Fix lifetime dependence demangling and add a new Sema diagnostic

docs/ABI/Mangling.rst

@@ -727,7 +727,7 @@ Types
   C-TYPE is mangled according to the Itanium ABI, and prefixed with the length.
   Non-ASCII identifiers are preserved as-is; we do not use Punycode.
 
-  function-signature ::= params-type params-type async? sendable? throws? differentiable? function-isolation? // results and parameters
+  function-signature ::= params-type params-type async? sendable? throws? differentiable? function-isolation? self-lifetime-dependence? // results and parameters
 
   params-type ::= type 'z'? 'h'?             // tuple in case of multiple parameters or a single parameter with a single tuple type
                                              // with optional inout convention, shared convention. parameters don't have labels,

include/swift/AST/DiagnosticsSema.def

@@ -7889,6 +7889,10 @@ ERROR(lifetime_dependence_cannot_infer_ambiguous_candidate, none,
        "invalid lifetime dependence on bitwise copyable type", ())
  ERROR(lifetime_dependence_cannot_be_applied_to_tuple_elt, none,
        "lifetime dependence specifiers cannot be applied to tuple elements", ())
+ ERROR(lifetime_dependence_method_escapable_bitwisecopyable_self, none,
+       "cannot infer lifetime dependence on a self which is BitwiseCopyable & "
+       "Escapable",
+       ())
 
  //===----------------------------------------------------------------------===//
  //                             MARK: Transferring

lib/Demangling/Demangler.cpp

@@ -1560,6 +1560,7 @@ NodePointer Demangler::popFunctionType(Node::Kind kind, bool hasClangType) {
     ClangType = demangleClangType();
   }
   addChild(FuncType, ClangType);
+  addChild(FuncType, popNode(Node::Kind::SelfLifetimeDependence));
   addChild(FuncType, popNode(Node::Kind::GlobalActorFunctionType));
   addChild(FuncType, popNode(Node::Kind::IsolatedAnyFunctionType));
   addChild(FuncType, popNode(Node::Kind::TransferringResultFunctionType));
@@ -1570,7 +1571,6 @@ NodePointer Demangler::popFunctionType(Node::Kind kind, bool hasClangType) {
   }));
   addChild(FuncType, popNode(Node::Kind::ConcurrentFunctionType));
   addChild(FuncType, popNode(Node::Kind::AsyncAnnotation));
-  addChild(FuncType, popNode(Node::Kind::SelfLifetimeDependence));
 
   FuncType = addChild(FuncType, popFunctionParams(Node::Kind::ArgumentTuple));
   FuncType = addChild(FuncType, popFunctionParams(Node::Kind::ReturnType));
@@ -1603,6 +1603,9 @@ NodePointer Demangler::popFunctionParamLabels(NodePointer Type) {
     return nullptr;
 
   unsigned FirstChildIdx = 0;
+  if (FuncType->getChild(FirstChildIdx)->getKind() ==
+      Node::Kind::SelfLifetimeDependence)
+    ++FirstChildIdx;
   if (FuncType->getChild(FirstChildIdx)->getKind()
         == Node::Kind::GlobalActorFunctionType)
     ++FirstChildIdx;
@@ -1629,9 +1632,6 @@ NodePointer Demangler::popFunctionParamLabels(NodePointer Type) {
   if (FuncType->getChild(FirstChildIdx)->getKind() ==
       Node::Kind::ParamLifetimeDependence)
     ++FirstChildIdx;
-  if (FuncType->getChild(FirstChildIdx)->getKind() ==
-      Node::Kind::SelfLifetimeDependence)
-    ++FirstChildIdx;
   auto ParameterType = FuncType->getChild(FirstChildIdx);
 
   assert(ParameterType->getKind() == Node::Kind::ArgumentTuple);

lib/Sema/LifetimeDependence.cpp

@@ -399,6 +399,7 @@ std::optional<LifetimeDependenceInfo>
 LifetimeDependenceInfo::infer(AbstractFunctionDecl *afd, Type resultType) {
   auto *dc = afd->getDeclContext();
   auto &ctx = dc->getASTContext();
+  auto *mod = afd->getModuleContext();
 
   if (!ctx.LangOpts.hasFeature(Feature::NonescapableTypes)) {
     return std::nullopt;
@@ -431,6 +432,19 @@ LifetimeDependenceInfo::infer(AbstractFunctionDecl *afd, Type resultType) {
 
   if (afd->getKind() != DeclKind::Constructor && afd->hasImplicitSelfDecl()) {
     Type selfTypeInContext = dc->getSelfTypeInContext();
+    if (selfTypeInContext->isEscapable()) {
+      if (ctx.LangOpts.hasFeature(Feature::BitwiseCopyable)) {
+        auto *bitwiseCopyableProtocol =
+            ctx.getProtocol(KnownProtocolKind::BitwiseCopyable);
+        if (bitwiseCopyableProtocol &&
+            mod->checkConformance(selfTypeInContext, bitwiseCopyableProtocol)) {
+          diags.diagnose(
+              returnLoc,
+              diag::lifetime_dependence_method_escapable_bitwisecopyable_self);
+          return std::nullopt;
+        }
+      }
+    }
     auto kind = getLifetimeDependenceKindFromType(selfTypeInContext);
     auto selfOwnership = afd->getImplicitSelfDecl()->getValueOwnership();
     if (!isLifetimeDependenceCompatibleWithOwnership(kind, selfOwnership,

test/SIL/implicit_lifetime_dependence.swift

@@ -1,5 +1,5 @@
 // RUN: %target-swift-frontend %s \
-// RUN: -emit-sil  \
+// RUN: -emit-sil  -disable-availability-checking \
 // RUN: -enable-experimental-feature NonescapableTypes \
 // RUN: -enable-experimental-feature NoncopyableGenerics | %FileCheck %s
 // REQUIRES: asserts
@@ -82,13 +82,13 @@ struct Wrapper : ~Escapable {
     self._view = view
   }
 // TODO: Investigate why it was mangled as Yli and not YLi before
-// CHECK: sil hidden @$s28implicit_lifetime_dependence7WrapperV8getView1AA10BufferViewVyYLiF : $@convention(method) (@guaranteed Wrapper) -> _inherit(0) @owned BufferView {
-  borrowing func getView1() -> BufferView {
+// CHECK: sil hidden @$s28implicit_lifetime_dependence7WrapperV8getView1AA10BufferViewVyKYLiF : $@convention(method) (@guaranteed Wrapper) -> _inherit(0)  (@owned BufferView, @error any Error) {
+  borrowing func getView1() throws -> BufferView {
     return _view
   }
 
-// CHECK:sil hidden @$s28implicit_lifetime_dependence7WrapperV8getView2AA10BufferViewVyYLiF : $@convention(method) (@owned Wrapper) -> _inherit(0) @owned BufferView {
-  consuming func getView2() -> BufferView {
+// CHECK: sil hidden @$s28implicit_lifetime_dependence7WrapperV8getView2AA10BufferViewVyYaKYLiF : $@convention(method) @async (@owned Wrapper) -> _inherit(0)  (@owned BufferView, @error any Error) {
+  consuming func getView2() async throws -> BufferView {
     return _view
   }
 }

test/Sema/explicit_lifetime_dependence_specifiers1.swift

@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift -disable-availability-checking -enable-experimental-feature NonescapableTypes -enable-experimental-feature NoncopyableGenerics
+// RUN: %target-typecheck-verify-swift -disable-availability-checking -enable-experimental-feature NonescapableTypes -enable-experimental-feature NoncopyableGenerics -enable-experimental-feature BitwiseCopyable
 // REQUIRES: asserts
 
 struct Container {
@@ -218,3 +218,17 @@ func derive(_ x: BufferView) -> dependsOn(x) BufferView { // expected-note{{'der
 func derive(_ x: BufferView) -> dependsOn(scoped x) BufferView { // expected-error{{invalid redeclaration of 'derive'}}
   return BufferView(x.ptr)
 }
+
+struct RawBufferView {
+  let ptr: UnsafeRawBufferPointer
+  @_unsafeNonescapableResult
+  init(_ ptr: UnsafeRawBufferPointer) {
+    self.ptr = ptr
+  }
+}
+
+extension RawBufferView {
+  mutating func zeroBufferView() throws -> BufferView { // expected-error{{cannot infer lifetime dependence on a self which is BitwiseCopyable & Escapable}}
+    return BufferView(ptr)
+  }
+}

test/Sema/implicit_lifetime_dependence.swift

@@ -1,11 +1,11 @@
-// RUN: %target-typecheck-verify-swift -disable-availability-checking -enable-experimental-feature NonescapableTypes -enable-experimental-feature NoncopyableGenerics
+// RUN: %target-typecheck-verify-swift -enable-experimental-feature NonescapableTypes -enable-experimental-feature NoncopyableGenerics
 // REQUIRES: asserts
 
 struct BufferView : ~Escapable, ~Copyable {
-  let ptr: UnsafeRawBufferPointer
+  let ptr: UnsafeRawBufferPointer?
   let c: Int
   @_unsafeNonescapableResult
-  init(_ ptr: UnsafeRawBufferPointer, _ c: Int) {
+  init(_ ptr: UnsafeRawBufferPointer?, _ c: Int) {
     self.ptr = ptr
     self.c = c
   }
@@ -23,3 +23,8 @@ struct ImplicitInit3 : ~Escapable, ~Copyable { // expected-error{{cannot infer l
   let mbv1: BufferView
   let mbv2: BufferView
 }
+
+func foo() -> BufferView { // expected-error{{cannot infer lifetime dependence , no parameters found that are ~Escapable or Escapable with a borrowing ownership}}
+  return BufferView(nil, 0)
+}
+