Revert "Fix a Family of Crashers in Availability Checking"

This reverts commit ae711a7.

Author: CodaFi

lib/Sema/TypeCheckAvailability.cpp

@@ -147,11 +147,7 @@ static void computeExportContextBits(ASTContext &Ctx, Decl *D,
   if (D->isSPI())
     *spi = true;
 
-  // Defer bodies are desugared to an implicit closure expression. We need to
-  // dilute the meaning of "implicit" to make sure we're still checking
-  // availability inside of defer statements.
-  const auto isDeferBody = isa<FuncDecl>(D) && cast<FuncDecl>(D)->isDeferBody();
-  if (D->isImplicit() && !isDeferBody)
+  if (D->isImplicit())
     *implicit = true;
 
   if (D->getAttrs().getDeprecated(Ctx))

test/Sema/availability.swift

@@ -195,32 +195,3 @@ struct VarToFunc {
   }
 }
 
-struct DeferBody {
-  func foo() {
-    enum No: Error {
-      case no
-    }
-
-    defer {
-      do {
-        throw No.no
-      } catch No.no {
-      } catch {
-      }
-    }
-    _ = ()
-  }
-
-  func bar() {
-    @available(*, unavailable)
-    enum No: Error { // expected-note 2 {{'No' has been explicitly marked unavailable here}}
-      case no
-    }
-    do {
-      throw No.no
-      // expected-error@-1 {{'No' is unavailable}}
-    } catch No.no {} catch _ {}
-    // expected-error@-1 {{'No' is unavailable}}
-  }
-}
-

test/attr/attr_inlinable.swift

@@ -357,12 +357,3 @@ public struct PrivateInlinableCrash {
     // expected-error@-2 {{initializer 'init()' is private and cannot be referenced from an '@inlinable' function}}
   }
 }
-
-// Just make sure we don't crash.
-private func deferBodyTestCall() {} // expected-note {{global function 'deferBodyTestCall()' is not '@usableFromInline' or public}}
-@inlinable public func deferBodyTest() {
-  defer {
-    deferBodyTestCall() // expected-error {{global function 'deferBodyTestCall()' is private and cannot be referenced from an '@inlinable' function}}
-  }
-  _ = ()
-}