[LLDB] Add type summaries for MSVC STL strings

Author: Nerixyz

lldb/include/lldb/DataFormatters/StringPrinter.h

@@ -152,6 +152,21 @@ class StringPrinter {
   template <StringElementType element_type>
   static bool
   ReadBufferAndDumpToStream(const ReadBufferAndDumpToStreamOptions &options);
+
+  template <StringElementType element_type>
+  static constexpr uint64_t ElementByteSize() {
+    switch (element_type) {
+    case StringElementType::ASCII:
+    case StringElementType::UTF8:
+      return 1;
+    case StringElementType::UTF16:
+      return 2;
+    case StringElementType::UTF32:
+      return 3;
+    default:
+      return 0;
+    }
+  }
 };
 
 } // namespace formatters

lldb/include/lldb/DataFormatters/TypeSummary.h

@@ -48,7 +48,14 @@ class TypeSummaryOptions {
 
 class TypeSummaryImpl {
 public:
-  enum class Kind { eSummaryString, eScript, eBytecode, eCallback, eInternal };
+  enum class Kind {
+    eSummaryString,
+    eScript,
+    eBytecode,
+    eCallback,
+    eCascading,
+    eInternal
+  };
 
   virtual ~TypeSummaryImpl() = default;
 
@@ -292,18 +299,29 @@ class TypeSummaryImpl {
   const TypeSummaryImpl &operator=(const TypeSummaryImpl &) = delete;
 };
 
-// simple string-based summaries, using ${var to show data
-struct StringSummaryFormat : public TypeSummaryImpl {
+struct StringSummaryData {
   std::string m_format_str;
   FormatEntity::Entry m_format;
   Status m_error;
 
+  StringSummaryData(const char *f);
+  void SetFormat(const char *f);
+
+  bool FormatObject(ValueObject *valobj, std::string &dest,
+                    const TypeSummaryOptions &options,
+                    const TypeSummaryImpl &summary);
+};
+
+// simple string-based summaries, using ${var to show data
+struct StringSummaryFormat : public TypeSummaryImpl {
+  StringSummaryData m_data;
+
   StringSummaryFormat(const TypeSummaryImpl::Flags &flags, const char *f,
                       uint32_t ptr_match_depth = 1);
 
   ~StringSummaryFormat() override = default;
 
-  const char *GetSummaryString() const { return m_format_str.c_str(); }
+  const char *GetSummaryString() const { return m_data.m_format_str.c_str(); }
 
   void SetSummaryString(const char *f);
 
@@ -323,15 +341,23 @@ struct StringSummaryFormat : public TypeSummaryImpl {
   const StringSummaryFormat &operator=(const StringSummaryFormat &) = delete;
 };
 
-// summaries implemented via a C++ function
-struct CXXFunctionSummaryFormat : public TypeSummaryImpl {
+struct CXXFunctionSummaryData {
   // we should convert these to SBValue and SBStream if we ever cross the
   // boundary towards the external world
-  typedef std::function<bool(ValueObject &, Stream &,
-                             const TypeSummaryOptions &)>
-      Callback;
+  using Callback =
+      std::function<bool(ValueObject &, Stream &, const TypeSummaryOptions &)>;
 
   Callback m_impl;
+
+  bool FormatObject(ValueObject *valobj, std::string &dest,
+                    const TypeSummaryOptions &options,
+                    const TypeSummaryImpl &summary);
+};
+
+// summaries implemented via a C++ function
+struct CXXFunctionSummaryFormat : public TypeSummaryImpl {
+  using Callback = CXXFunctionSummaryData::Callback;
+  CXXFunctionSummaryData m_data;
   std::string m_description;
 
   CXXFunctionSummaryFormat(const TypeSummaryImpl::Flags &flags, Callback impl,
@@ -340,11 +366,13 @@ struct CXXFunctionSummaryFormat : public TypeSummaryImpl {
 
   ~CXXFunctionSummaryFormat() override = default;
 
-  Callback GetBackendFunction() const { return m_impl; }
+  Callback GetBackendFunction() const { return m_data.m_impl; }
 
   const char *GetTextualInfo() const { return m_description.c_str(); }
 
-  void SetBackendFunction(Callback cb_func) { m_impl = std::move(cb_func); }
+  void SetBackendFunction(Callback cb_func) {
+    m_data.m_impl = std::move(cb_func);
+  }
 
   void SetTextualInfo(const char *descr) {
     if (descr)
@@ -372,6 +400,55 @@ struct CXXFunctionSummaryFormat : public TypeSummaryImpl {
   operator=(const CXXFunctionSummaryFormat &) = delete;
 };
 
+// Multiple summaries for the same type name but different type layouts.
+// A validator function checks the layout.
+struct CXXCascadingSummaryFormat : public TypeSummaryImpl {
+  using Validator = bool(ValueObject &valobj);
+  using Impl = std::variant<CXXFunctionSummaryData, StringSummaryData>;
+  using ImplEntry = std::pair<Validator *, Impl>;
+  using ImplList = llvm::SmallVector<ImplEntry, 2>;
+
+  ImplList m_impls;
+  std::string m_description;
+
+  CXXCascadingSummaryFormat(const TypeSummaryImpl::Flags &flags,
+                            const char *description, ImplList impls = {},
+                            uint32_t ptr_match_depth = 1);
+
+  ~CXXCascadingSummaryFormat() override = default;
+
+  const char *GetTextualInfo() const { return m_description.c_str(); }
+
+  CXXCascadingSummaryFormat *Append(Validator *validator, Impl impl);
+
+  void SetTextualInfo(const char *descr) {
+    if (descr)
+      m_description.assign(descr);
+    else
+      m_description.clear();
+  }
+
+  ImplList CopyImpls() const;
+
+  bool FormatObject(ValueObject *valobj, std::string &dest,
+                    const TypeSummaryOptions &options) override;
+
+  std::string GetDescription() override;
+
+  static bool classof(const TypeSummaryImpl *S) {
+    return S->GetKind() == Kind::eCascading;
+  }
+
+  std::string GetName() override;
+
+  using SharedPointer = std::shared_ptr<CXXCascadingSummaryFormat>;
+
+private:
+  CXXCascadingSummaryFormat(const CXXCascadingSummaryFormat &) = delete;
+  const CXXCascadingSummaryFormat &
+  operator=(const CXXCascadingSummaryFormat &) = delete;
+};
+
 // Python-based summaries, running script code to show data
 struct ScriptSummaryFormat : public TypeSummaryImpl {
   std::string m_function_name;

lldb/include/lldb/DataFormatters/ValueObjectPrinter.h

@@ -165,7 +165,7 @@ class ValueObjectPrinter {
   std::string m_error;
   bool m_val_summary_ok;
 
-  friend struct StringSummaryFormat;
+  friend struct StringSummaryData;
 
   ValueObjectPrinter(const ValueObjectPrinter &) = delete;
   const ValueObjectPrinter &operator=(const ValueObjectPrinter &) = delete;

lldb/packages/Python/lldbsuite/test/dotest.py

@@ -831,6 +831,26 @@ def checkLibstdcxxSupport():
     configuration.skip_categories.append("libstdcxx")
 
 
+def canRunMsvcStlTests():
+    from lldbsuite.test import lldbplatformutil
+
+    platform = lldbplatformutil.getPlatform()
+    if platform == "windows":
+        return True, "MSVC STL is present on Windows"
+    return False, f"Don't know how to build with MSVC's STL on {platform}"
+
+
+def checkMsvcStlSupport():
+    result, reason = canRunMsvcStlTests()
+    if result:
+        return  # msvcstl supported
+    if "msvcstl" in configuration.categories_list:
+        return  # msvcstl category explicitly requested, let it run.
+    if configuration.verbose:
+        print(f"msvcstl tests will not be run because: {reason}")
+    configuration.skip_categories.append("msvcstl")
+
+
 def canRunWatchpointTests():
     from lldbsuite.test import lldbplatformutil
 
