NCGenerics: handle MoveOnlyClasses correctly

Author: kavon

lib/Sema/TypeCheckInvertible.cpp

@@ -441,8 +441,13 @@ ProtocolConformance *deriveConformanceForInvertible(Evaluator &evaluator,
   };
 
   switch (*ip) {
-  case InvertibleProtocolKind::Escapable:
   case InvertibleProtocolKind::Copyable:
+    // If move-only classes is enabled, we'll check the markings.
+    if (ctx.LangOpts.hasFeature(Feature::MoveOnlyClasses))
+      break;
+
+  LLVM_FALLTHROUGH;
+  case InvertibleProtocolKind::Escapable:
     // Always derive unconditional IP conformance for classes
     if (isa<ClassDecl>(nominal))
       return generateConformance(nominal);
@@ -462,8 +467,10 @@ ProtocolConformance *deriveConformanceForInvertible(Evaluator &evaluator,
     return nullptr; // No positive IP conformance will be inferred.
 
   case InverseMarking::Kind::Inferred:
-    return generateConditionalConformance();
+    if (!isa<ClassDecl>(nominal))
+      return generateConditionalConformance();
 
+  LLVM_FALLTHROUGH;
   case InverseMarking::Kind::None:
     // All types already start with conformances to the invertible protocols in
     // this case, within `NominalTypeDecl::prepareConformanceTable`.

test/Generics/inverse_classes1.swift

@@ -0,0 +1,19 @@
+// RUN: %target-typecheck-verify-swift \
+// RUN:   -parse-stdlib -module-name Swift \
+// RUN:   -enable-experimental-feature MoveOnlyClasses \
+// RUN:   -enable-experimental-feature NoncopyableGenerics
+
+// NOTE: -parse-stdlib is a transitional workaround and should not be required.
+
+@_moveOnly
+class KlassLegacy {}
+
+class KlassModern: ~Copyable {}
+
+class Konditional<T: ~Copyable> {}
+
+func checks<T: ~Copyable, C>(
+          _ a: KlassLegacy, // expected-error {{parameter of noncopyable type 'KlassLegacy' must specify ownership}} // expected-note 3{{add}}
+          _ b: KlassModern, // expected-error {{parameter of noncopyable type 'KlassModern' must specify ownership}} // expected-note 3{{add}}
+          _ c: Konditional<T>,
+          _ d: Konditional<C>) {}

test/Generics/inverse_classes2.swift

@@ -0,0 +1,18 @@
+// RUN: %target-typecheck-verify-swift \
+// RUN:   -parse-stdlib -module-name Swift \
+// RUN:   -enable-experimental-feature NoncopyableGenerics
+
+// NOTE: -parse-stdlib is a transitional workaround and should not be required.
+
+@_moveOnly // expected-error {{'@_moveOnly' attribute is only valid on structs or enums}}
+class KlassLegacy {}
+
+class KlassModern: ~Copyable {} // expected-error {{classes cannot be '~Copyable'}}
+
+class Konditional<T: ~Copyable> {}
+
+func checks<T: ~Copyable, C>(
+          _ a: KlassLegacy,
+          _ b: KlassModern,
+          _ c: Konditional<T>,
+          _ d: Konditional<C>) {}