chore(3p/abseil_cpp): unvendor abseil_cpp r/3786

we weren't actually using these sources anymore, okay?

Change-Id: If701571d9716de308d3512e1eb22c35db0877a66
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5248
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Autosubmit: tazjin <tazjin@tvl.su>

1 files changed, 0 insertions, 1945 deletions

diff --git a/third_party/abseil_cpp/absl/debugging/internal/demangle.cc b/third_party/abseil_cpp/absl/debugging/internal/demangle.cc
deleted file mode 100644
index 46cdb67b1fbf..000000000000
--- a/third_party/abseil_cpp/absl/debugging/internal/demangle.cc
+++ /dev/null
@@ -1,1945 +0,0 @@
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// For reference check out:
-// https://itanium-cxx-abi.github.io/cxx-abi/abi.html#mangling
-//
-// Note that we only have partial C++11 support yet.
-
-#include "absl/debugging/internal/demangle.h"
-
-#include <cstdint>
-#include <cstdio>
-#include <limits>
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace debugging_internal {
-
-typedef struct {
-  const char *abbrev;
-  const char *real_name;
-  // Number of arguments in <expression> context, or 0 if disallowed.
-  int arity;
-} AbbrevPair;
-
-// List of operators from Itanium C++ ABI.
-static const AbbrevPair kOperatorList[] = {
-    // New has special syntax (not currently supported).
-    {"nw", "new", 0},
-    {"na", "new[]", 0},
-
-    // Works except that the 'gs' prefix is not supported.
-    {"dl", "delete", 1},
-    {"da", "delete[]", 1},
-
-    {"ps", "+", 1},  // "positive"
-    {"ng", "-", 1},  // "negative"
-    {"ad", "&", 1},  // "address-of"
-    {"de", "*", 1},  // "dereference"
-    {"co", "~", 1},
-
-    {"pl", "+", 2},
-    {"mi", "-", 2},
-    {"ml", "*", 2},
-    {"dv", "/", 2},
-    {"rm", "%", 2},
-    {"an", "&", 2},
-    {"or", "|", 2},
-    {"eo", "^", 2},
-    {"aS", "=", 2},
-    {"pL", "+=", 2},
-    {"mI", "-=", 2},
-    {"mL", "*=", 2},
-    {"dV", "/=", 2},
-    {"rM", "%=", 2},
-    {"aN", "&=", 2},
-    {"oR", "|=", 2},
-    {"eO", "^=", 2},
-    {"ls", "<<", 2},
-    {"rs", ">>", 2},
-    {"lS", "<<=", 2},
-    {"rS", ">>=", 2},
-    {"eq", "==", 2},
-    {"ne", "!=", 2},
-    {"lt", "<", 2},
-    {"gt", ">", 2},
-    {"le", "<=", 2},
-    {"ge", ">=", 2},
-    {"nt", "!", 1},
-    {"aa", "&&", 2},
-    {"oo", "||", 2},
-    {"pp", "++", 1},
-    {"mm", "--", 1},
-    {"cm", ",", 2},
-    {"pm", "->*", 2},
-    {"pt", "->", 0},  // Special syntax
-    {"cl", "()", 0},  // Special syntax
-    {"ix", "[]", 2},
-    {"qu", "?", 3},
-    {"st", "sizeof", 0},  // Special syntax
-    {"sz", "sizeof", 1},  // Not a real operator name, but used in expressions.
-    {nullptr, nullptr, 0},
-};
-
-// List of builtin types from Itanium C++ ABI.
-//
-// Invariant: only one- or two-character type abbreviations here.
-static const AbbrevPair kBuiltinTypeList[] = {
-    {"v", "void", 0},
-    {"w", "wchar_t", 0},
-    {"b", "bool", 0},
-    {"c", "char", 0},
-    {"a", "signed char", 0},
-    {"h", "unsigned char", 0},
-    {"s", "short", 0},
-    {"t", "unsigned short", 0},
-    {"i", "int", 0},
-    {"j", "unsigned int", 0},
-    {"l", "long", 0},
-    {"m", "unsigned long", 0},
-    {"x", "long long", 0},
-    {"y", "unsigned long long", 0},
-    {"n", "__int128", 0},
-    {"o", "unsigned __int128", 0},
-    {"f", "float", 0},
-    {"d", "double", 0},
-    {"e", "long double", 0},
-    {"g", "__float128", 0},
-    {"z", "ellipsis", 0},
-
-    {"De", "decimal128", 0},      // IEEE 754r decimal floating point (128 bits)
-    {"Dd", "decimal64", 0},       // IEEE 754r decimal floating point (64 bits)
-    {"Dc", "decltype(auto)", 0},
-    {"Da", "auto", 0},
-    {"Dn", "std::nullptr_t", 0},  // i.e., decltype(nullptr)
-    {"Df", "decimal32", 0},       // IEEE 754r decimal floating point (32 bits)
-    {"Di", "char32_t", 0},
-    {"Du", "char8_t", 0},
-    {"Ds", "char16_t", 0},
-    {"Dh", "float16", 0},         // IEEE 754r half-precision float (16 bits)
-    {nullptr, nullptr, 0},
-};
-
-// List of substitutions Itanium C++ ABI.
-static const AbbrevPair kSubstitutionList[] = {
-    {"St", "", 0},
-    {"Sa", "allocator", 0},
-    {"Sb", "basic_string", 0},
-    // std::basic_string<char, std::char_traits<char>,std::allocator<char> >
-    {"Ss", "string", 0},
-    // std::basic_istream<char, std::char_traits<char> >
-    {"Si", "istream", 0},
-    // std::basic_ostream<char, std::char_traits<char> >
-    {"So", "ostream", 0},
-    // std::basic_iostream<char, std::char_traits<char> >
-    {"Sd", "iostream", 0},
-    {nullptr, nullptr, 0},
-};
-
-// State needed for demangling.  This struct is copied in almost every stack
-// frame, so every byte counts.
-typedef struct {
-  int mangled_idx;                   // Cursor of mangled name.
-  int out_cur_idx;                   // Cursor of output string.
-  int prev_name_idx;                 // For constructors/destructors.
-  signed int prev_name_length : 16;  // For constructors/destructors.
-  signed int nest_level : 15;        // For nested names.
-  unsigned int append : 1;           // Append flag.
-  // Note: for some reason MSVC can't pack "bool append : 1" into the same int
-  // with the above two fields, so we use an int instead.  Amusingly it can pack
-  // "signed bool" as expected, but relying on that to continue to be a legal
-  // type seems ill-advised (as it's illegal in at least clang).
-} ParseState;
-
-static_assert(sizeof(ParseState) == 4 * sizeof(int),
-              "unexpected size of ParseState");
-
-// One-off state for demangling that's not subject to backtracking -- either
-// constant data, data that's intentionally immune to backtracking (steps), or
-// data that would never be changed by backtracking anyway (recursion_depth).
-//
-// Only one copy of this exists for each call to Demangle, so the size of this
-// struct is nearly inconsequential.
-typedef struct {
-  const char *mangled_begin;  // Beginning of input string.
-  char *out;                  // Beginning of output string.
-  int out_end_idx;            // One past last allowed output character.
-  int recursion_depth;        // For stack exhaustion prevention.
-  int steps;               // Cap how much work we'll do, regardless of depth.
-  ParseState parse_state;  // Backtrackable state copied for most frames.
-} State;
-
-namespace {
-// Prevent deep recursion / stack exhaustion.
-// Also prevent unbounded handling of complex inputs.
-class ComplexityGuard {
- public:
-  explicit ComplexityGuard(State *state) : state_(state) {
-    ++state->recursion_depth;
-    ++state->steps;
-  }
-  ~ComplexityGuard() { --state_->recursion_depth; }
-
-  // 256 levels of recursion seems like a reasonable upper limit on depth.
-  // 128 is not enough to demagle synthetic tests from demangle_unittest.txt:
-  // "_ZaaZZZZ..." and "_ZaaZcvZcvZ..."
-  static constexpr int kRecursionDepthLimit = 256;
-
-  // We're trying to pick a charitable upper-limit on how many parse steps are
-  // necessary to handle something that a human could actually make use of.
-  // This is mostly in place as a bound on how much work we'll do if we are
-  // asked to demangle an mangled name from an untrusted source, so it should be
-  // much larger than the largest expected symbol, but much smaller than the
-  // amount of work we can do in, e.g., a second.
-  //
-  // Some real-world symbols from an arbitrary binary started failing between
-  // 2^12 and 2^13, so we multiply the latter by an extra factor of 16 to set
-  // the limit.
-  //
-  // Spending one second on 2^17 parse steps would require each step to take
-  // 7.6us, or ~30000 clock cycles, so it's safe to say this can be done in
-  // under a second.
-  static constexpr int kParseStepsLimit = 1 << 17;
-
-  bool IsTooComplex() const {
-    return state_->recursion_depth > kRecursionDepthLimit ||
-           state_->steps > kParseStepsLimit;
-  }
-
- private:
-  State *state_;
-};
-}  // namespace
-
-// We don't use strlen() in libc since it's not guaranteed to be async
-// signal safe.
-static size_t StrLen(const char *str) {
-  size_t len = 0;
-  while (*str != '\0') {
-    ++str;
-    ++len;
-  }
-  return len;
-}
-
-// Returns true if "str" has at least "n" characters remaining.
-static bool AtLeastNumCharsRemaining(const char *str, int n) {
-  for (int i = 0; i < n; ++i) {
-    if (str[i] == '\0') {
-      return false;
-    }
-  }
-  return true;
-}
-
-// Returns true if "str" has "prefix" as a prefix.
-static bool StrPrefix(const char *str, const char *prefix) {
-  size_t i = 0;
-  while (str[i] != '\0' && prefix[i] != '\0' && str[i] == prefix[i]) {
-    ++i;
-  }
-  return prefix[i] == '\0';  // Consumed everything in "prefix".
-}
-
-static void InitState(State *state, const char *mangled, char *out,
-                      int out_size) {
-  state->mangled_begin = mangled;
-  state->out = out;
-  state->out_end_idx = out_size;
-  state->recursion_depth = 0;
-  state->steps = 0;
-
-  state->parse_state.mangled_idx = 0;
-  state->parse_state.out_cur_idx = 0;
-  state->parse_state.prev_name_idx = 0;
-  state->parse_state.prev_name_length = -1;
-  state->parse_state.nest_level = -1;
-  state->parse_state.append = true;
-}
-
-static inline const char *RemainingInput(State *state) {
-  return &state->mangled_begin[state->parse_state.mangled_idx];
-}
-
-// Returns true and advances "mangled_idx" if we find "one_char_token"
-// at "mangled_idx" position.  It is assumed that "one_char_token" does
-// not contain '\0'.
-static bool ParseOneCharToken(State *state, const char one_char_token) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (RemainingInput(state)[0] == one_char_token) {
-    ++state->parse_state.mangled_idx;
-    return true;
-  }
-  return false;
-}
-
-// Returns true and advances "mangled_cur" if we find "two_char_token"
-// at "mangled_cur" position.  It is assumed that "two_char_token" does
-// not contain '\0'.
-static bool ParseTwoCharToken(State *state, const char *two_char_token) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (RemainingInput(state)[0] == two_char_token[0] &&
-      RemainingInput(state)[1] == two_char_token[1]) {
-    state->parse_state.mangled_idx += 2;
-    return true;
-  }
-  return false;
-}
-
-// Returns true and advances "mangled_cur" if we find any character in
-// "char_class" at "mangled_cur" position.
-static bool ParseCharClass(State *state, const char *char_class) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (RemainingInput(state)[0] == '\0') {
-    return false;
-  }
-  const char *p = char_class;
-  for (; *p != '\0'; ++p) {
-    if (RemainingInput(state)[0] == *p) {
-      ++state->parse_state.mangled_idx;
-      return true;
-    }
-  }
-  return false;
-}
-
-static bool ParseDigit(State *state, int *digit) {
-  char c = RemainingInput(state)[0];
-  if (ParseCharClass(state, "0123456789")) {
-    if (digit != nullptr) {
-      *digit = c - '0';
-    }
-    return true;
-  }
-  return false;
-}
-
-// This function is used for handling an optional non-terminal.
-static bool Optional(bool /*status*/) { return true; }
-
-// This function is used for handling <non-terminal>+ syntax.
-typedef bool (*ParseFunc)(State *);
-static bool OneOrMore(ParseFunc parse_func, State *state) {
-  if (parse_func(state)) {
-    while (parse_func(state)) {
-    }
-    return true;
-  }
-  return false;
-}
-
-// This function is used for handling <non-terminal>* syntax. The function
-// always returns true and must be followed by a termination token or a
-// terminating sequence not handled by parse_func (e.g.
-// ParseOneCharToken(state, 'E')).
-static bool ZeroOrMore(ParseFunc parse_func, State *state) {
-  while (parse_func(state)) {
-  }
-  return true;
-}
-
-// Append "str" at "out_cur_idx".  If there is an overflow, out_cur_idx is
-// set to out_end_idx+1.  The output string is ensured to
-// always terminate with '\0' as long as there is no overflow.
-static void Append(State *state, const char *const str, const int length) {
-  for (int i = 0; i < length; ++i) {
-    if (state->parse_state.out_cur_idx + 1 <
-        state->out_end_idx) {  // +1 for '\0'
-      state->out[state->parse_state.out_cur_idx++] = str[i];
-    } else {
-      // signal overflow
-      state->parse_state.out_cur_idx = state->out_end_idx + 1;
-      break;
-    }
-  }
-  if (state->parse_state.out_cur_idx < state->out_end_idx) {
-    state->out[state->parse_state.out_cur_idx] =
-        '\0';  // Terminate it with '\0'
-  }
-}
-
-// We don't use equivalents in libc to avoid locale issues.
-static bool IsLower(char c) { return c >= 'a' && c <= 'z'; }
-
-static bool IsAlpha(char c) {
-  return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
-}
-
-static bool IsDigit(char c) { return c >= '0' && c <= '9'; }
-
-// Returns true if "str" is a function clone suffix.  These suffixes are used
-// by GCC 4.5.x and later versions (and our locally-modified version of GCC
-// 4.4.x) to indicate functions which have been cloned during optimization.
-// We treat any sequence (.<alpha>+.<digit>+)+ as a function clone suffix.
-static bool IsFunctionCloneSuffix(const char *str) {
-  size_t i = 0;
-  while (str[i] != '\0') {
-    // Consume a single .<alpha>+.<digit>+ sequence.
-    if (str[i] != '.' || !IsAlpha(str[i + 1])) {
-      return false;
-    }
-    i += 2;
-    while (IsAlpha(str[i])) {
-      ++i;
-    }
-    if (str[i] != '.' || !IsDigit(str[i + 1])) {
-      return false;
-    }
-    i += 2;
-    while (IsDigit(str[i])) {
-      ++i;
-    }
-  }
-  return true;  // Consumed everything in "str".
-}
-
-static bool EndsWith(State *state, const char chr) {
-  return state->parse_state.out_cur_idx > 0 &&
-         state->parse_state.out_cur_idx < state->out_end_idx &&
-         chr == state->out[state->parse_state.out_cur_idx - 1];
-}
-
-// Append "str" with some tweaks, iff "append" state is true.
-static void MaybeAppendWithLength(State *state, const char *const str,
-                                  const int length) {
-  if (state->parse_state.append && length > 0) {
-    // Append a space if the output buffer ends with '<' and "str"
-    // starts with '<' to avoid <<<.
-    if (str[0] == '<' && EndsWith(state, '<')) {
-      Append(state, " ", 1);
-    }
-    // Remember the last identifier name for ctors/dtors,
-    // but only if we haven't yet overflown the buffer.
-    if (state->parse_state.out_cur_idx < state->out_end_idx &&
-        (IsAlpha(str[0]) || str[0] == '_')) {
-      state->parse_state.prev_name_idx = state->parse_state.out_cur_idx;
-      state->parse_state.prev_name_length = length;
-    }
-    Append(state, str, length);
-  }
-}
-
-// Appends a positive decimal number to the output if appending is enabled.
-static bool MaybeAppendDecimal(State *state, unsigned int val) {
-  // Max {32-64}-bit unsigned int is 20 digits.
-  constexpr size_t kMaxLength = 20;
-  char buf[kMaxLength];
-
-  // We can't use itoa or sprintf as neither is specified to be
-  // async-signal-safe.
-  if (state->parse_state.append) {
-    // We can't have a one-before-the-beginning pointer, so instead start with
-    // one-past-the-end and manipulate one character before the pointer.
-    char *p = &buf[kMaxLength];
-    do {  // val=0 is the only input that should write a leading zero digit.
-      *--p = (val % 10) + '0';
-      val /= 10;
-    } while (p > buf && val != 0);
-
-    // 'p' landed on the last character we set.  How convenient.
-    Append(state, p, kMaxLength - (p - buf));
-  }
-
-  return true;
-}
-
-// A convenient wrapper around MaybeAppendWithLength().
-// Returns true so that it can be placed in "if" conditions.
-static bool MaybeAppend(State *state, const char *const str) {
-  if (state->parse_state.append) {
-    int length = StrLen(str);
-    MaybeAppendWithLength(state, str, length);
-  }
-  return true;
-}
-
-// This function is used for handling nested names.
-static bool EnterNestedName(State *state) {
-  state->parse_state.nest_level = 0;
-  return true;
-}
-
-// This function is used for handling nested names.
-static bool LeaveNestedName(State *state, int16_t prev_value) {
-  state->parse_state.nest_level = prev_value;
-  return true;
-}
-
-// Disable the append mode not to print function parameters, etc.
-static bool DisableAppend(State *state) {
-  state->parse_state.append = false;
-  return true;
-}
-
-// Restore the append mode to the previous state.
-static bool RestoreAppend(State *state, bool prev_value) {
-  state->parse_state.append = prev_value;
-  return true;
-}
-
-// Increase the nest level for nested names.
-static void MaybeIncreaseNestLevel(State *state) {
-  if (state->parse_state.nest_level > -1) {
-    ++state->parse_state.nest_level;
-  }
-}
-
-// Appends :: for nested names if necessary.
-static void MaybeAppendSeparator(State *state) {
-  if (state->parse_state.nest_level >= 1) {
-    MaybeAppend(state, "::");
-  }
-}
-
-// Cancel the last separator if necessary.
-static void MaybeCancelLastSeparator(State *state) {
-  if (state->parse_state.nest_level >= 1 && state->parse_state.append &&
-      state->parse_state.out_cur_idx >= 2) {
-    state->parse_state.out_cur_idx -= 2;
-    state->out[state->parse_state.out_cur_idx] = '\0';
-  }
-}
-
-// Returns true if the identifier of the given length pointed to by
-// "mangled_cur" is anonymous namespace.
-static bool IdentifierIsAnonymousNamespace(State *state, int length) {
-  // Returns true if "anon_prefix" is a proper prefix of "mangled_cur".
-  static const char anon_prefix[] = "_GLOBAL__N_";
-  return (length > static_cast<int>(sizeof(anon_prefix) - 1) &&
-          StrPrefix(RemainingInput(state), anon_prefix));
-}
-
-// Forward declarations of our parsing functions.
-static bool ParseMangledName(State *state);
-static bool ParseEncoding(State *state);
-static bool ParseName(State *state);
-static bool ParseUnscopedName(State *state);
-static bool ParseNestedName(State *state);
-static bool ParsePrefix(State *state);
-static bool ParseUnqualifiedName(State *state);
-static bool ParseSourceName(State *state);
-static bool ParseLocalSourceName(State *state);
-static bool ParseUnnamedTypeName(State *state);
-static bool ParseNumber(State *state, int *number_out);
-static bool ParseFloatNumber(State *state);
-static bool ParseSeqId(State *state);
-static bool ParseIdentifier(State *state, int length);
-static bool ParseOperatorName(State *state, int *arity);
-static bool ParseSpecialName(State *state);
-static bool ParseCallOffset(State *state);
-static bool ParseNVOffset(State *state);
-static bool ParseVOffset(State *state);
-static bool ParseCtorDtorName(State *state);
-static bool ParseDecltype(State *state);
-static bool ParseType(State *state);
-static bool ParseCVQualifiers(State *state);
-static bool ParseBuiltinType(State *state);
-static bool ParseFunctionType(State *state);
-static bool ParseBareFunctionType(State *state);
-static bool ParseClassEnumType(State *state);
-static bool ParseArrayType(State *state);
-static bool ParsePointerToMemberType(State *state);
-static bool ParseTemplateParam(State *state);
-static bool ParseTemplateTemplateParam(State *state);
-static bool ParseTemplateArgs(State *state);
-static bool ParseTemplateArg(State *state);
-static bool ParseBaseUnresolvedName(State *state);
-static bool ParseUnresolvedName(State *state);
-static bool ParseExpression(State *state);
-static bool ParseExprPrimary(State *state);
-static bool ParseExprCastValue(State *state);
-static bool ParseLocalName(State *state);
-static bool ParseLocalNameSuffix(State *state);
-static bool ParseDiscriminator(State *state);
-static bool ParseSubstitution(State *state, bool accept_std);
-
-// Implementation note: the following code is a straightforward
-// translation of the Itanium C++ ABI defined in BNF with a couple of
-// exceptions.
-//
-// - Support GNU extensions not defined in the Itanium C++ ABI
-// - <prefix> and <template-prefix> are combined to avoid infinite loop
-// - Reorder patterns to shorten the code
-// - Reorder patterns to give greedier functions precedence
-//   We'll mark "Less greedy than" for these cases in the code
-//
-// Each parsing function changes the parse state and returns true on
-// success, or returns false and doesn't change the parse state (note:
-// the parse-steps counter increases regardless of success or failure).
-// To ensure that the parse state isn't changed in the latter case, we
-// save the original state before we call multiple parsing functions
-// consecutively with &&, and restore it if unsuccessful.  See
-// ParseEncoding() as an example of this convention.  We follow the
-// convention throughout the code.
-//
-// Originally we tried to do demangling without following the full ABI
-// syntax but it turned out we needed to follow the full syntax to
-// parse complicated cases like nested template arguments.  Note that
-// implementing a full-fledged demangler isn't trivial (libiberty's
-// cp-demangle.c has +4300 lines).
-//
-// Note that (foo) in <(foo) ...> is a modifier to be ignored.
-//
-// Reference:
-// - Itanium C++ ABI
-//   <https://mentorembedded.github.io/cxx-abi/abi.html#mangling>
-
-// <mangled-name> ::= _Z <encoding>
-static bool ParseMangledName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  return ParseTwoCharToken(state, "_Z") && ParseEncoding(state);
-}
-
-// <encoding> ::= <(function) name> <bare-function-type>
-//            ::= <(data) name>
-//            ::= <special-name>
-static bool ParseEncoding(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  // Implementing the first two productions together as <name>
-  // [<bare-function-type>] avoids exponential blowup of backtracking.
-  //
-  // Since Optional(...) can't fail, there's no need to copy the state for
-  // backtracking.
-  if (ParseName(state) && Optional(ParseBareFunctionType(state))) {
-    return true;
-  }
-
-  if (ParseSpecialName(state)) {
-    return true;
-  }
-  return false;
-}
-
-// <name> ::= <nested-name>
-//        ::= <unscoped-template-name> <template-args>
-//        ::= <unscoped-name>
-//        ::= <local-name>
-static bool ParseName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseNestedName(state) || ParseLocalName(state)) {
-    return true;
-  }
-
-  // We reorganize the productions to avoid re-parsing unscoped names.
-  // - Inline <unscoped-template-name> productions:
-  //   <name> ::= <substitution> <template-args>
-  //          ::= <unscoped-name> <template-args>
-  //          ::= <unscoped-name>
-  // - Merge the two productions that start with unscoped-name:
-  //   <name> ::= <unscoped-name> [<template-args>]
-
-  ParseState copy = state->parse_state;
-  // "std<...>" isn't a valid name.
-  if (ParseSubstitution(state, /*accept_std=*/false) &&
-      ParseTemplateArgs(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Note there's no need to restore state after this since only the first
-  // subparser can fail.
-  return ParseUnscopedName(state) && Optional(ParseTemplateArgs(state));
-}
-
-// <unscoped-name> ::= <unqualified-name>
-//                 ::= St <unqualified-name>
-static bool ParseUnscopedName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseUnqualifiedName(state)) {
-    return true;
-  }
-
-  ParseState copy = state->parse_state;
-  if (ParseTwoCharToken(state, "St") && MaybeAppend(state, "std::") &&
-      ParseUnqualifiedName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <ref-qualifer> ::= R // lvalue method reference qualifier
-//                ::= O // rvalue method reference qualifier
-static inline bool ParseRefQualifier(State *state) {
-  return ParseCharClass(state, "OR");
-}
-
-// <nested-name> ::= N [<CV-qualifiers>] [<ref-qualifier>] <prefix>
-//                   <unqualified-name> E
-//               ::= N [<CV-qualifiers>] [<ref-qualifier>] <template-prefix>
-//                   <template-args> E
-static bool ParseNestedName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'N') && EnterNestedName(state) &&
-      Optional(ParseCVQualifiers(state)) &&
-      Optional(ParseRefQualifier(state)) && ParsePrefix(state) &&
-      LeaveNestedName(state, copy.nest_level) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// This part is tricky.  If we literally translate them to code, we'll
-// end up infinite loop.  Hence we merge them to avoid the case.
-//
-// <prefix> ::= <prefix> <unqualified-name>
-//          ::= <template-prefix> <template-args>
-//          ::= <template-param>
-//          ::= <substitution>
-//          ::= # empty
-// <template-prefix> ::= <prefix> <(template) unqualified-name>
-//                   ::= <template-param>
-//                   ::= <substitution>
-static bool ParsePrefix(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  bool has_something = false;
-  while (true) {
-    MaybeAppendSeparator(state);
-    if (ParseTemplateParam(state) ||
-        ParseSubstitution(state, /*accept_std=*/true) ||
-        ParseUnscopedName(state) ||
-        (ParseOneCharToken(state, 'M') && ParseUnnamedTypeName(state))) {
-      has_something = true;
-      MaybeIncreaseNestLevel(state);
-      continue;
-    }
-    MaybeCancelLastSeparator(state);
-    if (has_something && ParseTemplateArgs(state)) {
-      return ParsePrefix(state);
-    } else {
-      break;
-    }
-  }
-  return true;
-}
-
-// <unqualified-name> ::= <operator-name>
-//                    ::= <ctor-dtor-name>
-//                    ::= <source-name>
-//                    ::= <local-source-name> // GCC extension; see below.
-//                    ::= <unnamed-type-name>
-static bool ParseUnqualifiedName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  return (ParseOperatorName(state, nullptr) || ParseCtorDtorName(state) ||
-          ParseSourceName(state) || ParseLocalSourceName(state) ||
-          ParseUnnamedTypeName(state));
-}
-
-// <source-name> ::= <positive length number> <identifier>
-static bool ParseSourceName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  int length = -1;
-  if (ParseNumber(state, &length) && ParseIdentifier(state, length)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <local-source-name> ::= L <source-name> [<discriminator>]
-//
-// References:
-//   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31775
-//   https://gcc.gnu.org/viewcvs?view=rev&revision=124467
-static bool ParseLocalSourceName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'L') && ParseSourceName(state) &&
-      Optional(ParseDiscriminator(state))) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <unnamed-type-name> ::= Ut [<(nonnegative) number>] _
-//                     ::= <closure-type-name>
-// <closure-type-name> ::= Ul <lambda-sig> E [<(nonnegative) number>] _
-// <lambda-sig>        ::= <(parameter) type>+
-static bool ParseUnnamedTypeName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  // Type's 1-based index n is encoded as { "", n == 1; itoa(n-2), otherwise }.
-  // Optionally parse the encoded value into 'which' and add 2 to get the index.
-  int which = -1;
-
-  // Unnamed type local to function or class.
-  if (ParseTwoCharToken(state, "Ut") && Optional(ParseNumber(state, &which)) &&
-      which <= std::numeric_limits<int>::max() - 2 &&  // Don't overflow.
-      ParseOneCharToken(state, '_')) {
-    MaybeAppend(state, "{unnamed type#");
-    MaybeAppendDecimal(state, 2 + which);
-    MaybeAppend(state, "}");
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Closure type.
-  which = -1;
-  if (ParseTwoCharToken(state, "Ul") && DisableAppend(state) &&
-      OneOrMore(ParseType, state) && RestoreAppend(state, copy.append) &&
-      ParseOneCharToken(state, 'E') && Optional(ParseNumber(state, &which)) &&
-      which <= std::numeric_limits<int>::max() - 2 &&  // Don't overflow.
-      ParseOneCharToken(state, '_')) {
-    MaybeAppend(state, "{lambda()#");
-    MaybeAppendDecimal(state, 2 + which);
-    MaybeAppend(state, "}");
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <number> ::= [n] <non-negative decimal integer>
-// If "number_out" is non-null, then *number_out is set to the value of the
-// parsed number on success.
-static bool ParseNumber(State *state, int *number_out) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  bool negative = false;
-  if (ParseOneCharToken(state, 'n')) {
-    negative = true;
-  }
-  const char *p = RemainingInput(state);
-  uint64_t number = 0;
-  for (; *p != '\0'; ++p) {
-    if (IsDigit(*p)) {
-      number = number * 10 + (*p - '0');
-    } else {
-      break;
-    }
-  }
-  // Apply the sign with uint64_t arithmetic so overflows aren't UB.  Gives
-  // "incorrect" results for out-of-range inputs, but negative values only
-  // appear for literals, which aren't printed.
-  if (negative) {
-    number = ~number + 1;
-  }
-  if (p != RemainingInput(state)) {  // Conversion succeeded.
-    state->parse_state.mangled_idx += p - RemainingInput(state);
-    if (number_out != nullptr) {
-      // Note: possibly truncate "number".
-      *number_out = number;
-    }
-    return true;
-  }
-  return false;
-}
-
-// Floating-point literals are encoded using a fixed-length lowercase
-// hexadecimal string.
-static bool ParseFloatNumber(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  const char *p = RemainingInput(state);
-  for (; *p != '\0'; ++p) {
-    if (!IsDigit(*p) && !(*p >= 'a' && *p <= 'f')) {
-      break;
-    }
-  }
-  if (p != RemainingInput(state)) {  // Conversion succeeded.
