Remove the call-site @inlined attribute

CHANGELOG.md

@@ -14,6 +14,7 @@
 
 #### :boom: Breaking Change
 
+- Remove the call-site `@inlined` attribute, which was parsed but never affected code generation. It is now reported as a misplaced attribute (warning 53). https://github.com/rescript-lang/rescript/pull/8734
 - Remove `@deriving(abstract)` and `@deriving(jsConverter)`. Use record types (with optional fields, mutable fields and `@as` renaming) and polymorphic variants directly instead. https://github.com/rescript-lang/rescript/pull/8729
 
 #### :eyeglasses: Spec Compliance

compiler/core/lam_pass_remove_alias.ml

@@ -191,7 +191,6 @@ let simplify_alias (meta : Lam_stats.t) (lam : Lambda.t) : Lambda.t =
               (Lam_beta_reduce.propagate_beta_reduce meta params body ap_args)
           else if
             (* Lam_analysis.size body < Lam_analysis.small_inline_size *)
-            (* ap_inlined = Always_inline || *)
             Lam_analysis.ok_to_inline_fun_when_app m ap_args
           then
             let param_map =

compiler/ml/lambda.ml

@@ -362,7 +362,7 @@ and lfunction = {
 
 and prim_info = {primitive: primitive; args: t list; loc: Location.t}
 
-and ap_info = {ap_loc: Location.t; ap_inlined: inline_attribute}
+and ap_info = {ap_loc: Location.t}
 
 and lambda_apply = {
   ap_func: t;

compiler/ml/lambda.mli

@@ -375,10 +375,7 @@ and lfunction = {
 
 and prim_info = private {primitive: primitive; args: t list; loc: Location.t}
 
-and ap_info = {
-  ap_loc: Location.t;
-  ap_inlined: inline_attribute; (* specified with the [@inlined] attribute *)
-}
+and ap_info = {ap_loc: Location.t}
 
 and lambda_apply = private {
   ap_func: t;

compiler/ml/lambda_traverse.ml

@@ -124,8 +124,7 @@ let make_key e =
     | Lglobal_module _ | Lconst _ -> e
     | Lapply ap ->
       apply ~ap_transformed_jsx:ap.ap_transformed_jsx (tr_rec env ap.ap_func)
-        (tr_recs env ap.ap_args)
-        {ap.ap_info with ap_loc = Location.none}
+        (tr_recs env ap.ap_args) {ap_loc = Location.none}
     | Llet (Alias, x, ex, e) ->
       (* Ignore aliases -> substitute *)
       let ex = tr_rec env ex in

compiler/ml/printlambda.ml

@@ -231,19 +231,13 @@ let function_attribute ppf {inline; is_a_functor; return_unit} =
   | Always_inline -> fprintf ppf "always_inline@ "
   | Never_inline -> fprintf ppf "never_inline@ "
 
-let apply_inlined_attribute ppf = function
-  | Default_inline -> ()
-  | Always_inline -> fprintf ppf " always_inline"
-  | Never_inline -> fprintf ppf " never_inline"
-
 let rec lam ppf = function
   | Lvar id -> Ident.print ppf id
   | Lglobal_module id -> fprintf ppf "global %a" Ident.print id
   | Lconst cst -> struct_const ppf cst
   | Lapply ap ->
     let lams ppf largs = List.iter (fun l -> fprintf ppf "@ %a" lam l) largs in
-    fprintf ppf "@[<2>(apply@ %a%a%a)@]" lam ap.ap_func lams ap.ap_args
-      apply_inlined_attribute ap.ap_info.ap_inlined
+    fprintf ppf "@[<2>(apply@ %a%a)@]" lam ap.ap_func lams ap.ap_args
   | Lfunction {params; body; attr} ->
     let pr_params ppf params =
       List.iter (fun param -> fprintf ppf "@ %a" Ident.print param) params

compiler/ml/translattribute.ml

@@ -20,11 +20,6 @@ let is_inline_attribute (attr : t) =
   | {txt = "inline"}, _ -> true
   | _ -> false
 
-let is_inlined_attribute (attr : t) =
-  match attr with
-  | {txt = "inlined"}, _ -> true
-  | _ -> false
-
 let find_attribute p (attributes : t list) =
   let inline_attribute, other_attributes = List.partition p attributes in
   let attr =
@@ -57,7 +52,7 @@ let parse_inline_attribute (attr : t option) : Lambda.inline_attribute =
   | None -> Default_inline
   | Some ({txt; loc}, payload) -> (
     let open Parsetree in
-    (* the 'inline' and 'inlined' attributes can be used as
+    (* the 'inline' attribute can be used as
        [@inline], [@inline never] or [@inline always].
        [@inline] is equivalent to [@inline always] *)
     let warning txt =
@@ -98,33 +93,14 @@ let add_inline_attribute (expr : Lambda.t) loc attributes =
     Location.prerr_warning loc (Warnings.Misplaced_attribute "inline");
     expr
 
