Bug 17185 – Error: number '0x0.0123p-1022' is not representable

I had a line of code including `double(0x0.0123p-1022)` which compiled fine on Windows 7 and OSX; note that 0x0.0123p-1022 is representable as a subnormal double. When compiling on linux with dmd v2.073.0 I received a compile error "Error: number '0x0.0123p-1022' is not representable" - which is not correct, because it is representable as a subnormal. It is possible to write `double(0x0.0123p-1022L)` instead as a workaround. Parsing subnormal reals e.g. 0x0.0123p-16382L seems to work fine on all three platforms.

This occurred when compiling on ubuntu 12.04.04

This occurs because dmd's parser calls strtold from the c runtime to parse floats. apparently ubuntu 12.04 version of the runtime does mess this up.

Note that one possible solution to this bug would be to use a custom strtold implementation rather than relying on the runtime. For reference, here is one such function implemented in native D code: https://github.com/pineapplemachine/mach.d/blob/master/mach/text/numeric/hexfloats.d#L147

This code: void main() { import std.stdio : writeln; writeln(double(0x0.0123p-1022)); // Prints 64+64i, should print 64+0i } compiles just fine on my machine (Ubunutu 20.04.4).