[lldb] Register NSString summary provider for Swift.__StringStorage class

lldb/source/Plugins/Language/Swift/SwiftLanguage.cpp

@@ -497,6 +497,10 @@ static void LoadSwiftFormatters(lldb::TypeCategoryImplSP swift_category_sp) {
   AddCXXSummary(swift_category_sp, staticstring_summary_provider,
                 "Swift.StaticString summary provider",
                 ConstString("Swift.StaticString"), summary_flags);
+  AddCXXSummary(swift_category_sp,
+                lldb_private::formatters::NSStringSummaryProvider,
+                "Swift.__StringStorage summary provider",
+                "Swift.__StringStorage", summary_flags);
   AddCXXSummary(swift_category_sp,
                 lldb_private::formatters::swift::TaskPriority_SummaryProvider,
                 "Swift TaskPriority summary provider", "Swift.TaskPriority",

lldb/test/API/functionalities/data-formatter/swift/bridged-string/Makefile

@@ -0,0 +1,3 @@
+SWIFT_SOURCES := main.swift
+SWIFTFLAGS_EXTRAS := -parse-as-library
+include Makefile.rules

lldb/test/API/functionalities/data-formatter/swift/bridged-string/TestSwiftBridgedStringFormatters.py

@@ -0,0 +1,16 @@
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbutil as lldbutil
+
+
+class TestCase(TestBase):
+
+    @swiftTest
+    @skipUnlessFoundation
+    def test(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, "break here", lldb.SBFileSpec("main.swift")
+        )
+        self.expect("v d[0].value", substrs=['value = "one.2.three"'])

lldb/test/API/functionalities/data-formatter/swift/bridged-string/main.swift

@@ -0,0 +1,10 @@
+import Foundation
+
+@main struct Entry {
+    static func main() {
+        let s = "one.two.three"
+        let d = NSMutableDictionary()
+        d["key"] = s.replacingOccurrences(of: "two", with: "2")
+        print("break here")
+    }
+}