.kind == skField
if disc.loc.r == nil: disc.loc.r = mangleName(p.module, disc)
var setx: TCompRes
gen(p, checkExpr[1], setx)
var obj: TCompRes
gen(p, accessExpr[0], obj)
# Avoid evaluating the LHS twice (one to read the discriminant and one to read
# the field)
let tmp = p.getTemp()
lineF(p, "var $1 = $2;$n", tmp, obj.res)
useMagic(p, "raiseFieldError")
useMagic(p, "makeNimstrLit")
lineF(p, "if ($1[$2.$3]$4undefined) { raiseFieldError(makeNimstrLit($5)); }$n",
setx.res, tmp, disc.loc.r, if negCheck: ~"!==" else: ~"===",
makeJSString(field.name.s))
if addrTyp != nil and mapType(p, addrTyp) == etyBaseIndex:
r.typ = etyBaseIndex
r.res = makeJSString($field.loc.r)
r.address = tmp
else:
r.typ = etyNone
r.res = "$1.$2" % [tmp, field.loc.r]
r.kind = resExpr
proc genArrayAddr(p: PProc, n: PNode, r: var TCompRes) =
var
@ -1071,7 +1108,7 @@ proc genAddr(p: PProc, n: PNode, r: var TCompRes) =
#internalError(p.config, n.info, "genAddr: 4 " & renderTree(n))
else: internalError(p.config, n.info, "genAddr: 2")
of nkCheckedFieldExpr:
genCheckedFieldAddr(p, n, r)
genCheckedFieldOp(p, n[0], n.typ, r)
of nkDotExpr:
if mapType(p, n.typ) == etyBaseIndex:
genFieldAddr(p, n.sons[0], r)
@ -2140,7 +2177,7 @@ proc gen(p: PProc, n: PNode, r: var TCompRes) =
of nkDerefExpr, nkHiddenDeref: genDeref(p, n, r)
of nkBracketExpr: genArrayAccess(p, n, r)
of nkDotExpr: genFieldAccess(p, n, r)
of nkCheckedFieldExpr: genCheckedFieldAccess(p, n, r)
of nkCheckedFieldExpr: genCheckedFieldOp(p, n, nil, r)
of nkObjDownConv: gen(p, n.sons[0], r)
of nkObjUpConv: upConv(p, n, r)
of nkCast: genCast(p, n, r)