[LLDB] Add formatters for MSVC STL std::string_view and friends (llvm#150318)

Adds summaries for `std::{,w,u8,u16,u32}string_view`s from MSVC's STL. A
few functions from the string formatting can be reused.

Towards llvm#24834.

Author: Nerixyz

lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp

@@ -1363,6 +1363,28 @@ static void RegisterStdStringSummaryProvider(
       summary_sp);
 }
 
+static void RegisterStdStringViewSummaryProvider(
+    const lldb::TypeCategoryImplSP &category_sp, llvm::StringRef string_ty,
+    llvm::StringRef char_ty, lldb::TypeSummaryImplSP summary_sp) {
+  // std::string_view
+  category_sp->AddTypeSummary(
+      std::make_shared<lldb_private::TypeNameSpecifierImpl>(
+          string_ty, eFormatterMatchExact),
+      summary_sp);
+
+  // std::basic_string_view<char, std::char_traits<char>>
+  // NativePDB has spaces at different positions compared to PDB and DWARF, so
+  // use a regex and make them optional.
+  category_sp->AddTypeSummary(
+      std::make_shared<lldb_private::TypeNameSpecifierImpl>(
+          llvm::formatv(
+              "^std::basic_string_view<{0}, ?std::char_traits<{0}> ?>$",
+              char_ty)
+              .str(),
+          eFormatterMatchRegex),
+      summary_sp);
+}
+
 static void LoadLibStdcppFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
   if (!cpp_category_sp)
     return;
@@ -1863,6 +1885,36 @@ static void LoadMsvcStlFormatters(lldb::TypeCategoryImplSP cpp_category_sp) {
           MsvcStlStringSummaryProvider<StringElementType::UTF32>,
           "MSVC STL std::u32string summary provider"));
 
+  RegisterStdStringViewSummaryProvider(
+      cpp_category_sp, "std::string_view", "char",
+      std::make_shared<CXXFunctionSummaryFormat>(
+          stl_summary_flags,
+          MsvcStlStringViewSummaryProvider<StringElementType::ASCII>,
+          "MSVC STL std::string_view summary provider"));
+  RegisterStdStringViewSummaryProvider(
+      cpp_category_sp, "std::u8string_view", "char8_t",
+      std::make_shared<CXXFunctionSummaryFormat>(
+          stl_summary_flags,
+          MsvcStlStringViewSummaryProvider<StringElementType::UTF8>,
+          "MSVC STL std::u8string_view summary provider"));
+  RegisterStdStringViewSummaryProvider(
+      cpp_category_sp, "std::u16string_view", "char16_t",
+      std::make_shared<CXXFunctionSummaryFormat>(
+          stl_summary_flags,
+          MsvcStlStringViewSummaryProvider<StringElementType::UTF16>,
+          "MSVC STL std::u16string_view summary provider"));
+  RegisterStdStringViewSummaryProvider(
+      cpp_category_sp, "std::u32string_view", "char32_t",
+      std::make_shared<CXXFunctionSummaryFormat>(
+          stl_summary_flags,
+          MsvcStlStringViewSummaryProvider<StringElementType::UTF32>,
+          "MSVC STL std::u32string_view summary provider"));
+  RegisterStdStringViewSummaryProvider(
+      cpp_category_sp, "std::wstring_view", "wchar_t",
+      std::make_shared<CXXFunctionSummaryFormat>(
+          stl_summary_flags, MsvcStlWStringViewSummaryProvider,
+          "MSVC STL std::wstring_view summary provider"));
+
   stl_summary_flags.SetDontShowChildren(false);
 
   AddCXXSynthetic(cpp_category_sp, MsvcStlAtomicSyntheticFrontEndCreator,

lldb/source/Plugins/Language/CPlusPlus/MsvcStl.cpp

@@ -112,6 +112,33 @@ static bool formatStringImpl(ValueObject &valobj, Stream &stream,
   return true;
 }
 
+template <StringPrinter::StringElementType element_type>
+static bool formatStringViewImpl(ValueObject &valobj, Stream &stream,
+                                 const TypeSummaryOptions &summary_options,
+                                 std::string prefix_token) {
+  auto data_sp = valobj.GetChildMemberWithName("_Mydata");
+  auto size_sp = valobj.GetChildMemberWithName("_Mysize");
+  if (!data_sp || !size_sp)
+    return false;
+
+  bool success = false;
+  uint64_t size = size_sp->GetValueAsUnsigned(0, &success);
+  if (!success) {
+    stream << "Summary Unavailable";
+    return true;
+  }
+
+  StreamString scratch_stream;
+  success = StringBufferSummaryProvider<element_type>(
+      scratch_stream, summary_options, data_sp, size, prefix_token);
+
+  if (success)
+    stream << scratch_stream.GetData();
+  else
+    stream << "Summary Unavailable";
+  return true;
+}
+
 bool lldb_private::formatters::IsMsvcStlStringType(ValueObject &valobj) {
   std::vector<uint32_t> indexes;
   return valobj.GetCompilerType().GetIndexOfChildMemberWithName("_Mypair", true,
@@ -153,3 +180,39 @@ bool lldb_private::formatters::MsvcStlStringSummaryProvider<
   return MsvcStlStringSummaryProviderImpl<StringElementType::UTF32>(
       valobj, stream, summary_options, "U");
 }
+
+bool lldb_private::formatters::MsvcStlWStringViewSummaryProvider(
+    ValueObject &valobj, Stream &stream,
+    const TypeSummaryOptions &summary_options) {
+  return formatStringViewImpl<StringElementType::UTF16>(valobj, stream,
+                                                        summary_options, "L");
+}
+
+template <>
+bool lldb_private::formatters::MsvcStlStringViewSummaryProvider<
+    StringElementType::ASCII>(ValueObject &valobj, Stream &stream,
+                              const TypeSummaryOptions &summary_options) {
+  return formatStringViewImpl<StringElementType::ASCII>(valobj, stream,
+                                                        summary_options, "");
+}
+template <>
+bool lldb_private::formatters::MsvcStlStringViewSummaryProvider<
+    StringElementType::UTF8>(ValueObject &valobj, Stream &stream,
+                             const TypeSummaryOptions &summary_options) {
+  return formatStringViewImpl<StringElementType::UTF8>(valobj, stream,
+                                                       summary_options, "u8");
+}
+template <>
+bool lldb_private::formatters::MsvcStlStringViewSummaryProvider<
+    StringElementType::UTF16>(ValueObject &valobj, Stream &stream,
+                              const TypeSummaryOptions &summary_options) {
+  return formatStringViewImpl<StringElementType::UTF16>(valobj, stream,
+                                                        summary_options, "u");
+}
+template <>
+bool lldb_private::formatters::MsvcStlStringViewSummaryProvider<
+    StringElementType::UTF32>(ValueObject &valobj, Stream &stream,
+                              const TypeSummaryOptions &summary_options) {
+  return formatStringViewImpl<StringElementType::UTF32>(valobj, stream,
+                                                        summary_options, "U");
+}

