Allow parsing Self? as result type in initializers with explicit lifetime dependence

Author: meg-gupta

lib/Parse/ParseDecl.cpp

@@ -9921,8 +9921,19 @@ Parser::parseDeclInit(ParseDeclOptions Flags, DeclAttributes &Attributes) {
 
   if (auto *lifetimeTyR =
           dyn_cast_or_null<LifetimeDependentReturnTypeRepr>(FuncRetTy)) {
-    if (!lifetimeTyR->getBase()->isSimpleUnqualifiedIdentifier(
-            Context.Id_Self)) {
+    auto *base = lifetimeTyR->getBase();
+
+    auto isOptionalSimpleUnqualifiedIdentifier = [](TypeRepr *typeRepr,
+                                                    Identifier str) {
+      if (auto *optionalTR = dyn_cast<OptionalTypeRepr>(typeRepr)) {
+        return optionalTR->getBase()->isSimpleUnqualifiedIdentifier(str);
+      }
+      return false;
+    };
+
+    // Diagnose if return type is not Self or Self?
+    if (!base->isSimpleUnqualifiedIdentifier(Context.Id_Self) &&
+        !isOptionalSimpleUnqualifiedIdentifier(base, Context.Id_Self)) {
       diagnose(FuncRetTy->getStartLoc(),
                diag::lifetime_dependence_invalid_init_return);
       return nullptr;

test/Sema/explicit_lifetime_dependence_specifiers1.swift

@@ -11,17 +11,27 @@ struct BufferView : ~Escapable {
   init(_ ptr: UnsafeRawBufferPointer) {
     self.ptr = ptr
   }
-  init(_ c: borrowing Container) -> _borrow(c) Self { // expected-error{{invalid lifetime dependence on bitwise copyable type}}
-    self.ptr = c.ptr
-    return self
-  }
   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
   }
+  // TODO: Once Optional is ~Escapable, the error will go away
+  init?(_ ptr: UnsafeRawBufferPointer, _ arr: borrowing Array<Float>) -> _borrow(arr) Self? { // expected-error{{lifetime dependence can only be specified on ~Escapable results}}
+    if (Int.random(in: 1..<100) == 0) {
+      return nil
+    }
+    self.ptr = ptr
+  }
+  init?(_ ptr: UnsafeRawBufferPointer, _ arr: borrowing Array<String>) -> _borrow(arr) Self? { // expected-error{{lifetime dependence can only be specified on ~Escapable results}}
+    if (Int.random(in: 1..<100) == 0) {
+      return nil
+    }
+    self.ptr = ptr
+    return self
+  }
 }
 
 struct MutableBufferView : ~Escapable, ~Copyable {