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Warn when casting to a larger type (#20103)

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* Warn when casting to a larger type

* Revert change to error message to fix CI
This commit is contained in:
konsumlamm 2022-07-28 15:09:58 +02:00 • committed by GitHub
commit 528b6d1c3f
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2 changed files with 12 additions and 8 deletions
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2
compiler/lineinfos.nim
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@ -80,6 +80,7 @@ type
warnHoleEnumConv = "HoleEnumConv", warnHoleEnumConv = "HoleEnumConv",
warnCstringConv = "CStringConv", warnCstringConv = "CStringConv",
warnEffect = "Effect", warnEffect = "Effect",
warnCastSizes = "CastSizes"
warnUser = "User", warnUser = "User",
# hints # hints
hintSuccess = "Success", hintSuccessX = "SuccessX", hintSuccess = "Success", hintSuccessX = "SuccessX",
@ -173,6 +174,7 @@ const
warnHoleEnumConv: "$1", warnHoleEnumConv: "$1",
warnCstringConv: "$1", warnCstringConv: "$1",
warnEffect: "$1", warnEffect: "$1",
warnCastSizes: "$1",
warnUser: "$1", warnUser: "$1",
hintSuccess: "operation successful: $#", hintSuccess: "operation successful: $#",
# keep in sync with `testament.isSuccess` # keep in sync with `testament.isSuccess`

18
compiler/semexprs.nim
View file

@ -196,10 +196,10 @@ proc checkConvertible(c: PContext, targetTyp: PType, src: PNode): TConvStatus =
else: else:
discard discard
proc isCastable(c: PContext; dst, src: PType): bool = proc isCastable(c: PContext; dst, src: PType, info: TLineInfo): bool =
## Checks whether the source type can be cast to the destination type. ## Checks whether the source type can be cast to the destination type.
## Casting is very unrestrictive; casts are allowed as long as ## Casting is very unrestrictive; casts are allowed as long as
## castDest.size >= src.size, and typeAllowed(dst, skParam) ## dst.size >= src.size, and typeAllowed(dst, skParam)
#const #const
# castableTypeKinds = {tyInt, tyPtr, tyRef, tyCstring, tyString, # castableTypeKinds = {tyInt, tyPtr, tyRef, tyCstring, tyString,
# tySequence, tyPointer, tyNil, tyOpenArray, # tySequence, tyPointer, tyNil, tyOpenArray,
@ -228,19 +228,21 @@ proc isCastable(c: PContext; dst, src: PType): bool =
# Just assume the programmer knows what he is doing. # Just assume the programmer knows what he is doing.
return true return true
if dstSize < 0: if dstSize < 0:
result = false return false
elif srcSize < 0: elif srcSize < 0:
result = false return false
elif typeAllowed(dst, skParam, c) != nil: elif typeAllowed(dst, skParam, c) != nil:
result = false return false
elif dst.kind == tyProc and dst.callConv == ccClosure: elif dst.kind == tyProc and dst.callConv == ccClosure:
result = src.kind == tyProc and src.callConv == ccClosure return src.kind == tyProc and src.callConv == ccClosure
else: else:
result = (dstSize >= srcSize) or result = (dstSize >= srcSize) or
(skipTypes(dst, abstractInst).kind in IntegralTypes) or (skipTypes(dst, abstractInst).kind in IntegralTypes) or
(skipTypes(src, abstractInst-{tyTypeDesc}).kind in IntegralTypes) (skipTypes(src, abstractInst-{tyTypeDesc}).kind in IntegralTypes)
if result and (dstSize > srcSize):
message(conf, info, warnCastSizes, "target type is larger than source type")
if result and src.kind == tyNil: if result and src.kind == tyNil:
result = dst.size <= conf.target.ptrSize return dst.size <= conf.target.ptrSize
proc isSymChoice(n: PNode): bool {.inline.} = proc isSymChoice(n: PNode): bool {.inline.} =
result = n.kind in nkSymChoices result = n.kind in nkSymChoices
@ -359,7 +361,7 @@ proc semCast(c: PContext, n: PNode): PNode =
let castedExpr = semExprWithType(c, n[1]) let castedExpr = semExprWithType(c, n[1])
if tfHasMeta in targetType.flags: if tfHasMeta in targetType.flags:
localError(c.config, n[0].info, "cannot cast to a non concrete type: '$1'" % $targetType) localError(c.config, n[0].info, "cannot cast to a non concrete type: '$1'" % $targetType)
if not isCastable(c, targetType, castedExpr.typ): if not isCastable(c, targetType, castedExpr.typ, n.info):
let tar = $targetType let tar = $targetType
let alt = typeToString(targetType, preferDesc) let alt = typeToString(targetType, preferDesc)
let msg = if tar != alt: tar & "=" & alt else: tar let msg = if tar != alt: tar & "=" & alt else: tar