[flow] Add support for backup flowconfigs on ignored files

Summary:
This diff allows you to use our typical module-mapping syntax in the flowconfig to specify a backup for explicitly ignored files. It does not provide the same support when these files are passed on the command line.

Changelog: [internal]

Reviewed By: SamChou19815

Differential Revision: D69858997

fbshipit-source-id: 74497e7a70ec9a22c2274babe34fef220a933d5c

src/commands/commandUtils.ml

@@ -594,7 +594,7 @@ let assert_version flowconfig =
   | Error msg -> Exit.(exit ~msg Invalid_flowconfig)
 
 type flowconfig_params = {
-  ignores: string list;
+  ignores: (string * string option) list;
   untyped: string list;
   declarations: string list;
   includes: string list;
@@ -611,7 +611,7 @@ let list_of_string_arg = function
 
 let collect_flowconfig_flags
     main ignores_str untyped_str declarations_str includes_str lib_str lints_str =
-  let ignores = list_of_string_arg ignores_str in
+  let ignores = List.map (fun ignore -> (ignore, None)) (list_of_string_arg ignores_str) in
   let untyped = list_of_string_arg untyped_str in
   let declarations = list_of_string_arg declarations_str in
   let includes = list_of_string_arg includes_str in
@@ -626,15 +626,26 @@ let remove_exclusion pattern =
     pattern
 
 let file_options =
-  let ignores_of_arg root patterns extras =
+  let path_pattern_of_arg root pattern =
     let expand_project_root_token = Files.expand_project_root_token ~root in
+    pattern |> remove_exclusion |> expand_project_root_token |> Str.regexp
+  in
+  let path_patterns_of_args root patterns extras =
     let patterns = Base.List.rev_append extras patterns in
     Base.List.map
       ~f:(fun s ->
-        let reg = s |> remove_exclusion |> expand_project_root_token |> Str.regexp in
+        let reg = path_pattern_of_arg root s in
         (s, reg))
       patterns
   in
+  let ignores_of_args root patterns extras =
+    let patterns = Base.List.rev_append extras patterns in
+    Base.List.map
+      ~f:(fun (path, backup) ->
+        let reg = path_pattern_of_arg root path in
+        ((path, backup), reg))
+      patterns
+  in
   let includes_of_arg ~implicitly_include_root ~root ~lib_paths paths =
     (* Explicitly included paths are always added to the path_matcher *)
     let path_matcher =
@@ -703,9 +714,11 @@ let file_options =
       in
       Some libdir
     in
-    let ignores = ignores_of_arg root (FlowConfig.ignores flowconfig) ignores in
-    let untyped = ignores_of_arg root (FlowConfig.untyped flowconfig) untyped in
-    let declarations = ignores_of_arg root (FlowConfig.declarations flowconfig) declarations in
+    let ignores = ignores_of_args root (FlowConfig.ignores flowconfig) ignores in
+    let untyped = path_patterns_of_args root (FlowConfig.untyped flowconfig) untyped in
+    let declarations =
+      path_patterns_of_args root (FlowConfig.declarations flowconfig) declarations
+    in
     let lib_paths = lib_paths ~root flowconfig libs in
     let includes =
       includes

src/commands/config/flowConfig.ml

@@ -1201,8 +1201,12 @@ type rollout = {
 
 type config = {
   rollouts: rollout SMap.t;
-  (* completely ignored files (both module resolving and typing) *)
-  ignores: string list;
+  (* completely ignored files (both module resolving and typing)
+   * This type *should* just be a string list, but we have an undocumented feature that allows
+   * you to specify a backup flowconfig to use if a file is ignored using our module-mapper syntax.
+   * This should be reverted to string list after we properly support multiplatform flow roots.
+   *)
+  ignores: (string * string option) list;
   (* files that should be treated as untyped *)
   untyped: string list;
   (* files that should be treated as declarations *)
@@ -1230,7 +1234,12 @@ end = struct
 
   let section_header o section = fprintf o "[%s]\n" section
 
-  let ignores o = Base.List.iter ~f:(fprintf o "%s\n")
+  let ignores o =
+    Base.List.iter ~f:(fun (ignore, backup_opt) ->
+        match backup_opt with
+        | None -> fprintf o "%s\n" ignore
+        | Some backup -> fprintf o "%s -> %s\n" ignore backup
+    )
 
   let untyped o = Base.List.iter ~f:(fprintf o "%s\n")
 
