Use .dart_tool/pub as the cache directory

Pub will continue to read cached files from .pub if it exists. Any
time it modifies the cache, it will migrate .pub to .dart_tool/pub.

Closes #1795

.gitignore

@@ -1,7 +1,7 @@
 .buildlog
 .DS_Store
 .idea
-.pub/
+.dart_tool/
 .settings/
 /build/
 packages

lib/src/barback/asset_environment.dart

@@ -127,7 +127,8 @@ class AssetEnvironment {
         new Map.fromIterable(packages, value: (packageName) {
           var package = graph.packages[packageName];
           if (mode != BarbackMode.DEBUG) return package;
-          var cache = path.join('.pub/deps/debug', packageName);
+          var cache =
+              path.join(graph.entrypoint.cachePath, 'deps/debug', packageName);
           if (!dirExists(cache)) return package;
           return new CachedPackage(package, cache);
         }));

lib/src/barback/transformer_cache.dart

@@ -45,9 +45,9 @@ class TransformerCache {
   /// Loads the transformer cache for [environment].
   ///
   /// This may modify the cache.
-  TransformerCache.load(PackageGraph graph)
-      : _graph = graph,
-        _dir = graph.entrypoint.root.path(".pub/transformers") {
+  TransformerCache.load(PackageGraph graph) : _graph = graph {
+    graph.entrypoint.migrateCache();
+    _dir = p.join(graph.entrypoint.cachePath, "transformers");
     _oldTransformers = _parseManifest();
   }
 

lib/src/entrypoint.dart

@@ -133,15 +133,26 @@ class Entrypoint {
   /// The path to the entrypoint package's lockfile.
   String get lockFilePath => root.path('pubspec.lock');
 
+  /// The path to the entrypoint package's `.dart_tool/pub` cache directory.
+  ///
+  /// If the old-style `.pub` directory is being used, this returns that
+  /// instead.
+  String get cachePath {
+    var newPath = root.path('.dart_tool/pub');
+    var oldPath = root.path('.pub');
+    if (!dirExists(newPath) && dirExists(oldPath)) return oldPath;
+    return newPath;
+  }
+
   /// The path to the directory containing precompiled dependencies.
   ///
   /// We just precompile the debug version of a package. We're mostly interested
   /// in improving speed for development iteration loops, which usually use
   /// debug mode.
-  String get _precompiledDepsPath => root.path('.pub', 'deps', 'debug');
+  String get _precompiledDepsPath => p.join(cachePath, 'deps', 'debug');
 
   /// The path to the directory containing dependency executable snapshots.
-  String get _snapshotPath => root.path('.pub', 'bin');
+  String get _snapshotPath => p.join(cachePath, 'bin');
 
   /// Loads the entrypoint from a package at [rootDir].
   Entrypoint(String rootDir, SystemCache cache, {this.isGlobal: false})
@@ -370,6 +381,7 @@ class Entrypoint {
   /// Precompiles all executables from dependencies that don't transitively
   /// depend on [this] or on a path dependency.
   Future precompileExecutables({Iterable<String> changed}) async {
+    migrateCache();
     _deleteExecutableSnapshots(changed: changed);
 
     var executables = new Map<String, List<AssetId>>.fromIterable(
@@ -785,4 +797,21 @@ class Entrypoint {
     if (entryExists(symlink)) deleteEntry(symlink);
     if (packagesDir) createSymlink(packagesPath, symlink, relative: true);
   }
+
+  /// If the entrypoint uses the old-style `.pub` cache directory, migrates it
+  /// to the new-style `.dart_tool/pub` directory.
+  void migrateCache() {
+    var oldPath = root.path('.pub');
+    if (!dirExists(oldPath)) return;
+
+    var newPath = root.path('.dart_tool/pub');
+
+    // If both the old and new directories exist, something weird is going on.
+    // Do nothing to avoid making things worse. Pub will prefer the new
+    // directory anyway.
+    if (dirExists(newPath)) return;
+
+    ensureDir(p.dirname(newPath));
+    renameDir(oldPath, newPath);
+  }
 }

lib/src/executable.dart

@@ -50,6 +50,8 @@ Future<int> runExecutable(Entrypoint entrypoint, String package,
     }
   }
 
+  entrypoint.migrateCache();
+
   // Unless the user overrides the verbosity, we want to filter out the
   // normal pub output shown while loading the environment.
   if (log.verbosity == log.Verbosity.NORMAL) {
@@ -60,7 +62,7 @@ Future<int> runExecutable(Entrypoint entrypoint, String package,
   if (p.extension(executable) != ".dart") executable += ".dart";
 
   var localSnapshotPath =
-      p.join(".pub", "bin", package, "$executable.snapshot");
+      p.join(entrypoint.cachePath, "bin", package, "$executable.snapshot");
   if (!isGlobal &&
       fileExists(localSnapshotPath) &&
       // Dependencies are only snapshotted in release mode, since that's the

lib/src/io.dart

@@ -526,8 +526,6 @@ final bool runningFromSdk =
 final _dartRepoRegExp = new RegExp(r"/third_party/pkg/pub/("
     r"bin/pub\.dart"
     r"|"
-    r"\.pub/pub\.test\.snapshot"
-    r"|"
     r"test/.*_test\.dart"
     r")$");
 
@@ -584,7 +582,7 @@ final String pubRoot = (() {
     return path.joinAll(components.take(testIndex));
   }
 
-  // Pub is either run from ".pub/pub.test.snapshot" or "bin/pub.dart".
+  // Pub is run from "bin/pub.dart".
   return path.dirname(path.dirname(script));
 })();
 

lib/src/package.dart

@@ -152,7 +152,7 @@ class Package {
   /// This is similar to `p.join(dir, part1, ...)`, except that subclasses may
   /// override it to report that certain paths exist elsewhere than within
   /// [dir]. For example, a [CachedPackage]'s `lib` directory is in the
-  /// `.pub/deps` directory.
+  /// `.dart_tool/pub/deps` directory.
   String path(String part1,
       [String part2,
       String part3,

test/get/cache_transformed_dependency_test.dart

@@ -5,6 +5,8 @@
 import 'package:path/path.dart' as p;
 import 'package:test/test.dart';
 
+import 'package:pub/src/io.dart';
+
 import '../descriptor.dart' as d;
 import '../serve/utils.dart';
 import '../test_pub.dart';
@@ -115,7 +117,7 @@ main() {
     await pubGet(output: contains("Precompiled foo."));
 
     await d.dir(appPath, [
-      d.dir(".pub/deps/debug/foo/lib",
+      d.dir(".dart_tool/pub/deps/debug/foo/lib",
           [d.file("foo.dart", "final message = 'Goodbye!';")])
     ]).validate();
   });
@@ -146,7 +148,7 @@ main() {
     await pubGet(output: contains("Precompiled foo."));
 
     await d.dir(appPath, [
-      d.dir(".pub/deps/debug/foo/lib",
+      d.dir(".dart_tool/pub/deps/debug/foo/lib",
           [d.file("foo.dart", "final message = 'Goodbye!';")])
     ]).validate();
   });
@@ -164,7 +166,7 @@ main() {
 
     await pubGet(output: isNot(contains("Precompiled foo.")));
 
-    await d.dir(appPath, [d.nothing(".pub/deps")]).validate();
+    await d.dir(appPath, [d.nothing(".dart_tool/pub/deps")]).validate();
   });
 
   test("recaches when the dependency is updated", () async {
@@ -199,7 +201,7 @@ main() {
     await pubGet(output: contains("Precompiled foo."));
 
     await d.dir(appPath, [
-      d.dir(".pub/deps/debug/foo/lib",
+      d.dir(".dart_tool/pub/deps/debug/foo/lib",
           [d.file("foo.dart", "final message = 'Goodbye!';")])
     ]).validate();
 
