From 4a3fbb01850d0140e8406e7adc8675d18608df12 Mon Sep 17 00:00:00 2001
From: Minhyuk Kim <kimminhyuk1004@gmail.com>
Date: Mon, 16 Aug 2021 15:58:31 +0900
Subject: [PATCH] Modify diagnostics to suggest updating existing available
 attribute

---
 include/swift/AST/DiagnosticsSema.def            |  2 ++
 lib/Sema/TypeCheckAvailability.cpp               |  6 ++++--
 .../attr_main_struct_available_future.swift      |  3 +--
 test/attr/attr_availability_osx.swift            | 16 +++++++++++++---
 4 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/include/swift/AST/DiagnosticsSema.def b/include/swift/AST/DiagnosticsSema.def
index 4af092ddb775b..17d0ff704cb18 100644
--- a/include/swift/AST/DiagnosticsSema.def
+++ b/include/swift/AST/DiagnosticsSema.def
@@ -5327,6 +5327,8 @@ NOTE(availability_guard_with_version_check, none,
 
 NOTE(availability_add_attribute, none,
      "add @available attribute to enclosing %0", (DescriptiveDeclKind))
+NOTE(availability_update_attribute, none,
+     "update existing @available attribute", ())
 FIXIT(insert_available_attr,
       "@available(%0 %1, *)\n%2",
       (StringRef, StringRef, StringRef))
diff --git a/lib/Sema/TypeCheckAvailability.cpp b/lib/Sema/TypeCheckAvailability.cpp
index aa6262c0f8dd4..5789197ab0fa8 100644
--- a/lib/Sema/TypeCheckAvailability.cpp
+++ b/lib/Sema/TypeCheckAvailability.cpp
@@ -1453,8 +1453,10 @@ static void fixAvailabilityForDecl(SourceRange ReferenceRange, const Decl *D,
   if (TypeChecker::diagnosticIfDeclCannotBePotentiallyUnavailable(D).hasValue())
     return;
 
-  if (getActiveAvailableAttribute(D, Context)) {
-    // For QoI, in future should emit a fixit to update the existing attribute.
+  if (auto *attr = getActiveAvailableAttribute(D, Context)) {
+    D->diagnose(diag::availability_update_attribute)
+        .fixItReplace(attr->IntroducedRange,
+                      RequiredRange.getLowerEndpoint().getAsString());
     return;
   }
 
diff --git a/test/attr/ApplicationMain/attr_main_struct_available_future.swift b/test/attr/ApplicationMain/attr_main_struct_available_future.swift
index 5d36cda72d3c9..9c20d6ebbdef7 100644
--- a/test/attr/ApplicationMain/attr_main_struct_available_future.swift
+++ b/test/attr/ApplicationMain/attr_main_struct_available_future.swift
@@ -3,8 +3,7 @@
 // REQUIRES: OS=macosx
 
 @main // expected-error {{'main()' is only available in macOS 10.99 or newer}}
-@available(OSX 10.0, *)
-struct EntryPoint {
+@available(OSX 10.0, *) struct EntryPoint { // expected-note {{update existing @available attribute}} {{16-20=10.99}} 
   @available(OSX 10.99, *)
   static func main() {
   }
diff --git a/test/attr/attr_availability_osx.swift b/test/attr/attr_availability_osx.swift
index 4b44cf87981c4..ecaee9dbf902f 100644
--- a/test/attr/attr_availability_osx.swift
+++ b/test/attr/attr_availability_osx.swift
@@ -100,12 +100,14 @@ extension TestStruct { // expected-note {{enclosing scope here}}
   @available(swift 1)
   func doFourthThing() {}
 
+  @available(macOS 10.12, iOS 13, tvOS 13, *)
+  func doFifthThing() {}
+
   @available(*, deprecated)
   func doDeprecatedThing() {}
 }
 
-@available(macOS 10.11, *)
-func testMemberAvailability() {
+@available(macOS 10.11, *) func testMemberAvailability() { // expected-note {{update existing @available attribute}} {{18-23=10.12}}
   TestStruct().doTheThing() // expected-error {{'doTheThing()' is unavailable}}
   TestStruct().doAnotherThing() // expected-error {{'doAnotherThing()' is unavailable}}
   TestStruct().doThirdThing() // expected-error {{'doThirdThing()' is unavailable}}
@@ -113,6 +115,14 @@ func testMemberAvailability() {
   TestStruct().doDeprecatedThing() // expected-warning {{'doDeprecatedThing()' is deprecated}}
 }
 
+@available(iOS 11, macOS 10.11, *) func testUpdateAvailabilityAttribute() { // expected-note {{update existing @available attribute}} {{26-31=10.12}}
+  TestStruct().doFifthThing() // expected-error {{'doFifthThing()' is only available in macOS 10.12 or newer}} expected-note {{'if #available'}}
+}
+
+@available(macOS, introduced: 10.11) func testUpdateAvailabilityAttribute2() { // expected-note {{update existing @available attribute}} {{31-36=10.12}}
+  TestStruct().doFifthThing() // expected-error {{'doFifthThing()' is only available in macOS 10.12 or newer}} expected-note {{'if #available'}}
+}
+
 extension TestStruct {
   struct Data {
     mutating func mutate() {}
@@ -208,4 +218,4 @@ extension UnavailableStruct { } // no-error
 #if os(macOS)
 @available(macOS, unavailable)
 extension UnavailableStruct { } // no-error
-#endif
+#endif
\ No newline at end of file