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enforce the covariance rules for user-defined generic types

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This commit is contained in:
Zahary Karadjov 2017-05-13 14:38:07 +03:00
commit 0aede22e87
5 changed files with 105 additions and 17 deletions
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8
compiler/sigmatch.nim
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@ -883,7 +883,7 @@ proc isCovariantPtr(c: var TCandidate, f, a: PType): bool =
let body = f.base
return body == a.base and
a.sonsLen == 3 and
sfStrongCovariant in body.sons[0].sym.flags and
sfWeakCovariant notin body.sons[0].sym.flags and
baseTypesCheck(f.sons[1], a.sons[1])
else:
return false
@ -1305,10 +1305,10 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
let paramFlags = rootf.base.sons[i-1].sym.flags
hasCovariance =
if sfCovariant in paramFlags:
if sfStrongCovariant in paramFlags:
ff.kind notin {tyRef, tyPtr} and result == isSubtype
else:
if sfWeakCovariant in paramFlags:
isCovariantPtr(c, ff, aa)
else:
ff.kind notin {tyRef, tyPtr} and result == isSubtype
else:
sfContravariant in paramFlags and
typeRel(c, aa, ff) == isSubtype