@@ -209,7 +211,7 @@ main() {
     await pubGet(output: contains("Precompiled foo."));
 
     await d.dir(appPath, [
-      d.dir(".pub/deps/debug/foo/lib",
+      d.dir(".dart_tool/pub/deps/debug/foo/lib",
           [d.file("foo.dart", "final message = 'See ya!';")])
     ]).validate();
   });
@@ -286,7 +288,7 @@ main() {
     await pubGet(output: contains("Precompiled foo."));
 
     await d.dir(appPath, [
-      d.dir(".pub/deps/debug/foo/lib",
+      d.dir(".dart_tool/pub/deps/debug/foo/lib",
           [d.file("foo.dart", "final mode = 'debug';")])
     ]).validate();
   });
@@ -320,7 +322,7 @@ main() {
     await pubGet(output: contains("Precompiled foo."));
 
     await d.dir(appPath, [
-      d.dir(".pub/deps/debug/foo/lib",
+      d.dir(".dart_tool/pub/deps/debug/foo/lib",
           [d.file("foo.dart", "final message = 'Modified!';")])
     ]).create();
 
@@ -357,6 +359,51 @@ main() {
 
     await pubGet(output: contains("Precompiled foo."));
 
+    // Manually reset the cache to its original state to prove that the
+    // transformer won't be run again on it.
+    await d.dir(appPath, [
+      d.dir(".dart_tool/pub/deps/debug/foo/lib",
+          [d.file("foo.dart", "final message = 'Hello!';")])
+    ]).create();
+
+    var pub = await pubRun(args: ["bin/script"]);
+    expect(pub.stdout, emits("Hello!"));
+    await pub.shouldExit();
+  });
+
+  test("reads cached packages from the old-style cache", () async {
+    await servePackages((builder) {
+      builder.serveRealPackage('barback');
+
+      builder.serve("foo", "1.2.3", deps: {
+        'barback': 'any'
+      }, pubspec: {
+        'transformers': ['foo']
+      }, contents: [
+        d.dir("lib", [
+          d.file("transformer.dart", replaceTransformer("Hello", "Goodbye")),
+          d.file("foo.dart", "final message = 'Hello!';")
+        ])
+      ]);
+    });
+
+    await d.dir(appPath, [
+      d.appPubspec({"foo": "1.2.3"}),
+      d.dir('bin', [
+        d.file('script.dart', """
+          import 'package:foo/foo.dart';
+
+          void main() => print(message);""")
+      ])
+    ]).create();
+
+    await pubGet(output: contains("Precompiled foo."));
+
+    // Move the directory to the old location to simulate it being created by an
+    // older version of pub.
+    renameDir(p.join(d.sandbox, appPath, '.dart_tool', 'pub'),
+        p.join(d.sandbox, appPath, '.pub'));
+
     // Manually reset the cache to its original state to prove that the
     // transformer won't be run again on it.
     await d.dir(appPath, [
@@ -369,6 +416,42 @@ main() {
     await pub.shouldExit();
   });
 
+  test("migrates the old-style cache", () async {
+    await servePackages((builder) {
+      builder.serveRealPackage('barback');
+
+      builder.serve("foo", "1.2.3", deps: {
+        'barback': 'any'
+      }, pubspec: {
+        'transformers': ['foo']
+      }, contents: [
+        d.dir("lib", [
+          d.file("transformer.dart", replaceTransformer("Hello", "Goodbye")),
+          d.file("foo.dart", "final message = 'Hello!';")
+        ])
+      ]);
+    });
+
+    await d.dir(appPath, [
+      d.appPubspec({"foo": "1.2.3"}),
+
+      // Simulate an old-style cache directory.
+      d.dir(".pub", [d.file("junk", "junk")])
+    ]).create();
+
+    await pubGet(output: contains("Precompiled foo."));
+
+    await d.dir(appPath, [d.nothing(".pub")]).validate();
+
+    await d.dir(appPath, [
+      d.dir(".dart_tool/pub", [
+        d.file("junk", "junk"),
+        d.dir("deps/debug/foo/lib",
+            [d.file("foo.dart", "final message = 'Goodbye!';")])
+      ])
+    ]).validate();
+  });
+
   // Regression test for issue 21087.
   test("hasInput works for static packages", () async {
     await servePackages((builder) {
@@ -436,7 +519,7 @@ main() {
     await pubGet(output: contains("Precompiled foo."));
 
