Error on re-export, export and import of libraries with same name.

Fixes #12916.

Change-Id: Icef0f04f1575c8dad5f1cd23a9363f06fa2a2b35
Reviewed-on: https://dart-review.googlesource.com/74161
Commit-Queue: Jens Johansen <jensj@google.com>
Reviewed-by: Peter von der Ahé <ahe@google.com>

pkg/front_end/lib/src/fasta/builder/library_builder.dart

@@ -98,7 +98,8 @@ abstract class LibraryBuilder<T extends TypeBuilder, R>
   }
 
   /// Returns true if the export scope was modified.
-  bool addToExportScope(String name, Declaration member) {
+  bool addToExportScope(String name, Declaration member,
+      [int charOffset = -1]) {
     if (name.startsWith("_")) return false;
     if (member is PrefixBuilder) return false;
     Map<String, Declaration> map =
@@ -107,7 +108,7 @@ abstract class LibraryBuilder<T extends TypeBuilder, R>
     if (existing == member) return false;
     if (existing != null) {
       Declaration result = computeAmbiguousDeclaration(
-          name, existing, member, -1,
+          name, existing, member, charOffset,
           isExport: true);
       map[name] = result;
       return result != existing;

pkg/front_end/lib/src/fasta/export.dart

@@ -30,6 +30,6 @@ class Export {
         if (combinator.isHide && combinator.names.contains(name)) return false;
       }
     }
-    return exporter.addToExportScope(name, member);
+    return exporter.addToExportScope(name, member, charOffset);
   }
 }

pkg/front_end/lib/src/fasta/fasta_codes_generated.dart

@@ -2049,7 +2049,7 @@ const Code<Message Function(String name, Uri uri_, Uri uri2_)>
     codeDuplicatedExport =
     const Code<Message Function(String name, Uri uri_, Uri uri2_)>(
         "DuplicatedExport", templateDuplicatedExport,
-        analyzerCode: "AMBIGUOUS_EXPORT", severity: Severity.ignored);
+        analyzerCode: "AMBIGUOUS_EXPORT");
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 Message _withArgumentsDuplicatedExport(String name, Uri uri_, Uri uri2_) {
@@ -2133,6 +2133,86 @@ Message _withArgumentsDuplicatedImportInType(String name, Uri uri_, Uri uri2_) {
       arguments: {'name': name, 'uri': uri_, 'uri2': uri2_});
 }
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<Message Function(String name)> templateDuplicatedLibraryExport =
+    const Template<Message Function(String name)>(
+        messageTemplate:
+            r"""A library with name '#name' is exported more than once.""",
+        withArguments: _withArgumentsDuplicatedLibraryExport);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String name)> codeDuplicatedLibraryExport =
+    const Code<Message Function(String name)>(
+        "DuplicatedLibraryExport", templateDuplicatedLibraryExport,
+        analyzerCode: "EXPORT_DUPLICATED_LIBRARY_NAMED");
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsDuplicatedLibraryExport(String name) {
+  return new Message(codeDuplicatedLibraryExport,
+      message: """A library with name '${name}' is exported more than once.""",
+      arguments: {'name': name});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<Message Function(String name)>
+    templateDuplicatedLibraryExportContext =
+    const Template<Message Function(String name)>(
+        messageTemplate: r"""'#name' is also exported here.""",
+        withArguments: _withArgumentsDuplicatedLibraryExportContext);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String name)> codeDuplicatedLibraryExportContext =
+    const Code<Message Function(String name)>("DuplicatedLibraryExportContext",
+        templateDuplicatedLibraryExportContext,
+        severity: Severity.context);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsDuplicatedLibraryExportContext(String name) {
+  return new Message(codeDuplicatedLibraryExportContext,
+      message: """'${name}' is also exported here.""",
+      arguments: {'name': name});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<Message Function(String name)> templateDuplicatedLibraryImport =
+    const Template<Message Function(String name)>(
+        messageTemplate:
+            r"""A library with name '#name' is imported more than once.""",
+        withArguments: _withArgumentsDuplicatedLibraryImport);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String name)> codeDuplicatedLibraryImport =
+    const Code<Message Function(String name)>(
+        "DuplicatedLibraryImport", templateDuplicatedLibraryImport,
+        analyzerCode: "IMPORT_DUPLICATED_LIBRARY_NAMED");
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsDuplicatedLibraryImport(String name) {
+  return new Message(codeDuplicatedLibraryImport,
+      message: """A library with name '${name}' is imported more than once.""",
+      arguments: {'name': name});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<Message Function(String name)>
+    templateDuplicatedLibraryImportContext =
+    const Template<Message Function(String name)>(
+        messageTemplate: r"""'#name' is also imported here.""",
+        withArguments: _withArgumentsDuplicatedLibraryImportContext);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Message Function(String name)> codeDuplicatedLibraryImportContext =
+    const Code<Message Function(String name)>("DuplicatedLibraryImportContext",
+        templateDuplicatedLibraryImportContext,
+        severity: Severity.context);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsDuplicatedLibraryImportContext(String name) {
+  return new Message(codeDuplicatedLibraryImportContext,
+      message: """'${name}' is also imported here.""",
+      arguments: {'name': name});
+}
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<Message Function(Token token)> templateDuplicatedModifier =
     const Template<Message Function(Token token)>(