lldb/source/Plugins/Language/CPlusPlus/MsvcStl.h

@@ -29,6 +29,15 @@ bool MsvcStlWStringSummaryProvider(
     ValueObject &valobj, Stream &stream,
     const TypeSummaryOptions &options); // VC 2015+ std::wstring
 
+template <StringPrinter::StringElementType element_type>
+bool MsvcStlStringViewSummaryProvider(
+    ValueObject &valobj, Stream &stream,
+    const TypeSummaryOptions &summary_options); // std::{u8,u16,u32}?string_view
+
+bool MsvcStlWStringViewSummaryProvider(
+    ValueObject &valobj, Stream &stream,
+    const TypeSummaryOptions &options); // std::wstring_view
+
 // MSVC STL std::shared_ptr<> and std::weak_ptr<>
 bool IsMsvcStlSmartPointer(ValueObject &valobj);
 bool MsvcStlSmartPointerSummaryProvider(ValueObject &valobj, Stream &stream,

lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/string_view/TestDataFormatterStdStringView.py

@@ -78,9 +78,6 @@ def cleanup():
             "u32_string", type="std::u32string_view", summary='U"🍄🍅🍆🍌"'
         )
         self.expect_var_path("u32_empty", type="std::u32string_view", summary='U""')
-        self.expect_var_path(
-            "oops", type="std::string_view", summary='"Hellooo World\\n"'
-        )
 
         # GetSummary returns None so can't be checked by expect_var_path, so we
         # use the str representation instead
@@ -163,3 +160,8 @@ def cleanup():
     def test_libcxx(self):
         self.build(dictionary={"USE_LIBCPP": 1})
         self.do_test()
+
+    @add_test_categories(["msvcstl"])
+    def test_msvcstl(self):
+        self.build()
+        self.do_test()

lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/string_view/main.cpp

@@ -95,7 +95,6 @@ int main() {
   std::string_view *null_str = nullptr;
 
   std::string hello = "Hellooo ";
-  std::string_view oops = hello + "World\n";
 
   q_source[0] = 'H'; // Set break point at this line.
 

lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/u8string_view/Makefile

@@ -0,0 +1,4 @@
+CXX_SOURCES := main.cpp
+CXXFLAGS_EXTRAS := -std=c++20
+
+include Makefile.rules

lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/u8string_view/TestDataFormatterStdU8StringView.py

@@ -0,0 +1,44 @@
+# coding=utf8
+"""
+Test std::u8string_view summary.
+"""
+
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class StdU8StringViewDataFormatterTestCase(TestBase):
+    def do_test(self):
+        lldbutil.run_to_source_breakpoint(
+            self, "Set break point at this line.", lldb.SBFileSpec("main.cpp")
+        )
+
+        self.expect(
+            "frame variable",
+            substrs=[
+                '(std::u8string_view) u8_string_small = u8"🍄"',
+                '(std::u8string_view) u8_string = u8"❤️👍📄📁😃🧑‍🌾"',
+                '(std::u8string_view) u8_empty = u8""',
+                '(std::u8string_view) u8_text = u8"ABCd"',
+            ],
+        )
+
+    @expectedFailureAll(bugnumber="No libc++ formatters for std::u8string_view yet.")
+    @add_test_categories(["libc++"])
+    def test_libcxx(self):
+        self.build(dictionary={"USE_LIBCPP": 1})
+        self.do_test()
+
+    @expectedFailureAll(bugnumber="No libstdc++ formatters for std::u8string_view yet.")
+    @add_test_categories(["libstdcxx"])
+    def test_libstdcxx(self):
+        self.build(dictionary={"USE_LIBSTDCPP": 1})
+        self.do_test()
+
+    @add_test_categories(["msvcstl"])
+    def test_msvc(self):
+        self.build()
+        self.do_test()

lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/u8string_view/main.cpp

@@ -0,0 +1,12 @@
+#include <cstdio>
+#include <string_view>
+
+int main() {
+  std::u8string_view u8_string_small(u8"🍄");
+  std::u8string_view u8_string(u8"❤️👍📄📁😃🧑‍🌾");
+  std::u8string_view u8_empty(u8"");
+  std::u8string_view u8_text(u8"ABC");
+  u8_text = u8"ABCd";
+
+  std::puts("// Set break point at this line.");
+}