kill weak mode

Summary:
flow weak was designed to mimic TypeScript, in that missing annotations would
be treated as any instead of implicitly static types that can be inferred.

It's not been maintained for a while, so any continued use probably detracts
from the Flow experience while not giving a good TypeScript experience either.

TODO: update docs

Reviewed By: jeffmo

Differential Revision: D4475119

fbshipit-source-id: 7d912f14155a0396fc61fa810650d34506236aa9

Author: avikchaudhuri

src/flow_dot_js.ml

@@ -93,7 +93,6 @@ let stub_metadata ~root ~checked = { Context.
   suppress_comments = [];
   suppress_types = SSet.empty;
   verbose = None;
-  weak = false;
   jsx = None;
 }
 

src/parsing/docblock.ml

@@ -11,7 +11,7 @@
 module Ast = Spider_monkey_ast
 module Lex_result = Lexer_flow.Lex_result
 
-type flow_mode = OptIn | OptInWeak | OptOut
+type flow_mode = OptIn | OptOut
 
 type t = {
   flow: flow_mode option;
@@ -44,11 +44,6 @@ let extract : max_tokens:int -> Loc.filename -> string -> error list * t =
      if @flow or @providesModule is found more than once, the first one is used
      and an error is returned. *)
   let rec parse_attributes (errors, info) = function
-    | (loc, "@flow") :: (_, "weak") :: xs ->
-        let acc =
-          if info.flow <> None then (loc, MultipleFlowAttributes)::errors, info
-          else errors, { info with flow = Some OptInWeak } in
-        parse_attributes acc xs
     | (loc, "@flow") :: xs ->
         let acc =
           if info.flow <> None then (loc, MultipleFlowAttributes)::errors, info
@@ -201,8 +196,7 @@ let isDeclarationFile info = info.isDeclarationFile
 let jsx info = info.jsx
 
 let is_flow info = match info.flow with
-  | Some OptIn
-  | Some OptInWeak -> true
+  | Some OptIn -> true
   | Some OptOut
   | None -> false
 
@@ -211,7 +205,6 @@ let json_of_docblock info =
   let open Hh_json in
   let flow = match flow info with
   | Some OptIn -> JSON_String "OptIn"
-  | Some OptInWeak -> JSON_String "OptInWeak"
   | Some OptOut -> JSON_String "OptOut"
   | None -> JSON_Null in
 

src/parsing/parsing_service_js.ml

@@ -188,8 +188,7 @@ let do_parse ?(fail=true) ~types_mode ~use_strict ~info content file =
             begin match Docblock.flow info with
             | None
             | Some Docblock.OptOut -> false
-            | Some Docblock.OptIn
-            | Some Docblock.OptInWeak -> true
+            | Some Docblock.OptIn -> true
             end
       in
       (* don't bother to parse if types are disabled *)

src/services/inference/infer_service.ml

@@ -18,7 +18,6 @@ let apply_docblock_overrides metadata docblock_info =
   let metadata = match Docblock.flow docblock_info with
   | None -> metadata
   | Some Docblock.OptIn -> { metadata with checked = true; }
-  | Some Docblock.OptInWeak -> { metadata with checked = true; weak = true }
 
   (* --all (which sets metadata.checked = true) overrides @noflow, so there are
      currently no scenarios where we'd change checked = true to false. in the

src/services/inference/init_js.ml

@@ -32,7 +32,6 @@ let get_master_cx, restore_master_cx =
   | None ->
     let metadata = Context.({ (metadata_of_options options) with
       checked = false;
-      weak = false;
     }) in
     let cx = Flow.fresh_context
       metadata Loc.Builtins (Modulename.String Files.lib_module) in
@@ -99,7 +98,6 @@ let load_lib_files ~options files =
 
         let metadata = Context.({ (metadata_of_options options) with
           checked = false;
-          weak = false;
         }) in
 
         let cx, syms = Infer.infer_lib_file

src/typing/context.ml

@@ -31,7 +31,6 @@ type metadata = {
   suppress_comments: Str.regexp list;
   suppress_types: SSet.t;
   verbose: Verbose.t option;
-  weak: bool;
   max_workers: int;
   jsx: (string * Spider_monkey_ast.Expression.t) option;
 }
@@ -126,7 +125,6 @@ let metadata_of_options options = {
   suppress_comments = Options.suppress_comments options;
   suppress_types = Options.suppress_types options;
   verbose = Options.verbose options;
-  weak = Options.weak_by_default options;
   max_workers = Options.max_workers options;
   jsx = None;
 }
@@ -199,7 +197,6 @@ let import_stmts cx = cx.import_stmts
 let imported_ts cx = cx.imported_ts
 let is_checked cx = cx.metadata.checked
 let is_verbose cx = cx.metadata.verbose <> None
-let is_weak cx = cx.metadata.weak
 let max_trace_depth cx = cx.metadata.max_trace_depth
 let module_kind cx = cx.module_kind
 let module_map cx = cx.modulemap

src/typing/context.mli

@@ -30,7 +30,6 @@ type metadata = {
   suppress_comments: Str.regexp list;
   suppress_types: SSet.t;
   verbose: Verbose.t option;
-  weak: bool;
   max_workers: int;
   jsx: (string * Spider_monkey_ast.Expression.t) option;
 }
@@ -68,7 +67,6 @@ val import_stmts: t -> Spider_monkey_ast.Statement.ImportDeclaration.t list
 val imported_ts: t -> Type.t SMap.t
 val is_checked: t -> bool
 val is_verbose: t -> bool
-val is_weak: t -> bool
 val max_trace_depth: t -> int
 val module_kind: t -> module_kind
 val module_map: t -> Type.t SMap.t

src/typing/type_annotation.ml

@@ -683,11 +683,7 @@ and mk_rest cx = function
 
 and mk_type cx tparams_map reason = function
   | None ->
-      let t =
-        if Context.is_weak cx
-        then AnyT.why reason
-        else Flow_js.mk_tvar cx reason
-      in
+      let t = Flow_js.mk_tvar cx reason in
       Hashtbl.replace (Context.annot_table cx) (loc_of_reason reason) t;
       t