-    state->parse_state.mangled_idx += p - RemainingInput(state);
-    return true;
-  }
-  return false;
-}
-
-// The <seq-id> is a sequence number in base 36,
-// using digits and upper case letters
-static bool ParseSeqId(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  const char *p = RemainingInput(state);
-  for (; *p != '\0'; ++p) {
-    if (!IsDigit(*p) && !(*p >= 'A' && *p <= 'Z')) {
-      break;
-    }
-  }
-  if (p != RemainingInput(state)) {  // Conversion succeeded.
-    state->parse_state.mangled_idx += p - RemainingInput(state);
-    return true;
-  }
-  return false;
-}
-
-// <identifier> ::= <unqualified source code identifier> (of given length)
-static bool ParseIdentifier(State *state, int length) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (length < 0 || !AtLeastNumCharsRemaining(RemainingInput(state), length)) {
-    return false;
-  }
-  if (IdentifierIsAnonymousNamespace(state, length)) {
-    MaybeAppend(state, "(anonymous namespace)");
-  } else {
-    MaybeAppendWithLength(state, RemainingInput(state), length);
-  }
-  state->parse_state.mangled_idx += length;
-  return true;
-}
-
-// <operator-name> ::= nw, and other two letters cases
-//                 ::= cv <type>  # (cast)
-//                 ::= v  <digit> <source-name> # vendor extended operator
-static bool ParseOperatorName(State *state, int *arity) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (!AtLeastNumCharsRemaining(RemainingInput(state), 2)) {
-    return false;
-  }
-  // First check with "cv" (cast) case.
-  ParseState copy = state->parse_state;
-  if (ParseTwoCharToken(state, "cv") && MaybeAppend(state, "operator ") &&
-      EnterNestedName(state) && ParseType(state) &&
-      LeaveNestedName(state, copy.nest_level)) {
-    if (arity != nullptr) {
-      *arity = 1;
-    }
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Then vendor extended operators.
-  if (ParseOneCharToken(state, 'v') && ParseDigit(state, arity) &&
-      ParseSourceName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Other operator names should start with a lower alphabet followed
-  // by a lower/upper alphabet.
-  if (!(IsLower(RemainingInput(state)[0]) &&
-        IsAlpha(RemainingInput(state)[1]))) {
-    return false;
-  }
-  // We may want to perform a binary search if we really need speed.
-  const AbbrevPair *p;
-  for (p = kOperatorList; p->abbrev != nullptr; ++p) {
-    if (RemainingInput(state)[0] == p->abbrev[0] &&
-        RemainingInput(state)[1] == p->abbrev[1]) {
-      if (arity != nullptr) {
-        *arity = p->arity;
-      }
-      MaybeAppend(state, "operator");
-      if (IsLower(*p->real_name)) {  // new, delete, etc.
-        MaybeAppend(state, " ");
-      }
-      MaybeAppend(state, p->real_name);
-      state->parse_state.mangled_idx += 2;
-      return true;
-    }
-  }
-  return false;
-}
-
-// <special-name> ::= TV <type>
-//                ::= TT <type>
-//                ::= TI <type>
-//                ::= TS <type>
-//                ::= TH <type>  # thread-local
-//                ::= Tc <call-offset> <call-offset> <(base) encoding>
-//                ::= GV <(object) name>
-//                ::= T <call-offset> <(base) encoding>
-// G++ extensions:
-//                ::= TC <type> <(offset) number> _ <(base) type>
-//                ::= TF <type>
-//                ::= TJ <type>
-//                ::= GR <name>
-//                ::= GA <encoding>
-//                ::= Th <call-offset> <(base) encoding>
-//                ::= Tv <call-offset> <(base) encoding>
-//
-// Note: we don't care much about them since they don't appear in
-// stack traces.  The are special data.
-static bool ParseSpecialName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "VTISH") &&
-      ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "Tc") && ParseCallOffset(state) &&
-      ParseCallOffset(state) && ParseEncoding(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "GV") && ParseName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'T') && ParseCallOffset(state) &&
-      ParseEncoding(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // G++ extensions
-  if (ParseTwoCharToken(state, "TC") && ParseType(state) &&
-      ParseNumber(state, nullptr) && ParseOneCharToken(state, '_') &&
-      DisableAppend(state) && ParseType(state)) {
-    RestoreAppend(state, copy.append);
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "FJ") &&
-      ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "GR") && ParseName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "GA") && ParseEncoding(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'T') && ParseCharClass(state, "hv") &&
-      ParseCallOffset(state) && ParseEncoding(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <call-offset> ::= h <nv-offset> _
-//               ::= v <v-offset> _
-static bool ParseCallOffset(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'h') && ParseNVOffset(state) &&
-      ParseOneCharToken(state, '_')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'v') && ParseVOffset(state) &&
-      ParseOneCharToken(state, '_')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <nv-offset> ::= <(offset) number>
-static bool ParseNVOffset(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  return ParseNumber(state, nullptr);
-}
-
-// <v-offset>  ::= <(offset) number> _ <(virtual offset) number>
-static bool ParseVOffset(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseNumber(state, nullptr) && ParseOneCharToken(state, '_') &&
-      ParseNumber(state, nullptr)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <ctor-dtor-name> ::= C1 | C2 | C3 | CI1 <base-class-type> | CI2
-// <base-class-type>
-//                  ::= D0 | D1 | D2
-// # GCC extensions: "unified" constructor/destructor.  See
-// #
-// https://github.com/gcc-mirror/gcc/blob/7ad17b583c3643bd4557f29b8391ca7ef08391f5/gcc/cp/mangle.c#L1847
-//                  ::= C4 | D4
-static bool ParseCtorDtorName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'C')) {
-    if (ParseCharClass(state, "1234")) {
-      const char *const prev_name =
-          state->out + state->parse_state.prev_name_idx;
-      MaybeAppendWithLength(state, prev_name,
-                            state->parse_state.prev_name_length);
-      return true;
-    } else if (ParseOneCharToken(state, 'I') && ParseCharClass(state, "12") &&
-               ParseClassEnumType(state)) {
-      return true;
-    }
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'D') && ParseCharClass(state, "0124")) {
-    const char *const prev_name = state->out + state->parse_state.prev_name_idx;
-    MaybeAppend(state, "~");
-    MaybeAppendWithLength(state, prev_name,
-                          state->parse_state.prev_name_length);
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <decltype> ::= Dt <expression> E  # decltype of an id-expression or class
-//                                   # member access (C++0x)
-//            ::= DT <expression> E  # decltype of an expression (C++0x)
-static bool ParseDecltype(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'D') && ParseCharClass(state, "tT") &&
-      ParseExpression(state) && ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <type> ::= <CV-qualifiers> <type>
-//        ::= P <type>   # pointer-to
-//        ::= R <type>   # reference-to
-//        ::= O <type>   # rvalue reference-to (C++0x)
-//        ::= C <type>   # complex pair (C 2000)
-//        ::= G <type>   # imaginary (C 2000)
-//        ::= U <source-name> <type>  # vendor extended type qualifier
-//        ::= <builtin-type>
-//        ::= <function-type>
-//        ::= <class-enum-type>  # note: just an alias for <name>
-//        ::= <array-type>
-//        ::= <pointer-to-member-type>
-//        ::= <template-template-param> <template-args>
-//        ::= <template-param>
-//        ::= <decltype>
-//        ::= <substitution>
-//        ::= Dp <type>          # pack expansion of (C++0x)
-//        ::= Dv <num-elems> _   # GNU vector extension
-//
-static bool ParseType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-
-  // We should check CV-qualifers, and PRGC things first.
-  //
-  // CV-qualifiers overlap with some operator names, but an operator name is not
-  // valid as a type.  To avoid an ambiguity that can lead to exponential time
-  // complexity, refuse to backtrack the CV-qualifiers.
-  //
-  // _Z4aoeuIrMvvE
-  //  => _Z 4aoeuI        rM  v     v   E
-  //         aoeu<operator%=, void, void>
-  //  => _Z 4aoeuI r Mv v              E
-  //         aoeu<void void::* restrict>
-  //
-  // By consuming the CV-qualifiers first, the former parse is disabled.
