Revert "Use native async/await support in pub."

sdk/lib/_internal/pub_generated/lib/src/validator/dependency.dart

Index: sdk/lib/_internal/pub_generated/lib/src/validator/dependency.dart
diff --git a/sdk/lib/_internal/pub_generated/lib/src/validator/dependency.dart b/sdk/lib/_internal/pub_generated/lib/src/validator/dependency.dart
new file mode 100644
index 0000000000000000000000000000000000000000..e57b09660e27de70fc0a9d2c5572e0e704e5530b
--- /dev/null
+++ b/sdk/lib/_internal/pub_generated/lib/src/validator/dependency.dart
@@ -0,0 +1,273 @@
+// 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 pub.validator.dependency;
+
+import 'dart:async';
+
+import 'package:pub_semver/pub_semver.dart';
+
+import '../entrypoint.dart';
+import '../log.dart' as log;
+import '../package.dart';
+import '../utils.dart';
+import '../validator.dart';
+
+/// The range of all pub versions that don't support `^` version constraints.
+final _preCaretPubVersions = new VersionConstraint.parse("<1.8.0-dev.3.0");
+
+// TODO(nweiz): replace this with "^1.8.0" for the 1.8 release.
+/// The range of all pub versions that do support `^` version constraints.
+///
+/// This is intersected with the user's SDK constraint to provide a suggested
+/// constraint.
+final _postCaretPubVersions = new VersionConstraint.parse("^1.8.0-dev.3.0");
+
+/// A validator that validates a package's dependencies.
+class DependencyValidator extends Validator {
+  /// Whether the SDK constraint guarantees that `^` version constraints are
+  /// safe.
+  bool get _caretAllowed =>
+      entrypoint.root.pubspec.environment.sdkVersion.intersect(
+          _preCaretPubVersions).isEmpty;
+
+  DependencyValidator(Entrypoint entrypoint)
+      : super(entrypoint);
+
+  Future validate() {
+    final completer0 = new Completer();
+    scheduleMicrotask(() {
+      try {
+        var caretDeps = [];
+        var it0 = entrypoint.root.pubspec.dependencies.iterator;
+        break0() {
+          join0() {
+            completer0.complete();
+          }
+          if (caretDeps.isNotEmpty && !_caretAllowed) {
+            _errorAboutCaretConstraints(caretDeps);
+            join0();
+          } else {
+            join0();
+          }
+        }
+        var trampoline0;
+        continue0() {
+          trampoline0 = null;
+          if (it0.moveNext()) {
+            var dependency = it0.current;
+            join1() {
+              trampoline0 = continue0;
+              do trampoline0(); while (trampoline0 != null);
+            }
+            if (dependency.source != "hosted") {
+              new Future.value(_warnAboutSource(dependency)).then((x0) {
+                trampoline0 = () {
+                  trampoline0 = null;
+                  try {
+                    x0;
+                    join1();
+                  } catch (e0, s0) {
+                    completer0.completeError(e0, s0);
+                  }
+                };
+                do trampoline0(); while (trampoline0 != null);
+              }, onError: completer0.completeError);
+            } else {
+              join2() {
+                join1();
+              }
+              if (dependency.constraint.isAny) {
+                _warnAboutNoConstraint(dependency);
+                join2();
+              } else {
+                join3() {
+                  join2();
+                }
+                if (dependency.constraint is Version) {
+                  _warnAboutSingleVersionConstraint(dependency);
+                  join3();
+                } else {
+                  join4() {
+                    join3();
+                  }
+                  if (dependency.constraint is VersionRange) {
+                    join5() {
+                      join6() {
+                        join4();
+                      }
+                      if (dependency.constraint.toString().startsWith("^")) {
+                        caretDeps.add(dependency);
+                        join6();
+                      } else {
+                        join6();
+                      }
+                    }
+                    if (dependency.constraint.min == null) {
+                      _warnAboutNoConstraintLowerBound(dependency);
+                      join5();
+                    } else {
+                      join7() {
+                        join5();
+                      }
+                      if (dependency.constraint.max == null) {
+                        _warnAboutNoConstraintUpperBound(dependency);
+                        join7();
+                      } else {
+                        join7();
+                      }
+                    }
+                  } else {
+                    join4();
+                  }
+                }
+              }
+            }
+          } else {
+            break0();
+          }
+        }
+        trampoline0 = continue0;
+        do trampoline0(); while (trampoline0 != null);
+      } catch (e, s) {
+        completer0.completeError(e, s);
+      }
+    });
+    return completer0.future;
+  }
+
+  /// Warn that dependencies should use the hosted source.
+  Future _warnAboutSource(PackageDep dep) {
+    return entrypoint.cache.sources['hosted'].getVersions(
+        dep.name,
+        dep.name).catchError((e) => <Version>[]).then((versions) {
+      var constraint;
+      var primary = Version.primary(versions);
+      if (primary != null) {
+        constraint = _constraintForVersion(primary);
+      } else {
+        constraint = dep.constraint.toString();
+        if (!dep.constraint.isAny && dep.constraint is! Version) {
+          constraint = '"$constraint"';
+        }
+      }
+
+      // Path sources are errors. Other sources are just warnings.
