From f9f12455603c95e5203487b117851806fcfb63ac Mon Sep 17 00:00:00 2001
From: David Aurelio <davidaurelio@fb.com>
Date: Tue, 23 May 2017 10:24:59 -0700
Subject: [PATCH] Covariant properties for `ModuleTransportLike`

Summary:
Make all properties of `ModuleTraansportLike` covariant to enforce read-only behavior at all sites using it.
The type only exists for compatibility reasons between old and new output functionality, and covariant properties give us stronger guarantees.

Reviewed By: jeanlauliac

Differential Revision: D5111667

fbshipit-source-id: 674658b07eb3a229cbc4344cb636e4a9ea4126d1
---
 local-cli/bundle/types.flow.js      | 10 +++++-----
 packager/src/lib/ModuleTransport.js |  2 +-
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/local-cli/bundle/types.flow.js b/local-cli/bundle/types.flow.js
index 6939aab08..b72977004 100644
--- a/local-cli/bundle/types.flow.js
+++ b/local-cli/bundle/types.flow.js
@@ -12,7 +12,7 @@
 
 import type Bundle from '../../packager/src/Bundler/Bundle';
 import type {Unbundle} from '../../packager/src/Bundler/Bundle';
-import type ModuleTransport from '../../packager/src/lib/ModuleTransport';
+import type ModuleTransport, {SourceMapOrMappings} from '../../packager/src/lib/ModuleTransport';
 import type {FBSourceMap, SourceMap} from '../../packager/src/lib/SourceMap';
 
 export type {Bundle, FBSourceMap, ModuleTransport, SourceMap, Unbundle};
@@ -24,11 +24,11 @@ export type ModuleGroups = {|
 |};
 
 export type ModuleTransportLike = {
-  code: string,
-  id: number,
-  map?: $PropertyType<ModuleTransport, 'map'>,
+  +code: string,
+  +id: number,
+  +map: ?SourceMapOrMappings,
   +name?: string,
-  sourcePath: string,
+  +sourcePath: string,
 };
 
 export type OutputOptions = {
diff --git a/packager/src/lib/ModuleTransport.js b/packager/src/lib/ModuleTransport.js
index 4ba202673..9e91ef3c7 100644
--- a/packager/src/lib/ModuleTransport.js
+++ b/packager/src/lib/ModuleTransport.js
@@ -15,7 +15,7 @@ import type {RawMapping} from '../Bundler/source-map';
 import type Module from '../node-haste/Module';
 import type {SourceMap} from './SourceMap';
 
-type SourceMapOrMappings = SourceMap | Array<RawMapping>;
+export type SourceMapOrMappings = SourceMap | Array<RawMapping>;
 
 type Metadata = {
   dependencies?: ?Array<string>,