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August 31, 2014 [Issue 10124] Array length increases on subtraction of a big number instead of throwing RangeError | ||||
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https://issues.dlang.org/show_bug.cgi?id=10124 yebblies <yebblies@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |yebblies@gmail.com --- Comment #1 from yebblies <yebblies@gmail.com> --- I'm not sure it should fail. This is how unsigned types usually work. -- |
August 31, 2014 [Issue 10124] Array length increases on subtraction of a big number instead of throwing RangeError | ||||
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https://issues.dlang.org/show_bug.cgi?id=10124 monarchdodra@gmail.com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |monarchdodra@gmail.com --- Comment #2 from monarchdodra@gmail.com --- (In reply to yebblies from comment #1) > I'm not sure it should fail. This is how unsigned types usually work. Yeah... but it's not actually an arithmetic operations here. It's a setter operation. AFAIK, array resize detects overflow. I don't see why it wouldn't detect underflow? Just saying. -- |
September 01, 2014 [Issue 10124] Array length increases on subtraction of a big number instead of throwing RangeError | ||||
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https://issues.dlang.org/show_bug.cgi?id=10124 Marco Leise <Marco.Leise@gmx.de> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |Marco.Leise@gmx.de --- Comment #3 from Marco Leise <Marco.Leise@gmx.de> --- I see it like the others, Denis. Detecting overflow/underflow here is no different than on regular integer math in other places. The compiler's rewrite looks fine to me. If anything, we need a generic integer overflow check placed around integer math. Same goes for `arr.length -= -1': Again, this is how the language works. Mixing signed and unsigned is allowed, as is `a - (-1)'. While I am positive on these features in general as a nice-to-have, I think this bug report on array.length is invalid and too narrow. Consider for example some custom struct exposing some .length similar to arr.length, which would not be affected by a fix to this bug. We would get different semantics where we are striving to unify the experience. -- |
September 01, 2014 [Issue 10124] Array length increases on subtraction of a big number instead of throwing RangeError | ||||
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https://issues.dlang.org/show_bug.cgi?id=10124 --- Comment #4 from yebblies <yebblies@gmail.com> --- Overflow looks the same: void main() { int[] arr = [1,2,3,4]; arr.length += uint.max; } It's currently being rewritten to 'length = (length op arg)'. I'm not sure how to detect this easily without adding inline code, or an overload for each operation. I mean, for this: arr.length += -3; the compiler sees this: arr.length = arr.length + 4294967293u; -- |
August 29, 2020 [Issue 10124] Array length increases on subtraction of a big number instead of throwing RangeError | ||||
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https://issues.dlang.org/show_bug.cgi?id=10124 Walter Bright <bugzilla@digitalmars.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |backend Status|NEW |RESOLVED CC| |bugzilla@digitalmars.com Resolution|--- |WONTFIX --- Comment #5 from Walter Bright <bugzilla@digitalmars.com> --- This is an artifact of 2's complement arithmetic. Instrumenting the code to detect integer arithmetic overflows will have a large performance penalty, so is not done. -- |
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