Bug 20743 – Checked!(int, Abort) does not abort but raise SIGFPE

``` import std.experimental.checkedint; alias cint = Checked!(int, Abort); void works_okay () { cint a = cint.max; cint b = 1; cint c = a + b; } void raises_sigfpe_instead () { cint a = cint.min; cint b = -1; cint c = a / b; } void main () { import std.stdio; foreach (f; [&works_okay, &raises_sigfpe_instead]) try f (); catch (Throwable e) writefln ("caught Throwable <%s>", e.msg); } ``` Application output Overflow on binary operator: int(2147483647) + const(int)(1) caught Throwable <Assertion failure> Overflow on binary operator: int(-2147483648) / const(int)(-1) Error: program killed by signal 8

This is caused by Warn.onOverflow (which is called by Abort.onOverflow) returning the result of a / b. In case of an overflow, the IDIV instruction triggers a division error which then causes SIGFPE. On Windows, something similar happens. Although there are no POSIX signals, an EXCEPTION_INT_OVERFLOW (code 0xC0000095) is thrown (via "Structured Exception Handling"). This exception is seemingly caught by D runtime translated into a Throwable that is printed as "Integer Overflow" (so NOT an assertion fault). Note that this only happens for division. Overflows caused by multiplication do not behave like this (even though, mathematically speaking, a / -1 = a * -1). In my opinion, the best way to deal with this would be to specifically check if the offending calculation was a division, in which case int.min would be returned (otherwise, keep it as-is, i.e. use the mixin to get a result). Any other suggestions?

@wolframw created dlang/phobos pull request #7454 "Fix Issue 20743 - Checked!(int, Abort) does not abort but raise SIGFPE" fixing this issue: - Fix Issue 20743 - Checked!(int, Abort) does not abort but raise SIGFPE https://github.com/dlang/phobos/pull/7454

dlang/phobos pull request #7454 "Fix Issue 20743 - Checked!(int, Abort) does not abort but raise SIGFPE" was merged into master: - 658f8aeff6e6a70fe43edb685313e454c1ecff54 by wolframw: Fix Issue 20743 - Checked!(int, Abort) does not abort but raise SIGFPE https://github.com/dlang/phobos/pull/7454