Make sure protocol witness errors don't leave the conformance context

include/swift/AST/DiagnosticsSema.def

@@ -1498,7 +1498,7 @@ ERROR(witness_argument_name_mismatch,none,
       "%select{method|initializer}0 %1 has different argument labels from those "
       "required by protocol %2 (%3)", (bool, DeclName, Type, DeclName))
 ERROR(witness_initializer_not_required,none,
-      "initializer requirement %0 can only be satisfied by a `required` "
+      "initializer requirement %0 can only be satisfied by a 'required' "
       "initializer in%select{| the definition of}1 non-final class %2",
       (DeclName, bool, Type))
 ERROR(witness_initializer_failability,none,
@@ -1520,12 +1520,12 @@ NOTE(witness_self_weaken_same_type,none,
       "consider weakening the same-type requirement %0 == %1 to a superclass "
       "requirement", (Type, Type))
 ERROR(witness_requires_dynamic_self,none,
-      "method %0 in non-final class %1 must return `Self` to conform to "
+      "method %0 in non-final class %1 must return 'Self' to conform to "
       "protocol %2",
       (DeclName, Type, Type))
 ERROR(witness_requires_class_implementation,none,
       "method %0 in non-final class %1 cannot be implemented in a "
-      "protocol extension because it returns `Self` and has associated type "
+      "protocol extension because it returns 'Self' and has associated type "
       "requirements",
       (DeclName, Type))
 ERROR(witness_not_accessible_proto,none,
@@ -1553,6 +1553,9 @@ ERROR(type_witness_objc_generic_parameter,none,
       "type %0 involving Objective-C type parameter%select{| %1}2 cannot be "
       "used for associated type %3 of protocol %4",
       (Type, Type, bool, DeclName, DeclName))
+NOTE(witness_fix_access,none,
+     "mark the %0 as '%select{%error|fileprivate|internal|public|%error}1' to "
+     "satisfy the requirement", (DescriptiveDeclKind, AccessLevel))
 
 ERROR(protocol_refine_access,none,
       "%select{protocol must be declared %select{"
@@ -3395,10 +3398,10 @@ WARNING(objc_inference_swift3_objc_derived,none,
         "deprecated", ())
 
 NOTE(objc_inference_swift3_addobjc,none,
-     "add `@objc` to continue exposing an Objective-C entry point (Swift 3 "
+     "add '@objc' to continue exposing an Objective-C entry point (Swift 3 "
      "behavior)", ())
 NOTE(objc_inference_swift3_addnonobjc,none,
-     "add `@nonobjc` to suppress the Objective-C entry point (Swift 4 "
+     "add '@nonobjc' to suppress the Objective-C entry point (Swift 4 "
      "behavior)", ())
 
 ERROR(objc_for_generic_class,none,
@@ -3793,9 +3796,6 @@ ERROR(availability_protocol_requires_version,
 NOTE(availability_protocol_requirement_here, none,
      "protocol requirement here", ())
 
-NOTE(availability_conformance_introduced_here, none,
-     "conformance introduced here", ())
-
 // This doesn't display as an availability diagnostic, but it's
 // implemented there and fires when these subscripts are marked
 // unavailable, so it seems appropriate to put it here.

lib/AST/ASTContext.cpp

@@ -2250,6 +2250,9 @@ bool swift::fixDeclarationName(InFlightDiagnostic &diag, ValueDecl *decl,
 bool swift::fixDeclarationObjCName(InFlightDiagnostic &diag, ValueDecl *decl,
                                    Optional<ObjCSelector> targetNameOpt,
                                    bool ignoreImpliedName) {
+  if (decl->isImplicit())
+    return false;
+
   // Subscripts cannot be renamed, so handle them directly.
   if (isa<SubscriptDecl>(decl)) {
     diag.fixItInsert(decl->getAttributeInsertionLoc(/*forModifier=*/false),

lib/AST/Decl.cpp

@@ -2095,6 +2095,9 @@ bool ValueDecl::canInferObjCFromRequirement(ValueDecl *requirement) {
 }
 
 SourceLoc ValueDecl::getAttributeInsertionLoc(bool forModifier) const {
+  if (isImplicit())
+    return SourceLoc();
+
   if (auto var = dyn_cast<VarDecl>(this)) {
     // [attrs] var ...
     // The attributes are part of the VarDecl, but the 'var' is part of the PBD.

test/ClangImporter/objc_generics_conformance.swift

@@ -24,6 +24,16 @@ extension GenericClass : WithAssocOther {
   typealias Other = [T] // expected-error{{type 'GenericClass<T>.Other' involving Objective-C type parameter 'T' cannot be used for associated type 'Other' of protocol 'WithAssocOther'}}
 }
 
