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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

(cherry picked from commit 528b6d1c3f)
This commit is contained in:
konsumlamm
2022-07-28 15:09:58 +02:00
committed by narimiran
parent 42020a2331
commit f3300c1a9c
2 changed files with 12 additions and 8 deletions
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2
compiler/lineinfos.nim
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@@ -79,6 +79,7 @@ type
warnPtrToCstringConv = "PtrToCstringConv",
warnEffect = "Effect",
warnBareExcept = "BareExcept",
warnCastSizes = "CastSizes"
warnUser = "User",
# hints
hintSuccess = "Success", hintSuccessX = "SuccessX",
@@ -171,6 +172,7 @@ const
warnPtrToCstringConv: "unsafe conversion to 'cstring' from '$1'; this will become a compile time error in the future",
warnEffect: "$1",
warnBareExcept: "$1",
warnCastSizes: "$1",
warnUser: "$1",
hintSuccess: "operation successful: $#",
# 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:
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.
## 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
# castableTypeKinds = {tyInt, tyPtr, tyRef, tyCstring, tyString,
# 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.
return true
if dstSize < 0:
result = false
return false
elif srcSize < 0:
result = false
return false
elif typeAllowed(dst, skParam, c) != nil:
result = false
return false
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:
result = (dstSize >= srcSize) or
(skipTypes(dst, abstractInst).kind in IntegralTypes) or
(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:
result = dst.size <= conf.target.ptrSize
return dst.size <= conf.target.ptrSize
proc isSymChoice(n: PNode): bool {.inline.} =
result = n.kind in nkSymChoices
@@ -359,7 +361,7 @@ proc semCast(c: PContext, n: PNode): PNode =
let castedExpr = semExprWithType(c, n[1])
if tfHasMeta in targetType.flags:
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 alt = typeToString(targetType, preferDesc)
let msg = if tar != alt: tar & "=" & alt else: tar