Ensure that prefix?.loadLibrary() generates the proper compile-time error.

pkg/analyzer/test/generated/compile_time_error_code_test.dart

 // Copyright (c) 2014, 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 engine.compile_time_error_code_test;
 
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/parser.dart' show ParserErrorCode;
 import 'package:analyzer/src/generated/source_io.dart';
@@ skipping 4705 matching lines @@
 f() {
   p?.g();
 }
 ''');
     resolve(source);
     assertErrors(
         source, [CompileTimeErrorCode.PREFIX_IDENTIFIER_NOT_FOLLOWED_BY_DOT]);
     verify([source]);
   }
 
+  void test_prefix_conditionalPropertyAccess_call_loadLibrary() {
+    AnalysisOptionsImpl options = new AnalysisOptionsImpl();
+    options.enableNullAwareOperators = true;
+    resetWithOptions(options);
+    addNamedSource('/lib.dart', '''
+library lib;
+''');
+    Source source = addSource('''
+import 'lib.dart' deferred as p;
+f() {
+  p?.loadLibrary();
+}
+''');
+    resolve(source);
+    assertErrors(
+        source, [CompileTimeErrorCode.PREFIX_IDENTIFIER_NOT_FOLLOWED_BY_DOT]);
+    verify([source]);
+  }
+
+  void test_prefix_conditionalPropertyAccess_get() {
+    AnalysisOptionsImpl options = new AnalysisOptionsImpl();
+    options.enableNullAwareOperators = true;
+    resetWithOptions(options);
+    addNamedSource('/lib.dart', '''
+library lib;
+var x;
+''');
+    Source source = addSource('''
+import 'lib.dart' as p;
+f() {
+  return p?.x;
+}
+''');
+    resolve(source);
+    assertErrors(
+        source, [CompileTimeErrorCode.PREFIX_IDENTIFIER_NOT_FOLLOWED_BY_DOT]);
+    verify([source]);
+  }
+
+  void test_prefix_conditionalPropertyAccess_get_loadLibrary() {
+    AnalysisOptionsImpl options = new AnalysisOptionsImpl();
+    options.enableNullAwareOperators = true;
+    resetWithOptions(options);
+    addNamedSource('/lib.dart', '''
+library lib;
+''');
+    Source source = addSource('''
+import 'lib.dart' deferred as p;
+f() {
+  return p?.loadLibrary;
+}
+''');
+    resolve(source);
+    assertErrors(
+        source, [CompileTimeErrorCode.PREFIX_IDENTIFIER_NOT_FOLLOWED_BY_DOT]);
+    verify([source]);
+  }
+
+  void test_prefix_conditionalPropertyAccess_set() {
+    AnalysisOptionsImpl options = new AnalysisOptionsImpl();
+    options.enableNullAwareOperators = true;
+    resetWithOptions(options);
+    addNamedSource('/lib.dart', '''
+library lib;
+var x;
+''');
+    Source source = addSource('''
+import 'lib.dart' as p;
+f() {
+  p?.x = null;
+}
+''');
+    resolve(source);
+    assertErrors(
+        source, [CompileTimeErrorCode.PREFIX_IDENTIFIER_NOT_FOLLOWED_BY_DOT]);
+    verify([source]);
+  }
+
+  void test_prefix_conditionalPropertyAccess_set_loadLibrary() {
+    AnalysisOptionsImpl options = new AnalysisOptionsImpl();
+    options.enableNullAwareOperators = true;
+    resetWithOptions(options);
+    addNamedSource('/lib.dart', '''
+library lib;
+''');
+    Source source = addSource('''
+import 'lib.dart' deferred as p;
+f() {
+  p?.loadLibrary = null;
+}
+''');
+    resolve(source);
+    assertErrors(
+        source, [CompileTimeErrorCode.PREFIX_IDENTIFIER_NOT_FOLLOWED_BY_DOT]);
+    verify([source]);
+  }
+
   void test_prefixCollidesWithTopLevelMembers_functionTypeAlias() {
     addNamedSource("/lib.dart", r'''
 library lib;
 class A{}''');
     Source source = addSource(r'''
 import 'lib.dart' as p;
 typedef p();
 p.A a;''');
     computeLibrarySourceErrors(source);
     assertErrors(
@@ skipping 1209 matching lines @@
         source, [CompileTimeErrorCode.WRONG_NUMBER_OF_PARAMETERS_FOR_OPERATOR]);
     verify([source]);
     reset();
   }
 
   void _check_wrongNumberOfParametersForOperator1(String name) {
     _check_wrongNumberOfParametersForOperator(name, "");
     _check_wrongNumberOfParametersForOperator(name, "a, b");
   }
 }