[cxx-interop] Support nested templates for conditional escapability

rdar://140115862

Author: Gabor Horvath

lib/ClangImporter/ClangImporter.cpp

@@ -36,6 +36,7 @@
 #include "swift/AST/NameLookupRequests.h"
 #include "swift/AST/PrettyStackTrace.h"
 #include "swift/AST/SourceFile.h"
+#include "swift/AST/Type.h"
 #include "swift/AST/TypeCheckRequests.h"
 #include "swift/AST/Types.h"
 #include "swift/Basic/Assertions.h"
@@ -51,6 +52,7 @@
 #include "swift/Strings.h"
 #include "swift/Subsystems.h"
 #include "clang/AST/ASTContext.h"
+#include "clang/AST/DeclBase.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/Mangle.h"
@@ -5080,31 +5082,41 @@ ClangTypeEscapability::evaluate(Evaluator &evaluator,
         importer::getConditionalEscapableAttrParams(recordDecl);
     if (!conditionalParams.empty()) {
       auto specDecl = cast<clang::ClassTemplateSpecializationDecl>(recordDecl);
-      auto templateDecl = specDecl->getSpecializedTemplate();
       SmallVector<std::pair<unsigned, StringRef>, 4> argumentsToCheck;
-      for (auto [idx, param] :
-           llvm::enumerate(*templateDecl->getTemplateParameters())) {
-        if (conditionalParams.erase(param->getName()))
-          argumentsToCheck.push_back(std::make_pair(idx, param->getName()));
-      }
       HeaderLoc loc{recordDecl->getLocation()};
-      for (auto name : conditionalParams)
-        desc.impl.diagnose(loc, diag::unknown_template_parameter, name);
-
-      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;
+      while (specDecl) {
+        auto templateDecl = specDecl->getSpecializedTemplate();
+        for (auto [idx, param] :
+             llvm::enumerate(*templateDecl->getTemplateParameters())) {
+          if (conditionalParams.erase(param->getName()))
+            argumentsToCheck.push_back(std::make_pair(idx, param->getName()));
         }
+        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;
+          }
 
-        auto argEscapability = evaluateEscapability(
-            arg.getAsType()->getUnqualifiedDesugaredType());
-        if (argEscapability == CxxEscapability::NonEscapable)
-          return CxxEscapability::NonEscapable;
+          auto argEscapability = evaluateEscapability(
+              arg.getAsType()->getUnqualifiedDesugaredType());
+          if (argEscapability == CxxEscapability::NonEscapable)
+            return CxxEscapability::NonEscapable;
+        }
+        clang::DeclContext *rec = specDecl;
+        specDecl = nullptr;
+        while ((rec = rec->getParent())) {
+          specDecl = dyn_cast<clang::ClassTemplateSpecializationDecl>(rec);
+          if (specDecl)
+            break;
+        }
       }
+
+      for (auto name : conditionalParams)
+        desc.impl.diagnose(loc, diag::unknown_template_parameter, name);
+
       return hadUnknown ? CxxEscapability::Unknown : CxxEscapability::Escapable;
     }
     if (desc.annotationOnly)

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

@@ -61,6 +61,21 @@ struct SWIFT_ESCAPABLE_IF(F, S) MyType {
 MyPair2<Owner, Owner> i1();
 MyType<Owner, 0> i2();
 
+template<typename T>
+struct Outer {
+    struct NonTemplated {
+        template <typename S>
+        struct SWIFT_ESCAPABLE_IF(T, S) Inner {
+            T t;
+            S s;
+        };
+    };
+};
+
+Outer<View>::NonTemplated::Inner<Owner> j1();
+Outer<Owner>::NonTemplated::Inner<View> j2();
+Outer<Owner>::NonTemplated::Inner<Owner> j3();
+
 //--- test.swift
 
 import Test
@@ -85,6 +100,11 @@ public func noAnnotations() -> View {
     // CHECK: nonescapable.h:38:39: error: template parameter 'Missing' does not exist
     i2()
     // CHECK: nonescapable.h:44:33: error: template parameter 'S' expected to be a type parameter
+    j1()
+    // CHECK: nonescapable.h:62:41: error: cannot infer lifetime dependence, no parameters found that are either ~Escapable or Escapable with a borrowing ownership
+    j2()
+    // CHECK: nonescapable.h:63:41: error: cannot infer lifetime dependence, no parameters found that are either ~Escapable or Escapable with a borrowing ownership
+    j3()
     // CHECK-NOT: error
     // CHECK-NOT: warning
     return View()