[Sema] Require availability for inits and subscripts in extensions

Author: xymus

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -1685,6 +1685,8 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
 
     checkAccessControl(SD);
 
+    checkExplicitAvailability(SD);
+
     if (!checkOverrides(SD)) {
       // If a subscript has an override attribute but does not override
       // anything, complain.
@@ -2644,6 +2646,8 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
 
     checkAccessControl(CD);
 
+    checkExplicitAvailability(CD);
+
     if (requiresDefinition(CD) && !CD->hasBody()) {
       // Complain if we should have a body.
       CD->diagnose(diag::missing_initializer_def);

test/attr/require_explicit_availability.swift

@@ -137,3 +137,30 @@ public var computedOk1: S {
   get { return S() }
   set { }
 }
+
+public class SomeClass { // expected-warning {{public declarations should have an availability attribute when building with -require-explicit-availability}} {{1-1=@available(macOS 10.10, *)\n}}
+  public init () {}
+
+  public subscript(index: String) -> Int {
+    get { return 42; }
+    set(newValue) { }
+  }
+}
+
+extension SomeClass { // expected-warning {{public declarations should have an availability attribute when building with -require-explicit-availability}} {{1-1=@available(macOS 10.10, *)\n}}
+  public convenience init(s : S) {} // expected-warning {{public declarations should have an availability attribute when building with -require-explicit-availability}} {{3-3=@available(macOS 10.10, *)\n  }}
+
+  @available(macOS 10.10, *)
+  public convenience init(s : SomeClass) {}
+
+  public subscript(index: Int) -> Int { // expected-warning {{public declarations should have an availability attribute when building with -require-explicit-availability}} {{3-3=@available(macOS 10.10, *)\n  }}
+    get { return 42; }
+    set(newValue) { }
+  }
+
+  @available(macOS 10.10, *)
+  public subscript(index: S) -> Int {
+    get { return 42; }
+    set(newValue) { }
+  }
+}