Use access scopes instead of adjustAccessLevelForProtocolExtension

This gets adjustAccessLevelForProtocolExtension, a hack of sorts to
begin with, out of ValueDecl's general API, and down to a helper for
isAccessibleFrom and isSetterAccessibleFrom. (The only reason these
two don't go through access scopes is as an optimization.)

Author: jrose-apple

include/swift/AST/Decl.h

@@ -2356,18 +2356,6 @@ class ValueDecl : public Decl {
   /// \sa hasOpenAccess
   AccessLevel getFormalAccess() const;
 
-  /// If this declaration is a member of a protocol extension, return the
-  /// minimum of the given access level and the protocol's access level.
-  ///
-  /// Otherwise, return the given access level unmodified.
-  ///
-  /// This is used when checking name lookup visibility. Protocol extension
-  /// members can be found when performing name lookup on a concrete type;
-  /// if the concrete type is visible from the lookup context but the
-  /// protocol is not, we do not want the protocol extension members to be
-  /// visible.
-  AccessLevel adjustAccessLevelForProtocolExtension(AccessLevel access) const;
-
   /// Determine whether this Decl has either Private or FilePrivate access,
   /// and its DeclContext does not.
   bool isOutermostPrivateOrFilePrivateScope() const;

lib/AST/NameLookup.cpp

@@ -1520,9 +1520,9 @@ void ClassDecl::recordObjCMethod(AbstractFunctionDecl *method) {
   vec.push_back(method);
 }
 
-AccessLevel
-ValueDecl::adjustAccessLevelForProtocolExtension(AccessLevel access) const {
-  if (auto *ext = dyn_cast<ExtensionDecl>(getDeclContext())) {
+static AccessLevel
+adjustAccessLevelForProtocolExtension(const ValueDecl *VD, AccessLevel access) {
+  if (auto *ext = dyn_cast<ExtensionDecl>(VD->getDeclContext())) {
     if (auto *protocol = ext->getAsProtocolOrProtocolExtensionContext()) {
       // Note: it gets worse. The standard library has public methods
       // in protocol extensions of a @usableFromInline internal protocol,
@@ -1549,7 +1549,7 @@ static bool checkAccess(const DeclContext *useDC, const ValueDecl *VD,
   auto *sourceDC = VD->getDeclContext();
 
   if (!forConformance)
-    access = VD->adjustAccessLevelForProtocolExtension(access);
+    access = adjustAccessLevelForProtocolExtension(VD, access);
 
   switch (access) {
   case AccessLevel::Private:

lib/Sema/CSDiag.cpp

@@ -1662,8 +1662,7 @@ diagnoseUnviableLookupResults(MemberLookupResult &result, Type baseObjTy,
       // clamp the formal access for diagnostics purposes to the formal access
       // of the protocol itself.
       diagnose(nameLoc, diag::candidate_inaccessible, decl->getBaseName(),
-               decl->adjustAccessLevelForProtocolExtension(
-                 decl->getFormalAccess()));
+               decl->getFormalAccessScope().accessLevelForDiagnostics());
       for (auto cand : result.UnviableCandidates)
         diagnose(cand.first.getDecl(), diag::decl_declared_here, memberName);
 

lib/Sema/TypeCheckConstraints.cpp

@@ -540,8 +540,7 @@ resolveDeclRefExpr(UnresolvedDeclRefExpr *UDRE, DeclContext *DC) {
       // FIXME: What if the unviable candidates have different levels of access?
       const ValueDecl *first = inaccessibleResults.front().getValueDecl();
       diagnose(Loc, diag::candidate_inaccessible, Name,
-               first->adjustAccessLevelForProtocolExtension(
-                   first->getFormalAccess()));
+               first->getFormalAccessScope().accessLevelForDiagnostics());
 
       // FIXME: If any of the candidates (usually just one) are in the same
       // module we could offer a fix-it.

