Use updated fast_float::parse_options

Summary:
X-link: https://github.com/facebookincubator/zstrong/pull/1216

`str_to_floating_fast_float_from_chars` can be simplified using the new upstream option `allow_leading_plus`. It does mean that we also support parsing `+nan` and `+infinity` which we previously didn't.

Mapping to `Inf` is also handled by the parsing logic, so this custom branch can be removed.

Reviewed By: Gownta

Differential Revision: D70392258

fbshipit-source-id: 62972a6cadd1547d8ff0a3162510ae5e979d459f

Author: javache

build/fbcode_builder/manifests/fast_float

@@ -2,12 +2,12 @@
 name = fast_float
 
 [download]
-url = https://github.com/fastfloat/fast_float/archive/refs/tags/v6.1.4.tar.gz
-sha256 = 12cb6d250824160ca16bcb9d51f0ca7693d0d10cb444f34f1093bc02acfce704
+url = https://github.com/fastfloat/fast_float/archive/refs/tags/v8.0.0.tar.gz
+sha256 = f312f2dc34c61e665f4b132c0307d6f70ad9420185fa831911bc24408acf625d
 
 [build]
 builder = cmake
-subdir = fast_float-6.1.4
+subdir = fast_float-8.0.0
 
 [cmake.defines]
 FASTFLOAT_TEST = OFF

folly/Conv.cpp

@@ -359,16 +359,11 @@ Expected<Tgt, ConversionCode> str_to_floating_fast_float_from_chars(
     return makeUnexpected(ConversionCode::EMPTY_INPUT_STRING);
   }
 
-  if (*b == '+') {
-    // This function supports a leading + sign, but fast_float does not.
-    b += 1;
-    if (b == e || (!std::isdigit(*b) && *b != '.')) {
-      return makeUnexpected(ConversionCode::STRING_TO_FLOAT_ERROR);
-    }
-  }
-
   Tgt result;
-  auto [ptr, ec] = fast_float::from_chars(b, e, result);
+  fast_float::parse_options options{
+      fast_float::chars_format::general |
+      fast_float::chars_format::allow_leading_plus};
+  auto [ptr, ec] = fast_float::from_chars_advanced(b, e, result, options);
   bool isOutOfRange{ec == std::errc::result_out_of_range};
   bool isOk{ec == std::errc()};
   if (!isOk && !isOutOfRange) {
@@ -377,15 +372,6 @@ Expected<Tgt, ConversionCode> str_to_floating_fast_float_from_chars(
 
   auto numMatchedChars = ptr - src->data();
   src->advance(numMatchedChars);
-
-  if (isOutOfRange) {
-    if (*b == '-') {
-      return -std::numeric_limits<Tgt>::infinity();
-    } else {
-      return std::numeric_limits<Tgt>::infinity();
-    }
-  }
-
   return result;
 }
 

folly/test/ConvTest.cpp

@@ -1703,33 +1703,44 @@ void tryStringToFloat(const StrToFloat<String>& strToFloat) {
   }
 
   // NaN
-  const std::array<String, 6> kNanInputs{{
+  const std::array<String, 9> kNanInputs{{
       "nan",
       "NaN",
       "NAN",
       "-nan",
       "-NaN",
       "-NAN",
+      "+nan",
+      "+NaN",
+      "+NAN",
   }};
   for (const auto& input : kNanInputs) {
     auto rv = strToFloat(input);
     EXPECT_TRUE(std::isnan(rv.value())) << input;
   }
 
-  EXPECT_EQ(strToFloat("+nan").error(), ConversionCode::STRING_TO_FLOAT_ERROR);
-
-  const std::array<String, 6> kInfinityInputs{{
+  const std::array<String, 12> kInfinityInputs{{
       "-inf",
       "-INF",
       "-iNf",
       "-infinity",
       "-INFINITY",
       "-INFInITY",
+      "+inf",
+      "+INF",
+      "+iNf",
+      "+infinity",
+      "+INFINITY",
+      "+INFInITY",
   }};
   for (const auto& input : kInfinityInputs) {
     {
       auto rv = strToFloat(input);
-      EXPECT_EQ(rv.value(), -numeric_limits<float>::infinity()) << input;
+      if (input[0] == '-') {
+        EXPECT_EQ(rv.value(), -numeric_limits<float>::infinity()) << input;
+      } else {
+        EXPECT_EQ(rv.value(), numeric_limits<float>::infinity()) << input;
+      }
     }
 
     {
@@ -1739,10 +1750,6 @@ void tryStringToFloat(const StrToFloat<String>& strToFloat) {
     }
   }
 
-  EXPECT_EQ(
-      strToFloat("+infinity").error(), ConversionCode::STRING_TO_FLOAT_ERROR);
-  EXPECT_EQ(strToFloat("+inf").error(), ConversionCode::STRING_TO_FLOAT_ERROR);
-
   const std::array<String, 15> kScientificNotation{{
       "123.4560e0",
       "+123.4560e0",