How to avoid an unsolved constraint error on `if pagesizes > 0UL then pagesizes else 1UL`

[Kiwamu Okabe]

Dear all,

I wrote following ATS code:

```ats
#include "share/atspre_define.hats"
#include "share/atspre_staload.hats"

fun concat_rnd_base {i:int | i > 0} (align: ulint i): ulint =
undefined()

fun concat_exec_imgact {i:int} (pagesizes: ulint i): ulint = let
val psize = if pagesizes > 0UL then pagesizes else 1UL
in
concat_rnd_base(psize)
end

implement main0 () = {
}
```

but above code causes following error:

```
$ patscc main.dats
.../main.dats: 302(line=10, offs=21) -- 307(line=10, offs=26):
error(3): unsolved constraint: C3NSTRprop(C3TKmain();
S2Eeqeq(S2Evar(i(8481)); S2Eintinf
(1)))
```

I belive the `psize` depends on `{i:int | i > 0}`.
How to avoid the unsolved constraint error?

Best regards,
--
Kiwamu Okabe at METASEPI DESIGN

[Hongwei Xi]

For such a use, you need a type annotation:

fun concat_exec_imgact {i:int} (pagesizes: ulint i): ulint = let
val
psize =

(

if
pagesizes > 0UL
then pagesizes else 1UL

) : [i:pos] ulint(i)
in
  concat_rnd_base(psize)
end

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[Kiwamu Okabe]

Thanks. It works!