Merge pull request #22031 from github/copilot/tweak-csharp-extractor

Extract `TypeMention` for `catch (Exception)` clauses

Author: aschackmull

csharp/extractor/Semmle.Extraction.CSharp/Entities/Statements/Catch.cs

@@ -23,7 +23,9 @@ protected override void PopulateStatement(TextWriter trapFile)
             }
             else if (isSpecificCatchClause) // A catch clause of the form 'catch(Ex) { ... }'
             {
-                trapFile.catch_type(this, Type.Create(Context, Context.GetType(Stmt.Declaration!.Type)).TypeRef, true);
+                var type = Type.Create(Context, Context.GetType(Stmt.Declaration!.Type));
+                trapFile.catch_type(this, type.TypeRef, true);
+                TypeMention.Create(Context, Stmt.Declaration!.Type, this, type);
             }
             else // A catch clause of the form 'catch { ... }'
             {

csharp/ql/test/library-tests/csharp6/PrintAst.expected

@@ -101,6 +101,7 @@ csharp6.cs:
 #   32|                   0: [IntLiteral] 2
 #   32|                 0: [IntLiteral] 1
 #   34|         1: [SpecificCatchClause] catch (...) {...}
+#   34|           0: [TypeMention] IndexOutOfRangeException
 #   35|           1: [BlockStmt] {...}
 #   34|           2: [EQExpr] ... == ...
 #   34|             0: [PropertyCall] access to property Value

csharp/ql/test/library-tests/regressions/Program.cs

@@ -194,3 +194,16 @@ class C3<T> : C2<C4<T>> { }
 class C4<T> : C2<C3<T>> { }
 
 class C5 : C4<C5> { }
+
+class CatchTypeMentions
+{
+    void F()
+    {
+        try
+        {
+        }
+        catch (Exception)
+        {
+        }
+    }
+}

csharp/ql/test/library-tests/regressions/TypeMentions.expected

@@ -100,3 +100,5 @@
 | Program.cs:194:21:194:21 | T |
 | Program.cs:196:12:196:17 | C4<C5> |
 | Program.cs:196:15:196:16 | C5 |
+| Program.cs:200:5:200:8 | Void |
+| Program.cs:205:16:205:24 | Exception |