From 429f19a4b6b953de79aa9dc4e741772a0bad3ecd Mon Sep 17 00:00:00 2001
From: Allan Shortlidge <shortlidge@apple.com>
Date: Wed, 21 Sep 2022 18:24:52 -0700
Subject: [PATCH 1/2] Revert "[ConstraintSystem] Extend availability check to
 cover unavailable extensions."

This reverts commit 6de6de2e3a51741a047a9ec17ea33f4ea9d1ac24.
---
 lib/Sema/ConstraintSystem.cpp       |  2 +-
 test/Constraints/availability.swift | 22 ----------------------
 2 files changed, 1 insertion(+), 23 deletions(-)

diff --git a/lib/Sema/ConstraintSystem.cpp b/lib/Sema/ConstraintSystem.cpp
index 1558ddd586cff..69316147bfd3d 100644
--- a/lib/Sema/ConstraintSystem.cpp
+++ b/lib/Sema/ConstraintSystem.cpp
@@ -6540,7 +6540,7 @@ void ConstraintSystem::diagnoseFailureFor(SolutionApplicationTarget target) {
 bool ConstraintSystem::isDeclUnavailable(const Decl *D,
                                          ConstraintLocator *locator) const {
   // First check whether this declaration is universally unavailable.
-  if (AvailableAttr::isUnavailable(D))
+  if (D->getAttrs().isUnavailable(getASTContext()))
     return true;
 
   return TypeChecker::isDeclarationUnavailable(D, DC, [&] {
diff --git a/test/Constraints/availability.swift b/test/Constraints/availability.swift
index 633724f168c33..2b8be52b55bc8 100644
--- a/test/Constraints/availability.swift
+++ b/test/Constraints/availability.swift
@@ -43,25 +43,3 @@ func unavailableFunction(_ x: Int) -> Bool { true } // expected-note {{'unavaila
 func f_55700(_ arr: [Int]) {
   for x in arr where unavailableFunction(x) {} // expected-error {{'unavailableFunction' is unavailable}}
 }
-
-// rdar://92364955 - ambiguity with member declared in unavailable extension
- struct WithUnavailableExt {
- }
-
- @available(*, unavailable)
- extension WithUnavailableExt {
-   static var foo: WithUnavailableExt = WithUnavailableExt()
- }
-
- func test_no_ambiguity_with_unavailable_ext() {
-   struct A {
-     static var foo: A = A()
-   }
-
-   struct Test {
-     init(_: A) {}
-     init(_: WithUnavailableExt) {}
-   }
-
-   _ = Test(.foo) // Ok `A.foo` since `foo` from `WithUnavailableExt` is unavailable
- }

From cddd86f709566d53e6e3a9a169425f5482893141 Mon Sep 17 00:00:00 2001
From: Allan Shortlidge <shortlidge@apple.com>
Date: Tue, 1 Nov 2022 17:17:01 -0700
Subject: [PATCH 2/2] ConstraintSystem: Add a test case for rdar://101814209.

---
 test/Constraints/availability.swift | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/test/Constraints/availability.swift b/test/Constraints/availability.swift
index 2b8be52b55bc8..6b134d67a350f 100644
--- a/test/Constraints/availability.swift
+++ b/test/Constraints/availability.swift
@@ -43,3 +43,24 @@ func unavailableFunction(_ x: Int) -> Bool { true } // expected-note {{'unavaila
 func f_55700(_ arr: [Int]) {
   for x in arr where unavailableFunction(x) {} // expected-error {{'unavailableFunction' is unavailable}}
 }
+
+// rdar://101814209
+public struct Box<T> {
+  @usableFromInline
+  let value: T
+}
+
+@available(macOS, unavailable)
+extension Box where T == Int {
+  @usableFromInline
+  init(value: T) {
+    self.value = value
+  }
+}
+
+@available(macOS, unavailable)
+@_alwaysEmitIntoClient public func aeicFunction() {
+  // Select the unavailable @usableFromInline init over the synthesized internal
+  // memberwise initializer.
+  _ = Box(value: 42)
+}