Merge pull request #38534 from jckarter/key-path-private-set-visibility-public-5.5

[5.5] SIL: Private setters need at least hidden visibility for key paths in more cases.

Author: jckarter

lib/SIL/IR/SILDeclRef.cpp

@@ -367,12 +367,12 @@ SILLinkage SILDeclRef::getLinkage(ForDefinition_t forDefinition) const {
   auto effectiveAccess = d->getEffectiveAccess();
 
   // Private setter implementations for an internal storage declaration should
-  // be internal as well, so that a dynamically-writable
-  // keypath can be formed from other files.
+  // be at least internal as well, so that a dynamically-writable
+  // keypath can be formed from other files in the same module.
   if (auto accessor = dyn_cast<AccessorDecl>(d)) {
     if (accessor->isSetter()
-       && accessor->getStorage()->getEffectiveAccess() == AccessLevel::Internal)
-      effectiveAccess = AccessLevel::Internal;
+       && accessor->getStorage()->getEffectiveAccess() >= AccessLevel::Internal)
+      effectiveAccess = std::max(effectiveAccess, AccessLevel::Internal);
   }
 
   switch (effectiveAccess) {

test/SILGen/accessors_testing.swift

@@ -0,0 +1,27 @@
+// RUN: %target-swift-emit-silgen -parse-as-library -module-name accessors %s | %FileCheck %s
+// RUN: %target-swift-emit-silgen -parse-as-library -enable-testing -module-name accessors %s | %FileCheck %s
+
+// rdar://78523318: Ensure that private(set) accessors for internal or more
+// visible properties have hidden linkage, because other code inside the module
+// needs to reference the setter to form a key path.
+
+public struct Foo {
+    // CHECK-LABEL: sil hidden [ossa] @$s9accessors3FooV6internSivs
+    private(set) internal var intern: Int {
+        get { return 0 }
+        set {}
+    }
+    // CHECK-LABEL: sil hidden [ossa] @$s9accessors3FooV3pubSivs
+    private(set) public var pub: Int {
+        get { return 0 }
+        set {}
+    }
+
+    public mutating func exercise() {
+        _ = intern
+        _ = pub
+        intern = 0
+        pub = 0
+    }
+}
+