Diagnose resilient properties in objcImpl

…when the deployment target is not high enough to support them.

Author: beccadax

include/swift/AST/DiagnosticsIRGen.def

@@ -69,5 +69,11 @@ NOTE(layout_strings_blocked,none,
      "Layout string value witnesses have been disabled for module '%0' "
      "through block list entry", (StringRef))
 
+ERROR(attr_objc_implementation_resilient_property_unsupported, none,
+      "'@implementation' on %0 %1 does not support stored properties whose "
+      "size can change due to library evolution; raise the minimum deployment "
+      "target to %0 %2 or store this value in an object or 'any' type",
+      (StringRef, const llvm::VersionTuple, const llvm::VersionTuple))
+
 #define UNDEFINE_DIAGNOSTIC_MACROS
 #include "DefineDiagnosticMacros.h"

include/swift/AST/FeatureAvailability.def

@@ -75,6 +75,7 @@ FEATURE(TaskExecutor,                                   FUTURE)
 FEATURE(Differentiation,                                FUTURE)
 FEATURE(InitRawStructMetadata,                          FUTURE)
 FEATURE(ClearSensitive,                                 FUTURE)
+FEATURE(UpdatePureObjCClassMetadata,                    FUTURE)
 
 #undef FEATURE
 #undef FUTURE

lib/IRGen/GenMeta.cpp

@@ -5057,13 +5057,81 @@ static void emitObjCClassSymbol(IRGenModule &IGM, ClassDecl *classDecl,
       .to(alias, link.isForDefinition());
 }
 
+/// Check whether the metadata update strategy requires runtime support that is
+/// not guaranteed available by the minimum deployment target, and diagnose if
+/// so.
+static void
+diagnoseUnsupportedObjCImplLayout(IRGenModule &IGM, ClassDecl *classDecl,
+                                  const ClassLayout &fragileLayout) {
+  if (!fragileLayout.hasObjCImplementation())
+    return;
+
+  auto strategy = IGM.getClassMetadataStrategy(classDecl);
+
+  switch (strategy) {
+  case ClassMetadataStrategy::Fixed:
+    // Fixed is just fine; no special support needed.
+    break;
+
+  case ClassMetadataStrategy::FixedOrUpdate:
+  case ClassMetadataStrategy::Update: {
+    auto &ctx = IGM.Context;
+
+    // Update and FixedOrUpdate require support in both the Swift and ObjC
+    // runtimes.
+    auto requiredAvailability=ctx.getUpdatePureObjCClassMetadataAvailability();
+    // FIXME: Take the class's availability into account
+    auto currentAvailability = AvailabilityContext::forDeploymentTarget(ctx);
+    if (currentAvailability.isContainedIn(requiredAvailability))
+      break;
+
+    // We don't have the support we need. Find and diagnose the variable-size
+    // stored properties.
+    auto &diags = ctx.Diags;
+
+    bool diagnosed = false;
+    forEachField(IGM, classDecl, [&](Field field) {
+      auto elemLayout = fragileLayout.getFieldAccessAndElement(field).second;
+      if (field.getKind() != Field::Kind::Var ||
+            elemLayout.getType().isFixedSize())
+        return;
+
+      diags.diagnose(
+          field.getVarDecl(),
+          diag::attr_objc_implementation_resilient_property_unsupported,
+          prettyPlatformString(targetPlatform(ctx.LangOpts)),
+          currentAvailability.getOSVersion().getLowerEndpoint(),
+          requiredAvailability.getOSVersion().getLowerEndpoint());
+      diagnosed = true;
+    });
+
+    // We should have found at least one property to complain about.
+    if (diagnosed)
+      break;
+
+    LLVM_FALLTHROUGH;
+  }
+
+  case ClassMetadataStrategy::Singleton:
+  case ClassMetadataStrategy::Resilient:
+    // This isn't supposed to happen, but just in case, let's give some sort of
+    // vaguely legible output instead of using llvm_unreachable().
+    IGM.error(classDecl->getLoc(),
+              llvm::Twine("class '") + classDecl->getBaseIdentifier().str() +
+              "' needs a metadata strategy not supported by @implementation");
+    break;
+  }
+}
+
 /// Emit the type metadata or metadata template for a class.
 void irgen::emitClassMetadata(IRGenModule &IGM, ClassDecl *classDecl,
                               const ClassLayout &fragileLayout,
                               const ClassLayout &resilientLayout) {
   assert(!classDecl->isForeign());
   PrettyStackTraceDecl stackTraceRAII("emitting metadata for", classDecl);
 
