Share error messages for renamed/since/deleted etc.

Signed-off-by: Rudi Grinberg <rudi.grinberg@gmail.com>

src/super_context.ml

@@ -232,25 +232,24 @@ end = struct
 
     let rec expand t ~syntax_version ~var =
       let name = String_with_vars.Var.name var in
-      Option.bind (String.Map.find t name) ~f:(function
+      Option.bind (String.Map.find t name) ~f:(fun v ->
+        let what =
+          lazy (sprintf "Variable %s" (String_with_vars.Var.to_string var)) in
+        match v with
         | No_info v -> Some v
         | Since (v, min_version) ->
           if syntax_version >= min_version then
             Some v
           else
-            Loc.fail (String_with_vars.Var.loc var)
-              "Variable %a is available in since version %s. \
-               Current version is %s"
-              String_with_vars.Var.pp var
-              (Syntax.Version.to_string min_version)
-              (Syntax.Version.to_string syntax_version)
+            Syntax.Error.since (String_with_vars.Var.loc var)
+              Stanza.syntax syntax_version
+              ~what:(Lazy.force what)
         | Renamed_in (in_version, new_name) -> begin
             if syntax_version >= in_version then
-              Loc.fail (String_with_vars.Var.loc var)
-                "Variable %a has been renamed to %s since %s"
-                String_with_vars.Var.pp var
-                (String_with_vars.Var.(to_string (rename var ~new_name)))
-                (Syntax.Version.to_string in_version)
+              Syntax.Error.renamed_in (String_with_vars.Var.loc var)
+                Stanza.syntax syntax_version
+                ~what:(Lazy.force what)
+                ~to_:(String_with_vars.Var.(to_string (rename var ~new_name)))
             else
               expand t ~syntax_version:in_version
                 ~var:(String_with_vars.Var.rename var ~new_name)
@@ -259,12 +258,8 @@ end = struct
           if syntax_version < in_version then
             Some v
           else
-            Loc.fail (String_with_vars.Var.loc var)
-              "Variable %a has been deleted in version %s. \
-               Current version is: %s"
-              String_with_vars.Var.pp var
-              (Syntax.Version.to_string in_version)
-              (Syntax.Version.to_string syntax_version))
+            Syntax.Error.deleted_in (String_with_vars.Var.loc var)
+              Stanza.syntax syntax_version ~what:(Lazy.force what))
   end
 end
 

src/syntax.ml

@@ -56,6 +56,21 @@ type t =
   ; supported_versions : Supported_versions.t
   }
 
+module Error = struct
+  let since loc t ver ~what =
+    Loc.fail loc "%s is only available since version %s of %s"
+      what (Version.to_string ver) t.desc
+
+  let renamed_in loc t ver ~what ~to_ =
+    Loc.fail loc "%s was renamed to '%s' in the %s version of %s"
+      what to_ (Version.to_string ver) t.desc
+
+  let deleted_in loc t ver ~what =
+    Loc.fail loc "%s was deleted in version %s of %s"
+      what (Version.to_string ver) t.desc
+end
+
+
 let create ~name ~desc supported_versions =
   { name
   ; desc
@@ -112,9 +127,7 @@ let deleted_in t ver =
     return ()
   else begin
     desc () >>= fun (loc, what) ->
-    Loc.fail loc
-      "%s was deleted in version %s of %s" what
-      (Version.to_string ver) t.desc
+    Error.deleted_in loc t ver ~what
   end
 
 let renamed_in t ver ~to_ =
@@ -123,9 +136,7 @@ let renamed_in t ver ~to_ =
     return ()
   else begin
     desc () >>= fun (loc, what) ->
-    Loc.fail loc
-      "%s was renamed to '%s' in the %s version of %s" what to_
-      (Version.to_string ver) t.desc
+    Error.renamed_in loc t ver ~what ~to_
   end
 
 let since t ver =
@@ -134,7 +145,5 @@ let since t ver =
     return ()
   else begin
     desc () >>= fun (loc, what) ->
-    Loc.fail loc
-      "%s is only available since version %s of %s" what
-      (Version.to_string ver) t.desc
+    Error.since loc t ver ~what
   end

src/syntax.mli

@@ -20,6 +20,14 @@ end
 
 type t
 
+module Error : sig
+  val since      : Loc.t -> t -> Version.t -> what:string -> _
+
+  val renamed_in : Loc.t -> t -> Version.t -> what:string -> to_:string -> _
+
+  val deleted_in : Loc.t -> t -> Version.t -> what:string -> _
+end
+
 (** [create ~name ~desc supported_versions] defines a new
     syntax. [supported_version] is the list of the last minor version
     of each supported major version. [desc] is used to describe what

test/blackbox-tests/test-cases/dune-jbuild-var-case/run.t

@@ -6,7 +6,7 @@ All builtin variables are lower cased in Dune:
   $ dune runtest --root dune-upper
   Entering directory 'dune-upper'
   File "dune", line 3, characters 41-46:
-  Error: Variable %{MAKE} has been renamed to %{make} since 1.0
+  Error: Variable %{MAKE} was renamed to '%{make}' in the 1.0 version of the dune language
   [1]
 
 jbuild files retain the the old names:

test/blackbox-tests/test-cases/findlib-error/run.t

@@ -3,7 +3,7 @@ We are dropping support for findlib in dune
   $ dune build --root in-dune target.txt
   Entering directory 'in-dune'
   File "dune", line 2, characters 25-37:
-  Error: Variable %{findlib:pkg} has been renamed to %{lib:pkg} since 1.0
+  Error: Variable %{findlib:pkg} was renamed to '%{lib:pkg}' in the 1.0 version of the dune language
   [1]
 
 But it must still be available in jbuild files

test/blackbox-tests/test-cases/path-variables/run.t

@@ -9,7 +9,7 @@ In expands to a file name, and registers this as a dependency.
   $ dune build --root dune @test-dep
   Entering directory 'dune'
   File "dune", line 13, characters 17-47:
-  Error: Variable %{path:file-that-does-not-exist} has been renamed to %{dep:file-that-does-not-exist} since 1.0
+  Error: Variable %{path:file-that-does-not-exist} was renamed to '%{dep:file-that-does-not-exist}' in the 1.0 version of the dune language
   [1]
 
 %{path-no-dep:string}
@@ -20,7 +20,7 @@ This form does not exist, but displays an hint:
   $ dune build --root dune-invalid @test-path-no-dep
   Entering directory 'dune-invalid'
   File "dune", line 7, characters 17-54:
-  Error: Variable %{path-no-dep:file-that-does-not-exist} has been deleted in version 1.0. Current version is: 1.0
+  Error: Variable %{path-no-dep:file-that-does-not-exist} was deleted in version 1.0 of the dune language
   [1]
 
 jbuild files
@@ -53,5 +53,5 @@ This form does not exist, but displays an hint:
   $ dune build --root jbuild-invalid @test-dep
   Entering directory 'jbuild-invalid'
   File "jbuild", line 5, characters 16-37:
-  Error: Variable ${dep:generated-file} is available in since version 1.0. Current version is 0.0
+  Error: Variable ${dep:generated-file} is only available since version 0.0 of the dune language
   [1]