Merge pull request #80305 from swiftlang/gaborh/string-unsafe

[cxx-interop] Fix a regression making std::string unsafe

Author: Xazax-hun

include/swift/ClangImporter/ClangImporterRequests.h

@@ -537,6 +537,9 @@ enum class CxxEscapability { Escapable, NonEscapable, Unknown };
 struct EscapabilityLookupDescriptor final {
   const clang::Type *type;
   ClangImporter::Implementation *impl;
+  // Only explicitly ~Escapable annotated types are considered ~Escapable.
+  // This is for backward compatibility, so we continue to import aggregates
+  // containing pointers as Escapable types.
   bool annotationOnly = true;
 
   friend llvm::hash_code hash_value(const EscapabilityLookupDescriptor &desc) {

lib/ClangImporter/ClangImporter.cpp

@@ -55,6 +55,7 @@
 #include "swift/Strings.h"
 #include "swift/Subsystems.h"
 #include "clang/AST/ASTContext.h"
+#include "clang/AST/Decl.h"
 #include "clang/AST/DeclBase.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclTemplate.h"
@@ -5348,8 +5349,6 @@ ClangTypeEscapability::evaluate(Evaluator &evaluator,
       return hadUnknown ? CxxEscapability::Unknown : CxxEscapability::Escapable;
     }
   }
-  if (desc.annotationOnly)
-    return CxxEscapability::Unknown;
   if (desugared->isArrayType()) {
     auto elemTy = cast<clang::ArrayType>(desugared)
                       ->getElementType()
@@ -5363,7 +5362,8 @@ ClangTypeEscapability::evaluate(Evaluator &evaluator,
   // Base cases
   if (desugared->isAnyPointerType() || desugared->isBlockPointerType() ||
       desugared->isMemberPointerType() || desugared->isReferenceType())
-    return CxxEscapability::NonEscapable;
+    return desc.annotationOnly ? CxxEscapability::Unknown
+                               : CxxEscapability::NonEscapable;
   if (desugared->isScalarType())
     return CxxEscapability::Escapable;
   return CxxEscapability::Unknown;
@@ -8508,7 +8508,7 @@ ExplicitSafety ClangDeclExplicitSafety::evaluate(
   // Enums are always safe.
   if (isa<clang::EnumDecl>(decl))
     return ExplicitSafety::Safe;
-  
+
   // If it's not a record, leave it unspecified.
   auto recordDecl = dyn_cast<clang::RecordDecl>(decl);
   if (!recordDecl)

test/Interop/Cxx/class/safe-interop-mode.swift

@@ -91,9 +91,11 @@ func useSafeParams(x: Owner, y: View, z: SafeEscapableAggregate, c: MyContainer)
 }
 
 func useCfType(x: CFArray) {
+  _ = x
 }
 
 func useString(x: std.string) {
+  _ = x
 }
 
 func useVecOfPtr(x: VecOfPtr) {
@@ -102,9 +104,11 @@ func useVecOfPtr(x: VecOfPtr) {
 }
 
 func useVecOfInt(x: VecOfInt) {
+  _ = x
 }
 
 func useSafeTuple(x: SafeTuple) {
+  _ = x
 }
 
 func useUnsafeTuple(x: UnsafeTuple) {