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borrow checking refinements (#15290)

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* added basic borrowing test
This commit is contained in:
Andreas Rumpf 2020-09-09 14:19:22 +02:00 • committed by GitHub
commit 217675cf84
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3 changed files with 39 additions and 5 deletions
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20
compiler/varpartitions.nim
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@ -375,7 +375,7 @@ proc deps(c: var Partitions; dest, src: PNode) =
allRoots(src, sources)
proc wrap(t: PType): bool {.nimcall.} = t.kind in {tyRef, tyPtr}
let destIsComplex = types.searchTypeFor(dest.typ, wrap)
let destIsComplex = types.searchTypeFor(dest.typ, wrap) or isViewType(dest.typ)
for t in targets:
if dest.kind != nkSym and c.inNoSideEffectSection == 0:
@ -518,19 +518,35 @@ proc computeGraphPartitions*(s: PSym; n: PNode; cursorInference = false): Partit
traverse(result, n)
proc dangerousMutation(g: MutationInfo; v: VarIndex): bool =
#echo "range ", v.aliveStart, " .. ", v.aliveEnd
if isMutated in g.flags:
for m in g.mutations:
#echo "mutation ", m
if m in v.aliveStart..v.aliveEnd:
return true
return false
proc cannotBorrow(config: ConfigRef; s: PSym; g: MutationInfo) =
var m = "cannot borrow " & s.name.s &
"; what it borrows from is potentially mutated"
if g.mutatedHere != unknownLineInfo:
m.add "\n"
m.add config $ g.mutatedHere
m.add " the mutation is here"
if g.connectedVia != unknownLineInfo:
m.add "\n"
m.add config $ g.connectedVia
m.add " is the statement that connected the mutation to the parameter"
localError(config, s.info, m)
proc checkBorrowedLocations*(par: var Partitions; config: ConfigRef) =
for i in 0 ..< par.s.len:
let s = par.s[i].sym
if s.kind != skParam and isViewType(s.typ):
let rid = root(par, i)
if par.s[rid].kind == isRootOf and dangerousMutation(par.graphs[par.s[rid].graphIndex], par.s[i]):
localError(config, s.info, config $ par.graphs[par.s[rid].graphIndex])
cannotBorrow(config, s, par.graphs[par.s[rid].graphIndex])
proc computeCursors*(s: PSym; n: PNode; config: ConfigRef) =
var par = computeGraphPartitions(s, n, true)