Swift: extract UnresolvedPatternExpr

Author: redsun82

swift/codegen/schema.yml

@@ -561,6 +561,8 @@ UnresolvedMemberExpr:
 UnresolvedPatternExpr:
   _extends: Expr
   _pragma: qltest_skip  # we should really never extract these
+  _children:
+    sub_pattern: Pattern
 
 UnresolvedSpecializeExpr:
   _extends: Expr

swift/extractor/visitors/ExprVisitor.cpp

@@ -667,5 +667,11 @@ void ExprVisitor::emitLookupExpr(const swift::LookupExpr* expr, TrapLabel<Lookup
     dispatcher_.emit(LookupExprMembersTrap{label, declLabel});
   }
 }
+codeql::UnresolvedPatternExpr ExprVisitor::translateUnresolvedPatternExpr(
+    swift::UnresolvedPatternExpr& expr) {
+  auto entry = dispatcher_.createEntry(expr);
+  entry.sub_pattern = dispatcher_.fetchLabel(expr.getSubPattern());
+  return entry;
+}
 
 }  // namespace codeql

swift/extractor/visitors/ExprVisitor.h

@@ -84,6 +84,11 @@ class ExprVisitor : public AstVisitorBase<ExprVisitor> {
   codeql::BridgeFromObjCExpr translateBridgeFromObjCExpr(const swift::BridgeFromObjCExpr& expr);
   codeql::DotSelfExpr translateDotSelfExpr(const swift::DotSelfExpr& expr);
   codeql::ErrorExpr translateErrorExpr(const swift::ErrorExpr& expr);
+  // following requires non-const because:
+  // * `swift::UnresolvedPatternExpr::getSubPattern` gives `const swift::Pattern*` on const refs
+  // * `swift::ASTVisitor` only visits non-const pointers
+  // either we accept this, or we fix constness by providing our own const visiting in VisitorBase
+  codeql::UnresolvedPatternExpr translateUnresolvedPatternExpr(swift::UnresolvedPatternExpr& expr);
 
  private:
   void fillAbstractClosureExpr(const swift::AbstractClosureExpr& expr,

swift/extractor/visitors/VisitorBase.h

@@ -29,7 +29,7 @@ class VisitorBase {
  public:                                                                                          \
   void visit##CLASS##KIND(swift::CLASS##KIND* e) {                                                \
     using TranslateResult = std::invoke_result_t<decltype(&CrtpSubclass::translate##CLASS##KIND), \
-                                                 CrtpSubclass, swift::CLASS##KIND>;               \
+                                                 CrtpSubclass, swift::CLASS##KIND&>;              \
     constexpr bool hasTranslateImplementation = !std::is_same_v<TranslateResult, void>;           \
     if constexpr (hasTranslateImplementation) {                                                   \
       dispatcher_.emit(static_cast<CrtpSubclass*>(this)->translate##CLASS##KIND(*e));             \

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

@@ -144,6 +144,8 @@ Element getAnImmediateChild(Element e) {
       or
       unresolved_dot_exprs(e, x, _)
       or
+      unresolved_pattern_exprs(e, x)
+      or
       vararg_expansion_exprs(e, x)
       or
       binding_patterns(e, x)

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

@@ -1,6 +1,14 @@
 // generated by codegen/codegen.py
 import codeql.swift.elements.expr.Expr
+import codeql.swift.elements.pattern.Pattern
 
 class UnresolvedPatternExprBase extends @unresolved_pattern_expr, Expr {
   override string getAPrimaryQlClass() { result = "UnresolvedPatternExpr" }
+
+  Pattern getSubPattern() {
+    exists(Pattern x |
+      unresolved_pattern_exprs(this, x) and
+      result = x.resolve()
+    )
+  }
 }

swift/ql/lib/swift.dbscheme

@@ -1141,7 +1141,8 @@ unresolved_member_exprs(  //dir=expr
 );
 
 unresolved_pattern_exprs(  //dir=expr
-  unique int id: @unresolved_pattern_expr
+  unique int id: @unresolved_pattern_expr,
+  int sub_pattern: @pattern ref
 );
 
 unresolved_specialize_exprs(  //dir=expr