test/Sema/Inputs/accessibility_multi_other.swift

@@ -8,7 +8,7 @@ struct Members {
   }
 }
 
-struct PrivateConformance : PrivateProtocol {}
+struct PrivateConformance : PrivateProtocol, FilePrivateProtocol {}
 
 private protocol PrivateProtocol {}
 
@@ -19,3 +19,13 @@ extension PrivateProtocol {
   internal func internalExtensionMember() {}
   // expected-note@-1 {{'internalExtensionMember' declared here}}
 }
+
+fileprivate protocol FilePrivateProtocol {}
+
+extension FilePrivateProtocol {
+  public func publicFPExtensionMember() {}
+  // expected-note@-1 {{'publicFPExtensionMember' declared here}}
+
+  internal func internalFPExtensionMember() {}
+  // expected-note@-1 {{'internalFPExtensionMember' declared here}}
+}

test/Sema/Inputs/accessibility_multi_other_module.swift

@@ -1,4 +1,4 @@
-public struct PrivateConformance : PrivateProtocol {}
+public struct PrivateConformance : PrivateProtocol, FilePrivateProtocol {}
 
 private protocol PrivateProtocol {}
 
@@ -8,6 +8,17 @@ extension PrivateProtocol {
   internal func internalExtensionMember() {}
 }
 
+fileprivate protocol FilePrivateProtocol {}
+
+extension FilePrivateProtocol {
+  public func publicFPExtensionMember() {}
+  // expected-note@-1 {{'publicFPExtensionMember' declared here}}
+
+  internal func internalFPExtensionMember() {}
+  // expected-note@-1 {{'internalFPExtensionMember' declared here}}
+}
+
+
 public struct InternalConformance : InternalProtocol {}
 
 internal protocol InternalProtocol {}

test/Sema/accessibility_multi.swift

@@ -24,8 +24,14 @@ func testSubscript(_ instance: Members) {
 
 func testPrivateConformance(_ instance: PrivateConformance) {
   instance.publicExtensionMember()
-  // expected-error@-1 {{'publicExtensionMember' is inaccessible due to 'fileprivate' protection level}}
+  // expected-error@-1 {{'publicExtensionMember' is inaccessible due to 'private' protection level}}
 
   instance.internalExtensionMember()
-  // expected-error@-1 {{'internalExtensionMember' is inaccessible due to 'fileprivate' protection level}}
+  // expected-error@-1 {{'internalExtensionMember' is inaccessible due to 'private' protection level}}
+
+  instance.publicFPExtensionMember()
+  // expected-error@-1 {{'publicFPExtensionMember' is inaccessible due to 'fileprivate' protection level}}
+
+  instance.internalFPExtensionMember()
+  // expected-error@-1 {{'internalFPExtensionMember' is inaccessible due to 'fileprivate' protection level}}
 }

test/Sema/accessibility_multi_module.swift

@@ -6,10 +6,16 @@ import accessibility_multi_other_module
 
 func testPrivateConformance(_ instance: PrivateConformance) {
   instance.publicExtensionMember()
-  // expected-error@-1 {{'publicExtensionMember' is inaccessible due to 'fileprivate' protection level}}
+  // expected-error@-1 {{'publicExtensionMember' is inaccessible due to 'private' protection level}}
 
   instance.internalExtensionMember()
-  // expected-error@-1 {{'internalExtensionMember' is inaccessible due to 'fileprivate' protection level}}
+  // expected-error@-1 {{'internalExtensionMember' is inaccessible due to 'private' protection level}}
+
+  instance.publicFPExtensionMember()
+  // expected-error@-1 {{'publicFPExtensionMember' is inaccessible due to 'fileprivate' protection level}}
+
+  instance.internalFPExtensionMember()
+  // expected-error@-1 {{'internalFPExtensionMember' is inaccessible due to 'fileprivate' protection level}}
 }
 
 func testInternalConformance(_ instance: InternalConformance) {