Sema: Check reference to implicitly-generated super.init() call from inlinable context

Fixes <https://bugs.swift.org/browse/SR-10940>.

Author: slavapestov

Diff for: lib/Sema/TypeCheckStmt.cpp

@@ -15,6 +15,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "TypeChecker.h"
+#include "TypeCheckAvailability.h"
 #include "TypeCheckType.h"
 #include "MiscDiagnostics.h"
 #include "ConstraintSystem.h"
@@ -2050,8 +2051,19 @@ static bool checkSuperInit(TypeChecker &tc, ConstructorDecl *fromCtor,
       // super.init() call.
       return true;
     }
+
+    // Make sure we can reference the designated initializer correctly.
+    if (fromCtor->getResilienceExpansion() == ResilienceExpansion::Minimal) {
+      TypeChecker::FragileFunctionKind fragileKind;
+      bool treatUsableFromInlineAsPublic;
+      std::tie(fragileKind, treatUsableFromInlineAsPublic) =
+        tc.getFragileFunctionKind(fromCtor);
+      tc.diagnoseInlinableDeclRef(
+          fromCtor->getLoc(), ctor, fromCtor, fragileKind,
+          treatUsableFromInlineAsPublic);
+    }
   }
-  
+
   return false;
 }
 

Diff for: test/attr/attr_inlinable.swift

@@ -167,6 +167,7 @@ enum InternalEnum {
   _ = VersionedEnum.persimmon
 }
 
+
 // Inherited initializers - <rdar://problem/34398148>
 @usableFromInline
 @_fixed_layout
@@ -188,6 +189,7 @@ class Derived : Middle {
   }
 }
 
+
 // More inherited initializers
 @_fixed_layout
 public class Base2 {
@@ -208,6 +210,36 @@ class Derived2 : Middle2 {
   }
 }
 
+
+// Even more inherited initializers - https://bugs.swift.org/browse/SR-10940
+@_fixed_layout
+public class Base3 {}
+// expected-note@-1 {{initializer 'init()' is not '@usableFromInline' or public}}
+
+@_fixed_layout
+public class Derived3 : Base3 {
+  @inlinable
+  public init(_: Int) {}
+  // expected-error@-1 {{initializer 'init()' is internal and cannot be referenced from an '@inlinable' function}}
+}
+
+@_fixed_layout
+public class Base4 {}
+
+@_fixed_layout
+@usableFromInline
+class Middle4 : Base4 {}
+// expected-note@-1 {{initializer 'init()' is not '@usableFromInline' or public}}
+
+@_fixed_layout
+@usableFromInline
+class Derived4 : Middle4 {
+  @inlinable
+  public init(_: Int) {}
+  // expected-error@-1 {{initializer 'init()' is internal and cannot be referenced from an '@inlinable' function}}
+}
+
+
 // Stored property initializer expressions.
 //
 // Note the behavior here does not depend on the state of the -enable-library-evolution