fixes#24228, refs #22022
As described in
https://github.com/nim-lang/Nim/issues/24228#issuecomment-2392462221,
instantiating generic routines inside `typeof` causes all code inside to
be treated as being in a typeof context, and thus preventing compile
time proc folding, causing issues when code is generated for the
instantiated routine. Now, instantiated generic procs are treated as
never being inside a `typeof` context.
This is probably an arbitrary special case and more issues with the
`typeof` behavior from #22022 are likely. Ideally this behavior would be
removed but it's necessary to accomodate the current [proc `declval` in
the package `stew`](https://github.com/status-im/nim-stew/pull/190), at
least without changes to `compileTime` that would either break other
code (making it not eagerly fold by default) or still require a change
in stew (adding an option to disable the eager folding).
Alternatively we could also make the eager folding opt-in only for
generic compileTime procs so that #22022 breaks nothing whatsoever, but
a universal solution would be better. Edit: Done in #24230 via
experimental switch
fixes#24150, refs #22022
An exception is raised in the `semExprWithType` call, which means `dec
c.inTypeofContext` is never called, but `compiles` allows compilation to
continue. This means `c.inTypeofContext` is left perpetually nonzero,
which prevents `compileTime` evaluation for the rest of the program.
To fix this, `defer:` is used for the `dec c.inTypeofContext` call, as
is done for
[`instCounter`](d51d88700b/compiler/seminst.nim (L374))
in other parts of the compiler.
fixes#10753, fixes#22021, refs #19365 (was fixed by #22029, but more
faithful test added)
For whatever reason `compileTime` proc calls did not fold if the proc
was generic ([since this folding was
introduced](c25ffbf262 (diff-539da3a63df08fa987f1b0c67d26cdc690753843d110b6bf0805a685eeaffd40))).
I'm guessing the intention was for *unresolved* generic procs to not
fold, which is now the logic.
Non-magic `compileTime` procs also now don't fold at compile time in
`typeof` contexts to avoid possible runtime errors (only the important)
and prevent double/needless evaluation.
