Swift: Callable abstraction

This new class encompasses both `AbstractFunctionDecl` and
`AbstractClosureExpr`, together with their common parts (namely
parameters and the body).

`ClosureExpr` and `AutoClosureExpr` got ported to structured C++
generated translation in the process.

swift/codegen/schema.yml

@@ -54,6 +54,11 @@ NominalTypeDecl:
 AstNode:
   _extends: Locatable
 
+Callable:
+  _children:
+    params: ParamDecl*
+    body: BraceStmt?
+
 ConditionElement:
   _extends: Locatable
   _children:
@@ -290,9 +295,9 @@ ValueDecl:
   interface_type: Type
 
 AbstractClosureExpr:
-  _extends: Expr
-  _children:
-    params: ParamDecl*
+  _extends:
+    - Expr
+    - Callable
 
 AnyTryExpr:
   _extends: Expr
@@ -712,10 +717,8 @@ AbstractFunctionDecl:
   _extends:
     - GenericContext
     - ValueDecl
+    - Callable
   name: string
-  _children:
-    body: BraceStmt?
-    params: ParamDecl*
 
 AbstractStorageDecl:
   _extends: ValueDecl
@@ -735,13 +738,9 @@ TypeDecl:
 
 AutoClosureExpr:
   _extends: AbstractClosureExpr
-  _children:
-    body: BraceStmt
 
 ClosureExpr:
   _extends: AbstractClosureExpr
-  _children:
-    body: BraceStmt
 
 ForceTryExpr:
   _extends: AnyTryExpr

swift/extractor/visitors/ExprVisitor.h

@@ -363,20 +363,16 @@ class ExprVisitor : public AstVisitorBase<ExprVisitor> {
     dispatcher_.emit(DiscardAssignmentExprsTrap{label});
   }
 
-  void visitClosureExpr(swift::ClosureExpr* expr) {
-    auto label = dispatcher_.assignNewLabel(expr);
-    assert(expr->getBody() && "ClosureExpr has getBody()");
-    auto bodyLabel = dispatcher_.fetchLabel(expr->getBody());
-    dispatcher_.emit(ClosureExprsTrap{label, bodyLabel});
-    emitAbstractClosureExpr(expr, label);
+  codeql::ClosureExpr translateClosureExpr(const swift::ClosureExpr& expr) {
+    ClosureExpr entry{dispatcher_.assignNewLabel(expr)};
+    fillAbstractClosureExpr(expr, entry);
+    return entry;
   }
 
-  void visitAutoClosureExpr(swift::AutoClosureExpr* expr) {
-    auto label = dispatcher_.assignNewLabel(expr);
-    assert(expr->getBody() && "AutoClosureExpr has getBody()");
-    auto bodyLabel = dispatcher_.fetchLabel(expr->getBody());
-    dispatcher_.emit(AutoClosureExprsTrap{label, bodyLabel});
-    emitAbstractClosureExpr(expr, label);
+  codeql::AutoClosureExpr translateAutoClosureExpr(const swift::AutoClosureExpr& expr) {
+    AutoClosureExpr entry{dispatcher_.assignNewLabel(expr)};
+    fillAbstractClosureExpr(expr, entry);
+    return entry;
   }
 
   void visitCoerceExpr(swift::CoerceExpr* expr) {
@@ -536,14 +532,12 @@ class ExprVisitor : public AstVisitorBase<ExprVisitor> {
   }
 
  private:
-  void emitAbstractClosureExpr(swift::AbstractClosureExpr* expr,
-                               TrapLabel<AbstractClosureExprTag> label) {
-    assert(expr->getParameters() && "AbstractClosureExpr has getParameters()");
-    auto params = expr->getParameters();
-    for (auto i = 0u; i < params->size(); ++i) {
-      dispatcher_.emit(
-          AbstractClosureExprParamsTrap{label, i, dispatcher_.fetchLabel(params->get(i))});
-    }
+  void fillAbstractClosureExpr(const swift::AbstractClosureExpr& expr,
+                               codeql::AbstractClosureExpr& entry) {
+    assert(expr.getParameters() && "AbstractClosureExpr has getParameters()");
+    assert(expr.getBody() && "AbstractClosureExpr has getBody()");
+    entry.params = dispatcher_.fetchRepeatedLabels(*expr.getParameters());
+    entry.body = dispatcher_.fetchLabel(expr.getBody());
   }
 
