[IRGen] Don't use mangled names for metadata including Span et al when back-deploying

lib/IRGen/GenReflection.cpp

@@ -177,6 +177,25 @@ class PrintMetadataSource
   }
 };
 
+/// Determine whether the given generic nominal that involves inverse
+/// requirements (e.g., Optional, Span) is always available for demangling
+/// purposes.
+static bool nominalIsAlwaysAvailableForDemangling(const NominalTypeDecl *nom) {
+  // Only consider standard library types for this.
+  if (!nom->getModuleContext()->isStdlibModule())
+    return false;
+
+  // If there's an @_originallyDefined(in:) attribute, then the nominal is
+  // not always available for demangling.
+  for (auto attr: nom->getAttrs().getAttributes<OriginallyDefinedInAttr>()) {
+    if (!attr->isInvalid() && attr->isActivePlatform(nom->getASTContext()))
+      return false;
+  }
+
+  // Everything else is available.
+  return true;
+}
+
 std::optional<llvm::VersionTuple>
 getRuntimeVersionThatSupportsDemanglingType(CanType type) {
   enum VersionRequirement {
@@ -185,9 +204,10 @@ getRuntimeVersionThatSupportsDemanglingType(CanType type) {
     Swift_5_5,
     Swift_6_0,
     Swift_6_1,
+    Swift_6_2,
 
     // Short-circuit if we find this requirement.
-    Latest = Swift_6_1
+    Latest = Swift_6_2
   };
 
   VersionRequirement latestRequirement = None;
@@ -204,6 +224,11 @@ getRuntimeVersionThatSupportsDemanglingType(CanType type) {
       auto isolation = fn->getIsolation();
       auto sendingResult = fn->hasSendingResult();
 
+      // The mangling for nonisolated(nonsending) function types was introduced
+      // in Swift 6.2.
+      if (isolation.isNonIsolatedCaller())
+        return addRequirement(Swift_6_2);
+
       // The Swift 6.1 runtime fixes a bug preventing successful demangling
       // when @isolated(any) or global actor isolation is combined with a
       // sending result.
@@ -246,16 +271,16 @@ getRuntimeVersionThatSupportsDemanglingType(CanType type) {
     /// signature uses NoncopyableGenerics. Since inverses are mangled into
     /// symbols, a Swift 6.0+ runtime is generally needed to demangle them.
     ///
-    /// We make an exception for types in the stdlib, like Optional, since the
-    /// runtime should still be able to demangle them, based on the availability
-    /// of the type.
+    /// We make an exception for some types in the stdlib, like Optional, since
+    /// the runtime should still be able to demangle them, based on the
+    /// availability of the type.
     if (auto nominalTy = dyn_cast<NominalOrBoundGenericNominalType>(t)) {
       auto *nom = nominalTy->getDecl();
       if (auto sig = nom->getGenericSignature()) {
         SmallVector<InverseRequirement, 2> inverses;
         SmallVector<Requirement, 2> reqs;
         sig->getRequirementsWithInverses(reqs, inverses);
-        if (!inverses.empty() && !nom->getModuleContext()->isStdlibModule()) {
+        if (!inverses.empty() && !nominalIsAlwaysAvailableForDemangling(nom)) {
           return addRequirement(Swift_6_0);
         }
       }
@@ -271,6 +296,7 @@ getRuntimeVersionThatSupportsDemanglingType(CanType type) {
   });
 
   switch (latestRequirement) {
+  case Swift_6_2: return llvm::VersionTuple(6, 2);
   case Swift_6_1: return llvm::VersionTuple(6, 1);
   case Swift_6_0: return llvm::VersionTuple(6, 0);
   case Swift_5_5: return llvm::VersionTuple(5, 5);

test/IRGen/backward_deploy_nonisolated_nonsending_function_type.swift

@@ -0,0 +1,17 @@
+// RUN: %target-swift-frontend -target %target-cpu-apple-macos12 -emit-ir -o - -primary-file %s | %FileCheck %s
+// REQUIRES: concurrency
+// REQUIRES: OS=macosx
+
+func useGenericMetatype(_ type: Any.Type) { }
+
+// CHECK-LABEL: define hidden swiftcc void @"$s52backward_deploy_nonisolated_nonsending_function_type29testNonisolatedNonsendingTypeyyF"()
+func testNonisolatedNonsendingType() {
+  typealias Fn = nonisolated(nonsending) () async throws -> Int
+
+  // CHECK: call swiftcc %swift.metadata_response @"$sSiyYaKYCcMa"
+  // CHECK: call swiftcc void @"$s52backward_deploy_nonisolated_nonsending_function_type18useGenericMetatypeyyypXpF"
+  useGenericMetatype(Fn.self)
+}
+
+// CHECK-LABEL: define linkonce_odr hidden swiftcc %swift.metadata_response @"$sSiyYaKYCcMa"
+// CHECK: call ptr @swift_getExtendedFunctionTypeMetadata(i{{32|64}} 2768240640, {{i32|i64}} 0, ptr null, ptr null, ptr @"$sSiN"

test/IRGen/backward_deploy_span.swift

@@ -0,0 +1,14 @@
+// RUN: %target-swift-frontend -target %target-cpu-apple-macos12 -emit-ir -o - -primary-file %s | %FileCheck %s
+// REQUIRES: OS=macosx
+
+func useGenericMetatype(_ type: any ~Escapable.Type) { }
+
+// CHECK-LABEL: define hidden swiftcc void @"$s20backward_deploy_span11testSpanIntyyF"()
+func testSpanInt() {
+  // CHECK: call swiftcc %swift.metadata_response @"$ss4SpanVySiGMa"
+  // CHECK: call swiftcc void @"$s20backward_deploy_span18useGenericMetatypeyyypRi0_s_XPXpF"
+  useGenericMetatype(Span<Int>.self)
+}
+
+// CHECK-LABEL: define linkonce_odr hidden swiftcc %swift.metadata_response @"$ss4SpanVySiGMa"
+// CHECK: call swiftcc %swift.metadata_response @"$ss4SpanVMa"({{i32|i64}} %0, ptr @"$sSiN")