+protocol WithAssocSeparate {
+  associatedtype Separate
+}
+
+extension GenericClass {
+  typealias Separate = T // expected-note {{'Separate' declared here}}
+}
+extension GenericClass : WithAssocSeparate { // expected-error {{type 'GenericClass<T>.Separate' involving Objective-C type parameter 'T' cannot be used for associated type 'Separate' of protocol 'WithAssocSeparate'}}
+}
+
 protocol WithAssocElement {
   associatedtype Element
 }

test/Compatibility/accessibility_private.swift

@@ -118,18 +118,21 @@ protocol VeryImportantProto {
 }
 
 private struct VIPPrivateType : VeryImportantProto {
-  private typealias Assoc = Int // expected-error {{type alias 'Assoc' must be as accessible as its enclosing type because it matches a requirement in protocol 'VeryImportantProto'}}
+  private typealias Assoc = Int // expected-error {{type alias 'Assoc' must be as accessible as its enclosing type because it matches a requirement in protocol 'VeryImportantProto'}} {{none}}
+  // expected-note@-1 {{mark the type alias as 'fileprivate' to satisfy the requirement}} {{3-10=fileprivate}}
   var value: Int
 }
 
 private struct VIPPrivateProp : VeryImportantProto {
   typealias Assoc = Int
-  private var value: Int // expected-error {{property 'value' must be as accessible as its enclosing type because it matches a requirement in protocol 'VeryImportantProto'}} {{3-10=fileprivate}}
+  private var value: Int // expected-error {{property 'value' must be as accessible as its enclosing type because it matches a requirement in protocol 'VeryImportantProto'}} {{none}}
+  // expected-note@-1 {{mark the var as 'fileprivate' to satisfy the requirement}} {{3-10=fileprivate}}
 }
 
 private struct VIPPrivateSetProp : VeryImportantProto {
   typealias Assoc = Int
-  private(set) var value: Int // expected-error {{setter for property 'value' must be as accessible as its enclosing type because it matches a requirement in protocol 'VeryImportantProto'}} {{3-10=fileprivate}}
+  private(set) var value: Int // expected-error {{setter for property 'value' must be as accessible as its enclosing type because it matches a requirement in protocol 'VeryImportantProto'}} {{none}}
+  // expected-note@-1 {{mark the var as 'fileprivate' to satisfy the requirement}} {{3-10=fileprivate}}
 }
 
 private class VIPPrivateSetBase {
@@ -140,9 +143,11 @@ private class VIPPrivateSetSub : VIPPrivateSetBase, VeryImportantProto { // expe
 }
 
 private class VIPPrivateSetPropBase {
-  private(set) var value: Int = 0 // expected-error {{setter for property 'value' must be as accessible as its enclosing type because it matches a requirement in protocol 'VeryImportantProto'}} {{3-10=fileprivate}}
+  private(set) var value: Int = 0
+  // expected-note@-1 {{mark the var as 'fileprivate' to satisfy the requirement}} {{3-10=fileprivate}}
 }
 private class VIPPrivateSetPropSub : VIPPrivateSetPropBase, VeryImportantProto {
+  // expected-error@-1 {{setter for property 'value' must be as accessible as its enclosing type because it matches a requirement in protocol 'VeryImportantProto'}} {{none}}
   typealias Assoc = Int
 }
 

test/NameBinding/accessibility.swift

@@ -132,19 +132,22 @@ func privateInOtherFile() {}
 
 #if !ACCESS_DISABLED
 struct ConformerByTypeAlias : TypeProto {
-  private typealias TheType = Int // expected-error {{type alias 'TheType' must be declared internal because it matches a requirement in internal protocol 'TypeProto'}} {{3-10=internal}}
+  private typealias TheType = Int // expected-error {{type alias 'TheType' must be declared internal because it matches a requirement in internal protocol 'TypeProto'}} {{none}}
+  // expected-note@-1 {{mark the type alias as 'internal' to satisfy the requirement}} {{3-10=internal}}
 }
 
 struct ConformerByLocalType : TypeProto {
-  private struct TheType {} // expected-error {{struct 'TheType' must be declared internal because it matches a requirement in internal protocol 'TypeProto'}} {{3-10=internal}}
+  private struct TheType {} // expected-error {{struct 'TheType' must be declared internal because it matches a requirement in internal protocol 'TypeProto'}} {{none}}
+  // expected-note@-1 {{mark the struct as 'internal' to satisfy the requirement}} {{3-10=internal}}
 }
 
 private struct PrivateConformerByLocalType : TypeProto {
   struct TheType {} // okay
 }
 
 private struct PrivateConformerByLocalTypeBad : TypeProto {
-  private struct TheType {} // expected-error {{struct 'TheType' must be as accessible as its enclosing type because it matches a requirement in protocol 'TypeProto'}} {{3-10=fileprivate}}
+  private struct TheType {} // expected-error {{struct 'TheType' must be as accessible as its enclosing type because it matches a requirement in protocol 'TypeProto'}} {{none}}
+  // expected-note@-1 {{mark the struct as 'fileprivate' to satisfy the requirement}} {{3-10=fileprivate}}
 }
 #endif