@@ -1044,6 +1064,7 @@ def run_suite():
 
     checkLibcxxSupport()
     checkLibstdcxxSupport()
+    checkMsvcStlSupport()
     checkWatchpointSupport()
     checkDebugInfoSupport()
     checkDebugServerSupport()

lldb/packages/Python/lldbsuite/test/test_categories.py

@@ -33,6 +33,7 @@
     "lldb-server": "Tests related to lldb-server",
     "lldb-dap": "Tests for the Debug Adapter Protocol with lldb-dap",
     "llgs": "Tests for the gdb-server functionality of lldb-server",
+    "msvcstl": "Test for MSVC STL data formatters",
     "pexpect": "Tests requiring the pexpect library to be available",
     "objc": "Tests related to the Objective-C programming language support",
     "pyapi": "Tests related to the Python API",

lldb/source/API/SBTypeSummary.cpp

@@ -370,6 +370,9 @@ bool SBTypeSummary::IsEqualTo(lldb::SBTypeSummary &rhs) {
     if (IsSummaryString() != rhs.IsSummaryString())
       return false;
     return GetOptions() == rhs.GetOptions();
+  case TypeSummaryImpl::Kind::eCascading:
+    return llvm::dyn_cast<CXXCascadingSummaryFormat>(m_opaque_sp.get()) ==
+           llvm::dyn_cast<CXXCascadingSummaryFormat>(rhs.m_opaque_sp.get());
   case TypeSummaryImpl::Kind::eInternal:
     return (m_opaque_sp.get() == rhs.m_opaque_sp.get());
   }
@@ -406,7 +409,7 @@ bool SBTypeSummary::CopyOnWrite_Impl() {
   if (CXXFunctionSummaryFormat *current_summary_ptr =
           llvm::dyn_cast<CXXFunctionSummaryFormat>(m_opaque_sp.get())) {
     new_sp = TypeSummaryImplSP(new CXXFunctionSummaryFormat(
-        GetOptions(), current_summary_ptr->m_impl,
+        GetOptions(), current_summary_ptr->m_data.m_impl,
         current_summary_ptr->m_description.c_str()));
   } else if (ScriptSummaryFormat *current_summary_ptr =
                  llvm::dyn_cast<ScriptSummaryFormat>(m_opaque_sp.get())) {
@@ -417,6 +420,11 @@ bool SBTypeSummary::CopyOnWrite_Impl() {
                  llvm::dyn_cast<StringSummaryFormat>(m_opaque_sp.get())) {
     new_sp = TypeSummaryImplSP(new StringSummaryFormat(
         GetOptions(), current_summary_ptr->GetSummaryString()));
+  } else if (CXXCascadingSummaryFormat *current_summary_ptr =
+                 llvm::dyn_cast<CXXCascadingSummaryFormat>(m_opaque_sp.get())) {
+    new_sp = TypeSummaryImplSP(new CXXCascadingSummaryFormat(
+        GetOptions(), current_summary_ptr->GetTextualInfo(),
+        current_summary_ptr->CopyImpls()));
   }
 
   SetSP(new_sp);

lldb/source/Commands/CommandObjectType.cpp

@@ -1397,9 +1397,10 @@ bool CommandObjectTypeSummaryAdd::Execute_StringSummary(
     result.AppendError("summary creation failed");
     return false;
   }
-  if (string_format->m_error.Fail()) {
-    result.AppendErrorWithFormat("syntax error: %s",
-                                 string_format->m_error.AsCString("<unknown>"));
+  if (string_format->m_data.m_error.Fail()) {
+    result.AppendErrorWithFormat(
+        "syntax error: %s",
+        string_format->m_data.m_error.AsCString("<unknown>"));
     return false;
   }
   lldb::TypeSummaryImplSP entry(string_format.release());