On 7/2/2017 11:19 AM, Florian Klämpfl wrote:
Am 02.07.2017 um 00:26 schrieb Martok:
So, we have a problem here: either the type system is broken because we can put
stuff in a type without being able to check if it actually belongs there, or
Tcgcasenode is broken because it (and _only_ it, as far as I can see) wants to
be clever by omitting an essentially free check for very little benefit.
I know which interpretation I would choose: the one with the easier fix ;-)
Yes, checking the data. I can easily create a similar problem as above with the
"range checks" for
the jump table by reading a negative value into the enum. Unfortunately, the
checks are unsigned ...
The correct solution is to provide a function which checks an integer based on
rtti if it is valid
for a certain enum. Everything else is curing only symptoms.
Indeed, I've done some tests and found out that when range checking is enabled enums are not checked at all. Even array
access with enum index is not checked.
According to docs enums should be range checked:
https://www.freepascal.org/docs-html/prog/progsu65.html#x72-710001.2.65
As Florian has said, the correct solution for this issue is to add range checking for enum types when range checking is
ON. Including the "CASE <enum> OF". The check via RTTI should be fine.
At least you will be able to generate slower but safe code by enabling range
checks and overflow checks.
Yury.
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