Fix int64 min issue#1722
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This patch invokes Undefined Behavior. You aren't allowed to take the negative of "min int". Eg, for Int8, the negative of -128 is +128, which is not representable in Int8. This is UB in C++. |
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Maybe you could do something like |
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@jaredgrubb Thanks for the review. Good point. Your suggestion is pretty close to the old solution prior to 546e2cb. I've used that one, but also moved the code into functions to avoid the warning which 546e2cb wanted to fix. Let's see what CI says. |
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I have some minor change requests.
For some gcc version (Ubuntu 5.5.0-12ubuntu1~16.04) the existing code crashes when the minimum value of int64_t is outputted. Resurrect the code from before 546e2cb (:rotating_light: fixed some warnings, 2019-03-13) but delegate the sign removal so that the compilers don't complain about taking the negative value of an unsigned value. In addition we also rewrite the expression so that we first increment and then negate. The definition of remove_sign(number_unsigned_t) is never called as unsigned values are never negative.
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@nlohmann Thanks for the review. |
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Thanks a lot! |
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This includes the following fixes: nlohmann/json#1436 > For a deeply-nested JSON object, the recursive implementation of json_value::destroy function causes stack overflow. nlohmann/json#1708 nlohmann/json#1722 Stack size nlohmann/json#1693 (comment) Integer Overflow nlohmann/json#1447 UTF8, json dump out of bounds nlohmann/json#1445 Possibly influences #7532
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This includes the following fixes: nlohmann/json#1436 > For a deeply-nested JSON object, the recursive implementation of json_value::destroy function causes stack overflow. nlohmann/json#1708 nlohmann/json#1722 Stack size nlohmann/json#1693 (comment) Integer Overflow nlohmann/json#1447 UTF8, json dump out of bounds nlohmann/json#1445 Possibly influences #7532
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This includes the following fixes: nlohmann/json#1436 > For a deeply-nested JSON object, the recursive implementation of json_value::destroy function causes stack overflow. nlohmann/json#1708 nlohmann/json#1722 Stack size nlohmann/json#1693 (comment) Integer Overflow nlohmann/json#1447 UTF8, json dump out of bounds nlohmann/json#1445 Possibly influences #7532
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Close #1708.
For some gcc version (Ubuntu 5.5.0-12ubuntu1~16.04) the existing code
crashes when the minimum value of int64_t is outputted.
Rewrite the code to be less complicated to avoid it. This partially
reverts what was done in 546e2cb (rotating_light fixed some warnings,
2019-03-13).
It might be the case that this reintroduces the warning removed earlier. If that is the case, I will rewrite the code using templates to conditionally remove the sign for the negative case only.
Do we need static assertions which ensure that every positive number_integer_t fits into a number_unsigned_t?