Merge branch 'master' into claudio/sha224

Changelog.md

@@ -1,9 +1,19 @@
 # Motoko compiler changelog
 
+
 ## Unreleased
 
 * motoko (`moc`)
 
+  * Warn on detection of unused identifiers (code `M0194`) (#4377).
+
+    - By design, warnings are not emitted for code imported from a package.
+    - A warning can be suppressed by replacing the identifier entirely by a wildcard `_`,
+      or by prefixing it with an `_`, e.g. replace `x` by `_x`.
+
+    **Limitations**: recursive and mutually recursive definitions are considered used,
+    even if never referenced outside the recursive definition.
+
   * Remove `__get_candid_interface_tmp_hack` endpoint. Candid interface is already stored as canister metadata, this temporary endpoint is redundant, thus removed. (#4386)
 
 ## 0.10.4 (2024-01-10)
@@ -12,7 +22,7 @@
 
   * Officializing the new **incremental garbage collector** after a successful beta testing phase.
     The incremental GC can be enabled by the `moc` flag `--incremental-gc` (#3837) and is designed to scale for large program heap sizes.
-    
+
     **Note**: While resolving scalability issues with regard to the instruction limit of the GC work, it is now possible to hit other scalability limits:
     - _Out of memory_: A program can run out of memory if it fills the entire memory space with live objects.
     - _Upgrade limits_: When using stable variables, the current mechanism of serialization and deserialization to and from stable memory can exceed the instruction limit or run out of memory.

doc/md/language-manual.md

@@ -2305,7 +2305,7 @@ If `<exp>` in `label <id> (: <typ>)? <exp>` is a looping construct:
 
 the body, `<exp1>`, of the loop is implicitly enclosed in `label <id_continue> (…​)` allowing early continuation of the loop by the evaluation of expression `continue <id>`.
 
-`<id_continue>` is fresh identifier that can only be referenced by `continue <id>` (through its implicit expansion to `break <id_continue>`).
+`<id_continue>` is a fresh identifier that can only be referenced by `continue <id>` (through its implicit expansion to `break <id_continue>`).
 
 ### Break
 
@@ -2317,7 +2317,7 @@ The expression `break <id> <exp>` has type `None` provided:
 
 -   `<exp>` has type `T`.
 
-The evaluation of `break <id> <exp>` evaluates exp to some result `r`. If `r` is `trap`, the result is `trap`. If `r` is a value `v`, the evaluation abandons the current computation up to dynamically enclosing declaration `label <id> …​` using the value `v` as the result of that labelled expression.
+The evaluation of `break <id> <exp>` evaluates `<exp>` to some result `r`. If `r` is `trap`, the result is `trap`. If `r` is a value `v`, the evaluation abandons the current computation up to the dynamically enclosing declaration `label <id> …​` using the value `v` as the result of that labelled expression.
 
 ### Continue
 

nix/sources.json

@@ -75,10 +75,10 @@
         "homepage": null,
         "owner": "dfinity",
         "repo": "motoko-base",
-        "rev": "b772c9e49d94e725fcca64fc1c891ec1fb1baab3",
-        "sha256": "1ci0nink9sqrx4317svaz0y22cargfvlqqsnzi9vylafh0a76yg5",
+        "rev": "712d0587b0c8d2958adf450bd2e1554f2b0ff258",
+        "sha256": "17ghrfgzwlz7hbapy4sq9wbckxqy4xmcj8jpqv68bng9s83zvvvn",
         "type": "tarball",
-        "url": "https://github.com/dfinity/motoko-base/archive/b772c9e49d94e725fcca64fc1c891ec1fb1baab3.tar.gz",
+        "url": "https://github.com/dfinity/motoko-base/archive/712d0587b0c8d2958adf450bd2e1554f2b0ff258.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "motoko-matchers": {

rts/cargo-vendor-tools/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "cargo-vendor-tools"
 version = "0.1.0"
-authors = ["dfinity <sdk@dfinity.org>"]
+authors = ["dfinity <team-motoko@dfinity.org>"]
 edition = "2018"
 
 [[bin]]

rts/motoko-rts-macros/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "motoko-rts-macros"
 version = "0.1.0"
-authors = ["dfinity <sdk@dfinity.org>"]
+authors = ["dfinity <team-motoko@dfinity.org>"]
 edition = "2018"
 
 [lib]

rts/motoko-rts-tests/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "motoko-rts-tests"
 version = "0.1.0"
-authors = ["dfinity <sdk@dfinity.org"]
+authors = ["dfinity <team-motoko@dfinity.org"]
 edition = "2018"
 
 [features]

rts/motoko-rts/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "motoko-rts"
 version = "0.1.0"
-authors = ["dfinity <sdk@dfinity.org>"]
+authors = ["dfinity <team-motoko@dfinity.org>"]
 edition = "2018"
 
