Export of internal Abseil changes

--
317c7bd0caa12fa0a4dc65dc9c8e645211f85872 by Abseil Team <absl-team@google.com>:

Elide the Emscripten JS-based stack trace and symbolization functions when
building in Standalone Mode.

Users will need to set `-DSTANDALONE_WASM=1` in some toolchain(s).

PiperOrigin-RevId: 408961649

--
92ba3ab1ef3edee4b7fb9e151f2061661e7beb0a by Derek Mauro <dmauro@google.com>:

Suppress MSVC warning "C4127: conditional expression is constant"

Fixes #1004

PiperOrigin-RevId: 408920356
GitOrigin-RevId: 317c7bd0caa12fa0a4dc65dc9c8e645211f85872
Change-Id: Ieca0a9e263874ba5bd93110dc437c56bc59ad5a7

absl/debugging/internal/stacktrace_config.h

@@ -37,7 +37,8 @@
   "absl/debugging/internal/stacktrace_generic-inl.inc"
 #endif  // defined(ABSL_HAVE_THREAD_LOCAL)
 
-#elif defined(__EMSCRIPTEN__)
+// Emscripten stacktraces rely on JS. Do not use them in standalone mode.
+#elif defined(__EMSCRIPTEN__) && !defined(STANDALONE_WASM)
 #define ABSL_STACKTRACE_INL_HEADER \
   "absl/debugging/internal/stacktrace_emscripten-inl.inc"
 

absl/debugging/symbolize.cc

@@ -23,6 +23,11 @@
 #endif
 #endif
 
+// Emscripten symbolization relies on JS. Do not use them in standalone mode.
+#if defined(__EMSCRIPTEN__) && !defined(STANDALONE_WASM)
+#define ABSL_INTERNAL_HAVE_SYMBOLIZE_WASM
+#endif
+
 #if defined(ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE)
 #include "absl/debugging/symbolize_elf.inc"
 #elif defined(ABSL_INTERNAL_HAVE_SYMBOLIZE_WIN32)
@@ -31,7 +36,7 @@
 #include "absl/debugging/symbolize_win32.inc"
 #elif defined(__APPLE__)
 #include "absl/debugging/symbolize_darwin.inc"
-#elif defined(__EMSCRIPTEN__)
+#elif defined(ABSL_INTERNAL_HAVE_SYMBOLIZE_WASM)
 #include "absl/debugging/symbolize_emscripten.inc"
 #else
 #include "absl/debugging/symbolize_unimplemented.inc"

absl/strings/numbers.h

@@ -181,16 +181,19 @@ char* FastIntToBuffer(int_type i, char* buffer) {
   // TODO(jorg): This signed-ness check is used because it works correctly
   // with enums, and it also serves to check that int_type is not a pointer.
   // If one day something like std::is_signed<enum E> works, switch to it.
-  if (static_cast<int_type>(1) - 2 < 0) {  // Signed
-    if (sizeof(i) > 32 / 8) {           // 33-bit to 64-bit
+  // These conditions are constexpr bools to suppress MSVC warning C4127.
+  constexpr bool kIsSigned = static_cast<int_type>(1) - 2 < 0;
+  constexpr bool kUse64Bit = sizeof(i) > 32 / 8;
+  if (kIsSigned) {
+    if (kUse64Bit) {
       return FastIntToBuffer(static_cast<int64_t>(i), buffer);
-    } else {  // 32-bit or less
+    } else {
       return FastIntToBuffer(static_cast<int32_t>(i), buffer);
     }
-  } else {                     // Unsigned
-    if (sizeof(i) > 32 / 8) {  // 33-bit to 64-bit
+  } else {
+    if (kUse64Bit) {
       return FastIntToBuffer(static_cast<uint64_t>(i), buffer);
-    } else {  // 32-bit or less
+    } else {
       return FastIntToBuffer(static_cast<uint32_t>(i), buffer);
     }
   }
@@ -209,22 +212,25 @@ ABSL_MUST_USE_RESULT bool safe_strtoi_base(absl::string_view s, int_type* out,
   // TODO(jorg): This signed-ness check is used because it works correctly
   // with enums, and it also serves to check that int_type is not a pointer.
   // If one day something like std::is_signed<enum E> works, switch to it.
-  if (static_cast<int_type>(1) - 2 < 0) {  // Signed
-    if (sizeof(*out) == 64 / 8) {       // 64-bit
+  // These conditions are constexpr bools to suppress MSVC warning C4127.
+  constexpr bool kIsSigned = static_cast<int_type>(1) - 2 < 0;
+  constexpr bool kUse64Bit = sizeof(*out) == 64 / 8;
+  if (kIsSigned) {
+    if (kUse64Bit) {
       int64_t val;
       parsed = numbers_internal::safe_strto64_base(s, &val, base);
       *out = static_cast<int_type>(val);
-    } else {  // 32-bit
+    } else {
       int32_t val;
       parsed = numbers_internal::safe_strto32_base(s, &val, base);
       *out = static_cast<int_type>(val);
     }
-  } else {                         // Unsigned
-    if (sizeof(*out) == 64 / 8) {  // 64-bit
+  } else {
+    if (kUse64Bit) {
       uint64_t val;
       parsed = numbers_internal::safe_strtou64_base(s, &val, base);
       *out = static_cast<int_type>(val);
-    } else {  // 32-bit
+    } else {
       uint32_t val;
       parsed = numbers_internal::safe_strtou32_base(s, &val, base);
       *out = static_cast<int_type>(val);