Restructure modal and with-bounds (fka baggage) in jkind

This commit contains a significant restructuring of the modal upper bounds and
with-bounds (which is the new name for what was previously called "baggage") in
the innards of Jkind.t

Previously, jkinds morally consisted of:

- a layout
- a map from axis, to a pair of upper bound and a list of types (the with-bounds
  for that axis)

now, we instead have, morally:
- a layout
- a map from axis to the upper bound for that axis
- a list of (type, modality) pairs, where the modality is effectively providing
  us the way that the type operates on the axis

This behavior is both much closer to the syntactic representation of jkinds,
making it simpler both to construct and to print, and probably more efficient,
since the usual behavior is that a type appears on the with-bounds for all
axes (this is only not the case in the presence of modalities)

The test changes are mostly innocuous:

1. Printing changed slightly when illegal crossing is used - actually I'm
   reasonably sure that this change *fixed* printing of kind annotations for
   types with illegal crossing
2. We're no longer deduplicating types for printing kinds (we used to do this
   only when constructing outcometrees); this will come back later as we do
   deduplication of with-bounds at construction time.
3. We actually got better at printing kinds in general, eg we're now better at
   figuring out built-in aliases to print under some with-bounds.

Past the actual internals of with-bounds, we frequently /reconstruct/ the
list-of-types-per-axis shape, eg in subsumption - this is mostly done to avoid
this commit getting too large and hairy, and in follow-up I plan on refactoring
to do more algorithms such as bound extension holistically rather than per-axis,
which ought to also realize more performance gains here.

testsuite/tests/parsetree/source_jane_street.ml

@@ -1066,14 +1066,10 @@ type 'a contended : immutable_data with 'a @@ contended
 type 'a contended_with_int : immutable_data with 'a @@ contended with int
 
 [%%expect{|
-type 'a list : value mod many uncontended portable with 'a
-type ('a, 'b) either : value mod many uncontended portable with 'a * 'b
-type 'a contended : value mod many uncontended portable with 'a @@ contended
-type 'a contended_with_int
-  : value mod many uncontended portable
-  with 'a @@ contended
-
-  with int
+type 'a list : immutable_data with 'a
+type ('a, 'b) either : immutable_data with 'a * 'b
+type 'a contended : immutable_data with 'a @@ contended
+type 'a contended_with_int : immutable_data with 'a @@ contended with int
 |}]
 
 (* not yet supported *)

testsuite/tests/typing-jkind-bounds/allow_illegal_crossing.ml

@@ -12,21 +12,21 @@ type a
 type b : value mod portable = { a : int; b : int }
 [%%expect {|
 type a
-type b = { a : int; b : int; }
+type b : immutable_data = { a : int; b : int; }
 |}]
 
 type a
 type b : value mod uncontended = Foo of int
 [%%expect {|
 type a
-type b = Foo of int
+type b : immutable_data = Foo of int
 |}]
 
 type a
 type b : value mod uncontended portable = Foo of int | Bar of int
 [%%expect {|
 type a
-type b = Foo of int | Bar of int
+type b : immutable_data = Foo of int | Bar of int
 |}]
 
 type a
@@ -59,7 +59,7 @@ Error: The kind of type "a" is value
 
 type t : value mod portable uncontended = { a : int; b : int }
 [%%expect {|
-type t = { a : int; b : int; }
+type t : immutable_data = { a : int; b : int; }
 |}]
 
 type ('a, 'b) t : value mod portable uncontended = { a : 'a; b : 'b }
@@ -69,40 +69,40 @@ type ('a, 'b) t : immutable_data = { a : 'a; b : 'b; }
 
 type t : value mod portable = private { foo : string }
 [%%expect {|
-type t = private { foo : string; }
+type t : immutable_data = private { foo : string; }
 |}]
 
