[lldb][DataFormatters] Support pretty printing std::string when built with -funsigned-char.

[rupprecht]

Summary

When built w/ -funsigned-char, std::string becomes equivalent to std::basic_string<unsigned char>, causing these formatters to not match. This patch adds overloads for both libstdc++ and libc++ string formatters that accepts unsigned char.

Motivated by the following example:

$ cat pretty_print.cc

template <typename T>
void print_val(T s) {
  std::cerr << s << '\n';  // Set a breakpoint here!
}

int main() {
  std::string val = "hello";
  print_val(val);
  return 0;
}
$ clang++ -stdlib=libc++ -funsigned-char -fstandalone-debug -g pretty_print.cc
$ lldb ./a.out -b -o 'b pretty_print.cc:6' -o r -o 'fr v'
...
(lldb) fr v
(std::__1::basic_string<unsigned char, std::__1::char_traits<unsigned char>, std::__1::allocator<unsigned char> >) s = {
  __r_ = {
    std::__1::__compressed_pair_elem<std::__1::basic_string<unsigned char, std::__1::char_traits<unsigned char>, std::__1::allocator<unsigned char> >::__rep, 0, false> = {
      __value_ = {
         = {
          __l = (__cap_ = 122511465736202, __size_ = 0, __data_ = 0x0000000000000000)
          __s = {
             = (__size_ = '\n', __lx = '\n')
            __data_ = {
              [0] = 'h'
              [1] = 'e'
              [2] = 'l'
              [3] = 'l'
              [4] = 'o'
              [5] = '\0'
...

[merge_guards_bot]

Build result: pass - 60200 tests passed, 0 failed and 732 were skipped.
Log files: console-log.txt, CMakeCache.txt

[labath]

Adding a basic_string<unsigned char> formatter seems reasonable, though I have to say that I was very surprised that adding -funsinged-char should cause the type name of the variable to come out different. I tried building the example program with -funsigned-char and without, and literally the only difference was the value of the DW_AT_encoding attribute on the "char" type -- everything else (including the names of all types) remained the same.

Overall, I am not sure that support for non-native char signedness is really sound in lldb. I wouldn't be surprised if we run into other problems with these kinds of binaries. The first thing that comes to mind is expression evaluation not being able to find the correct function (because it's searching for the wrong char), or it selecting the wrong overload. Unfortunately, making it "sound" could be tricky because of the impedance mismatch between what DWARF provides vs. what clang expects.

lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-stl/libcxx/string/TestDataFormatterLibcxxString.py

def test_with_run_command(self):
                 '(%s::string) Q = "quite a long std::strin with lots of info inside it"'%ns,
                 '(%s::string) IHaveEmbeddedZeros = "a\\0b\\0c\\0d"'%ns,
                 '(%s::wstring) IHaveEmbeddedZerosToo = L"hello world!\\0てざ ル゜䋨ミ㠧槊 きゅへ狦穤襩 じゃ馩リョ 䤦監"'%ns,
                 '(%s::u16string) u16_string = u"ß水氶"'%ns,
                 # FIXME: This should have a 'u' prefix.
                 '(%s::u16string) u16_empty = ""'%ns,
                 '(%s::u32string) u32_string = U"🍄🍅🍆🍌"'%ns,
                 # FIXME: This should have a 'U' prefix.
-                '(%s::u32string) u32_empty = ""'%ns
+                '(%s::u32string) u32_empty = ""'%ns,
+                '(%s::basic_string<unsigned char, %s::char_traits<unsigned char>, '
+                '%s::allocator<unsigned char> >) uchar = "aaaaa"'%(ns,ns,ns),
         ])
 
         self.runCmd("n")
 
