Quote a few paths in error messages when necessary

src/import.ml

@@ -475,6 +475,16 @@ let hint name candidates =
     in
     sprintf "\nHint: did you mean %s?" (mk_hint l)
 
+
+(* [maybe_quoted s] is [s] if [s] doesn't need escaping according to OCaml lexing
+   conventions and [sprintf "%S" s] otherwise. *)
+let maybe_quoted s =
+  let escaped = String.escaped s in
+  if s == escaped || s = escaped then
+    s
+  else
+    sprintf {|"%s"|} escaped
+
 (* Disable file operations to force to use the IO module *)
 let open_in      = `Use_Io
 let open_in_bin  = `Use_Io

src/path.ml

@@ -238,6 +238,9 @@ let to_string = function
   | "" -> "."
   | t  -> t
 
+let to_string_maybe_quoted t =
+  maybe_quoted (to_string t)
+
 let root = ""
 
 let relative t fn =

src/path.mli

@@ -46,6 +46,9 @@ val kind : t -> Kind.t
 val of_string : string -> t
 val to_string : t -> string
 
+(** [to_string_maybe_quoted t] is [maybe_quoted (to_string t)] *)
+val to_string_maybe_quoted : t -> string
+
 val root : t
 val is_root : t -> bool
 

src/super_context.ml

@@ -413,13 +413,13 @@ module Deps = struct
       >>^ fun _ -> []
     | Glob_files s -> begin
         let path = Path.relative dir (expand_vars t ~scope ~dir s) in
-        let dir = Path.parent path in
-        let s = Path.basename path in
-        match Glob_lexer.parse_string s with
+        match Glob_lexer.parse_string (Path.basename path) with
         | Ok re ->
+          let dir = Path.parent path in
           Build.paths_glob ~dir (Re.compile re)
         | Error (_pos, msg) ->
-          die "invalid glob in %s/jbuild: %s" (Path.to_string dir) msg
+          let loc = String_with_vars.loc s in
+          Loc.fail loc "invalid glob: %s" msg
       end
     | Files_recursively_in s ->
       let path = Path.relative dir (expand_vars t ~scope ~dir s) in

src/utils.ml

@@ -67,10 +67,10 @@ let signal_name =
 let jbuild_name_in ~dir =
   match Path.extract_build_context dir with
   | None ->
-    Path.to_string (Path.relative dir "jbuild")
+    Path.to_string_maybe_quoted (Path.relative dir "jbuild")
   | Some (ctx_name, dir) ->
     sprintf "%s (context %s)"
-      (Path.to_string (Path.relative dir "jbuild"))
+      (Path.to_string_maybe_quoted (Path.relative dir "jbuild"))
       ctx_name
 
 let describe_target fn =
@@ -84,12 +84,12 @@ let describe_target fn =
         assert (String.length digest = 32);
         name
     in
-    sprintf "alias %s" name
+    sprintf "alias %s" (maybe_quoted name)
   | _ ->
-    Path.to_string fn
+    Path.to_string_maybe_quoted fn
 
 let program_not_found ?context ?(in_the_tree=false) ?hint prog =
-  die "@{<error>Error@}: Program %s not found in%s PATH%s%a" prog
+  die "@{<error>Error@}: Program %s not found in%s PATH%s%a" (maybe_quoted prog)
     (if in_the_tree then
        " the tree or in"
      else
@@ -103,7 +103,7 @@ let program_not_found ?context ?(in_the_tree=false) ?hint prog =
     hint
 
 let library_not_found ?context ?hint lib =
-  die "@{<error>Error@}: Library %s not found%s%a" lib
+  die "@{<error>Error@}: Library %s not found%s%a" (maybe_quoted lib)
     (match context with
      | None -> ""
      | Some name -> sprintf " (context: %s)" name)
@@ -122,12 +122,14 @@ let find_module ~dir modules name =
   String_map.find_exn name modules
     ~string_of_key:(sprintf "%S")
     ~desc:(fun _ ->
-      sprintf "<module name to module info in %s>" (Path.to_string dir))
+      sprintf "<module name to module info in %s>"
+        (Path.to_string_maybe_quoted dir))
 
 let find_deps ~dir dep_graph name =
   String_map.find_exn name dep_graph
     ~string_of_key:(sprintf "%S")
-    ~desc:(fun _ -> sprintf "<dependency graph in %s>" (Path.to_string dir))
+    ~desc:(fun _ -> sprintf "<dependency graph in %s>"
+                      (Path.to_string_maybe_quoted dir))
 
 let obj_name_of_basename fn =
   match String.index fn '.' with