Don't try to import variants for FieldDecls

lib/ClangImporter/ImportDecl.cpp

@@ -4251,6 +4251,13 @@ namespace {
       if (!importedName) {
         return nullptr;
       }
+      if (correctSwiftName) {
+        // FIXME: We should import this as a variant, but to do that, we'll also
+        // need to make this a computed variable or otherwise fix how the rest
+        // of the compiler thinks about stored properties in imported structs.
+        // For now, just don't import it at all. (rdar://86069786)
+        return nullptr;
+      }
 
       auto name = importedName.getDeclName().getBaseIdentifier();
 
@@ -4301,6 +4308,7 @@ namespace {
 
       // If this is a compatibility stub, handle it as such.
       if (correctSwiftName)
+        // FIXME: Temporarily unreachable because of check above.
         markAsVariant(result, *correctSwiftName);
 
       return result;

test/ClangImporter/ctypes_ir.swift

@@ -45,3 +45,12 @@ func testBigArrays(_ maxSize: UnsafeMutablePointer<Int8>?, _ maxSizePlusOne: Uns
 func testBigArrays2d(_ maxSize: UnsafeMutablePointer<IntTuple4096>?, _ maxSizePlusOne: OpaquePointer?) {
     useBigArray2d(maxSize, maxSizePlusOne)
 }
+
+
+// Make sure fields with a swift_name attribute only produce one stored
+// property, not two. (rdar://86069786)
+// CHECK-LABEL: define swiftcc void @"$s9ctypes_ir22testFieldWithSwiftName1oySo12Rdar86069786V_tF"
+// CHECK-SAME: (double %0)
+
+public func testFieldWithSwiftName(o : Rdar86069786) {
+}

test/Inputs/clang-importer-sdk/usr/include/ctypes.h

@@ -196,6 +196,11 @@ STDLIB_TYPEDEF(unsigned int, UInt);
 void noreturnFunction() __attribute__((noreturn));
 void couldReturnFunction() __attribute__((noreturn));
 
+// Struct with an __attribute((swift_name)) field.
+struct Rdar86069786 {
+    double c_name __attribute__((swift_name("swiftName")));
+};
+
 
 //===---
 // Function pointers