@@ -1368,7 +1377,16 @@ let parse_libs lines config : (config * warning list, error) result =
   Ok ({ config with libs }, [])
 
 let parse_ignores lines config =
-  let ignores = trim_lines lines in
+  let raw_ignores = trim_lines lines in
+  let ignores =
+    raw_ignores
+    |> Base.List.map ~f:(fun ignore ->
+           if Str.string_match Opts.mapping_regexp ignore 0 then
+             (Str.matched_group 1 ignore, Some (Str.matched_group 2 ignore))
+           else
+             (ignore, None)
+       )
+  in
   Ok ({ config with ignores }, [])
 
 let parse_untyped lines config =

src/commands/config/flowConfig.mli

@@ -46,7 +46,7 @@ val write : config -> out_channel -> unit
 (* Accessors *)
 
 (* completely ignored files (both module resolving and typing) *)
-val ignores : config -> string list
+val ignores : config -> (string * string option) list
 
 (* files that should be treated as untyped *)
 val untyped : config -> string list

src/commands/initCommand.ml

@@ -64,7 +64,16 @@ let main base_flags flowconfig_flags options root () =
     Exit.(exit ~msg Invalid_flowconfig)
   );
 
-  let config = FlowConfig.init ~ignores ~untyped ~declarations ~includes ~libs ~options ~lints in
+  let config =
+    FlowConfig.init
+      ~ignores:(List.map fst ignores)
+      ~untyped
+      ~declarations
+      ~includes
+      ~libs
+      ~options
+      ~lints
+  in
   let config =
     match config with
     | Ok (config, []) -> config

src/commands/lsCommand.ml

@@ -119,7 +119,9 @@ let rec iter_get_next ~f get_next =
 
 let make_options ~flowconfig ~root ~ignore_flag ~include_flag ~untyped_flag ~declaration_flag =
   let includes = CommandUtils.list_of_string_arg include_flag in
-  let ignores = CommandUtils.list_of_string_arg ignore_flag in
+  let ignores =
+    List.map (fun ignore -> (ignore, None)) (CommandUtils.list_of_string_arg ignore_flag)
+  in
   let untyped = CommandUtils.list_of_string_arg untyped_flag in
   let declarations = CommandUtils.list_of_string_arg declaration_flag in
   let libs = [] in

src/common/files.ml

@@ -13,7 +13,7 @@ type lib_dir =
 
 type options = {
   default_lib_dir: lib_dir option;
-  ignores: (string * Str.regexp) list;
+  ignores: ((string * string option) * Str.regexp) list;
   untyped: (string * Str.regexp) list;
   declarations: (string * Str.regexp) list;
   implicitly_include_root: bool;
@@ -521,7 +521,7 @@ let dir_filter_of_options (options : options) f =
        to be un-ignored. similarly, if an ignore ends in $, we could still prune if
        the current path isn't a prefix of it. *)
     Base.List.for_all
-      ~f:(fun (pattern, _rx) ->
+      ~f:(fun ((pattern, _), _rx) ->
         (not (String.starts_with ~prefix:"!" pattern)) && not (String.ends_with ~suffix:"$" pattern))
       options.ignores
   in
@@ -615,7 +615,7 @@ let is_ignored (options : options) path =
   (* On Windows, the path may use \ instead of /, but let's standardize the
    * ignore regex to use / *)
   let path = Sys_utils.normalize_filename_dir_sep path in
-  is_matching path options.ignores
+  is_matching path (options.ignores |> List.map (fun ((x, _y), z) -> (x, z)))
 
 (* true if a file path matches an [untyped] entry in config *)
 let is_untyped (options : options) path =

src/common/files.mli

@@ -15,7 +15,7 @@ type options
 
 val mk_options :
   default_lib_dir:lib_dir option ->
-  ignores:(string * Str.regexp) list ->
+  ignores:((string * string option) * Str.regexp) list ->
   untyped:(string * Str.regexp) list ->
   declarations:(string * Str.regexp) list ->
   implicitly_include_root:bool ->
@@ -35,7 +35,7 @@ val default_options : options
 
 val default_lib_dir : options -> lib_dir option
 
-val ignores : options -> (string * Str.regexp) list
+val ignores : options -> ((string * string option) * Str.regexp) list
 
 val untyped : options -> (string * Str.regexp) list
 

tests/flowconfig_ignore/.flowconfig

@@ -6,6 +6,7 @@
 !<PROJECT_ROOT>/my_declarations/root_typecheck/.*
 
 [ignore]
+'.*/my_ignores_with_backup/.*' -> '.flowconfig'
 .*/my_ignores/.*
 !.*/my_ignores/typecheck/.*
 !.*/my_ignores/actually_typecheck\.js

tests/flowconfig_ignore/my_ignores_with_backup/with_backup.js

@@ -0,0 +1,2 @@
+// @flow
+const x: string = 3; // NO ERROR