[Issue 17843] -betterC struct with `double` field generates references to TypeInfo

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=17843

--- Comment #2 from Walter Bright <bugzilla at digitalmars.com> ---
For older compilers, a workaround is to add a toHash() dummy member function:

  extern (D) size_t toHash() const nothrow @safe { return 0; }

for the struct with a float/double/real in it.

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