-  if (ParseCVQualifiers(state)) {
-    const bool result = ParseType(state);
-    if (!result) state->parse_state = copy;
-    return result;
-  }
-  state->parse_state = copy;
-
-  // Similarly, these tag characters can overlap with other <name>s resulting in
-  // two different parse prefixes that land on <template-args> in the same
-  // place, such as "C3r1xI...".  So, disable the "ctor-name = C3" parse by
-  // refusing to backtrack the tag characters.
-  if (ParseCharClass(state, "OPRCG")) {
-    const bool result = ParseType(state);
-    if (!result) state->parse_state = copy;
-    return result;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "Dp") && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'U') && ParseSourceName(state) &&
-      ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseBuiltinType(state) || ParseFunctionType(state) ||
-      ParseClassEnumType(state) || ParseArrayType(state) ||
-      ParsePointerToMemberType(state) || ParseDecltype(state) ||
-      // "std" on its own isn't a type.
-      ParseSubstitution(state, /*accept_std=*/false)) {
-    return true;
-  }
-
-  if (ParseTemplateTemplateParam(state) && ParseTemplateArgs(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Less greedy than <template-template-param> <template-args>.
-  if (ParseTemplateParam(state)) {
-    return true;
-  }
-
-  if (ParseTwoCharToken(state, "Dv") && ParseNumber(state, nullptr) &&
-      ParseOneCharToken(state, '_')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <CV-qualifiers> ::= [r] [V] [K]
-// We don't allow empty <CV-qualifiers> to avoid infinite loop in
-// ParseType().
-static bool ParseCVQualifiers(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  int num_cv_qualifiers = 0;
-  num_cv_qualifiers += ParseOneCharToken(state, 'r');
-  num_cv_qualifiers += ParseOneCharToken(state, 'V');
-  num_cv_qualifiers += ParseOneCharToken(state, 'K');
-  return num_cv_qualifiers > 0;
-}
-
-// <builtin-type> ::= v, etc.  # single-character builtin types
-//                ::= u <source-name>
-//                ::= Dd, etc.  # two-character builtin types
-//
-// Not supported:
-//                ::= DF <number> _ # _FloatN (N bits)
-//
-static bool ParseBuiltinType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  const AbbrevPair *p;
-  for (p = kBuiltinTypeList; p->abbrev != nullptr; ++p) {
-    // Guaranteed only 1- or 2-character strings in kBuiltinTypeList.
-    if (p->abbrev[1] == '\0') {
-      if (ParseOneCharToken(state, p->abbrev[0])) {
-        MaybeAppend(state, p->real_name);
-        return true;
-      }
-    } else if (p->abbrev[2] == '\0' && ParseTwoCharToken(state, p->abbrev)) {
-      MaybeAppend(state, p->real_name);
-      return true;
-    }
-  }
-
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'u') && ParseSourceName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-//  <exception-spec> ::= Do                # non-throwing
-//                                           exception-specification (e.g.,
-//                                           noexcept, throw())
-//                   ::= DO <expression> E # computed (instantiation-dependent)
-//                                           noexcept
-//                   ::= Dw <type>+ E      # dynamic exception specification
-//                                           with instantiation-dependent types
-static bool ParseExceptionSpec(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-
-  if (ParseTwoCharToken(state, "Do")) return true;
-
-  ParseState copy = state->parse_state;
-  if (ParseTwoCharToken(state, "DO") && ParseExpression(state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-  if (ParseTwoCharToken(state, "Dw") && OneOrMore(ParseType, state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <function-type> ::= [exception-spec] F [Y] <bare-function-type> [O] E
-static bool ParseFunctionType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (Optional(ParseExceptionSpec(state)) && ParseOneCharToken(state, 'F') &&
-      Optional(ParseOneCharToken(state, 'Y')) && ParseBareFunctionType(state) &&
-      Optional(ParseOneCharToken(state, 'O')) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <bare-function-type> ::= <(signature) type>+
-static bool ParseBareFunctionType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  DisableAppend(state);
-  if (OneOrMore(ParseType, state)) {
-    RestoreAppend(state, copy.append);
-    MaybeAppend(state, "()");
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <class-enum-type> ::= <name>
-static bool ParseClassEnumType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  return ParseName(state);
-}
-
-// <array-type> ::= A <(positive dimension) number> _ <(element) type>
-//              ::= A [<(dimension) expression>] _ <(element) type>
-static bool ParseArrayType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'A') && ParseNumber(state, nullptr) &&
-      ParseOneCharToken(state, '_') && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'A') && Optional(ParseExpression(state)) &&
-      ParseOneCharToken(state, '_') && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <pointer-to-member-type> ::= M <(class) type> <(member) type>
-static bool ParsePointerToMemberType(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'M') && ParseType(state) && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <template-param> ::= T_
-//                  ::= T <parameter-2 non-negative number> _
-static bool ParseTemplateParam(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseTwoCharToken(state, "T_")) {
-    MaybeAppend(state, "?");  // We don't support template substitutions.
-    return true;
-  }
-
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'T') && ParseNumber(state, nullptr) &&
-      ParseOneCharToken(state, '_')) {
-    MaybeAppend(state, "?");  // We don't support template substitutions.
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <template-template-param> ::= <template-param>
-//                           ::= <substitution>
-static bool ParseTemplateTemplateParam(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  return (ParseTemplateParam(state) ||
-          // "std" on its own isn't a template.
-          ParseSubstitution(state, /*accept_std=*/false));
-}
-
-// <template-args> ::= I <template-arg>+ E
-static bool ParseTemplateArgs(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  DisableAppend(state);
-  if (ParseOneCharToken(state, 'I') && OneOrMore(ParseTemplateArg, state) &&
-      ParseOneCharToken(state, 'E')) {
-    RestoreAppend(state, copy.append);
-    MaybeAppend(state, "<>");
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <template-arg>  ::= <type>
-//                 ::= <expr-primary>
-//                 ::= J <template-arg>* E        # argument pack
-//                 ::= X <expression> E
-static bool ParseTemplateArg(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'J') && ZeroOrMore(ParseTemplateArg, state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // There can be significant overlap between the following leading to
-  // exponential backtracking:
-  //
-  //   <expr-primary> ::= L <type> <expr-cast-value> E
-  //                 e.g. L 2xxIvE 1                 E
-  //   <type>         ==> <local-source-name> <template-args>
-  //                 e.g. L 2xx               IvE
-  //
-  // This means parsing an entire <type> twice, and <type> can contain
-  // <template-arg>, so this can generate exponential backtracking.  There is
-  // only overlap when the remaining input starts with "L <source-name>", so
-  // parse all cases that can start this way jointly to share the common prefix.
-  //
-  // We have:
-  //
-  //   <template-arg> ::= <type>
-  //                  ::= <expr-primary>
-  //
-  // First, drop all the productions of <type> that must start with something
-  // other than 'L'.  All that's left is <class-enum-type>; inline it.