pkg/front_end/lib/src/fasta/source/source_loader.dart

@@ -49,6 +49,8 @@ import '../builder/builder.dart'
 
 import '../export.dart' show Export;
 
+import '../import.dart' show Import;
+
 import '../fasta_codes.dart'
     show
         LocatedMessage,
@@ -60,6 +62,10 @@ import '../fasta_codes.dart'
         templateAmbiguousSupertypes,
         templateCantReadFile,
         templateCyclicClassHierarchy,
+        templateDuplicatedLibraryExport,
+        templateDuplicatedLibraryExportContext,
+        templateDuplicatedLibraryImport,
+        templateDuplicatedLibraryImportContext,
         templateExtendingEnum,
         templateExtendingRestricted,
         templateIllegalMixin,
@@ -650,6 +656,80 @@ class SourceLoader<L> extends Loader<L> {
       }
     }
     ticker.logMs("Checked restricted supertypes");
+
+    // Check imports and exports for duplicate names.
+    // This is rather silly, e.g. it makes importing 'foo' and exporting another
+    // 'foo' ok.
+    builders.forEach((Uri uri, LibraryBuilder library) {
+      if (library is SourceLibraryBuilder && library.loader == this) {
+        // Check exports.
+        if (library.exports.isNotEmpty) {
+          Map<String, List<Export>> nameToExports;
+          bool errorExports = false;
+          for (Export export in library.exports) {
+            String name = export.exported?.name ?? '';
+            if (name != '') {
+              nameToExports ??= new Map<String, List<Export>>();
+              List<Export> exports = nameToExports[name] ??= <Export>[];
+              exports.add(export);
+              if (exports[0].exported != export.exported) errorExports = true;
+            }
+          }
+          if (errorExports) {
+            for (String name in nameToExports.keys) {
+              List<Export> exports = nameToExports[name];
+              if (exports.length < 2) continue;
+              List<LocatedMessage> context = <LocatedMessage>[];
+              for (Export export in exports.skip(1)) {
+                context.add(templateDuplicatedLibraryExportContext
+                    .withArguments(name)
+                    .withLocation(uri, export.charOffset, noLength));
+              }
+              library.addProblem(
+                  templateDuplicatedLibraryExport.withArguments(name),
+                  exports[0].charOffset,
+                  noLength,
+                  uri,
+                  context: context);
+            }
+          }
+        }
+
+        // Check imports.
+        if (library.imports.isNotEmpty) {
+          Map<String, List<Import>> nameToImports;
+          bool errorImports;
+          for (Import import in library.imports) {
+            String name = import.imported?.name ?? '';
+            if (name != '') {
+              nameToImports ??= new Map<String, List<Import>>();
+              List<Import> imports = nameToImports[name] ??= <Import>[];
+              imports.add(import);
+              if (imports[0].imported != import.imported) errorImports = true;
+            }
+          }
+          if (errorImports != null) {
+            for (String name in nameToImports.keys) {
+              List<Import> imports = nameToImports[name];
+              if (imports.length < 2) continue;
+              List<LocatedMessage> context = <LocatedMessage>[];
+              for (Import import in imports.skip(1)) {
+                context.add(templateDuplicatedLibraryImportContext
+                    .withArguments(name)
+                    .withLocation(uri, import.charOffset, noLength));
+              }
+              library.addProblem(
+                  templateDuplicatedLibraryImport.withArguments(name),
+                  imports[0].charOffset,
+                  noLength,
+                  uri,
+                  context: context);
+            }
+          }
+        }
+      }
+    });
+    ticker.logMs("Checked imports and exports for duplicate names");
   }
 
   void buildComponent() {

pkg/front_end/messages.yaml

@@ -1577,8 +1577,23 @@ PrefixAfterCombinator:
 
