pigeon: fixed windows execution by using posix path imports

Author: gaaclarke

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.1.13
+
+* Fixed execution on Windows with certain setups where Dart didn't allow
+  backslashes in `import` statements.
+
 ## 0.1.12
 
 * Fixed assert failure with creating a PlatformException as a result of an

packages/pigeon/bin/pigeon.dart

@@ -18,7 +18,11 @@ Future<void> main(List<String> args) async {
     final String rawInputPath = opts.input;
     final String absInputPath = File(rawInputPath).absolute.path;
     final String relInputPath = path.relative(absInputPath, from: tempDir.path);
-    importLine = 'import \'$relInputPath\';\n';
+
+    final List<String> relInputComponents = path.split(relInputPath);
+    final path.Context context = path.Context(style: path.Style.posix);
+    final String posixRelInputPath = context.joinAll(relInputComponents);
+    importLine = 'import \'$posixRelInputPath\';\n';
   }
   final String code = """$importLine
 import 'dart:io';

packages/pigeon/lib/generator_tools.dart

@@ -8,7 +8,7 @@ import 'dart:mirrors';
 import 'ast.dart';
 
 /// The current version of pigeon.
-const String pigeonVersion = '0.1.12';
+const String pigeonVersion = '0.1.13';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {

packages/pigeon/pubspec.yaml

@@ -1,5 +1,5 @@
 name: pigeon
-version: 0.1.12
+version: 0.1.13
 description: Code generator tool to make communication between Flutter and the host platform type-safe and easier.
 homepage: https://github.com/flutter/packages/tree/master/packages/pigeon
 dependencies: