Remove diagnostic error when 'return self' is missing in an initializer with explicit lifetime dependence

Also, handle it similar to other initializers in SILGen and ASTVerifier

Author: meg-gupta

include/swift/AST/AnyFunctionRef.h

@@ -115,11 +115,6 @@ class AnyFunctionRef {
     if (auto *AFD = TheFunction.dyn_cast<AbstractFunctionDecl *>()) {
       if (auto *FD = dyn_cast<FuncDecl>(AFD))
         return FD->mapTypeIntoContext(FD->getResultInterfaceType());
-      if (auto *CD = dyn_cast<ConstructorDecl>(AFD)) {
-        if (CD->hasLifetimeDependentReturn()) {
-          return CD->mapTypeIntoContext(CD->getResultInterfaceType());
-        }
-      }
       return TupleType::getEmpty(AFD->getASTContext());
     }
     return TheFunction.get<AbstractClosureExpr *>()->getResultType();

lib/AST/ASTVerifier.cpp

@@ -1076,12 +1076,7 @@ class Verifier : public ASTWalker {
       } else if (auto closure = dyn_cast<AbstractClosureExpr>(func)) {
         resultType = closure->getResultType();
       } else if (auto *CD = dyn_cast<ConstructorDecl>(func)) {
-        if (CD->hasLifetimeDependentReturn()) {
-          resultType = CD->getResultInterfaceType();
-          resultType = CD->mapTypeIntoContext(resultType);
-        } else {
-          resultType = TupleType::getEmpty(Ctx);
-        }
+        resultType = TupleType::getEmpty(Ctx);
       } else {
         resultType = TupleType::getEmpty(Ctx);
       }

lib/SILGen/SILGenConstructor.cpp

@@ -683,13 +683,8 @@ void SILGenFunction::emitValueConstructor(ConstructorDecl *ctor) {
   // Create a basic block to jump to for the implicit 'self' return.
   // We won't emit this until after we've emitted the body.
   // The epilog takes a void return because the return of 'self' is implicit.
-  // When lifetime dependence specifiers are present, epilog will take the
-  // explicit 'self' return.
-  prepareEpilog(ctor,
-                ctor->hasLifetimeDependentReturn()
-                    ? std::optional<Type>(ctor->getResultInterfaceType())
-                    : std::nullopt,
-                ctor->getEffectiveThrownErrorType(), CleanupLocation(ctor));
+  prepareEpilog(ctor, std::nullopt, ctor->getEffectiveThrownErrorType(),
+                CleanupLocation(ctor));
 
   // If the constructor can fail, set up an alternative epilog for constructor
   // failure.
@@ -773,11 +768,6 @@ void SILGenFunction::emitValueConstructor(ConstructorDecl *ctor) {
   // Emit the constructor body.
   emitStmt(ctor->getTypecheckedBody());
 
-  if (ctor->hasLifetimeDependentReturn()) {
-    emitEpilog(ctor, /*UsesCustomEpilog*/ false);
-    return;
-  }
-
   // Build a custom epilog block, since the AST representation of the
   // constructor decl (which has no self in the return type) doesn't match the
   // SIL representation.

lib/Sema/TypeCheckStmt.cpp

@@ -1723,6 +1723,10 @@ Stmt *PreCheckReturnStmtRequest::evaluate(Evaluator &evaluator, ReturnStmt *RS,
         bool isSelf = false;
         if (auto *UDRE = dyn_cast<UnresolvedDeclRefExpr>(E)) {
           isSelf = UDRE->getName().isSimpleName(ctx.Id_self);
+          // Result the result expression so that rest of the compilation
+          // pipeline handles initializers with lifetime dependence specifiers
+          // in the same way as other initializers.
+          RS->setResult(nullptr);
         }
         if (!isSelf) {
           ctx.Diags.diagnose(

test/Sema/explicit_lifetime_dependence_specifiers.swift renamed to test/Sema/explicit_lifetime_dependence_specifiers1.swift

@@ -1,20 +1,10 @@
-// RUN: %target-typecheck-verify-swift -disable-availability-checking -enable-experimental-feature NonescapableTypes -disable-experimental-parser-round-trip   -enable-experimental-feature NoncopyableGenerics -enable-experimental-feature BitwiseCopyable
+// RUN: %target-typecheck-verify-swift -disable-availability-checking -enable-experimental-feature NonescapableTypes -disable-experimental-parser-round-trip   -enable-experimental-feature NoncopyableGenerics
 // REQUIRES: asserts
-// REQUIRES: noncopyable_generics
-// REQUIRES: nonescapable_types
 
 struct Container {
   let ptr: UnsafeRawBufferPointer
 }
 
-struct AnotherBufferView : ~Escapable, _BitwiseCopyable {
-  let ptr: UnsafeRawBufferPointer
-  @_unsafeNonescapableResult
-  init(_ ptr: UnsafeRawBufferPointer) {
-    self.ptr = ptr
-  }
-}
-
 struct BufferView : ~Escapable {
   let ptr: UnsafeRawBufferPointer
   @_unsafeNonescapableResult
@@ -25,10 +15,13 @@ struct BufferView : ~Escapable {
     self.ptr = c.ptr
     return self
   }
-  init(_ bv: borrowing AnotherBufferView) -> _borrow(bv) Self {
-    self.ptr = bv.ptr
+  init(_ ptr: UnsafeRawBufferPointer, _ arr: borrowing Array<Int>) -> _borrow(arr) Self {
+    self.ptr = ptr
     return self
   }
+  init(_ ptr: UnsafeRawBufferPointer, _ arr: borrowing Array<Double>) -> _borrow(arr) Self {
+    self.ptr = ptr
+  }
 }
 
 struct MutableBufferView : ~Escapable, ~Copyable {

test/Sema/explicit_lifetime_dependence_specifiers2.swift

@@ -0,0 +1,21 @@
+// RUN: %target-typecheck-verify-swift -disable-availability-checking -enable-experimental-feature NonescapableTypes -disable-experimental-parser-round-trip   -enable-experimental-feature NoncopyableGenerics -enable-experimental-feature BitwiseCopyable
+// REQUIRES: asserts
+// REQUIRES: noncopyable_generics
+// REQUIRES: nonescapable_types
+
+struct AnotherBufferView : ~Escapable, _BitwiseCopyable {
+  let ptr: UnsafeRawBufferPointer
+  @_unsafeNonescapableResult
+  init(_ ptr: UnsafeRawBufferPointer) {
+    self.ptr = ptr
+  }
+}
+
+struct BufferView : ~Escapable {
+  let ptr: UnsafeRawBufferPointer
+  init(_ bv: borrowing AnotherBufferView) -> _borrow(bv) Self {
+    self.ptr = bv.ptr
+    return self
+  }
+}
+