+  diagnoseUnsupportedObjCImplLayout(IGM, classDecl, fragileLayout);
+
   emitFieldOffsetGlobals(IGM, classDecl, fragileLayout, resilientLayout);
 
   // Set up a dummy global to stand in for the metadata object while we produce

test/IRGen/objc_implementation.swift

@@ -1,7 +1,7 @@
 // Test doesn't pass on all platforms (rdar://101420862)
 // REQUIRES: OS=macosx
 
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-experimental-feature CImplementation -I %S/Inputs/abi -F %clang-importer-sdk-path/frameworks %s -import-objc-header %S/Inputs/objc_implementation.h -emit-ir > %t.ir
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -enable-experimental-feature CImplementation -I %S/Inputs/abi -F %clang-importer-sdk-path/frameworks %s -import-objc-header %S/Inputs/objc_implementation.h -emit-ir -target %target-future-triple > %t.ir
 // RUN: %FileCheck --input-file %t.ir %s
 // RUN: %FileCheck --input-file %t.ir --check-prefix NEGATIVE %s
 // REQUIRES: objc_interop
@@ -17,7 +17,7 @@
 
 // Metaclass
 // CHECK: @"OBJC_METACLASS_$_ImplClass" = global %objc_class { ptr @"OBJC_METACLASS_$_NSObject", ptr @"OBJC_METACLASS_$_NSObject", ptr @_objc_empty_cache, ptr null, {{.*}}ptr [[_METACLASS_DATA_ImplClass:@[^, ]+]]{{.*}}, align 8
-// CHECK: @_PROTOCOLS_ImplClass = internal constant { i64, [2 x ptr] } { i64 2, [2 x ptr] [ptr @_PROTOCOL_NSCopying, ptr @_PROTOCOL_NSMutableCopying] }, section "__DATA, __objc_const", align 8
+// CHECK: @_PROTOCOLS_ImplClass = internal constant { i64, [2 x ptr] } { i64 2, [2 x ptr] [ptr @"_OBJC_PROTOCOL_$_NSCopying", ptr @"_OBJC_PROTOCOL_$_NSMutableCopying"] }, section "__DATA, __objc_const", align 8
 // CHECK: [[_METACLASS_DATA_ImplClass]] = internal constant { i32, i32, i32, i32, ptr, ptr, ptr, ptr, ptr, ptr, ptr } { i32 129, i32 40, i32 40, i32 0, ptr null, ptr @.str.9.ImplClass, ptr null, ptr @_PROTOCOLS_ImplClass, ptr null, ptr null, ptr null }, section "__DATA, __objc_const", align 8
 // TODO: Why the extra i32 field above?
 