   TrapLabel<ArgumentTag> emitArgument(const swift::Argument& arg) {

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

@@ -1,5 +1,6 @@
 // generated by codegen/codegen.py
 import codeql.swift.elements.AstNode
+import codeql.swift.elements.Callable
 import codeql.swift.elements.Element
 import codeql.swift.elements.File
 import codeql.swift.elements.Locatable

swift/ql/lib/codeql/swift/elements/Callable.qll

@@ -0,0 +1,4 @@
+private import codeql.swift.generated.Callable
+private import codeql.swift.elements.AstNode
+
+class Callable extends CallableBase, AstNode { }

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

@@ -1,10 +1,10 @@
 private import codeql.swift.generated.decl.ParamDecl
-private import codeql.swift.elements.decl.AbstractFunctionDecl
+private import codeql.swift.elements.Callable
 
 class ParamDecl extends ParamDeclBase {
   /** Gets the function which declares this parameter. */
-  AbstractFunctionDecl getDeclaringFunction() { result.getAParam() = this }
+  Callable getDeclaringFunction() { result.getAParam() = this }
 
   /** Gets the index of this parameter in its declaring function's parameter list. */
-  int getIndex() { exists(AbstractFunctionDecl func | func.getParam(result) = this) }
+  int getIndex() { exists(Callable func | func.getParam(result) = this) }
 }

swift/ql/lib/codeql/swift/generated/Callable.qll

@@ -0,0 +1,26 @@
+// generated by codegen/codegen.py
+import codeql.swift.elements.stmt.BraceStmt
+import codeql.swift.elements.Element
+import codeql.swift.elements.decl.ParamDecl
+
+class CallableBase extends @callable, Element {
+  ParamDecl getParam(int index) {
+    exists(ParamDecl x |
+      callable_params(this, index, x) and
+      result = x.resolve()
+    )
+  }
+
+  ParamDecl getAParam() { result = getParam(_) }
+
+  int getNumberOfParams() { result = count(getAParam()) }
+
+  BraceStmt getBody() {
+    exists(BraceStmt x |
+      callable_bodies(this, x) and
+      result = x.resolve()
+    )
+  }
+
+  predicate hasBody() { exists(getBody()) }
+}

swift/ql/lib/codeql/swift/generated/GetImmediateParent.qll

@@ -18,9 +18,9 @@ Element getAnImmediateChild(Element e) {
     (
       none()
       or
-      abstract_function_decl_bodies(e, x)
+      callable_params(e, _, x)
       or
-      abstract_function_decl_params(e, _, x)
+      callable_bodies(e, x)
       or
       abstract_storage_decl_accessor_decls(e, _, x)
       or
@@ -36,8 +36,6 @@ Element getAnImmediateChild(Element e) {
       or
       top_level_code_decls(e, x)
       or
-      abstract_closure_expr_params(e, _, x)
-      or
       any_try_exprs(e, x)
       or
       apply_exprs(e, x)
@@ -52,16 +50,12 @@ Element getAnImmediateChild(Element e) {
       or
       assign_exprs(e, _, x)
       or
-      auto_closure_exprs(e, x)
-      or
       bind_optional_exprs(e, x)
       or
       capture_list_expr_binding_decls(e, _, x)
       or
       capture_list_exprs(e, x)
       or
-      closure_exprs(e, x)
-      or
       dictionary_expr_elements(e, _, x)
       or
       dot_syntax_base_ignored_exprs(e, x, _)

swift/ql/lib/codeql/swift/generated/decl/AbstractFunctionDecl.qll

@@ -1,29 +1,8 @@
 // generated by codegen/codegen.py
-import codeql.swift.elements.stmt.BraceStmt
+import codeql.swift.elements.Callable
 import codeql.swift.elements.decl.GenericContext
-import codeql.swift.elements.decl.ParamDecl
 import codeql.swift.elements.decl.ValueDecl
 
