Compilation does not terminate

[pqwy]

More precisely, compilation time is exponential in the constant given to fun1 in this program:

let app fb x = fb x

let rec fun1 = function
  | 0 -> ()
  | n -> app (fun _ -> fun1 (pred n)) ()

let _ = app (fun () -> fun1 1000000) ()

Attaching gdb, the stack is 4144 deep, with this at the top:

#0  0x00000000006bc8a8 in caml_oldify_one ()
#1  0x00000000006bcaea in caml_oldify_mopup ()
#2  0x00000000006bcbb0 in caml_empty_minor_heap ()
#3  0x00000000006bcda9 in caml_minor_collection ()
#4  0x00000000006bb87a in caml_garbage_collection ()
#5  0x00000000006cd514 in caml_call_gc ()
#6  0x0000000000444491 in camlFreshening__func_decls_subst_closure_5785 () at middle_end/freshening.ml:286
#7  0x000000000044465c in camlFreshening__apply_function_decls_and_free_vars_closure_5991 ()
    at middle_end/freshening.ml:306
#8  0x0000000000475df5 in camlInline_and_simplify__simplify_set_of_closures_28040 ()
    at middle_end/inline_and_simplify.ml:571
#9  0x000000000047569e in camlInline_and_simplify__simplify_named_28045 () at middle_end/inline_and_simplify.ml:847
#10 0x00000000004783cc in camlInline_and_simplify__for_defining_expr_closure_29729 ()
    at middle_end/inline_and_simplify.ml:928
#11 0x000000000043307f in camlFlambda__loop_18560 () at middle_end/flambda.ml:834
#12 0x000000000047476d in camlInline_and_simplify__simplify_28048 () at middle_end/inline_and_simplify.ml:1186
#13 0x0000000000473ede in camlInline_and_simplify__simplify_function_closure_28679 ()
    at middle_end/inline_and_simplify.ml:626
#14 0x0000000000688654 in camlMap__fold_4315 () at map.ml:193
#15 0x0000000000476053 in camlInline_and_simplify__simplify_set_of_closures_28040 ()
    at middle_end/inline_and_simplify.ml:644
#16 0x000000000047569e in camlInline_and_simplify__simplify_named_28045 () at middle_end/inline_and_simplify.ml:847
#17 0x00000000004783cc in camlInline_and_simplify__for_defining_expr_closure_29729 ()
    at middle_end/inline_and_simplify.ml:928
#18 0x000000000043307f in camlFlambda__loop_18560 () at middle_end/flambda.ml:834
#19 0x000000000047476d in camlInline_and_simplify__simplify_28048 () at middle_end/inline_and_simplify.ml:1186
#20 0x0000000000473ede in camlInline_and_simplify__simplify_function_closure_28679 ()
    at middle_end/inline_and_simplify.ml:626
#21 0x0000000000688654 in camlMap__fold_4315 () at map.ml:193
#22 0x0000000000476053 in camlInline_and_simplify__simplify_set_of_closures_28040 ()
    at middle_end/inline_and_simplify.ml:644
#23 0x000000000047569e in camlInline_and_simplify__simplify_named_28045 () at middle_end/inline_and_simplify.ml:847
#24 0x00000000004783cc in camlInline_and_simplify__for_defining_expr_closure_29729 ()
    at middle_end/inline_and_simplify.ml:928
#25 0x000000000043307f in camlFlambda__loop_18560 () at middle_end/flambda.ml:834

Using version 4.03.0+dev11-2015-10-19, the one currently in opam.

[pqwy]

In addition, using -no-functor-heuristics prevents this issue.

[mshinwell]

The toplevel function is being caught by the functor heuristics, even though it is not a functor, I presume. I think the forthcoming work to functor heuristics should fix this, at which point we should retest this example.

[mshinwell]

I tested this and it appears to have been fixed.