C#: Add support for the global modifier for using directives.

Author: michaelnebel

csharp/extractor/Semmle.Extraction.CSharp/Entities/UsingDirective.cs

@@ -47,6 +47,11 @@ protected override void Populate(TextWriter trapFile)
                 trapFile.using_directive_location(this, Context.CreateLocation(ReportingLocation));
             }
 
+            if (node.GlobalKeyword.Kind() == SyntaxKind.GlobalKeyword)
+            {
+                trapFile.using_global(this);
+            }
+
             if (parent is not null)
             {
                 trapFile.parent_namespace_declaration(this, parent);

csharp/extractor/Semmle.Extraction.CSharp/Tuples.cs

@@ -371,6 +371,9 @@ internal static void using_directive_location(this TextWriter trapFile, UsingDir
         internal static void using_static_directives(this TextWriter trapFile, UsingDirective @using, Type type) =>
             trapFile.WriteTuple("using_static_directives", @using, type);
 
+        internal static void using_global(this TextWriter trapFile, UsingDirective @using) =>
+            trapFile.WriteTuple("using_global", @using);
+
         internal static void preprocessor_directive_location<TDirective>(this TextWriter trapFile,
             PreprocessorDirective<TDirective> directive, Location location)
             where TDirective : DirectiveTriviaSyntax =>

csharp/ql/lib/semmle/code/csharp/Using.qll

@@ -36,6 +36,9 @@ class UsingDirective extends Element, @using_directive {
   }
 
   override Location getALocation() { using_directive_location(this, result) }
+
+  /** Holds if this directive is `global`. */
+  predicate isGlobal() { using_global(this) }
 }
 
 /**

csharp/ql/lib/semmlecode.csharp.dbscheme

@@ -324,6 +324,10 @@ parent_namespace_declaration(
 
 @using_directive = @using_namespace_directive | @using_static_directive;
 
+using_global(
+  unique int id: @using_directive ref
+);
+
 using_namespace_directives(
   unique int id: @using_namespace_directive,
   int namespace_id: @namespace ref);