Return a SwiftArrayEmptyBufferHandler if loc points to an EmptyArray Symbol.

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

@@ -14,7 +14,9 @@
 
 #include "Plugins/LanguageRuntime/Swift/SwiftLanguageRuntime.h"
 #include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
+#include "Plugins/TypeSystem/Swift/SwiftDemangle.h"
 #include "Plugins/TypeSystem/Swift/TypeSystemSwiftTypeRef.h"
+#include "lldb/Core/Address.h"
 #include "lldb/DataFormatters/FormattersHelpers.h"
 #include "lldb/Target/Process.h"
 #include "lldb/Target/Target.h"
@@ -23,6 +25,7 @@
 // FIXME: we should not need this
 #include "Plugins/Language/ObjC/Cocoa.h"
 #include "lldb/lldb-enumerations.h"
+#include "swift/Demangling/Demangler.h"
 
 using namespace lldb;
 using namespace lldb_private;
@@ -460,6 +463,41 @@ SwiftArrayBufferHandler::CreateBufferHandler(ValueObject &static_valobj) {
     lldb::addr_t storage_location =
         buffer_sp->GetValueAsUnsigned(LLDB_INVALID_ADDRESS);
 
+    lldb_private::Address addr = Address();
+    addr.SetLoadAddress(storage_location, exe_ctx.GetTargetPtr());
+
+    // If the storage_location points to a swiftEmptyArrayStorage symbol, return
+    // a SwiftArrayEmptyBufferHandler.
+    if (auto *symbol = addr.CalculateSymbolContextSymbol()) {
+      auto mangledName = symbol->GetMangled().GetMangledName().GetStringRef();
+      using namespace ::swift::Demangle;
+      Demangler dem;
+      NodePointer node = dem.demangleSymbol(mangledName);
+      if (node && swift_demangle::NodeAtPath(node, Node::Kind::Global)) {
+        auto *class_node = swift_demangle::ChildAtPath(
+            node,
+            {Node::Kind::TypeMetadata, Node::Kind::Type, Node::Kind::Class});
+        if (class_node && class_node->getNumChildren() == 2) {
+          auto *module_node = class_node->getFirstChild();
+          auto *ident_node = class_node->getLastChild();
+          if (module_node->getKind() == Node::Kind::Module &&
+              module_node->hasText() &&
+              ident_node->getKind() == Node::Kind::Identifier &&
+              ident_node->hasText()) {
+            auto module_name = module_node->getText();
+            auto class_name = ident_node->getText();
+            if (module_name == ::swift::STDLIB_NAME &&
+                class_name == "__EmptyArrayStorage") {
+              CompilerType elem_type(
+                  valobj.GetCompilerType().GetArrayElementType(exe_scope));
+              return std::unique_ptr<SwiftArrayBufferHandler>(
+                  new SwiftArrayEmptyBufferHandler(elem_type));
+            }
+          }
+        }
+      }
+    }
+
     if (storage_location != LLDB_INVALID_ADDRESS) {
       ProcessSP process_sp(valobj.GetProcessSP());
       if (!process_sp)

lldb/test/API/lang/swift/swift_empty_arr/Makefile

@@ -0,0 +1,2 @@
+SWIFT_SOURCES := main.swift
+include Makefile.rules

lldb/test/API/lang/swift/swift_empty_arr/TestSwiftGlobalEmptyArray.py

@@ -0,0 +1,18 @@
+import lldb
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbtest as lldbtest
+import lldbsuite.test.lldbutil as lldbutil
+
+
+class TestSwiftGlobalEmptyArray(lldbtest.TestBase):
+    @swiftTest
+    def test(self):
+        """Test that printing a global swift array of type SwiftEmptyArrayStorage uses the correct data formatter"""
+
+        self.build()
+        filespec = lldb.SBFileSpec("main.swift")
+        lldbutil.run_to_source_breakpoint(
+            self, "break here", filespec
+        )
+        x = self.frame().FindVariable("x")
+        self.assertEqual(x.GetSummary(), "0 values")

lldb/test/API/lang/swift/swift_empty_arr/main.swift

@@ -0,0 +1,9 @@
+protocol P {}
+
+func go() {
+    let x: [any P] = []
+    print("break here")
+    print(x)
+}
+
+go()