         TheVeryLongOne = self.frame().FindVariable("TheVeryLongOne")
         summaryOptions = lldb.SBTypeSummaryOptions()
         summaryOptions.SetCapping(lldb.eTypeSummaryUncapped)
         uncappedSummaryStream = lldb.SBStream()
         TheVeryLongOne.GetSummary(uncappedSummaryStream, summaryOptions)
def test_with_run_command(self):
                 '(%s::wstring) S = L"!!!!!"'%ns,
                 '(const wchar_t *) mazeltov = 0x',
                 'L"מזל טוב"',
                 '(%s::string) q = "hello world"'%ns,
                 '(%s::string) Q = "quite a long std::strin with lots of info inside it"'%ns,
                 '(%s::string) IHaveEmbeddedZeros = "a\\0b\\0c\\0d"'%ns,
                 '(%s::wstring) IHaveEmbeddedZerosToo = L"hello world!\\0てざ ル゜䋨ミ㠧槊 きゅへ狦穤襩 じゃ馩リョ 䤦監"'%ns,
                 '(%s::u16string) u16_string = u"ß水氶"'%ns,
-                '(%s::u32string) u32_string = U"🍄🍅🍆🍌"'%ns])
+                '(%s::u32string) u32_string = U"🍄🍅🍆🍌"'%ns,
+                '(%s::u32string) u32_empty = ""'%ns,
+                '(%s::basic_string<unsigned char, %s::char_traits<unsigned char>, '
+                '%s::allocator<unsigned char> >) uchar = "aaaaa"'%(ns,ns,ns),
+        ])

lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-stl/libcxx/string/main.cpp

int main()
     std::string Q("quite a long std::strin with lots of info inside it");
     std::string TheVeryLongOne("1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890someText1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890");
     std::string IHaveEmbeddedZeros("a\0b\0c\0d",7);
     std::wstring IHaveEmbeddedZerosToo(L"hello world!\0てざ ル゜䋨ミ㠧槊 きゅへ狦穤襩 じゃ馩リョ 䤦監", 38);
     std::u16string u16_string(u"ß水氶");
     std::u16string u16_empty(u"");
     std::u32string u32_string(U"🍄🍅🍆🍌");
     std::u32string u32_empty(U"");
+    std::basic_string<unsigned char> uchar(5, 'a');
     S.assign(L"!!!!!"); // Set break point at this line.
     return 0;
 }

lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-stl/libstdcpp/string/TestDataFormatterStdString.py

def test_with_run_command(self):
 
         var_wempty = self.frame().FindVariable('wempty')
         var_s = self.frame().FindVariable('s')
         var_S = self.frame().FindVariable('S')
         var_mazeltov = self.frame().FindVariable('mazeltov')
         var_empty = self.frame().FindVariable('empty')
         var_q = self.frame().FindVariable('q')
         var_Q = self.frame().FindVariable('Q')
+        var_uchar = self.frame().FindVariable('uchar')
 
         # TODO: This is currently broken
-        # self.assertTrue(var_wempty.GetSummary() == 'L""', "wempty summary wrong")
-        self.assertTrue(
-            var_s.GetSummary() == 'L"hello world! מזל טוב!"',
+        # self.assertEqual(var_wempty.GetSummary(), 'L""', "wempty summary wrong")
+        self.assertEqual(
+            var_s.GetSummary(), 'L"hello world! מזל טוב!"',
             "s summary wrong")
-        self.assertTrue(var_S.GetSummary() == 'L"!!!!"', "S summary wrong")
-        self.assertTrue(
-            var_mazeltov.GetSummary() == 'L"מזל טוב"',
+        self.assertEqual(var_S.GetSummary(), 'L"!!!!"', "S summary wrong")
+        self.assertEqual(
+            var_mazeltov.GetSummary(), 'L"מזל טוב"',
             "mazeltov summary wrong")
-        self.assertTrue(var_empty.GetSummary() == '""', "empty summary wrong")
-        self.assertTrue(
-            var_q.GetSummary() == '"hello world"',
+        self.assertEqual(var_empty.GetSummary(), '""', "empty summary wrong")
+        self.assertEqual(
+            var_q.GetSummary(), '"hello world"',
             "q summary wrong")
-        self.assertTrue(
-            var_Q.GetSummary() == '"quite a long std::strin with lots of info inside it"',
+        self.assertEqual(
+            var_Q.GetSummary(), '"quite a long std::strin with lots of info inside it"',
             "Q summary wrong")
+        self.assertEqual(var_uchar.GetSummary(), '"aaaaa"', "u summary wrong")
 
         self.runCmd("next")
 
