Swift: Extract self parameter declarations.

swift/codegen/schema.yml

@@ -81,6 +81,7 @@ AstNode:
 Callable:
   _children:
     params: ParamDecl*
+    self_param: ParamDecl?
     body: BraceStmt?
 
 ConditionElement:

swift/extractor/visitors/DeclVisitor.cpp

@@ -327,6 +327,8 @@ void DeclVisitor::fillAbstractFunctionDecl(const swift::AbstractFunctionDecl& de
   entry.name = !decl.hasName() ? "(unnamed function decl)" : constructName(decl.getName());
   entry.body = dispatcher_.fetchOptionalLabel(decl.getBody());
   entry.params = dispatcher_.fetchRepeatedLabels(*decl.getParameters());
+  auto self = const_cast<swift::ParamDecl* const>(decl.getImplicitSelfDecl());
+  entry.self_param = dispatcher_.fetchOptionalLabel(self);
   fillValueDecl(decl, entry);
   fillGenericContext(decl, entry);
 }

swift/ql/lib/codeql/swift/elements/decl/ParamDecl.qll

@@ -5,6 +5,20 @@ class ParamDecl extends ParamDeclBase {
   /** Gets the function which declares this parameter. */
   Callable getDeclaringFunction() { result.getAParam() = this }
 
-  /** Gets the index of this parameter in its declaring function's parameter list. */
+  /**
+   * Gets the index of this parameter in its declaring function's parameter list,
+   * or -1 if this is `self`.
+   */
   int getIndex() { exists(Callable func | func.getParam(result) = this) }
 }
+
+/** A `self` parameter. */
+class SelfParamDecl extends ParamDecl {
+  Callable call;
+
+  SelfParamDecl() { call.getSelfParam() = this }
+
+  override Callable getDeclaringFunction() { result = call }
+
+  override int getIndex() { result = -1 }
+}