[Issue 19164] malloc may be considered pure when failure results in program exit (no need to reset errno)

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19164

--- Comment #3 from Nathan S. <n8sh.secondary at hotmail.com> ---
The pattern is correct when it is known the argument to malloc cannot be zero.
For instance, in std.container.array.Array.length(size_t newLength), allocation
is only attempted if newLength is greater than the current length.

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