Fix crash when duplicate fields have annotations

Fixes #36793.

Change-Id: I007699978219dc642e23951ab78858504a192c03
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/100646
Reviewed-by: Kevin Millikin <[email protected]>
Commit-Queue: Jens Johansen <[email protected]>

Author: jensjoha

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

@@ -601,7 +601,9 @@ abstract class BodyBuilder extends ScopeListener<JumpTarget>
       buildDartType(pop()); // Type.
     }
     List<Expression> annotations = pop();
-    if (annotations != null) {
+    // Fields with duplicate names are sorted out in the else branch of the
+    // `declaration.next == null` above.
+    if (annotations != null && fields.isNotEmpty) {
       inferAnnotations(annotations);
       Field field = fields.first.target;
       // The first (and often only field) will not get a clone.

pkg/front_end/testcases/regress/issue_36793.dart

@@ -0,0 +1,14 @@
+// Copyright (c) 2019, 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.
+
+const int y = 42;
+
+@y
+int x = 1;
+@y
+int x = 2;
+
+main() {
+  print(y);
+}

pkg/front_end/testcases/regress/issue_36793.dart.legacy.expect

@@ -0,0 +1,19 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/issue_36793.dart:10:5: Error: 'x' is already declared in this scope.
+// int x = 2;
+//     ^
+// pkg/front_end/testcases/regress/issue_36793.dart:8:5: Context: Previous declaration of 'x'.
+// int x = 1;
+//     ^
+//
+import self as self;
+import "dart:core" as core;
+
+static const field core::int y = 42;
+static field core::int x;
+static method main() → dynamic {
+  core::print(self::y);
+}

pkg/front_end/testcases/regress/issue_36793.dart.legacy.transformed.expect

@@ -0,0 +1,19 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/issue_36793.dart:10:5: Error: 'x' is already declared in this scope.
+// int x = 2;
+//     ^
+// pkg/front_end/testcases/regress/issue_36793.dart:8:5: Context: Previous declaration of 'x'.
+// int x = 1;
+//     ^
+//
+import self as self;
+import "dart:core" as core;
+
+static const field core::int y = 42;
+static field core::int x;
+static method main() → dynamic {
+  core::print(self::y);
+}

pkg/front_end/testcases/regress/issue_36793.dart.outline.expect

@@ -0,0 +1,18 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/issue_36793.dart:10:5: Error: 'x' is already declared in this scope.
+// int x = 2;
+//     ^
+// pkg/front_end/testcases/regress/issue_36793.dart:8:5: Context: Previous declaration of 'x'.
+// int x = 1;
+//     ^
+//
+import self as self;
+import "dart:core" as core;
+
+static const field core::int y;
+static field core::int x;
+static method main() → dynamic
+  ;

pkg/front_end/testcases/regress/issue_36793.dart.strong.expect

@@ -0,0 +1,19 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/issue_36793.dart:10:5: Error: 'x' is already declared in this scope.
+// int x = 2;
+//     ^
+// pkg/front_end/testcases/regress/issue_36793.dart:8:5: Context: Previous declaration of 'x'.
+// int x = 1;
+//     ^
+//
+import self as self;
+import "dart:core" as core;
+
+static const field core::int y = 42;
+static field core::int x;
+static method main() → dynamic {
+  core::print(self::y);
+}

pkg/front_end/testcases/regress/issue_36793.dart.strong.transformed.expect

@@ -0,0 +1,19 @@
+library;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/regress/issue_36793.dart:10:5: Error: 'x' is already declared in this scope.
+// int x = 2;
+//     ^
+// pkg/front_end/testcases/regress/issue_36793.dart:8:5: Context: Previous declaration of 'x'.
+// int x = 1;
+//     ^
+//
+import self as self;
+import "dart:core" as core;
+
+static const field core::int y = 42;
+static field core::int x;
+static method main() → dynamic {
+  core::print(self::y);
+}

pkg/front_end/testcases/text_serialization.status

@@ -922,6 +922,7 @@ regress/issue_35900: TextSerializationFailure
 regress/issue_36400: TextSerializationFailure
 regress/issue_36647: TextSerializationFailure
 regress/issue_36647_2: TextSerializationFailure
+regress/issue_36793: TextSerializationFailure
 reject_generic_function_types_in_bounds: TextSerializationFailure # Was: RuntimeError # Expected
 return_with_unknown_type_in_context: TextSerializationFailure # Was: Pass
 runtime_checks/call_kinds: TextSerializationFailure # Was: Pass