denormalized floatingpoint number literals do not work

[dlangBugzillaToGithub]

berni44 (@berni44) reported this on 2019-11-06T15:28:43Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=20361

Description

void main()
{
    float f = 1e-40f;
}

Compiling with dmd produces:

test.d(3): Error: number 1e-40f is not representable

But it is representable. The bit pattern is:

0 00000000 00000010001011011000010