Export of internal Abseil changes

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5b9d5ce21074c0541432555d383d1b9c5898b553 by Gennadiy Rozental <rogeeff@google.com>:

Convert FlagSaver into public API

PiperOrigin-RevId: 314799739

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5f796c9862b1177f161f4b10fe1a84698ebbb5cf by Abseil Team <absl-team@google.com>:

Google-internal changes only.

PiperOrigin-RevId: 314786474

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67f2ae0ac5ae73bcd9d57a058ac4fea8fc1243ba by Gennadiy Rozental <rogeeff@google.com>:

Makes sure stacktrace_generic is only used with glibc.

Fixes #701

PiperOrigin-RevId: 314726944

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efb1ef3636b0698b79d3ee3590f12c4dff32a3cb by Samuel Benzaquen <sbenza@google.com>:

Take the bits into account when reserving the space for the operation, not just
the exponent.

PiperOrigin-RevId: 314622744
GitOrigin-RevId: 5b9d5ce21074c0541432555d383d1b9c5898b553
Change-Id: I080a5e333e2dc1545b5aa0417882f7ac7116a20c

2 files changed, 12 insertions, 6 deletions

diff --git a/absl/strings/internal/str_format/convert_test.cc b/absl/strings/internal/str_format/convert_test.cc
index 20c6229f..0e8535c2 100644
--- a/absl/strings/internal/str_format/convert_test.cc
+++ b/absl/strings/internal/str_format/convert_test.cc
@@ -764,6 +764,12 @@ TEST_F(FormatConvertTest, LongDouble) {
     }
   }
 
+  // Regression tests
+  //
+  // Using a string literal because not all platforms support hex literals or it
+  // might be out of range.
+  doubles.push_back(std::strtold("-0xf.ffffffb5feafffbp-16324L", nullptr));
+
   for (const char *fmt : kFormats) {
     for (char f : {'f', 'F',  //
                    'g', 'G',  //
diff --git a/absl/strings/internal/str_format/float_conversion.cc b/absl/strings/internal/str_format/float_conversion.cc
index a761a5a5..10e46954 100644
--- a/absl/strings/internal/str_format/float_conversion.cc
+++ b/absl/strings/internal/str_format/float_conversion.cc
@@ -224,13 +224,13 @@ class FractionalDigitGenerator {
   // This function will allocate enough stack space to perform the conversion.
   static void RunConversion(
       uint128 v, int exp, absl::FunctionRef<void(FractionalDigitGenerator)> f) {
+    using Limits = std::numeric_limits<long double>;
     assert(-exp < 0);
-    assert(-exp >= std::numeric_limits<long double>::min_exponent - 128);
-    static_assert(
-        StackArray::kMaxCapacity >=
-            (128 - std::numeric_limits<long double>::min_exponent + 31) / 32,
-        "");
-    StackArray::RunWithCapacity((exp + 31) / 32,
+    assert(-exp >= Limits::min_exponent - 128);
+    static_assert(StackArray::kMaxCapacity >=
+                      (Limits::digits + 128 - Limits::min_exponent + 31) / 32,
+                  "");
+    StackArray::RunWithCapacity((Limits::digits + exp + 31) / 32,
                                 [=](absl::Span<uint32_t> input) {
                                   f(FractionalDigitGenerator(input, v, exp));
                                 });