@@ -121,7 +121,7 @@
 // CHECK: @"$s19objc_implementationMXM" = linkonce_odr hidden constant <{ i32, i32, i32 }> <{ i32 0, i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @.str.19.objc_implementation to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32 }>, ptr @"$s19objc_implementationMXM", i32 0, i32 2) to i64)) to i32) }>, section "__TEXT,__constg_swiftt", align 4
 // CHECK: @"symbolic So9ImplClassC" = linkonce_odr hidden constant <{ [13 x i8], i8 }> <{ [13 x i8] c"So9ImplClassC", i8 0 }>, section "__TEXT,__swift5_typeref, regular"{{.*}}, align 2
 // CHECK: @"$s19objc_implementation13SwiftSubclassCMn" = constant <{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }> <{ i32 80, i32 trunc (i64 sub (i64 ptrtoint (ptr @"$s19objc_implementationMXM" to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }>, ptr @"$s19objc_implementation13SwiftSubclassCMn", i32 0, i32 1) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @.str.13.SwiftSubclass to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }>, ptr @"$s19objc_implementation13SwiftSubclassCMn", i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @"$s19objc_implementation13SwiftSubclassCMa" to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }>, ptr @"$s19objc_implementation13SwiftSubclassCMn", i32 0, i32 3) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @"$s19objc_implementation13SwiftSubclassCMF" to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }>, ptr @"$s19objc_implementation13SwiftSubclassCMn", i32 0, i32 4) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @"symbolic So9ImplClassC" to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }>, ptr @"$s19objc_implementation13SwiftSubclassCMn", i32 0, i32 5) to i64)) to i32), i32 3, i32 10, i32 0, i32 0, i32 10 }>, section "__TEXT,__constg_swiftt", align 4
-// CHECK: @"$s19objc_implementation13SwiftSubclassCMf" = internal global <{ ptr, ptr, ptr, i64, ptr, ptr, ptr, i64, i32, i32, i32, i16, i16, i32, i32, ptr, ptr }> <{ ptr null, ptr @"$s19objc_implementation13SwiftSubclassCfD", ptr @"$sBOWV", i64 ptrtoint (ptr @"OBJC_METACLASS_$__TtC19objc_implementation13SwiftSubclass" to i64), ptr @"OBJC_CLASS_$_ImplClass", ptr @_objc_empty_cache, ptr null, i64 add (i64 ptrtoint (ptr @_DATA__TtC19objc_implementation13SwiftSubclass to i64), i64 1), i32 0, i32 0, i32 24, i16 7, i16 0, i32 104, i32 24, ptr @"$s19objc_implementation13SwiftSubclassCMn", ptr null }>, section "__DATA,__objc_data, regular", align 8
+// CHECK: @"$s19objc_implementation13SwiftSubclassCMf" = internal global <{ ptr, ptr, ptr, i64, ptr, ptr, ptr, i64, i32, i32, i32, i16, i16, i32, i32, ptr, ptr }> <{ ptr null, ptr @"$s19objc_implementation13SwiftSubclassCfD", ptr @"$sBOWV", i64 ptrtoint (ptr @"OBJC_METACLASS_$__TtC19objc_implementation13SwiftSubclass" to i64), ptr @"OBJC_CLASS_$_ImplClass", ptr @_objc_empty_cache, ptr null, i64 add (i64 ptrtoint (ptr @_DATA__TtC19objc_implementation13SwiftSubclass to i64), i64 2), i32 0, i32 0, i32 24, i16 7, i16 0, i32 104, i32 24, ptr @"$s19objc_implementation13SwiftSubclassCMn", ptr null }>, section "__DATA,__objc_data, regular", align 8
 // CHECK: @"symbolic _____ 19objc_implementation13SwiftSubclassC" = linkonce_odr hidden constant <{ i8, i32, i8 }> <{ i8 1, i32 trunc (i64 sub (i64 ptrtoint (ptr @"$s19objc_implementation13SwiftSubclassCMn" to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i8, i32, i8 }>, ptr @"symbolic _____ 19objc_implementation13SwiftSubclassC", i32 0, i32 1) to i64)) to i32), i8 0 }>, section "__TEXT,__swift5_typeref, regular"{{.*}}, align 2
 // CHECK: @"$s19objc_implementation13SwiftSubclassCMF" = internal constant { i32, i32, i16, i16, i32 } { i32 trunc (i64 sub (i64 ptrtoint (ptr @"symbolic _____ 19objc_implementation13SwiftSubclassC" to i64), i64 ptrtoint (ptr @"$s19objc_implementation13SwiftSubclassCMF" to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @"symbolic So9ImplClassC" to i64), i64 ptrtoint (ptr getelementptr inbounds ({ i32, i32, i16, i16, i32 }, ptr @"$s19objc_implementation13SwiftSubclassCMF", i32 0, i32 1) to i64)) to i32), i16 7, i16 12, i32 0 }, section "__TEXT,__swift5_fieldmd, regular"{{.*}}, align 4
 open class SwiftSubclass: ImplClass {

test/IRGen/objc_implementation_deployment_target_resilience.swift

@@ -0,0 +1,25 @@
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -target %target-stable-abi-triple -I %S/Inputs/abi -F %clang-importer-sdk-path/frameworks %s -import-objc-header %S/Inputs/objc_implementation.h -emit-ir -o %t.ir -enable-library-evolution -verify
+// REQUIRES: objc_interop
+
+@_objcImplementation extension ImplClassWithResilientStoredProperty {
+  @objc var beforeInt: Int32 = 0    // no-error
+  final var a: Mirror?              // expected-error {{does not support stored properties whose size can change due to library evolution; raise the minimum deployment target to}}
+  final var b: AnyKeyPath?          // no-error
+  final var c: Int = 0              // no-error
+  final var d: S1?                  // no-error
+  final var e: S2?                  // expected-error {{does not support stored properties whose size can change due to library evolution; raise the minimum deployment target to}}
+  final var f: C1?                  // no-error
+  @objc var afterInt: Int32 = 0     // no-error
+}
+
+public struct S1 {
+  var int = 1
+}
+
+public struct S2 {
+  var mirror: Mirror?
+}
+
+public class C1 {
+  var mirror: Mirror?
+}