Add warning for unknown annotations

Author: WardBrian

src/frontend/Annotations.ml

@@ -0,0 +1,21 @@
+open Ast
+open Core
+
+let message a = "Unknown annotation '" ^ a ^ "' will be ignored by the compiler"
+
+let unused_list pred id anns =
+  List.filter_map
+    ~f:(fun a -> if pred a then None else Some (id.id_loc, message a))
+    anns
+
+let rec collect_stmt pred (acc : Warnings.t list) {stmt; _} =
+  match stmt with
+  | FunDef {annotations; funname; _} ->
+      acc @ (unused_list pred funname) annotations
+  | VarDecl {annotations; variables; _} ->
+      acc @ (unused_list pred (List.hd_exn variables).identifier) annotations
+  | _ -> fold_statement Fn.const (collect_stmt pred) Fn.const Fn.const acc stmt
+
+let find_unrecognized (pred : string -> bool) (prog : Ast.untyped_program) :
+    Warnings.t list =
+  fold_program (collect_stmt pred) [] prog

src/frontend/Annotations.mli

@@ -0,0 +1,2 @@
+val find_unrecognized :
+  (string -> bool) -> Ast.untyped_program -> Warnings.t list

src/stan_math_backend/Transform_Mir.ml

@@ -1012,6 +1012,8 @@ let map_prog_stmt_lists f (p : ('a, 'b, 'c) Program.t) =
   ; transform_inits= f p.transform_inits
   ; unconstrain_array= f p.unconstrain_array }
 
+let recognized_annotation _ = false
+
 let trans_prog (p : Program.Typed.t) =
   (* name mangling of c++ keywords*)
   let rec map_stmt {Stmt.Fixed.pattern; meta} =

src/stan_math_backend/Transform_Mir.mli

@@ -7,3 +7,4 @@ open Middle
 val trans_prog : Program.Typed.t -> Program.Typed.t
 val is_opencl_var : string -> bool
 val use_opencl : bool ref
+val recognized_annotation : string -> bool

src/stanc/stanc.ml

@@ -285,6 +285,9 @@ let use_file filename =
     get_ast_or_exit ?printed_filename filename
       ~print_warnings:(not !canonicalize_settings.deprecations)
       ~bare_functions:!bare_functions in
+  let unused_annotations =
+    Annotations.find_unrecognized Transform_Mir.recognized_annotation ast in
+  Warnings.pp_warnings ?printed_filename Fmt.stderr unused_annotations;
   Debugging.ast_logger ast;
   let typed_ast = type_ast_or_exit ?printed_filename ast in
   let canonical_ast =

src/stancjs/stancjs.ml

@@ -32,11 +32,14 @@ let stan2cpp model_name model_string is_flag_set flag_val includes :
       let open Result.Monad_infix in
       let result =
         ast >>= fun ast ->
+        let unused_annotations =
+          Annotations.find_unrecognized Transform_Mir.recognized_annotation ast
+        in
         let typed_ast =
           Typechecker.check_program ast
           |> Result.map_error ~f:(fun e -> Errors.Semantic_error e) in
         typed_ast >>| fun (typed_ast, type_warnings) ->
-        let warnings = parser_warnings @ type_warnings in
+        let warnings = parser_warnings @ unused_annotations @ type_warnings in
         if is_flag_set "info" then
           r.return (Result.Ok (Info.info typed_ast), warnings, []);
         let canonicalizer_settings =

test/integration/good/lang/pretty.expected

@@ -35,6 +35,20 @@ generated quantities {
   matrix[34, 10000] a_bit_too_long = rep_matrix(1, 34, 10000);
 }
 
+Warning in 'good_annotations.stan', line 2, column 17: Unknown annotation
+    'foo' will be ignored by the compiler
+Warning in 'good_annotations.stan', line 2, column 17: Unknown annotation
+    'biz' will be ignored by the compiler
+Warning in 'good_annotations.stan', line 7, column 19: Unknown annotation
+    'baz' will be ignored by the compiler
+Warning in 'good_annotations.stan', line 12, column 89: Unknown annotation
+    'bar' will be ignored by the compiler
+Warning in 'good_annotations.stan', line 12, column 89: Unknown annotation
+    'baz' will be ignored by the compiler
+Warning in 'good_annotations.stan', line 12, column 89: Unknown annotation
+    'flux' will be ignored by the compiler
+Warning in 'good_annotations.stan', line 12, column 89: Unknown annotation
+    'really_extra_long_now' will be ignored by the compiler
   $ ../../../../../install/default/bin/stanc --auto-format good_const.stan
 transformed data {
   real y;

test/integration/good/warning/pretty.expected

@@ -589,6 +589,13 @@ Warning in 'self-assign.stan', line 22, column 2: Assignment of variable to
     itself.
 Warning in 'self-assign.stan', line 24, column 2: Assignment of variable to
     itself during declaration. This is almost certainly a bug.
+  $ ../../../../../install/default/bin/stanc --auto-format unknown_annotation.stan
+parameters {
+  @not_a_real_annotation real unused;
+}
+
+Warning in 'unknown_annotation.stan', line 2, column 31: Unknown annotation
+    'not_a_real_annotation' will be ignored by the compiler
   $ ../../../../../install/default/bin/stanc --auto-format unreachable_statement.stan
 functions {
   void foo(real x) {

test/integration/good/warning/unknown_annotation.stan

@@ -0,0 +1,3 @@
+parameters {
+   @not_a_real_annotation real unused;
+}