 type a : value mod portable = { foo : string }
 type b : value mod portable = a = { foo : string }
 [%%expect {|
-type a = { foo : string; }
-type b = a = { foo : string; }
+type a : immutable_data = { foo : string; }
+type b = a : immutable_data = { foo : string; }
 |}]
 
 type a : value mod uncontended = private { foo : string }
 type b : value mod uncontended = a = private { foo : string }
 [%%expect {|
-type a = private { foo : string; }
-type b = a = private { foo : string; }
+type a : immutable_data = private { foo : string; }
+type b = a : immutable_data = private { foo : string; }
 |}]
 
 type t : value mod uncontended = private Foo of int | Bar
 [%%expect {|
-type t = private Foo of int | Bar
+type t : immutable_data = private Foo of int | Bar
 |}]
 
 type a : value mod uncontended = Foo of int | Bar
 type b : value mod uncontended = a = Foo of int | Bar
 [%%expect {|
-type a = Foo of int | Bar
-type b = a = Foo of int | Bar
+type a : immutable_data = Foo of int | Bar
+type b = a : immutable_data = Foo of int | Bar
 |}]
 
 type a : value mod portable = private Foo of int | Bar
 type b : value mod portable = a = private Foo of int | Bar
 [%%expect {|
-type a = private Foo of int | Bar
-type b = a = private Foo of int | Bar
+type a : immutable_data = private Foo of int | Bar
+type b = a : immutable_data = private Foo of int | Bar
 |}]
 
 type t : value mod uncontended = private Foo of int ref | Bar
@@ -130,7 +130,7 @@ end = struct
   type t = { a : string }
 end
 [%%expect {|
-module A : sig type t = { a : string; } end
+module A : sig type t : immutable_data = { a : string; } end
 |}]
 
 (********************************************)
@@ -140,7 +140,7 @@ type a : value mod portable uncontended = Foo of string
 type ('a : value mod portable uncontended) b
 type c = a b
 [%%expect {|
-type a = Foo of string
+type a : immutable_data = Foo of string
 type ('a : value mod uncontended portable) b
 type c = a b
 |}]
@@ -158,15 +158,15 @@ type t : value mod portable uncontended = { a : string; b : int }
 let f : ('a : value mod portable uncontended). 'a -> 'a = fun x -> x
 let g (x : t) = f x
 [%%expect {|
-type t = { a : string; b : int; }
+type t : immutable_data = { a : string; b : int; }
 val f : ('a : value mod uncontended portable). 'a -> 'a = <fun>
 val g : t -> t = <fun>
 |}]
 
 type t : value mod portable uncontended = { a : int; b : int }
 let x : _ as (_ : value mod portable uncontended) = { a = 5; b = 5 }
 [%%expect {|
-type t = { a : int; b : int; }
+type t : immutable_data = { a : int; b : int; }
 val x : t = {a = 5; b = 5}
 |}]
 
@@ -180,7 +180,7 @@ val x : (int, int) t = {a = 5; b = 5}
 type t : value mod portable uncontended = Foo of string | Bar of int
 let x : _ as (_ : value mod portable uncontended) = Foo "hello world"
 [%%expect {|
-type t = Foo of string | Bar of int
+type t : immutable_data = Foo of string | Bar of int
 val x : t = Foo "hello world"
 |}]
 
