Diagnosing a private setter being accessed from the inlinable function.

rdar://81879146

Author: sepy97

lib/Sema/ResilienceDiagnostics.cpp

@@ -78,6 +78,20 @@ bool TypeChecker::diagnoseInlinableDeclRefAccess(SourceLoc loc,
   // Remember that the module defining the decl must be imported publicly.
   recordRequiredImportAccessLevelForDecl(D, DC, AccessLevel::Public, loc);
 
+  // Accessing a private setter from inlinable function is deprecated
+  if (auto *accessor = dyn_cast<AccessorDecl>(D)) {
+    if (accessor->getAccessorKind() == AccessorKind::Set &&
+        accessor->getFormalAccess() == AccessLevel::Private) {
+      auto *storage = accessor->getStorage();
+      if (storage->getAttrs().hasAttribute<UsableFromInlineAttr>()) {
+        auto diagID = diag::resilience_decl_unavailable;
+        Context.Diags.diagnose(loc, diagID, D, accessor->getFormalAccess(),
+                               fragileKind.getSelector());
+        Context.Diags.diagnose(D, diag::resilience_decl_declared_here, D);
+      }
+    }
+  }
+
   // General check on access-level of the decl.
   auto declAccessScope =
       D->getFormalAccessScope(/*useDC=*/DC,

test/attr/attr_inlinable.swift

@@ -314,6 +314,17 @@ public struct HasInternalSetProperty {
   }
 }
 
+public struct HasUsableFromInlinePrivateSetProperty {
+  @usableFromInline private(set) var bytes: UnsafeMutableRawPointer // expected-note {{setter for property 'bytes' is not '@usableFromInline' or public}}
+  public init() {
+      self.bytes = UnsafeMutableRawPointer.allocate(byteCount: 1024, alignment: 8)
+  }
+  @inlinable
+  public mutating func resetPointer() {
+      self.bytes = UnsafeMutableRawPointer.allocate(byteCount: 2048, alignment: 8) // expected-error {{setter for property 'bytes' is private and cannot be referenced from an '@inlinable' function}}
+  }
+}
+
 @usableFromInline protocol P {
   typealias T = Int
 }