-        self.assertTrue(
-            var_S.GetSummary() == 'L"!!!!!"',
+        self.assertEqual(
+            var_S.GetSummary(), 'L"!!!!!"',
             "new S summary wrong")

lldb/packages/Python/lldbsuite/test/functionalities/data-formatter/data-formatter-stl/libstdcpp/string/main.cpp

 #include <string>
 
 int main()
 {
     std::wstring wempty(L"");
     std::wstring s(L"hello world! מזל טוב!");
     std::wstring S(L"!!!!");
     const wchar_t *mazeltov = L"מזל טוב";
     std::string empty("");
     std::string q("hello world");
     std::string Q("quite a long std::strin with lots of info inside it");
+    std::basic_string<unsigned char> uchar(5, 'a');
     S.assign(L"!!!!!"); // Set break point at this line.
     return 0;
 }

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

AddCXXSummary(cpp_category_sp,
                 true);
   AddCXXSummary(cpp_category_sp,
                 lldb_private::formatters::LibcxxStringSummaryProviderASCII,
                 "std::string summary provider",
                 ConstString("^std::__[[:alnum:]]+::basic_string<char, "
                             "std::__[[:alnum:]]+::char_traits<char>, "
                             "std::__[[:alnum:]]+::allocator<char> >$"),
                 stl_summary_flags, true);
+  AddCXXSummary(cpp_category_sp,
+                lldb_private::formatters::LibcxxStringSummaryProviderASCII,
+                "std::string summary provider",
+                ConstString("^std::__[[:alnum:]]+::basic_string<unsigned char, "
+                            "std::__[[:alnum:]]+::char_traits<unsigned char>, "
+                            "std::__[[:alnum:]]+::allocator<unsigned char> >$"),
+                stl_summary_flags, true);
 
   AddCXXSummary(cpp_category_sp,
                 lldb_private::formatters::LibcxxStringSummaryProviderUTF16,
                 "std::u16string summary provider",
                 ConstString(
                     "^std::__[[:alnum:]]+::basic_string<char16_t, "
                     "std::__[[:alnum:]]+::char_traits<char16_t>, "
                     "std::__[[:alnum:]]+::allocator<char16_t> >$"),
cpp_category_sp->GetTypeSummariesContainer()->Add(
       std_string_summary_sp);
 
   cpp_category_sp->GetTypeSummariesContainer()->Add(
       ConstString("std::__cxx11::string"), cxx11_string_summary_sp);
   cpp_category_sp->GetTypeSummariesContainer()->Add(
       ConstString("std::__cxx11::basic_string<char, std::char_traits<char>, "
                   "std::allocator<char> >"),
       cxx11_string_summary_sp);
+  cpp_category_sp->GetTypeSummariesContainer()->Add(
+      ConstString("std::__cxx11::basic_string<unsigned char, std::char_traits<unsigned char>, "
+                  "std::allocator<unsigned char> >"),
+      cxx11_string_summary_sp);
 
   // making sure we force-pick the summary for printing wstring (_M_p is a
   // wchar_t*)
   lldb::TypeSummaryImplSP std_wstring_summary_sp(
       new StringSummaryFormat(stl_summary_flags, "${var._M_dataplus._M_p%S}"));
 
   cpp_category_sp->GetTypeSummariesContainer()->Add(ConstString("std::wstring"),
                                                     std_wstring_summary_sp);