Validate packages against their SDK constraints.

utils/pub/entrypoint.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library entrypoint;
 
 import 'dart:async';
 import 'io.dart';
 import 'lock_file.dart';
 import 'log.dart' as log;
 import 'package.dart';
+import 'sdk.dart' as sdk;
 import 'system_cache.dart';
 import 'utils.dart';
 import 'version.dart';
 import 'version_solver.dart';
 
 /// Pub operates over a directed graph of dependencies that starts at a root
 /// "entrypoint" package. This is typically the package where the current
 /// working directory is located. An entrypoint knows the [root] package it is
 /// associated with and is responsible for managing the "packages" directory
 /// for it.
@@ skipping 110 matching lines @@
     return cleanDir(path).then((_) {
       return Future.wait(packageVersions.mappedBy((id) {
         if (id.isRoot) return new Future.immediate(id);
         return install(id);
       }));
     }).then(_saveLockFile)
       .then(_installSelfReference)
       .then(_linkSecondaryPackageDirs);
   }
 
+  /// Traverses the root's package dependency graph and loads each of the
+  /// reached packages. This should only be called after the lockfile has been
+  /// successfully generated.
+  Future<List<Package>> walkDependencies() {

[nweiz, 2013/01/31 22:38:53]

Maybe this and validateSdkConstraints should be methods on LockFile? It weirds
me out that they have this weird "should only be called" requirement.

[Bob Nystrom, 2013/02/01 16:53:29]

I put it here because walking the locked transitive deps is really only
meaningful for the root package. Seemed like it made sense here. LockFile is
really just the state for the file itself and not the root package that owns it.
Yeah, I'm not crazy about that either. Before when this was a separate command,
it would throw an error if an entry wasn't in the lock file. For now, I think
the comment is enough?

[nweiz, 2013/02/01 22:24:54]

I'd like to at least get an exception if this is called incorrectly. Right now
it'll just use an empty lockfile and return [].

[Bob Nystrom, 2013/02/02 00:02:31]

It should fail if called with an out of date lockfile. It will try to look up a
dependency in it and get null back and then barf on that.

+    return loadLockFile().then((lockFile) {
+      var group = new FutureGroup<Package>();
+      var visited = new Set<String>();
+
+      // Include the root package in the results.
+      group.add(new Future.immediate(root));
+
+      visitPackage(Package package) {
+        for (var ref in package.dependencies) {
+          if (visited.contains(ref.name)) continue;
+
+          // Look up the concrete version.
+          var id = lockFile.packages[ref.name];
+
+          visited.add(ref.name);
+          var future = cache.describe(id);
+          group.add(future.then(visitPackage));
+        }
+
+        return package;
+      }
+
+      visitPackage(root);
+      return group.future;
+    });
+  }
+
+  /// Validates that the current Dart SDK version matches the SDK constraints
+  /// of every package in the dependency graph. If a package's constraint does
+  /// not match, prints an error.
+  Future validateSdkConstraints() {
+    return walkDependencies().then((packages) {
+      var errors = [];
+
+      for (var package in packages) {
+        var sdkConstraint = package.pubspec.environment.sdkVersion;
+        if (!sdkConstraint.allows(sdk.version)) {
+          errors.add("- '${package.name}' requires ${sdkConstraint}");
+        }
+      }
+
+      if (errors.length > 0) {
+        log.error("Some packages are not compatible with SDK version "
+            "${sdk.version}:\n${errors.join('\n')}\n\n"

[nweiz, 2013/01/31 22:38:53]

When I'm formatting multiline strings like this, I usually add an additional
four spaces of indentation when there's a line break in the source but no line
break in the output. I'd also probably add a source newline after the first
"\n". For example:

    log.error("Some packages are not compatible with SDK version "
            "${sdk.version}:\n"
        "${errors.join('\n')}\n\n"
        "You may be able to resolve this by upgrading to the latest Dart "
            "SDK\n"
        "or adding a version constraint to use an older version of a "
            "package.");

Also, maybe "with SDK version" -> "with your SDK version".

[Bob Nystrom, 2013/02/01 16:53:29]

Done and done.

+            "You may be able to resolve this by upgrading to the latest Dart "
+            "SDK\n"
+            "or adding a version constraint to use an older version of a "
+            "package.");
+      }
+    });
+  }
+
   /// Loads the list of concrete package versions from the `pubspec.lock`, if it
   /// exists. If it doesn't, this completes to an empty [LockFile].
   Future<LockFile> loadLockFile() {
     var lockFilePath = join(root.dir, 'pubspec.lock');
 
     log.fine("Loading lockfile.");
     return fileExists(lockFilePath).then((exists) {
       if (!exists) {
         log.fine("No lock file at $lockFilePath, creating empty one.");
         return new LockFile.empty();
@@ skipping 86 matching lines @@
 
   /// Creates a symlink to the `packages` directory in [dir] if none exists.
   Future _linkSecondaryPackageDir(String dir) {
     var to = join(dir, 'packages');
     return exists(to).then((exists) {
       if (exists) return;
       return createSymlink(path, to);
     });
   }
 }