-  //
-  //   <type> ::= <nested-name> # starts with 'N'
-  //          ::= <unscoped-name>
-  //          ::= <unscoped-template-name> <template-args>
-  //          ::= <local-name> # starts with 'Z'
-  //
-  // Drop and inline again:
-  //
-  //   <type> ::= <unscoped-name>
-  //          ::= <unscoped-name> <template-args>
-  //          ::= <substitution> <template-args> # starts with 'S'
-  //
-  // Merge the first two, inline <unscoped-name>, drop last:
-  //
-  //   <type> ::= <unqualified-name> [<template-args>]
-  //          ::= St <unqualified-name> [<template-args>] # starts with 'S'
-  //
-  // Drop and inline:
-  //
-  //   <type> ::= <operator-name> [<template-args>] # starts with lowercase
-  //          ::= <ctor-dtor-name> [<template-args>] # starts with 'C' or 'D'
-  //          ::= <source-name> [<template-args>] # starts with digit
-  //          ::= <local-source-name> [<template-args>]
-  //          ::= <unnamed-type-name> [<template-args>] # starts with 'U'
-  //
-  // One more time:
-  //
-  //   <type> ::= L <source-name> [<template-args>]
-  //
-  // Likewise with <expr-primary>:
-  //
-  //   <expr-primary> ::= L <type> <expr-cast-value> E
-  //                  ::= LZ <encoding> E # cannot overlap; drop
-  //                  ::= L <mangled_name> E # cannot overlap; drop
-  //
-  // By similar reasoning as shown above, the only <type>s starting with
-  // <source-name> are "<source-name> [<template-args>]".  Inline this.
-  //
-  //   <expr-primary> ::= L <source-name> [<template-args>] <expr-cast-value> E
-  //
-  // Now inline both of these into <template-arg>:
-  //
-  //   <template-arg> ::= L <source-name> [<template-args>]
-  //                  ::= L <source-name> [<template-args>] <expr-cast-value> E
-  //
-  // Merge them and we're done:
-  //   <template-arg>
-  //     ::= L <source-name> [<template-args>] [<expr-cast-value> E]
-  if (ParseLocalSourceName(state) && Optional(ParseTemplateArgs(state))) {
-    copy = state->parse_state;
-    if (ParseExprCastValue(state) && ParseOneCharToken(state, 'E')) {
-      return true;
-    }
-    state->parse_state = copy;
-    return true;
-  }
-
-  // Now that the overlapping cases can't reach this code, we can safely call
-  // both of these.
-  if (ParseType(state) || ParseExprPrimary(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'X') && ParseExpression(state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <unresolved-type> ::= <template-param> [<template-args>]
-//                   ::= <decltype>
-//                   ::= <substitution>
-static inline bool ParseUnresolvedType(State *state) {
-  // No ComplexityGuard because we don't copy the state in this stack frame.
-  return (ParseTemplateParam(state) && Optional(ParseTemplateArgs(state))) ||
-         ParseDecltype(state) || ParseSubstitution(state, /*accept_std=*/false);
-}
-
-// <simple-id> ::= <source-name> [<template-args>]
-static inline bool ParseSimpleId(State *state) {
-  // No ComplexityGuard because we don't copy the state in this stack frame.
-
-  // Note: <simple-id> cannot be followed by a parameter pack; see comment in
-  // ParseUnresolvedType.
-  return ParseSourceName(state) && Optional(ParseTemplateArgs(state));
-}
-
-// <base-unresolved-name> ::= <source-name> [<template-args>]
-//                        ::= on <operator-name> [<template-args>]
-//                        ::= dn <destructor-name>
-static bool ParseBaseUnresolvedName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-
-  if (ParseSimpleId(state)) {
-    return true;
-  }
-
-  ParseState copy = state->parse_state;
-  if (ParseTwoCharToken(state, "on") && ParseOperatorName(state, nullptr) &&
-      Optional(ParseTemplateArgs(state))) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "dn") &&
-      (ParseUnresolvedType(state) || ParseSimpleId(state))) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <unresolved-name> ::= [gs] <base-unresolved-name>
-//                   ::= sr <unresolved-type> <base-unresolved-name>
-//                   ::= srN <unresolved-type> <unresolved-qualifier-level>+ E
-//                         <base-unresolved-name>
-//                   ::= [gs] sr <unresolved-qualifier-level>+ E
-//                         <base-unresolved-name>
-static bool ParseUnresolvedName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-
-  ParseState copy = state->parse_state;
-  if (Optional(ParseTwoCharToken(state, "gs")) &&
-      ParseBaseUnresolvedName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "sr") && ParseUnresolvedType(state) &&
-      ParseBaseUnresolvedName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseTwoCharToken(state, "sr") && ParseOneCharToken(state, 'N') &&
-      ParseUnresolvedType(state) &&
-      OneOrMore(/* <unresolved-qualifier-level> ::= */ ParseSimpleId, state) &&
-      ParseOneCharToken(state, 'E') && ParseBaseUnresolvedName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (Optional(ParseTwoCharToken(state, "gs")) &&
-      ParseTwoCharToken(state, "sr") &&
-      OneOrMore(/* <unresolved-qualifier-level> ::= */ ParseSimpleId, state) &&
-      ParseOneCharToken(state, 'E') && ParseBaseUnresolvedName(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <expression> ::= <1-ary operator-name> <expression>
-//              ::= <2-ary operator-name> <expression> <expression>
-//              ::= <3-ary operator-name> <expression> <expression> <expression>
-//              ::= cl <expression>+ E
-//              ::= cv <type> <expression>      # type (expression)
-//              ::= cv <type> _ <expression>* E # type (expr-list)
-//              ::= st <type>
-//              ::= <template-param>
-//              ::= <function-param>
-//              ::= <expr-primary>
-//              ::= dt <expression> <unresolved-name> # expr.name
-//              ::= pt <expression> <unresolved-name> # expr->name
-//              ::= sp <expression>         # argument pack expansion
-//              ::= sr <type> <unqualified-name> <template-args>
-//              ::= sr <type> <unqualified-name>
-// <function-param> ::= fp <(top-level) CV-qualifiers> _
-//                  ::= fp <(top-level) CV-qualifiers> <number> _
-//                  ::= fL <number> p <(top-level) CV-qualifiers> _
-//                  ::= fL <number> p <(top-level) CV-qualifiers> <number> _
-static bool ParseExpression(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseTemplateParam(state) || ParseExprPrimary(state)) {
-    return true;
-  }
-
-  // Object/function call expression.
-  ParseState copy = state->parse_state;
-  if (ParseTwoCharToken(state, "cl") && OneOrMore(ParseExpression, state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Function-param expression (level 0).
-  if (ParseTwoCharToken(state, "fp") && Optional(ParseCVQualifiers(state)) &&
-      Optional(ParseNumber(state, nullptr)) && ParseOneCharToken(state, '_')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Function-param expression (level 1+).
-  if (ParseTwoCharToken(state, "fL") && Optional(ParseNumber(state, nullptr)) &&
-      ParseOneCharToken(state, 'p') && Optional(ParseCVQualifiers(state)) &&
-      Optional(ParseNumber(state, nullptr)) && ParseOneCharToken(state, '_')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Parse the conversion expressions jointly to avoid re-parsing the <type> in
-  // their common prefix.  Parsed as:
-  // <expression> ::= cv <type> <conversion-args>
-  // <conversion-args> ::= _ <expression>* E
-  //                   ::= <expression>
-  //
-  // Also don't try ParseOperatorName after seeing "cv", since ParseOperatorName
-  // also needs to accept "cv <type>" in other contexts.
-  if (ParseTwoCharToken(state, "cv")) {
-    if (ParseType(state)) {
-      ParseState copy2 = state->parse_state;
-      if (ParseOneCharToken(state, '_') && ZeroOrMore(ParseExpression, state) &&
-          ParseOneCharToken(state, 'E')) {
-        return true;
-      }
-      state->parse_state = copy2;
-      if (ParseExpression(state)) {
-        return true;
-      }
-    }
-  } else {
-    // Parse unary, binary, and ternary operator expressions jointly, taking
-    // care not to re-parse subexpressions repeatedly. Parse like:
-    //   <expression> ::= <operator-name> <expression>
-    //                    [<one-to-two-expressions>]
-    //   <one-to-two-expressions> ::= <expression> [<expression>]
-    int arity = -1;
-    if (ParseOperatorName(state, &arity) &&
-        arity > 0 &&  // 0 arity => disabled.