@@ -200,7 +200,7 @@ type ('a : value mod portable) u = 'a
 type v = A.t u
 let x : _ as (_ : value mod portable) = ({ a = "hello" } : A.t)
 [%%expect {|
-module A : sig type t = { a : string; } end
+module A : sig type t : immutable_data = { a : string; } end
 type ('a : value mod portable) u = 'a
 type v = A.t u
 val x : A.t = {A.a = "hello"}
@@ -210,7 +210,7 @@ type t : value mod portable = { a : string }
 let my_str : string @@ nonportable = ""
 let y = ({ a = my_str } : t @@ portable)
 [%%expect {|
-type t = { a : string; }
+type t : immutable_data = { a : string; }
 val my_str : string = ""
 val y : t = {a = ""}
 |}]
@@ -230,7 +230,7 @@ let f () =
   let _ = ({ a = make_str () } : t @@ uncontended) in
   ()
 [%%expect {|
-type t = { a : string; }
+type t : immutable_data = { a : string; }
 val make_str : unit -> string = <fun>
 val f : unit -> unit = <fun>
 |}]
@@ -241,7 +241,7 @@ let f () =
   let _ : t @@ uncontended = { a = make_str () } in
   ()
 [%%expect {|
-type t = { a : string; }
+type t : immutable_data = { a : string; }
 val make_str : unit -> string = <fun>
 val f : unit -> unit = <fun>
 |}]
@@ -282,7 +282,7 @@ type t : value mod portable uncontended = Foo of string | Bar of int
 let g (x : t @@ nonportable contended) = f x; f (Foo ""); f (Bar 10)
 [%%expect {|
 val f : 'a @ portable -> unit = <fun>
-type t = Foo of string | Bar of int
+type t : immutable_data = Foo of string | Bar of int
 val g : t @ contended -> unit = <fun>
 |}]
 
@@ -545,7 +545,7 @@ end = struct
   type v = t u
 end
 [%%expect {|
-module A : sig type t = { a : string; } end
+module A : sig type t : immutable_data = { a : string; } end
 |}, Principal{|
 Line 6, characters 11-12:
 6 |   type v = t u
@@ -582,7 +582,7 @@ end = struct
   let x : _ as (_ : value mod portable) = { a = "hello" }
 end
 [%%expect {|
-module A : sig type t = { a : string; } end
+module A : sig type t : immutable_data = { a : string; } end
 |}, Principal{|
 Line 5, characters 42-57:
 5 |   let x : _ as (_ : value mod portable) = { a = "hello" }
@@ -687,14 +687,14 @@ type a = { foo : string }
 type b : value mod portable = a = { foo : string }
 [%%expect {|
 type a = { foo : string; }
-type b = a = { foo : string; }
+type b = a : immutable_data = { foo : string; }
 |}]
 
 type a = private { foo : string }
 type b : value mod uncontended = a = private { foo : string }
 [%%expect {|
 type a = private { foo : string; }
-type b = a = private { foo : string; }
+type b = a : immutable_data = private { foo : string; }
 |}]
 
 type a = { foo : string -> string }
@@ -727,14 +727,14 @@ type a = Foo of string | Bar
 type b : value mod uncontended = a = Foo of string | Bar
 [%%expect {|
 type a = Foo of string | Bar
-type b = a = Foo of string | Bar
+type b = a : immutable_data = Foo of string | Bar
 |}]
 
 type a = private Foo of string | Bar
 type b : value mod portable = a = private Foo of string | Bar
 [%%expect {|
 type a = private Foo of string | Bar
-type b = a = private Foo of string | Bar
+type b = a : immutable_data = private Foo of string | Bar
 |}]
 
 type a = Foo of { mutable x : int } | Bar

testsuite/tests/typing-jkind-bounds/modalities.ml

@@ -96,12 +96,8 @@ Error: This expression has type "string t"
        but an expression was expected of type
          "('a : value mod global & value mod global)"
        The kind of string t is
-         value_or_null mod global unique many uncontended portable external_
-                           non_null
-         with string @@ global
-         & value_or_null mod global unique many uncontended portable
-                             external_ non_null
-         with string @@ global
+         immediate with string @@ global with string @@ global & immediate
+         with string @@ global with string @@ global
          because of the definition of t at line 4, characters 0-51.
        But the kind of string t must be a subkind of
          value mod global & value mod global
@@ -128,12 +124,9 @@ Line 1, characters 65-66:
 Error: This expression has type "(string -> string) t"
        but an expression was expected of type "('a : value & value)"
        The kind of (string -> string) t is
-         value_or_null mod global unique many uncontended portable external_
-                           non_null
-         with string -> string @@ global
-         & value_or_null mod global unique many uncontended portable
-                             external_ non_null
-         with string -> string @@ global
+         immediate with string -> string @@ global
+         with string -> string @@ global & immediate
+         with string -> string @@ global with string -> string @@ global
          because of the definition of t at line 4, characters 0-51.
        But the kind of (string -> string) t must be a subkind of
          value & value

