Merge pull request #77764 from swiftlang/gaborh/conditional-escapability-variadic

[cxx-interop] Support parameter packs in escapability annotations

Author: Xazax-hun

lib/ClangImporter/ClangImporter.cpp

@@ -5099,21 +5099,29 @@ ClangTypeEscapability::evaluate(Evaluator &evaluator,
         auto &argList = specDecl->getTemplateArgs();
         for (auto argToCheck : argumentsToCheck) {
           auto arg = argList[argToCheck.first];
-          if (arg.getKind() != clang::TemplateArgument::Type) {
-            desc.impl.diagnose(loc, diag::type_template_parameter_expected,
-                               argToCheck.second);
-            return CxxEscapability::Unknown;
-          }
+          llvm::SmallVector<clang::TemplateArgument, 1> nonPackArgs;
+          if (arg.getKind() == clang::TemplateArgument::Pack) {
+            auto pack = arg.getPackAsArray();
+            nonPackArgs.assign(pack.begin(), pack.end());
+          } else
+            nonPackArgs.push_back(arg);
+          for (auto nonPackArg : nonPackArgs) {
+            if (nonPackArg.getKind() != clang::TemplateArgument::Type) {
+              desc.impl.diagnose(loc, diag::type_template_parameter_expected,
+                                 argToCheck.second);
+              return CxxEscapability::Unknown;
+            }
 
-          auto argEscapability = evaluateEscapability(
-              arg.getAsType()->getUnqualifiedDesugaredType());
-          if (argEscapability == CxxEscapability::NonEscapable)
-            return CxxEscapability::NonEscapable;
+            auto argEscapability = evaluateEscapability(
+                nonPackArg.getAsType()->getUnqualifiedDesugaredType());
+            if (argEscapability == CxxEscapability::NonEscapable)
+              return CxxEscapability::NonEscapable;
+          }
         }
-        clang::DeclContext *rec = specDecl;
+        clang::DeclContext *dc = specDecl;
         specDecl = nullptr;
-        while ((rec = rec->getParent())) {
-          specDecl = dyn_cast<clang::ClassTemplateSpecializationDecl>(rec);
+        while ((dc = dc->getParent())) {
+          specDecl = dyn_cast<clang::ClassTemplateSpecializationDecl>(dc);
           if (specDecl)
             break;
         }

test/Interop/Cxx/class/nonescapable-errors.swift

@@ -77,6 +77,13 @@ Outer<View>::NonTemplated::Inner<Owner> j1();
 Outer<Owner>::NonTemplated::Inner<View> j2();
 Outer<Owner>::NonTemplated::Inner<Owner> j3();
 
+template<typename... Ts>
+struct SWIFT_ESCAPABLE_IF(Ts) MyTuple {};
+
+MyTuple<View> k1();
+MyTuple<Owner, View> k2();
+MyTuple<Owner, Owner> k3();
+
 //--- test.swift
 import Test
 
@@ -113,6 +120,13 @@ public func noAnnotations() -> View {
     // CHECK: nonescapable.h:63:41: error: cannot infer lifetime dependence, no parameters found that are either ~Escapable or Escapable with a borrowing ownership
     // CHECK-NO-LIFETIMES: nonescapable.h:63:41: error: returning ~Escapable type requires '-enable-experimental-feature LifetimeDependence'
     j3()
+    k1();
+    // CHECK: nonescapable.h:69:15: error: cannot infer lifetime dependence, no parameters found that are either ~Escapable or Escapable with a borrowing ownership
+    // CHECK-NO-LIFETIMES: nonescapable.h:69:15: error: returning ~Escapable type requires '-enable-experimental-feature LifetimeDependence'
+    k2();
+    // CHECK: nonescapable.h:70:22: error: cannot infer lifetime dependence, no parameters found that are either ~Escapable or Escapable with a borrowing ownership
+    // CHECK-NO-LIFETIMES: nonescapable.h:70:22: error: returning ~Escapable type requires '-enable-experimental-feature LifetimeDependence'
+    k3();
     // CHECK-NOT: error
     // CHECK-NOT: warning
     return View()