 DuplicatedExport:
   template: "'#name' is exported from both '#uri' and '#uri2'."
-  severity: IGNORED
   analyzerCode: AMBIGUOUS_EXPORT
+  script:
+    lib1.dart: "class A {}"
+    lib2.dart: "class A {}"
+    main.dart: "export 'lib1.dart'; export 'lib2.dart';"
+
+DuplicatedLibraryExport:
+  template: "A library with name '#name' is exported more than once."
+  analyzerCode: EXPORT_DUPLICATED_LIBRARY_NAMED
+  script:
+    lib1.dart: "library foo;"
+    lib2.dart: "library foo;"
+    main.dart: "export 'lib1.dart'; export 'lib2.dart';"
+
+DuplicatedLibraryExportContext:
+  template: "'#name' is also exported here."
+  severity: CONTEXT
 
 DuplicatedExportInType:
   template: "'#name' is exported from both '#uri' and '#uri2'."
@@ -1588,6 +1603,18 @@ DuplicatedImport:
   template: "'#name' is imported from both '#uri' and '#uri2'."
   severity: IGNORED
 
+DuplicatedLibraryImport:
+  template: "A library with name '#name' is imported more than once."
+  analyzerCode: IMPORT_DUPLICATED_LIBRARY_NAMED
+  script:
+    lib1.dart: "library foo;"
+    lib2.dart: "library foo;"
+    main.dart: "import 'lib1.dart'; import 'lib2.dart';"
+
+DuplicatedLibraryImportContext:
+  template: "'#name' is also imported here."
+  severity: CONTEXT
+
 DuplicatedImportInType:
   template: "'#name' is imported from both '#uri' and '#uri2'."
   severity: ERROR_LEGACY_WARNING

pkg/front_end/testcases/ambiguous_exports.dart.direct.expect

@@ -1,3 +1,15 @@
+// Formatted problems:
+//
+// pkg/front_end/testcases/ambiguous_exports.dart:7:1: Error: 'main' is exported from both 'pkg/front_end/testcases/hello.dart' and 'pkg/front_end/testcases/map.dart'.
+// export 'map.dart' show main;
+// ^
+
+// Unhandled errors:
+//
+// pkg/front_end/testcases/ambiguous_exports.dart:7:1: Error: 'main' is exported from both 'pkg/front_end/testcases/hello.dart' and 'pkg/front_end/testcases/map.dart'.
+// export 'map.dart' show main;
+// ^
+
 library;
 import self as self;
 

pkg/front_end/testcases/ambiguous_exports.dart.direct.transformed.expect

@@ -1,3 +1,9 @@
+// Unhandled errors:
+//
+// pkg/front_end/testcases/ambiguous_exports.dart:7:1: Error: 'main' is exported from both 'pkg/front_end/testcases/hello.dart' and 'pkg/front_end/testcases/map.dart'.
+// export 'map.dart' show main;
+// ^
+
 library;
 import self as self;
 

pkg/front_end/testcases/ambiguous_exports.dart.outline.expect

@@ -1,3 +1,9 @@
+// Formatted problems:
+//
+// pkg/front_end/testcases/ambiguous_exports.dart:7:1: Error: 'main' is exported from both 'pkg/front_end/testcases/hello.dart' and 'pkg/front_end/testcases/map.dart'.
+// export 'map.dart' show main;
+// ^
+
 library;
 import self as self;
 

pkg/front_end/testcases/ambiguous_exports.dart.strong.expect

@@ -1,3 +1,15 @@
+// Formatted problems:
+//
+// pkg/front_end/testcases/ambiguous_exports.dart:7:1: Error: 'main' is exported from both 'pkg/front_end/testcases/hello.dart' and 'pkg/front_end/testcases/map.dart'.
+// export 'map.dart' show main;
+// ^
+
+// Unhandled errors:
+//
+// pkg/front_end/testcases/ambiguous_exports.dart:7:1: Error: 'main' is exported from both 'pkg/front_end/testcases/hello.dart' and 'pkg/front_end/testcases/map.dart'.
+// export 'map.dart' show main;
+// ^
+
 library;
 import self as self;
 

pkg/front_end/testcases/ambiguous_exports.dart.strong.transformed.expect

@@ -1,3 +1,9 @@
+// Unhandled errors:
+//
+// pkg/front_end/testcases/ambiguous_exports.dart:7:1: Error: 'main' is exported from both 'pkg/front_end/testcases/hello.dart' and 'pkg/front_end/testcases/map.dart'.
+// export 'map.dart' show main;
+// ^
+
 library;
 import self as self;
 

tests/co19/co19-co19.status

@@ -909,6 +909,8 @@ Utils/tests/Expect/identical_A01_t01: CompileTimeError # Uses Dart 1 constants
 Utils/tests/Expect/setEquals_A01_t02: CompileTimeError # Uses Dart 1 constants
 