testsuite/tests/typing-layouts-or-null/reexport.ml

@@ -21,8 +21,8 @@ Lines 2-4, characters 2-16:
 4 |     | This of 'a
 Error: The kind of type "'a or_null" is value_or_null
          because it is the primitive value_or_null type or_null.
-       But the kind of type "'a or_null" must be a subkind of
-         value mod many uncontended portable with 'a
+       But the kind of type "'a or_null" must be a subkind of immutable_data
+         with 'a
          because of the definition of t at lines 2-4, characters 2-16.
 |}]
 

testsuite/tests/typing-layouts-products/basics_alpha.ml

@@ -67,9 +67,9 @@ Line 3, characters 0-39:
 3 | type t3 : any mod non_null = #(t1 * t2);;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Error: The kind of type "#(t1 * t2)" is
-         any mod global unique many uncontended portable external_ non_null
+         any_non_null mod global unique many uncontended portable external_
          with t1 with t2
-         & any mod global unique many uncontended portable external_ non_null
+         & any_non_null mod global unique many uncontended portable external_
          with t1 with t2
          because it is an unboxed tuple.
        But the kind of type "#(t1 * t2)" must be a subkind of any_non_null
@@ -86,9 +86,9 @@ Line 3, characters 0-45:
 3 | type t3 : any & any mod non_null = #(t1 * t2);;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Error: The kind of type "#(t1 * t2)" is
-         any mod global unique many uncontended portable external_ non_null
+         any_non_null mod global unique many uncontended portable external_
          with t1 with t2
-         & any mod global unique many uncontended portable external_ non_null
+         & any_non_null mod global unique many uncontended portable external_
          with t1 with t2
          because it is an unboxed tuple.
        But the kind of type "#(t1 * t2)" must be a subkind of
@@ -106,9 +106,9 @@ Line 3, characters 0-62:
 3 | type t3 : (any mod non_null) & (any mod non_null) = #(t1 * t2);;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Error: The kind of type "#(t1 * t2)" is
-         any mod global unique many uncontended portable external_ non_null
+         any_non_null mod global unique many uncontended portable external_
          with t1 with t2
-         & any mod global unique many uncontended portable external_ non_null
+         & any_non_null mod global unique many uncontended portable external_
          with t1 with t2
          because it is an unboxed tuple.
        But the kind of type "#(t1 * t2)" must be a subkind of

testsuite/tests/typing-layouts-unboxed-records/basics.ml

@@ -760,12 +760,8 @@ Line 1, characters 0-61:
 1 | type q : any mod portable = #{ x : int -> int; y : int -> q }
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Error: The kind of type "q" is
-         value_or_null mod global unique many uncontended portable external_
-                           non_null
-         with int -> int with int -> q
-         & value_or_null mod global unique many uncontended portable
-                             external_ non_null
-         with int -> int with int -> q
+         immediate with int -> int with int -> q & immediate with int -> int
+         with int -> q
          because it is an unboxed record.
        But the kind of type "q" must be a subkind of
          value_or_null mod portable & value_or_null mod portable

typing/ctype.ml

@@ -2207,7 +2207,7 @@ let rec estimate_type_jkind ~expand_component env ty =
       (* Checking [has_baggage] here is needed for correctness, because
          intersection types sometimes do not unify with themselves. Removing
          this check causes typing-misc/pr7937.ml to fail. *)
-      if Jkind.has_baggage jkind
+      if Jkind.has_with_bounds jkind
       then
         let level = get_level ty in
         (* CR layouts v2.8: We could possibly skip this substitution if we're