[flow][codemod] Only keep react import for component syntax if it use…

…d ref param

Reviewed By: alexmckenley

Differential Revision: D54970188

fbshipit-source-id: 4051327310bad13036ea5d32373c858c5f2dbb6b

src/codemods/remove_react_import.ml

@@ -87,7 +87,24 @@ let has_unaccounted_react_value_usage_visitor =
       t'
 
     method! component_declaration loc c =
-      this#update_acc (fun _ -> true);
+      let open Ast.Statement.ComponentDeclaration in
+      let { params = (_, { Params.params; _ }); _ } = c in
+      if
+        Base.List.exists
+          params
+          ~f:(fun
+               ( _,
+                 {
+                   Param.name =
+                     ( Param.Identifier (_, { Ast.Identifier.name; _ })
+                     | Param.StringLiteral (_, { Ast.StringLiteral.value = name; _ }) );
+                   _;
+                 }
+               )
+             -> name = "ref"
+        )
+      then
+        this#update_acc (fun _ -> true);
       super#component_declaration loc c
 
     method! identifier ((_, { Ast.Identifier.name; _ }) as id) =

tests/codemod_remove_react_import/codemod_remove_react_import.exp

@@ -4,10 +4,14 @@
 type Foo = React.AbstractComponent<{}>;
 <div />;
 
+component Foo() {
+  return <div />;
+}
+
 >>> Launching report...
 
 Stats:
   Files changed:                            1
   Removed instances:                        1
-  Still useful instances:                   3
+  Still useful instances:                   4
 

tests/codemod_remove_react_import/removed.js

@@ -2,3 +2,7 @@ import * as React from 'react';
 
 type Foo = React.AbstractComponent<{}>;
 <div />;
+
+component Foo() {
+  return <div />;
+}

tests/codemod_remove_react_import/still_useful_4.js

@@ -0,0 +1,3 @@
+import * as React from 'react';
+
+component C('ref' as ref: any) { return <div /> };