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Replace tfHasRequiresInit with a more accurate mechanism

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The new mechanism can deal with more complex scenarios such as
not nil field appearing in a non-default case object branch or
a field within a generic object that may depend on a when branch.

The commit also plugs another hole: the user is no longer able
to create illegal default values through seq.setLen(N).
This commit is contained in:
Zahary Karadjov 2020-03-30 18:56:03 +03:00 • committed by Andreas Rumpf
commit ce9a4ed124
11 changed files with 179 additions and 43 deletions
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6
compiler/sempass2.nim
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@ -184,7 +184,7 @@ proc initVar(a: PEffects, n: PNode; volatileCheck: bool) =
proc initVarViaNew(a: PEffects, n: PNode) =
if n.kind != nkSym: return
let s = n.sym
if {tfRequiresInit, tfHasRequiresInit, tfNotNil} * s.typ.flags <= {tfNotNil}:
if {tfRequiresInit, tfNotNil} * s.typ.flags <= {tfNotNil}:
# 'x' is not nil, but that doesn't mean its "not nil" children
# are initialized:
initVar(a, n, volatileCheck=true)
@ -590,7 +590,7 @@ proc trackCase(tracked: PEffects, n: PNode) =
track(tracked, n[0])
let oldState = tracked.init.len
let oldFacts = tracked.guards.s.len
let stringCase = skipTypes(n[0].typ,
let stringCase = n[0].typ != nil and skipTypes(n[0].typ,
abstractVarRange-{tyTypeDesc}).kind in {tyFloat..tyFloat128, tyString}
let interesting = not stringCase and interestingCaseExpr(n[0]) and
tracked.config.hasWarn(warnProveField)
@ -838,7 +838,7 @@ proc track(tracked: PEffects, n: PNode) =
# may not look like an assignment, but it is:
let arg = n[1]
initVarViaNew(tracked, arg)
if arg.typ.len != 0 and {tfRequiresInit, tfHasRequiresInit} * arg.typ.lastSon.flags != {}:
if arg.typ.len != 0 and {tfRequiresInit} * arg.typ.lastSon.flags != {}:
if a.sym.magic == mNewSeq and n[2].kind in {nkCharLit..nkUInt64Lit} and
n[2].intVal == 0:
# var s: seq[notnil]; newSeq(s, 0) is a special case!