+      var messages = warnings;
+      if (dep.source == "path") {
+        messages = errors;
+      }
+
+      messages.add(
+          'Don\'t depend on "${dep.name}" from the ${dep.source} '
+              'source. Use the hosted source instead. For example:\n' '\n' 'dependencies:\n'
+              '  ${dep.name}: $constraint\n' '\n'
+              'Using the hosted source ensures that everyone can download your '
+              'package\'s dependencies along with your package.');
+    });
+  }
+
+  /// Warn that dependencies should have version constraints.
+  void _warnAboutNoConstraint(PackageDep dep) {
+    var message =
+        'Your dependency on "${dep.name}" should have a version ' 'constraint.';
+    var locked = entrypoint.lockFile.packages[dep.name];
+    if (locked != null) {
+      message =
+          '$message For example:\n' '\n' 'dependencies:\n'
+              '  ${dep.name}: ${_constraintForVersion(locked.version)}\n';
+    }
+    warnings.add(
+        "$message\n"
+            'Without a constraint, you\'re promising to support ${log.bold("all")} '
+            'future versions of "${dep.name}".');
+  }
+
+  /// Warn that dependencies should allow more than a single version.
+  void _warnAboutSingleVersionConstraint(PackageDep dep) {
+    warnings.add(
+        'Your dependency on "${dep.name}" should allow more than one version. '
+            'For example:\n' '\n' 'dependencies:\n'
+            '  ${dep.name}: ${_constraintForVersion(dep.constraint)}\n' '\n'
+            'Constraints that are too tight will make it difficult for people to '
+            'use your package\n'
+            'along with other packages that also depend on "${dep.name}".');
+  }
+
+  /// Warn that dependencies should have lower bounds on their constraints.
+  void _warnAboutNoConstraintLowerBound(PackageDep dep) {
+    var message = 'Your dependency on "${dep.name}" should have a lower bound.';
+    var locked = entrypoint.lockFile.packages[dep.name];
+    if (locked != null) {
+      var constraint;
+      if (locked.version == (dep.constraint as VersionRange).max) {
+        constraint = _constraintForVersion(locked.version);
+      } else {
+        constraint = '">=${locked.version} ${dep.constraint}"';
+      }
+
+      message =
+          '$message For example:\n' '\n' 'dependencies:\n' '  ${dep.name}: $constraint\n';
+    }
+    warnings.add(
+        "$message\n"
+            'Without a constraint, you\'re promising to support ${log.bold("all")} '
+            'previous versions of "${dep.name}".');
+  }
+
+  /// Warn that dependencies should have upper bounds on their constraints.
+  void _warnAboutNoConstraintUpperBound(PackageDep dep) {
+    var constraint;
+    if ((dep.constraint as VersionRange).includeMin) {
+      constraint = _constraintForVersion((dep.constraint as VersionRange).min);
+    } else {
+      constraint =
+          '"${dep.constraint} ' '<${(dep.constraint as VersionRange).min.nextBreaking}"';
+    }
+
+    warnings.add(
+        'Your dependency on "${dep.name}" should have an upper bound. For ' 'example:\n'
+            '\n' 'dependencies:\n' '  ${dep.name}: $constraint\n' '\n'
+            'Without an upper bound, you\'re promising to support '
+            '${log.bold("all")} future versions of ${dep.name}.');
+  }
+
+  /// Emits an error for any version constraints that use `^` without an
+  /// appropriate SDK constraint.
+  void _errorAboutCaretConstraints(List<PackageDep> caretDeps) {
+    var newSdkConstraint =
+        entrypoint.root.pubspec.environment.sdkVersion.intersect(_postCaretPubVersions);
+
+    if (newSdkConstraint.isEmpty) newSdkConstraint = _postCaretPubVersions;
+
+    var buffer = new StringBuffer(
+        "Older versions of pub don't support ^ version constraints.\n"
+            "Make sure your SDK constraint excludes those old versions:\n" "\n"
+            "environment:\n" "  sdk: \"$newSdkConstraint\"\n" "\n");
+
+    if (caretDeps.length == 1) {
+      buffer.writeln("Or use a fully-expanded constraint:");
+    } else {
+      buffer.writeln("Or use fully-expanded constraints:");
+    }
+
+    buffer.writeln();
+    buffer.writeln("dependencies:");
+
+    caretDeps.forEach((dep) {
+      VersionRange constraint = dep.constraint;
+      buffer.writeln(
+          "  ${dep.name}: \">=${constraint.min} <${constraint.max}\"");
+    });
+
+    errors.add(buffer.toString().trim());
+  }
+
+  /// Returns the suggested version constraint for a dependency that was tested
+  /// against [version].
+  String _constraintForVersion(Version version) {
+    if (_caretAllowed) return "^$version";
+    return '">=$version <${version.nextBreaking}"';
+  }
+}