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Disallow nil dereference at compile time (#16032)

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* bring back the semfold of nil

* remove space

* fix test

* proc type can't be dereferenced

* disallow nil dereference at compile time

* changelog
This commit is contained in:
cooldome 2020-11-18 22:30:28 +00:00 • committed by GitHub
commit acf8316e50
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4 changed files with 12 additions and 2 deletions
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5
compiler/semexprs.nim
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@ -1440,6 +1440,11 @@ proc buildOverloadedSubscripts(n: PNode, ident: PIdent): PNode =
proc semDeref(c: PContext, n: PNode): PNode =
checkSonsLen(n, 1, c.config)
n[0] = semExprWithType(c, n[0])
let a = getConstExpr(c.module, n[0], c.idgen, c.graph)
if a != nil:
if a.kind == nkNilLit:
localError(c.config, n.info, "nil dereference is not allowed")
n[0] = a
result = n
var t = skipTypes(n[0].typ, {tyGenericInst, tyVar, tyLent, tyAlias, tySink, tyOwned})
case t.kind

4
compiler/semfold.nim
View file

@ -671,6 +671,10 @@ proc getConstExpr(m: PSym, n: PNode; idgen: IdGenerator; g: ModuleGraph): PNode
var a = getConstExpr(m, n[1], idgen, g)
if a == nil: return
result = foldConv(n, a, g, check=true)
of nkDerefExpr, nkHiddenDeref:
let a = getConstExpr(m, n[0], idgen, g)
if a != nil and a.kind == nkNilLit:
localError(g.config, n.info, "nil dereference is not allowed")
of nkCast:
var a = getConstExpr(m, n[1], idgen, g)
if a == nil: return