-(* Get the [@inlined] attribute payload (or default if not present).
-   It also returns the expression without this attribute. This is
-   used to ensure that this attribute is not misplaced: If it
-   appears on any expression, it is an error, otherwise it would
-   have been removed by this function *)
-let get_and_remove_inlined_attribute (e : Typedtree.expression) =
-  let attr, exp_attributes =
-    find_attribute is_inlined_attribute e.exp_attributes
-  in
-  let inlined = parse_inline_attribute attr in
-  (inlined, {e with exp_attributes})
-
-let get_and_remove_inlined_attribute_on_module (e : Typedtree.module_expr) =
-  let attr, mod_attributes =
-    find_attribute is_inlined_attribute e.mod_attributes
-  in
-  let inlined = parse_inline_attribute attr in
-  (inlined, {e with mod_attributes})
-
 let check_attribute (e : Typedtree.expression) (({txt; loc}, _) : t) =
   match txt with
   | "inline" -> (
     match e.exp_desc with
     | Texp_function _ -> ()
     | _ -> Location.prerr_warning loc (Warnings.Misplaced_attribute txt))
   | "inlined" ->
-    (* Removed by the Texp_apply cases *)
+    (* Call-site inlining hints are not supported *)
     Location.prerr_warning loc (Warnings.Misplaced_attribute txt)
   | _ -> ()
 
@@ -136,6 +112,6 @@ let check_attribute_on_module (e : Typedtree.module_expr) (({txt; loc}, _) : t)
     | Tmod_functor _ -> ()
     | _ -> Location.prerr_warning loc (Warnings.Misplaced_attribute txt))
   | "inlined" ->
-    (* Removed by the Texp_apply cases *)
+    (* Call-site inlining hints are not supported *)
     Location.prerr_warning loc (Warnings.Misplaced_attribute txt)
   | _ -> ()

compiler/ml/translattribute.mli

@@ -24,9 +24,3 @@ val add_inline_attribute :
 val get_inline_attribute : Parsetree.attributes -> Lambda.inline_attribute
 
 val get_empty_attribute : string -> Parsetree.attributes -> Location.t option
-
-val get_and_remove_inlined_attribute :
-  Typedtree.expression -> Lambda.inline_attribute * Typedtree.expression
-
-val get_and_remove_inlined_attribute_on_module :
-  Typedtree.module_expr -> Lambda.inline_attribute * Typedtree.module_expr

compiler/ml/translcore.ml

@@ -909,8 +909,7 @@ let wrap_exn loc arg =
        ~args:
          [global_module (Ident.create_persistent Primitive_modules.exceptions)]
        loc)
-    [arg]
-    {ap_loc = loc; ap_inlined = Default_inline}
+    [arg] {ap_loc = loc}
 let exception_id_destructed (l : Lambda.t) (fv : Ident.t) : bool =
   let rec hit_opt = function
     | None -> false
@@ -1038,20 +1037,15 @@ and transl_exp0 (e : Typedtree.expression) : Lambda.t =
           {
             exp_desc = Texp_ident (_, _, ({val_kind = Val_prim p} as prim_vd));
             exp_type = prim_type;
-          } as funct;
+          };
         args = oargs;
         transformed_jsx;
       }
     when List.length oargs >= p.prim_arity
          && List.for_all (fun (_, arg) -> arg <> None) oargs -> (
     let args, args' = cut p.prim_arity oargs in
     let wrap f =
-      if args' = [] then f
-      else
-        let inlined, _ =
-          Translattribute.get_and_remove_inlined_attribute funct
-        in
-        transl_apply ~inlined ~transformed_jsx f args' e.exp_loc
+      if args' = [] then f else transl_apply ~transformed_jsx f args' e.exp_loc
     in
     let args =
       List.map
@@ -1104,9 +1098,6 @@ and transl_exp0 (e : Typedtree.expression) : Lambda.t =
           warn_polymorphic_comparison e.exp_loc builtin argl;
           wrap (mk_builtin builtin argl e.exp_loc))))
   | Texp_apply {funct; args = oargs; partial; transformed_jsx} ->
-    let inlined, funct =
-      Translattribute.get_and_remove_inlined_attribute funct
-    in
     let uncurried_partial_application =
       (* In case of partial application foo(args, ...) when some args are missing,
          get the arity *)
@@ -1119,7 +1110,7 @@ and transl_exp0 (e : Typedtree.expression) : Lambda.t =
         | None -> None
       else None
     in
-    transl_apply ~inlined ~uncurried_partial_application ~transformed_jsx
+    transl_apply ~uncurried_partial_application ~transformed_jsx
       (transl_exp funct) oargs e.exp_loc
   | Texp_match (arg, pat_expr_list, exn_pat_expr_list, partial) ->
     transl_match e arg pat_expr_list exn_pat_expr_list partial
@@ -1315,12 +1306,10 @@ and transl_case {c_lhs; c_guard; c_rhs} = (c_lhs, transl_guard c_guard c_rhs)
 