     await d.dir(appPath, [
-      d.dir(".pub/deps/debug/foo/lib",
+      d.dir(".dart_tool/pub/deps/debug/foo/lib",
           [d.file("foo.dart", "final message = 'Goodbye!';")])
     ]).validate();
 
@@ -445,7 +528,8 @@ main() {
 
     await pubGet(output: isNot(contains("Precompiled foo.")));
 
-    await d.dir(appPath, [d.nothing(".pub/deps/debug/foo")]).validate();
+    await d
+        .dir(appPath, [d.nothing(".dart_tool/pub/deps/debug/foo")]).validate();
   });
 
   // Regression test for https://github.com/dart-lang/pub/issues/1586.
@@ -472,7 +556,8 @@ main() {
     await pubGet(output: contains("Precompiled foo"));
 
     await d.dir(appPath, [
-      d.file(".pub/deps/debug/foo/lib/inputs.txt", contains('hello.dart.copy'))
+      d.file(".dart_tool/pub/deps/debug/foo/lib/inputs.txt",
+          contains('hello.dart.copy'))
     ]).validate();
 
     await pubServe();
@@ -508,7 +593,7 @@ foo|lib/list_transformer.dart.copy""");
       await pubGet(
           args: ["--no-precompile"], output: isNot(contains("Precompiled")));
 
-      await d.nothing(p.join(appPath, ".pub")).validate();
+      await d.nothing(p.join(appPath, ".dart_tool/pub")).validate();
     });
 
     test("deletes the cache when the dependency is updated", () async {
@@ -543,7 +628,7 @@ foo|lib/list_transformer.dart.copy""");
       await pubGet(output: contains("Precompiled foo."));
 
       await d.dir(appPath, [
-        d.dir(".pub/deps/debug/foo/lib",
+        d.dir(".dart_tool/pub/deps/debug/foo/lib",
             [d.file("foo.dart", "final message = 'Goodbye!';")])
       ]).validate();
 
@@ -553,7 +638,9 @@ foo|lib/list_transformer.dart.copy""");
       await pubGet(
           args: ["--no-precompile"], output: isNot(contains("Precompiled")));
 
-      await d.nothing(p.join(appPath, ".pub/deps/debug/foo")).validate();
+      await d
+          .nothing(p.join(appPath, ".dart_tool/pub/deps/debug/foo"))
+          .validate();
     });
 
     test(
@@ -580,7 +667,7 @@ foo|lib/list_transformer.dart.copy""");
       await pubGet(output: contains("Precompiled foo."));
 
       await d.dir(appPath, [
-        d.dir(".pub/deps/debug/foo/lib",
+        d.dir(".dart_tool/pub/deps/debug/foo/lib",
             [d.file("foo.dart", "final message = 'Goodbye!';")])
       ]).validate();
 
@@ -589,7 +676,7 @@ foo|lib/list_transformer.dart.copy""");
           args: ["--no-precompile"], output: isNot(contains("Precompiled")));
 
       await d.dir(appPath, [
-        d.dir(".pub/deps/debug/foo/lib",
+        d.dir(".dart_tool/pub/deps/debug/foo/lib",
             [d.file("foo.dart", "final message = 'Goodbye!';")])
       ]).validate();
     });