[Issue 23999] literal suffixes dont mix well with template instantiations

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23999

--- Comment #8 from Nick Treleaven <nick at geany.org> ---
> This is impossible to express in the lexical grammar

I have changed the pull to a warning rather than an error, like the dangling
else warning.

> it isn't the compiler's job to enforce good style

Style is a matter of preference. No reasonable person's preference can allow
one of these suffixes right next to an identifier, because people read the
suffix as part of the identifier.

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