 [ !$strong ]
+Language/Libraries_and_Scripts/Exports/reexport_t01: MissingCompileTimeError
+Language/Libraries_and_Scripts/Exports/reexport_t02: MissingCompileTimeError
 LibTest/async/Stream/Stream.fromIterable_A02_t01: RuntimeError # Assumes no close after error.
 LibTest/async/Stream/firstWhere_A01_t01: RuntimeError # co19 issue 137
 LibTest/async/Stream/firstWhere_A02_t01: RuntimeError # co19 issue 137

tests/co19/co19-kernel.status

@@ -11,6 +11,8 @@ Language/Expressions/Method_Invocation/Ordinary_Invocation/function_type_t01: Co
 Language/Expressions/Method_Invocation/Ordinary_Invocation/static_type_t01: CompileTimeError # Expects a warning, but this is an error in Dart 2
 Language/Functions/Formal_Parameters/Optional_Formals/default_value_t01: MissingCompileTimeError
 Language/Functions/Formal_Parameters/Optional_Formals/default_value_t02: MissingCompileTimeError
+Language/Libraries_and_Scripts/Exports/same_name_t01: CompileTimeError # Expects a warning, but this is an error in Dart 2
+Language/Libraries_and_Scripts/Imports/library_name_t01: CompileTimeError # Expects a warning, but this is an error in Dart 2
 Language/Types/Parameterized_Types/arity_mismatch_t01: CompileTimeError
 Language/Types/Parameterized_Types/arity_mismatch_t05: CompileTimeError
 Language/Types/Parameterized_Types/arity_mismatch_t07: CompileTimeError
@@ -920,7 +922,6 @@ Language/Interfaces/Superinterfaces/Inheritance_and_Overriding/same_name_getters
 Language/Interfaces/Superinterfaces/Inheritance_and_Overriding/same_name_getters_type_t06: CompileTimeError
 Language/Interfaces/Superinterfaces/Inheritance_and_Overriding/same_name_getters_type_t07: CompileTimeError
 Language/Interfaces/Superinterfaces/Inheritance_and_Overriding/same_name_getters_type_t08: CompileTimeError
-Language/Libraries_and_Scripts/Exports/reexport_t01: MissingCompileTimeError
 Language/Libraries_and_Scripts/Exports/show_hide_t01: CompileTimeError
 Language/Libraries_and_Scripts/Exports/show_hide_t02: CompileTimeError
 Language/Libraries_and_Scripts/Exports/syntax_t02: CompileTimeError

tests/co19_2/co19_2-kernel.status

@@ -113,8 +113,7 @@ Language/Generics/scope_t06: MissingCompileTimeError # Issue 33308
 Language/Generics/syntax_t02: CompileTimeError
 Language/Generics/syntax_t03: CompileTimeError
 Language/Generics/upper_bound_t01: MissingCompileTimeError # Issue 33308
-Language/Libraries_and_Scripts/Exports/reexport_t01: MissingCompileTimeError # Issue 12916
-Language/Libraries_and_Scripts/Exports/same_name_t01: MissingCompileTimeError # Issue 12916
+Language/Libraries_and_Scripts/Imports/library_name_t01: CompileTimeError # Test is wrong. Spec says error not warning.
 Language/Mixins/Mixin_Application/deferred_t01: MissingCompileTimeError # Issue 30273
 Language/Mixins/Mixin_Application/static_warning_t01: MissingCompileTimeError # Mixin super equirement
 Language/Mixins/Mixin_Application/syntax_t21: CompileTimeError # The test even says in the comment it should be a compile time error

tests/compiler/dart2js/dart2js.status

@@ -25,6 +25,7 @@ inference/simple_inferrer_global_field_closure_test: Fail # Issue 16507
 inference/swarm_test: Slow, Pass, Fail #
 inference/type_mask2_test: RuntimeError # Issue 34095
 inlining/inlining_test: Slow, Pass
+model/in_user_code_test: RuntimeError # Two libraries with the same name -- actually a CompileTimeError
 model/native_test: Pass, Slow
 model/no_such_method_enabled_test: Pass, Slow
 model/subtype_test: Pass, Slow

