Polymorphic function fails to compile in C

[jrfondren]

This foldl with some usage:

#include "share/atspre_staload.hats"

fun foldl{a,b:t@ype}(f: (a, b) -> a, acc: a, list: List(b)): a =
        case+ list of
        | list_nil() => acc
        | list_cons(x, xs) => foldl(f, f(acc, x), xs)

implement main0() =
        let
                val list = $list{int}(1, 2, 3, 4, 5)
                //val sum = foldl(lam (acc, n) => acc + n, 0, list)
                val sum = foldl(f, 0, list): int where {
                        fun f(a: int, b: int): int = a + b
                }
        in
                println!("sum1: ", sum);
        end

Fails to compile with these errors:

patscc -DATS_MEMALLOC_GCBDW -o foldlgc foldlgc.dats -latslib -lgc
foldlgc_dats.c:317:1: error: ‘foldl_0’ declared as function returning an array
 foldl_0(atstype_funptr, atstyvar_type(a), atstype_boxed) ;
 ^~~~~~~
foldlgc_dats.c:340:1: error: ‘foldl_0’ declared as function returning an array
 foldl_0(atstype_funptr arg0, atstyvar_type(a) arg1, atstype_boxed arg2)
 ^~~~~~~
In file included from foldlgc_dats.c:15:0:
foldlgc_dats.c: In function ‘foldl_0’:
/home/fondren/sea/ats/ATS2/ccomp/runtime/pats_ccomp_instrset.h:276:35: error: assignment to expression with array type
 #define ATSINSmove(tmp, val) (tmp = val)
                                   ^
foldlgc_dats.c:385:1: note: in expansion of macro ‘ATSINSmove’
 ATSINSmove(tmpret0, arg1) ;
 ^~~~~~~~~~
/home/fondren/sea/ats/ATS2/ccomp/runtime/pats_ccomp_instrset.h:276:35: error: assignment to expression with array type
 #define ATSINSmove(tmp, val) (tmp = val)
                                   ^
foldlgc_dats.c:406:1: note: in expansion of macro ‘ATSINSmove’
 ATSINSmove(tmp1, ATSSELcon(arg2, postiats_tysum_0, atslab__0)) ;
 ^~~~~~~~~~
foldlgc_dats.c:420:1: error: type name declared as function returning an array
 ATSINSmove(tmp3, ATSfunclo_fun(arg0, (atstyvar_type(a), atstyvar_type(b)), atstyvar_type(a))(arg1, tmp1)) ;
 ^~~~~~~~~~
In file included from foldlgc_dats.c:15:0:
/home/fondren/sea/ats/ATS2/ccomp/runtime/pats_ccomp_instrset.h:276:35: error: assignment to expression with array type
 #define ATSINSmove(tmp, val) (tmp = val)
                                   ^
foldlgc_dats.c:420:1: note: in expansion of macro ‘ATSINSmove’
 ATSINSmove(tmp3, ATSfunclo_fun(arg0, (atstyvar_type(a), atstyvar_type(b)), atstyvar_type(a))(arg1, tmp1)) ;
 ^~~~~~~~~~
/home/fondren/sea/ats/ATS2/ccomp/runtime/pats_ccomp_instrset.h:320:41: error: assignment to expression with array type
 #define ATSINSmove_tlcal(apy, tmp) (apy = tmp)
                                         ^
foldlgc_dats.c:427:1: note: in expansion of macro ‘ATSINSmove_tlcal’
 ATSINSmove_tlcal(apy1, tmp3) ;
 ^~~~~~~~~~~~~~~~
/home/fondren/sea/ats/ATS2/ccomp/runtime/pats_ccomp_instrset.h:97:28: warning: return makes integer from pointer without a cast [-Wint-conversion]
 #define ATSreturn(x) return(x)
                            ^
foldlgc_dats.c:443:1: note: in expansion of macro ‘ATSreturn’
 ATSreturn(tmpret0) ;
 ^~~~~~~~~
/home/fondren/sea/ats/ATS2/ccomp/runtime/pats_ccomp_instrset.h:97:28: warning: function returns address of local variable [-Wreturn-local-addr]
 #define ATSreturn(x) return(x)
                            ^
foldlgc_dats.c:443:1: note: in expansion of macro ‘ATSreturn’
 ATSreturn(tmpret0) ;
 ^~~~~~~~~
Makefile:13: recipe for target 'foldlgc' failed
make: *** [foldlgc] Error 1

[githwxi]

The following poly function cannot be compiled into C code
because a and b are of unknown size:

fun foldl{a,b:t@ype}(f: (a, b) -> a, acc: a, list: List(b)): a = ...

It needs to be written as a function template:

fun{a,b:t@ype}  foldl(f: (a, b) -> a, acc: a, list: List(b)): a = ...

Or 't@ype' needs to be changed to 'type', which is for boxed types.