Export of internal Abseil changes

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a9ac6567c0933d786d68c10011e3f3ff9deedf89 by Greg Falcon <gfalcon@google.com>:

Add absl::FunctionRef, a type analogous to the proposed C++23 std::function_ref.

Like std::function, FunctionRef can be used to type-erase any callable (invokable) object.  However, FunctionRef works by reference: it does not store a copy of the type-erased object.  If the wrapped object is destroyed before the FunctionRef, the reference becomes dangling.

FunctionRef relates to std::function in much the same way that string_view relates to std::string.

Because of these limitations, FunctionRef is best used only as a function argument type, and only where the function will be invoked immediately (rather than saved for later use).  When `const std::function<...>&` is used in this way, `absl::FunctionRef<...>` is a better-performing replacement.

PiperOrigin-RevId: 275484044

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1f7c4df3760f8b93e5a5baf40b070eca1d3f4c98 by Abseil Team <absl-team@google.com>:

Add FastHexToBufferZeroPad16() function for blazingly fast hex encoding of uint64_t.

PiperOrigin-RevId: 275420901

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08d48ac004eba57cf2f1ada827181a2995f74807 by Abseil Team <absl-team@google.com>:

Avoid applying the workaround for MSVC's static initialization problems when using clang-cl.

PiperOrigin-RevId: 275366326

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40be82bd2b34670b5458c0a72a0475086153c2d6 by Abseil Team <absl-team@google.com>:

Added comments to SimpleAtof()/SimpleAtod() that clarify that they
always use the "C" locale, unlike the standard functions strtod()
and strtof() referenced now in the comments.

PiperOrigin-RevId: 275355815

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086779dacb3f6f2b3ab59947e94e79046bdb1fe1 by Jorg Brown <jorg@google.com>:

Move the hex conversion table used by escaping.cc into numbers.h so
that other parts of Abseil can more efficiently access it.

PiperOrigin-RevId: 275331251

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3c4ed1b04e55d96a40cbe70fb70929ffbb0c0432 by Abseil Team <absl-team@google.com>:

Avoid applying the workaround for MSVC's static initialization problems when using clang-cl.

PiperOrigin-RevId: 275323858

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56ceb58ab688c3761978308609b09a1ac2739c9a by Derek Mauro <dmauro@google.com>:

Add script for testing on Alpine Linux (for musl test coverage)

PiperOrigin-RevId: 275321244
GitOrigin-RevId: a9ac6567c0933d786d68c10011e3f3ff9deedf89
Change-Id: I39799fa03768ddb44f3166200c860e1da4461807

1 files changed, 2 insertions, 3 deletions

diff --git a/absl/strings/substitute.cc b/absl/strings/substitute.cc
index bc176950e453..36dbfe7d42ff 100644
--- a/absl/strings/substitute.cc
+++ b/absl/strings/substitute.cc
@@ -94,7 +94,6 @@ void SubstituteAndAppendArray(std::string* output, absl::string_view format,
   assert(target == output->data() + output->size());
 }
 
-static const char kHexDigits[] = "0123456789abcdef";
 Arg::Arg(const void* value) {
   static_assert(sizeof(scratch_) >= sizeof(value) * 2 + 2,
                 "fix sizeof(scratch_)");
@@ -104,7 +103,7 @@ Arg::Arg(const void* value) {
     char* ptr = scratch_ + sizeof(scratch_);
     uintptr_t num = reinterpret_cast<uintptr_t>(value);
     do {
-      *--ptr = kHexDigits[num & 0xf];
+      *--ptr = absl::numbers_internal::kHexChar[num & 0xf];
       num >>= 4;
     } while (num != 0);
     *--ptr = 'x';
@@ -119,7 +118,7 @@ Arg::Arg(Hex hex) {
   char* writer = end;
   uint64_t value = hex.value;
   do {
-    *--writer = kHexDigits[value & 0xF];
+    *--writer = absl::numbers_internal::kHexChar[value & 0xF];
     value >>= 4;
   } while (value != 0);