Convert the full parser into constexpr now that Abseil requires C++14, and use

this parser for the static checker.
This fixes some outstanding bugs where the static checker differed from the
dynamic one.
Also, fix `%v` to be accepted with POSIX syntax.

Tested:
  Presubmit
  TGP OCL:487237262:BASE:490275393:1669141454896:92dd62e3
PiperOrigin-RevId: 491650577
Change-Id: Id138c108187428b3aea46f8887495f1da12c91b2

1 files changed, 5 insertions, 208 deletions

diff --git a/absl/strings/internal/str_format/parser.cc b/absl/strings/internal/str_format/parser.cc
index 13731ee2..5aaab698 100644
--- a/absl/strings/internal/str_format/parser.cc
+++ b/absl/strings/internal/str_format/parser.cc
@@ -31,211 +31,14 @@ namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace str_format_internal {
 
-using CC = FormatConversionCharInternal;
-using LM = LengthMod;
+// Define the array for non-constexpr uses.
+constexpr ConvTag ConvTagHolder::value[256];
 
-// Abbreviations to fit in the table below.
-constexpr auto f_sign = Flags::kSignCol;
-constexpr auto f_alt = Flags::kAlt;
-constexpr auto f_pos = Flags::kShowPos;
-constexpr auto f_left = Flags::kLeft;
-constexpr auto f_zero = Flags::kZero;
-
-ABSL_CONST_INIT const ConvTag kTags[256] = {
-    {},     {},    {},    {},    {},    {},     {},    {},     // 00-07
-    {},     {},    {},    {},    {},    {},     {},    {},     // 08-0f
-    {},     {},    {},    {},    {},    {},     {},    {},     // 10-17
-    {},     {},    {},    {},    {},    {},     {},    {},     // 18-1f
-    f_sign, {},    {},    f_alt, {},    {},     {},    {},     //  !"#$%&'
-    {},     {},    {},    f_pos, {},    f_left, {},    {},     // ()*+,-./
-    f_zero, {},    {},    {},    {},    {},     {},    {},     // 01234567
-    {},     {},    {},    {},    {},    {},     {},    {},     // 89:;<=>?
-    {},     CC::A, {},    {},    {},    CC::E,  CC::F, CC::G,  // @ABCDEFG
-    {},     {},    {},    {},    LM::L, {},     {},    {},     // HIJKLMNO
-    {},     {},    {},    {},    {},    {},     {},    {},     // PQRSTUVW
-    CC::X,  {},    {},    {},    {},    {},     {},    {},     // XYZ[\]^_
-    {},     CC::a, {},    CC::c, CC::d, CC::e,  CC::f, CC::g,  // `abcdefg
-    LM::h,  CC::i, LM::j, {},    LM::l, {},     CC::n, CC::o,  // hijklmno
-    CC::p,  LM::q, {},    CC::s, LM::t, CC::u,  CC::v, {},     // pqrstuvw
-    CC::x,  {},    LM::z, {},    {},    {},     {},    {},     // xyz{|}!
-    {},     {},    {},    {},    {},    {},     {},    {},     // 80-87
-    {},     {},    {},    {},    {},    {},     {},    {},     // 88-8f
-    {},     {},    {},    {},    {},    {},     {},    {},     // 90-97
-    {},     {},    {},    {},    {},    {},     {},    {},     // 98-9f
-    {},     {},    {},    {},    {},    {},     {},    {},     // a0-a7
-    {},     {},    {},    {},    {},    {},     {},    {},     // a8-af
-    {},     {},    {},    {},    {},    {},     {},    {},     // b0-b7
-    {},     {},    {},    {},    {},    {},     {},    {},     // b8-bf
-    {},     {},    {},    {},    {},    {},     {},    {},     // c0-c7
-    {},     {},    {},    {},    {},    {},     {},    {},     // c8-cf
-    {},     {},    {},    {},    {},    {},     {},    {},     // d0-d7
-    {},     {},    {},    {},    {},    {},     {},    {},     // d8-df
-    {},     {},    {},    {},    {},    {},     {},    {},     // e0-e7
-    {},     {},    {},    {},    {},    {},     {},    {},     // e8-ef
-    {},     {},    {},    {},    {},    {},     {},    {},     // f0-f7
-    {},     {},    {},    {},    {},    {},     {},    {},     // f8-ff
-};
-
-namespace {
-
-bool CheckFastPathSetting(const UnboundConversion& conv) {
-  bool width_precision_needed =
-      conv.width.value() >= 0 || conv.precision.value() >= 0;
-  if (width_precision_needed && conv.flags == Flags::kBasic) {
-    fprintf(stderr,
-            "basic=%d left=%d show_pos=%d sign_col=%d alt=%d zero=%d "
-            "width=%d precision=%d\n",
-            conv.flags == Flags::kBasic ? 1 : 0,
-            FlagsContains(conv.flags, Flags::kLeft) ? 1 : 0,
-            FlagsContains(conv.flags, Flags::kShowPos) ? 1 : 0,
-            FlagsContains(conv.flags, Flags::kSignCol) ? 1 : 0,
-            FlagsContains(conv.flags, Flags::kAlt) ? 1 : 0,
-            FlagsContains(conv.flags, Flags::kZero) ? 1 : 0, conv.width.value(),
-            conv.precision.value());
-    return false;
-  }
-  return true;
-}
-
-template <bool is_positional>
-const char *ConsumeConversion(const char *pos, const char *const end,
-                              UnboundConversion *conv, int *next_arg) {
-  const char* const original_pos = pos;
-  char c;
-  // Read the next char into `c` and update `pos`. Returns false if there are
-  // no more chars to read.
-#define ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR()          \
-  do {                                                  \
-    if (ABSL_PREDICT_FALSE(pos == end)) return nullptr; \
-    c = *pos++;                                         \
-  } while (0)
-
-  const auto parse_digits = [&] {
-    int digits = c - '0';