-class AbstractFunctionDeclBase extends @abstract_function_decl, GenericContext, ValueDecl {
+class AbstractFunctionDeclBase extends @abstract_function_decl, Callable, GenericContext, ValueDecl {
   string getName() { abstract_function_decls(this, result) }
-
-  BraceStmt getBody() {
-    exists(BraceStmt x |
-      abstract_function_decl_bodies(this, x) and
-      result = x.resolve()
-    )
-  }
-
-  predicate hasBody() { exists(getBody()) }
-
-  ParamDecl getParam(int index) {
-    exists(ParamDecl x |
-      abstract_function_decl_params(this, index, x) and
-      result = x.resolve()
-    )
-  }
-
-  ParamDecl getAParam() { result = getParam(_) }
-
-  int getNumberOfParams() { result = count(getAParam()) }
 }

swift/ql/lib/codeql/swift/generated/expr/AbstractClosureExpr.qll

@@ -1,16 +1,5 @@
 // generated by codegen/codegen.py
+import codeql.swift.elements.Callable
 import codeql.swift.elements.expr.Expr
-import codeql.swift.elements.decl.ParamDecl
 
-class AbstractClosureExprBase extends @abstract_closure_expr, Expr {
-  ParamDecl getParam(int index) {
-    exists(ParamDecl x |
-      abstract_closure_expr_params(this, index, x) and
-      result = x.resolve()
-    )
-  }
-
-  ParamDecl getAParam() { result = getParam(_) }
-
-  int getNumberOfParams() { result = count(getAParam()) }
-}
+class AbstractClosureExprBase extends @abstract_closure_expr, Callable, Expr { }

swift/ql/lib/codeql/swift/generated/expr/AutoClosureExpr.qll

@@ -1,14 +1,6 @@
 // generated by codegen/codegen.py
 import codeql.swift.elements.expr.AbstractClosureExpr
-import codeql.swift.elements.stmt.BraceStmt
 
 class AutoClosureExprBase extends @auto_closure_expr, AbstractClosureExpr {
   override string getAPrimaryQlClass() { result = "AutoClosureExpr" }
-
-  BraceStmt getBody() {
-    exists(BraceStmt x |
-      auto_closure_exprs(this, x) and
-      result = x.resolve()
-    )
-  }
 }

swift/ql/lib/codeql/swift/generated/expr/ClosureExpr.qll

@@ -1,14 +1,6 @@
 // generated by codegen/codegen.py
 import codeql.swift.elements.expr.AbstractClosureExpr
-import codeql.swift.elements.stmt.BraceStmt
 
 class ClosureExprBase extends @closure_expr, AbstractClosureExpr {
   override string getAPrimaryQlClass() { result = "ClosureExpr" }
-
-  BraceStmt getBody() {
-    exists(BraceStmt x |
-      closure_exprs(this, x) and
-      result = x.resolve()
-    )
-  }
 }

swift/ql/lib/swift.dbscheme

@@ -14,6 +14,7 @@ sourceLocationPrefix(
 
 @element =
   @argument
+| @callable
 | @file
 | @generic_context
 | @iterable_decl_context
@@ -125,6 +126,24 @@ nominal_type_decls(
 | @type_repr
 ;
 
+@callable =
+  @abstract_closure_expr
+| @abstract_function_decl
+;
+
+#keyset[id, index]
+callable_params(
+  int id: @callable ref,
+  int index: int ref,
+  int param: @param_decl ref
+);
+
+#keyset[id]
+callable_bodies(
+  int id: @callable ref,
+  int body: @brace_stmt ref
+);
+
 condition_elements(
   unique int id: @condition_element
 );
@@ -659,13 +678,6 @@ value_decls(
 | @closure_expr
 ;
 
-#keyset[id, index]
-abstract_closure_expr_params(
-  int id: @abstract_closure_expr ref,
-  int index: int ref,
-  int param: @param_decl ref
-);
-
 @any_try_expr =
   @force_try_expr
 | @optional_try_expr
@@ -1392,19 +1404,6 @@ abstract_function_decls(
   string name: string ref
 );
 
-#keyset[id]
-abstract_function_decl_bodies(
-  int id: @abstract_function_decl ref,
-  int body: @brace_stmt ref
-);
-
-#keyset[id, index]
-abstract_function_decl_params(
-  int id: @abstract_function_decl ref,
-  int index: int ref,
-  int param: @param_decl ref
-);
-
 @abstract_storage_decl =
   @subscript_decl
 | @var_decl
@@ -1449,13 +1448,11 @@ type_decl_base_types(
 );
 
 auto_closure_exprs(
-  unique int id: @auto_closure_expr,
-  int body: @brace_stmt ref
+  unique int id: @auto_closure_expr
 );
 
 closure_exprs(
-  unique int id: @closure_expr,
-  int body: @brace_stmt ref
+  unique int id: @closure_expr
 );
 
 force_try_exprs(