 # For rlib use native/Cargo.toml

rts/motoko-rts/native/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "motoko-rts"
 version = "0.1.0"
-authors = ["dfinity <sdk@dfinity.org>"]
+authors = ["dfinity <team-motoko@dfinity.org>"]
 edition = "2018"
 
 [lib]

src/exes/candid_tests.ml

@@ -76,7 +76,7 @@ let mo_of_test tenv test : (string * expected_behaviour, string) result =
 
   try
     let defs =
-      "import Prim \"mo:⛔\";" ^
+      "import _Prim \"mo:⛔\";" ^
       String.concat "" (List.map (fun (n,candid_typ) ->
         let mo_typ = Idl_to_mo.check_typ tenv candid_typ in
         "type " ^ n ^ " = " ^ Pretty.string_of_typ mo_typ ^ ";\n"

src/lang_utils/error_codes.ml

@@ -197,4 +197,5 @@ let error_codes : (string * string option) list =
     "M0191", None; (* Code requires Wasm features ... to execute *)
     "M0192", None; (* Object/Actor/Module body type mismatch *)
     "M0193", None; (* Can't declare actor class to have `async*` result *)
+    "M0194", Some([%blob "lang_utils/error_codes/M0194.md"]); (* Unused identifier warning *)
   ]

src/lang_utils/error_codes/M0194.md

@@ -0,0 +1,31 @@
+# M0194
+
+This warning means that you defined an identifier without
+referencing it later, a good indicator of dead code.
+
+Dubious code example:
+
+```motoko
+let nickname = "klutz";
+// code that never uses `nickname`
+```
+
+If you encounter this warning, you can either delete the definition (if the code has no other side-effect),
+
+```motoko
+// code that never uses `nickname`
+```
+
+replace it by a wildcard pattern:
+
+```motoko
+let _ = "klutz";
+// code that never uses `nickname`
+```
+
+or just prefix the identifier with an underscore:
+
+```motoko
+let _nickname = "klutz";
+// code that never uses `nickname`
+```

src/languageServer/declaration_index.ml

@@ -313,13 +313,14 @@ let list_files_recursively dir =
   in
   loop [] [ dir ]
 
-let scan_packages : unit -> string list =
+let scan_packages : unit -> lib_path list =
  fun _ ->
-  let scan_package path =
+  let scan_package p path =
     list_files_recursively path
     |> List.filter (fun f -> Filename.extension f = ".mo")
+    |> List.map (fun f -> { package = Some p; path = f })
   in
-  Flags.M.fold (fun _ v acc -> scan_package v @ acc) !Flags.package_urls []
+  Flags.M.fold (fun p v acc -> scan_package p v @ acc) !Flags.package_urls []
 
 let scan_actors : unit -> string list =
  fun _ ->
@@ -347,7 +348,7 @@ let index_from_scope : string -> t -> Syntax.lib list -> Scope.t -> t =
 
 let make_index_inner project_root vfs entry_points : t Diag.result =
   let package_paths =
-    List.map (fun f -> LibPath f @@ Source.no_region) (scan_packages ())
+    List.map (fun lp -> LibPath lp @@ Source.no_region) (scan_packages ())
   in
   let package_env =
     Pipeline.chase_imports

src/lowering/desugar.ml

@@ -1006,7 +1006,7 @@ let transform_import (i : S.import) : import_declaration =
   assert (t <> T.Pre);
   let rhs = match !ir with
     | S.Unresolved -> raise (Invalid_argument ("Unresolved import " ^ f))
-    | S.LibPath fp ->
+    | S.LibPath {path = fp; _} ->
       varE (var (id_of_full_path fp) t)
     | S.PrimPath ->
       varE (var (id_of_full_path "@prim") t)

src/mo_def/syntax.ml

@@ -12,9 +12,10 @@ let empty_typ_note = {note_typ = Type.Pre; note_eff = Type.Triv}
 
 (* Resolved imports (filled in separately after parsing) *)
 
+type lib_path = {package : string option; path : string}
 type resolved_import =
   | Unresolved
-  | LibPath of string
+  | LibPath of lib_path
   | IDLPath of (string * string) (* filepath * bytes *)
   | PrimPath (* the built-in prim module *)
 
@@ -125,6 +126,7 @@ and vis' =
   | System
 
 let is_public vis = match vis.Source.it with Public _ -> true | _ -> false
+let is_private vis = match vis.Source.it with Private -> true | _ -> false
 
 type stab = stab' Source.phrase
 and stab' = Stable | Flexible
@@ -296,8 +298,8 @@ open Source
 
 (* Identifiers *)
 
-let anon_id sort at = "anon-" ^ sort ^ "-" ^ string_of_pos at.left
-let is_anon_id id = Lib.String.chop_prefix "anon-" id.it <> None
+let anon_id sort at = "@anon-" ^ sort ^ "-" ^ string_of_pos at.left
+let is_anon_id id = Lib.String.chop_prefix "@anon-" id.it <> None
 
 (* Types & Scopes *)