-    // We do not want to overflow `digits` so we consume at most digits10
-    // digits. If there are more digits the parsing will fail later on when the
-    // digit doesn't match the expected characters.
-    int num_digits = std::numeric_limits<int>::digits10;
-    for (;;) {
-      if (ABSL_PREDICT_FALSE(pos == end)) break;
-      c = *pos++;
-      if (!std::isdigit(c)) break;
-      --num_digits;
-      if (ABSL_PREDICT_FALSE(!num_digits)) break;
-      digits = 10 * digits + c - '0';
-    }
-    return digits;
-  };
-
-  if (is_positional) {
-    ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR();
-    if (ABSL_PREDICT_FALSE(c < '1' || c > '9')) return nullptr;
-    conv->arg_position = parse_digits();
-    assert(conv->arg_position > 0);
-    if (ABSL_PREDICT_FALSE(c != '$')) return nullptr;
-  }
-
-  ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR();
-
-  // We should start with the basic flag on.
-  assert(conv->flags == Flags::kBasic);
-
-  // Any non alpha character makes this conversion not basic.
-  // This includes flags (-+ #0), width (1-9, *) or precision (.).
-  // All conversion characters and length modifiers are alpha characters.
-  if (c < 'A') {
-    while (c <= '0') {
-      auto tag = GetTagForChar(c);
-      if (tag.is_flags()) {
-        conv->flags = conv->flags | tag.as_flags();
-        ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR();
-      } else {
-        break;
-      }
-    }
-
-    if (c <= '9') {
-      if (c >= '0') {
-        int maybe_width = parse_digits();
-        if (!is_positional && c == '$') {
-          if (ABSL_PREDICT_FALSE(*next_arg != 0)) return nullptr;
-          // Positional conversion.
-          *next_arg = -1;
-          return ConsumeConversion<true>(original_pos, end, conv, next_arg);
-        }
-        conv->flags = conv->flags | Flags::kNonBasic;
-        conv->width.set_value(maybe_width);
-      } else if (c == '*') {
-        conv->flags = conv->flags | Flags::kNonBasic;
-        ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR();
-        if (is_positional) {
-          if (ABSL_PREDICT_FALSE(c < '1' || c > '9')) return nullptr;
-          conv->width.set_from_arg(parse_digits());
-          if (ABSL_PREDICT_FALSE(c != '$')) return nullptr;
-          ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR();
-        } else {
-          conv->width.set_from_arg(++*next_arg);
-        }
-      }
-    }
-
-    if (c == '.') {
-      conv->flags = conv->flags | Flags::kNonBasic;
-      ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR();
-      if (std::isdigit(c)) {
-        conv->precision.set_value(parse_digits());
-      } else if (c == '*') {
-        ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR();
-        if (is_positional) {
-          if (ABSL_PREDICT_FALSE(c < '1' || c > '9')) return nullptr;
-          conv->precision.set_from_arg(parse_digits());
-          if (c != '$') return nullptr;
-          ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR();
-        } else {
-          conv->precision.set_from_arg(++*next_arg);
-        }
-      } else {
-        conv->precision.set_value(0);
-      }
-    }
-  }
-
-  auto tag = GetTagForChar(c);
-
-  if (ABSL_PREDICT_FALSE(c == 'v' && (pos - original_pos) != 1)) return nullptr;
-
-  if (ABSL_PREDICT_FALSE(!tag.is_conv())) {
-    if (ABSL_PREDICT_FALSE(!tag.is_length())) return nullptr;
-
-    // It is a length modifier.
-    using str_format_internal::LengthMod;
-    LengthMod length_mod = tag.as_length();
-    ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR();
-    if (c == 'h' && length_mod == LengthMod::h) {
-      conv->length_mod = LengthMod::hh;
-      ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR();
-    } else if (c == 'l' && length_mod == LengthMod::l) {
-      conv->length_mod = LengthMod::ll;
-      ABSL_FORMAT_PARSER_INTERNAL_GET_CHAR();
-    } else {
-      conv->length_mod = length_mod;
-    }
-    tag = GetTagForChar(c);
-
-    if (ABSL_PREDICT_FALSE(c == 'v')) return nullptr;
-    if (ABSL_PREDICT_FALSE(!tag.is_conv())) return nullptr;
-  }
-
-  assert(CheckFastPathSetting(*conv));
-  (void)(&CheckFastPathSetting);
-
-  conv->conv = tag.as_conv();
-  if (!is_positional) conv->arg_position = ++*next_arg;
-  return pos;
+ABSL_ATTRIBUTE_NOINLINE const char* ConsumeUnboundConversionNoInline(
+    const char* p, const char* end, UnboundConversion* conv, int* next_arg) {
+  return ConsumeUnboundConversion(p, end, conv, next_arg);
 }
 
-}  // namespace
-
 std::string LengthModToString(LengthMod v) {
   switch (v) {
     case LengthMod::h:
@@ -262,12 +65,6 @@ std::string LengthModToString(LengthMod v) {
   return "";
 }
 
-const char *ConsumeUnboundConversion(const char *p, const char *end,
-                                     UnboundConversion *conv, int *next_arg) {
-  if (*next_arg < 0) return ConsumeConversion<true>(p, end, conv, next_arg);
-  return ConsumeConversion<false>(p, end, conv, next_arg);
-}
-
 struct ParsedFormatBase::ParsedFormatConsumer {
   explicit ParsedFormatConsumer(ParsedFormatBase *parsedformat)
       : parsed(parsedformat), data_pos(parsedformat->data_.get()) {}