 and transl_cases cases = List.map transl_case cases
 
-and transl_apply ?(inlined = Default_inline)
-    ?(uncurried_partial_application = None) ?(transformed_jsx = false) lam sargs
-    loc =
+and transl_apply ?(uncurried_partial_application = None)
+    ?(transformed_jsx = false) lam sargs loc =
   let lapply ap_func ap_args =
-    apply ~ap_transformed_jsx:transformed_jsx ap_func ap_args
-      {ap_loc = loc; ap_inlined = inlined}
+    apply ~ap_transformed_jsx:transformed_jsx ap_func ap_args {ap_loc = loc}
   in
   let rec build_apply lam args = function
     | (None, optional) :: l ->
@@ -1371,8 +1360,7 @@ and transl_apply ?(inlined = Default_inline)
     let extra_args = Ext_list.map extra_ids (fun id -> var id) in
     let ap_args = args @ extra_args in
     let l0 =
-      apply ~ap_transformed_jsx:transformed_jsx lam ap_args
-        {ap_loc = loc; ap_inlined = inlined}
+      apply ~ap_transformed_jsx:transformed_jsx lam ap_args {ap_loc = loc}
     in
     function_ ~loc ~attr:default_function_attribute
       ~params:(List.rev_append !none_ids extra_ids)

compiler/ml/translmod.ml

@@ -126,7 +126,7 @@ and apply_coercion_result loc strict funct param arg cc_res =
         ~body:
           (apply_coercion loc Strict cc_res
              (Lambda.apply ~ap_transformed_jsx:false (Lambda.var id) [arg]
-                {ap_loc = loc; ap_inlined = Default_inline})))
+                {ap_loc = loc})))
 
 and wrap_id_pos_list loc id_pos_list get_field lam =
   let fv = Lambda_traverse.free_variables lam in
@@ -277,14 +277,11 @@ and transl_module cc rootpath mexp =
     | Tmod_structure str -> fst (transl_struct loc [] cc rootpath str)
     | Tmod_functor _ -> compile_functor mexp cc rootpath loc
     | Tmod_apply (funct, arg, ccarg) ->
-      let inlined_attribute, funct =
-        Translattribute.get_and_remove_inlined_attribute_on_module funct
-      in
       apply_coercion loc Strict cc
         (Lambda.apply ~ap_transformed_jsx:false
            (transl_module Tcoerce_none None funct)
            [transl_module ccarg None arg]
-           {ap_loc = loc; ap_inlined = inlined_attribute})
+           {ap_loc = loc})
     | Tmod_constraint (arg, _, _, ccarg) ->
       transl_module (compose_coercions cc ccarg) rootpath arg
     | Tmod_unpack (arg, _) ->

tests/build_tests/super_errors/expected/warning_53_inlined_attribute.res.expected

@@ -0,0 +1,22 @@
+
+  Warning number 53
+  /.../fixtures/warning_53_inlined_attribute.res:4:9-16
+
+  2 │ 
+  3 │ let a = (@inlined f)(1)
+  4 │ let b = @inlined f(2)
+  5 │ 
+
+  the @inlined attribute cannot appear in this context
+
+
+  Warning number 53
+  /.../fixtures/warning_53_inlined_attribute.res:3:10-17
+
+  1 │ let f = x => x + 1
+  2 │ 
+  3 │ let a = (@inlined f)(1)
+  4 │ let b = @inlined f(2)
+  5 │ 
+
+  the @inlined attribute cannot appear in this context

tests/build_tests/super_errors/fixtures/warning_53_inlined_attribute.res

@@ -0,0 +1,4 @@
+let f = x => x + 1
+
+let a = (@inlined f)(1)
+let b = @inlined f(2)

tests/ounit_tests/ounit_lambda_traverse_tests.ml

@@ -10,7 +10,7 @@ let var = Lambda.var x
    would pass either check below without exercising anything. *)
 let nodes : (string * Lambda.t) list =
   [
-    ("apply", Lambda.apply var [var] {ap_loc = loc; ap_inlined = Default_inline});
+    ("apply", Lambda.apply var [var] {ap_loc = loc});
     ( "function",
       Lambda.function_ ~loc ~attr:Lambda.default_function_attribute ~params:[x]
         ~body:debugger );