tests/language_2/language_2_dartdevc.status

@@ -285,7 +285,6 @@ deferred_load_library_wrong_args_test/01: CompileTimeError
 double_identical_test: RuntimeError # Negative and positive zero are distinct, but not in ddk
 dynamic_prefix_core_test/none: CompileTimeError
 emit_const_fields_test: CompileTimeError # Issue 31533
-export_ambiguous_main_test: MissingCompileTimeError
 external_test/21: CompileTimeError
 external_test/24: CompileTimeError
 function_propagation_test: RuntimeError

tests/language_2/language_2_kernel.status

@@ -234,7 +234,6 @@ constructor_reference_test/27: MissingCompileTimeError # Issue 34403
 deferred_inheritance_constraints_test/extends: MissingCompileTimeError # Fasta/KernelVM bug: Deferred loading kernel issue 30273.
 deferred_inheritance_constraints_test/implements: MissingCompileTimeError # Fasta/KernelVM bug: Deferred loading kernel issue 30273.
 deferred_inheritance_constraints_test/mixin: MissingCompileTimeError # Fasta/KernelVM bug: Deferred loading kernel issue 30273.
-duplicate_export_collision_test/01: MissingCompileTimeError # Issue 12916
 f_bounded_quantification_test/01: MissingCompileTimeError # Issue 33308
 f_bounded_quantification_test/02: MissingCompileTimeError # Issue 33308
 generic_methods_bounds_test/01: MissingCompileTimeError # Issue 33308
@@ -336,9 +335,6 @@ vm/debug_break_enabled_vm_test/01: CompileTimeError # KernelVM bug: Bad test usi
 vm/debug_break_enabled_vm_test/none: CompileTimeError # KernelVM bug: Bad test using extended break syntax.
 vm/regress_27201_test: CompileTimeError # Fasta/KernelVM bug: Deferred loading kernel issue 30273.
 
-[ $arch != simarm && $arch != simarm64 && $arch != simdbc64 && $compiler == dartk && $runtime == vm && $strong ]
-export_ambiguous_main_test: Crash # Issue 32618
-
 [ $compiler == app_jitk && $mode == product ]
 vm/causal_async_exception_stack2_test: RuntimeError
 vm/causal_async_exception_stack_test: RuntimeError
@@ -767,7 +763,6 @@ constants_test/05: MissingCompileTimeError
 deferred_load_library_wrong_args_test/01: CompileTimeError
 dynamic_prefix_core_test/none: CompileTimeError
 emit_const_fields_test: CompileTimeError
-export_ambiguous_main_test: MissingCompileTimeError
 external_test/21: CompileTimeError
 external_test/24: CompileTimeError
 generic_methods_generic_function_result_test/01: MissingCompileTimeError
@@ -1487,7 +1482,6 @@ dynamic_prefix_core_test/01: MissingCompileTimeError
 empty_block_case_test: MissingCompileTimeError
 enum_private_test/02: MissingCompileTimeError
 error_stacktrace_test/00: MissingCompileTimeError
-export_ambiguous_main_test: MissingCompileTimeError
 external_test/21: CompileTimeError
 external_test/24: CompileTimeError
 factory1_test/00: MissingCompileTimeError

tests/lib_2/lib_2_kernel.status

@@ -26,6 +26,7 @@ isolate/spawn_function_custom_class_test: Skip # Timeout
 html/*: Skip # TODO(ahe): Make dart:html available.
 isolate/browser/*: Skip # TODO(ahe): Make dart:html available.
 js/*: Skip # TODO(ahe): Make dart:js available.
+mirrors/repeated_private_anon_mixin_app_test: CompileTimeError # Two libraries with same name inported.
 
 [ $fasta ]
 mirrors/deferred_constraints_constants_test/default_argument2: MissingCompileTimeError
@@ -204,7 +205,7 @@ mirrors/regress_26187_test: RuntimeError
 mirrors/relation_assignable_test: RuntimeError
 mirrors/relation_subclass_test: RuntimeError
 mirrors/relation_subtype_test: RuntimeError
-mirrors/repeated_private_anon_mixin_app_test: RuntimeError
+mirrors/repeated_private_anon_mixin_app_test: CompileTimeError # Two libraries with same name inported.
 mirrors/static_members_easier_test: RuntimeError # Issue 31402 (Invocation arguments)
 mirrors/static_members_test: RuntimeError # Issue 31402 (Invocation arguments)
 mirrors/symbol_validation_test/01: RuntimeError # Issue 31537