-        (arity < 3 || ParseExpression(state)) &&
-        (arity < 2 || ParseExpression(state)) &&
-        (arity < 1 || ParseExpression(state))) {
-      return true;
-    }
-  }
-  state->parse_state = copy;
-
-  // sizeof type
-  if (ParseTwoCharToken(state, "st") && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Object and pointer member access expressions.
-  if ((ParseTwoCharToken(state, "dt") || ParseTwoCharToken(state, "pt")) &&
-      ParseExpression(state) && ParseType(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Pointer-to-member access expressions.  This parses the same as a binary
-  // operator, but it's implemented separately because "ds" shouldn't be
-  // accepted in other contexts that parse an operator name.
-  if (ParseTwoCharToken(state, "ds") && ParseExpression(state) &&
-      ParseExpression(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Parameter pack expansion
-  if (ParseTwoCharToken(state, "sp") && ParseExpression(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return ParseUnresolvedName(state);
-}
-
-// <expr-primary> ::= L <type> <(value) number> E
-//                ::= L <type> <(value) float> E
-//                ::= L <mangled-name> E
-//                // A bug in g++'s C++ ABI version 2 (-fabi-version=2).
-//                ::= LZ <encoding> E
-//
-// Warning, subtle: the "bug" LZ production above is ambiguous with the first
-// production where <type> starts with <local-name>, which can lead to
-// exponential backtracking in two scenarios:
-//
-// - When whatever follows the E in the <local-name> in the first production is
-//   not a name, we backtrack the whole <encoding> and re-parse the whole thing.
-//
-// - When whatever follows the <local-name> in the first production is not a
-//   number and this <expr-primary> may be followed by a name, we backtrack the
-//   <name> and re-parse it.
-//
-// Moreover this ambiguity isn't always resolved -- for example, the following
-// has two different parses:
-//
-//   _ZaaILZ4aoeuE1x1EvE
-//   => operator&&<aoeu, x, E, void>
-//   => operator&&<(aoeu::x)(1), void>
-//
-// To resolve this, we just do what GCC's demangler does, and refuse to parse
-// casts to <local-name> types.
-static bool ParseExprPrimary(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-
-  // The "LZ" special case: if we see LZ, we commit to accept "LZ <encoding> E"
-  // or fail, no backtracking.
-  if (ParseTwoCharToken(state, "LZ")) {
-    if (ParseEncoding(state) && ParseOneCharToken(state, 'E')) {
-      return true;
-    }
-
-    state->parse_state = copy;
-    return false;
-  }
-
-  // The merged cast production.
-  if (ParseOneCharToken(state, 'L') && ParseType(state) &&
-      ParseExprCastValue(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseOneCharToken(state, 'L') && ParseMangledName(state) &&
-      ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <number> or <float>, followed by 'E', as described above ParseExprPrimary.
-static bool ParseExprCastValue(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  // We have to be able to backtrack after accepting a number because we could
-  // have e.g. "7fffE", which will accept "7" as a number but then fail to find
-  // the 'E'.
-  ParseState copy = state->parse_state;
-  if (ParseNumber(state, nullptr) && ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  if (ParseFloatNumber(state) && ParseOneCharToken(state, 'E')) {
-    return true;
-  }
-  state->parse_state = copy;
-
-  return false;
-}
-
-// <local-name> ::= Z <(function) encoding> E <(entity) name> [<discriminator>]
-//              ::= Z <(function) encoding> E s [<discriminator>]
-//
-// Parsing a common prefix of these two productions together avoids an
-// exponential blowup of backtracking.  Parse like:
-//   <local-name> := Z <encoding> E <local-name-suffix>
-//   <local-name-suffix> ::= s [<discriminator>]
-//                       ::= <name> [<discriminator>]
-
-static bool ParseLocalNameSuffix(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-
-  if (MaybeAppend(state, "::") && ParseName(state) &&
-      Optional(ParseDiscriminator(state))) {
-    return true;
-  }
-
-  // Since we're not going to overwrite the above "::" by re-parsing the
-  // <encoding> (whose trailing '\0' byte was in the byte now holding the
-  // first ':'), we have to rollback the "::" if the <name> parse failed.
-  if (state->parse_state.append) {
-    state->out[state->parse_state.out_cur_idx - 2] = '\0';
-  }
-
-  return ParseOneCharToken(state, 's') && Optional(ParseDiscriminator(state));
-}
-
-static bool ParseLocalName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'Z') && ParseEncoding(state) &&
-      ParseOneCharToken(state, 'E') && ParseLocalNameSuffix(state)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <discriminator> := _ <(non-negative) number>
-static bool ParseDiscriminator(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, '_') && ParseNumber(state, nullptr)) {
-    return true;
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// <substitution> ::= S_
-//                ::= S <seq-id> _
-//                ::= St, etc.
-//
-// "St" is special in that it's not valid as a standalone name, and it *is*
-// allowed to precede a name without being wrapped in "N...E".  This means that
-// if we accept it on its own, we can accept "St1a" and try to parse
-// template-args, then fail and backtrack, accept "St" on its own, then "1a" as
-// an unqualified name and re-parse the same template-args.  To block this
-// exponential backtracking, we disable it with 'accept_std=false' in
-// problematic contexts.
-static bool ParseSubstitution(State *state, bool accept_std) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseTwoCharToken(state, "S_")) {
-    MaybeAppend(state, "?");  // We don't support substitutions.
-    return true;
-  }
-
-  ParseState copy = state->parse_state;
-  if (ParseOneCharToken(state, 'S') && ParseSeqId(state) &&
-      ParseOneCharToken(state, '_')) {
-    MaybeAppend(state, "?");  // We don't support substitutions.
-    return true;
-  }
-  state->parse_state = copy;
-
-  // Expand abbreviations like "St" => "std".
-  if (ParseOneCharToken(state, 'S')) {
-    const AbbrevPair *p;
-    for (p = kSubstitutionList; p->abbrev != nullptr; ++p) {
-      if (RemainingInput(state)[0] == p->abbrev[1] &&
-          (accept_std || p->abbrev[1] != 't')) {
-        MaybeAppend(state, "std");
-        if (p->real_name[0] != '\0') {
-          MaybeAppend(state, "::");
-          MaybeAppend(state, p->real_name);
-        }
-        ++state->parse_state.mangled_idx;
-        return true;
-      }
-    }
-  }
-  state->parse_state = copy;
-  return false;
-}
-
-// Parse <mangled-name>, optionally followed by either a function-clone suffix
-// or version suffix.  Returns true only if all of "mangled_cur" was consumed.
-static bool ParseTopLevelMangledName(State *state) {
-  ComplexityGuard guard(state);
-  if (guard.IsTooComplex()) return false;
-  if (ParseMangledName(state)) {
-    if (RemainingInput(state)[0] != '\0') {
-      // Drop trailing function clone suffix, if any.
-      if (IsFunctionCloneSuffix(RemainingInput(state))) {
-        return true;
-      }
-      // Append trailing version suffix if any.
-      // ex. _Z3foo@@GLIBCXX_3.4
-      if (RemainingInput(state)[0] == '@') {
-        MaybeAppend(state, RemainingInput(state));
-        return true;
-      }
-      return false;  // Unconsumed suffix.
-    }
-    return true;
-  }
-  return false;
-}
-
-static bool Overflowed(const State *state) {
-  return state->parse_state.out_cur_idx >= state->out_end_idx;
-}
-
-// The demangler entry point.
-bool Demangle(const char *mangled, char *out, int out_size) {
-  State state;
-  InitState(&state, mangled, out, out_size);
-  return ParseTopLevelMangledName(&state) && !Overflowed(&state) &&
-         state.parse_state.out_cur_idx > 0;
-}
-
-}  // namespace debugging_internal
-ABSL_NAMESPACE_END
-}  // namespace absl