Export of internal Abseil changes

--
389189dbb322df0d0468ab13edf7dc185dc63833 by Abseil Team <absl-team@google.com>:

absl str_format.h can compile with -Wconversion and -Wsign-compare

PiperOrigin-RevId: 420799960

--
762e5adc429fc143756c42fe92fe8073c87c075f by Abseil Team <absl-team@google.com>:

GetStackTraceWithContext: Fix min_dropped_frames when no frames are recorded

Previously, if there were still frames to skip, they would be included
in min_dropped_frames.

PiperOrigin-RevId: 420766341

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7d4374b8eaa410f4f98ec03d6a8997dccadfb271 by Abseil Team <absl-team@google.com>:

absl::flags compiles with -Wconversion and -Wsign-compare

PiperOrigin-RevId: 420476807

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5f00f7805419d725fa1ff57b388e4c0750d1d6b0 by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 420282152

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bd5471fc34956acf3888bf90287b2aee4415c96d by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 420282033

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61c78020804e4290e9b2fe151aeaf99b198716ee by Derek Mauro <dmauro@google.com>:

Internal change

PiperOrigin-RevId: 420281867

--
dbe3aad24b65ea11664401a307ea3d2f28e8a7b9 by Derek Mauro <dmauro@google.com>:

Remove the incorrect test for the availability of [[nodiscard]]

It should have been ABSL_HAVE_CPP_ATTRIBUTE(nodiscard) instead of
ABSL_HAVE_ATTRIBUTE(nodiscard). As a result, some code is not
compliant with [[nodiscard]], so we cannot simply correct the availability
test.

Recommend that C++17-only code use the standard [[nodiscard] directly.

PiperOrigin-RevId: 420150702
GitOrigin-RevId: 389189dbb322df0d0468ab13edf7dc185dc63833
Change-Id: Idf6ebae3c4edd945c9032c7db3d0ab32d16e8078

11 files changed, 63 insertions, 27 deletions

diff --git a/absl/base/attributes.h b/absl/base/attributes.h
index f180cd77..00aad489 100644
--- a/absl/base/attributes.h
+++ b/absl/base/attributes.h
@@ -401,6 +401,9 @@
 //
 // Tells the compiler to warn about unused results.
 //
+// For code or headers that are assured to only build with C++17 and up, prefer
+// just using the standard `[[nodiscard]]` directly over this macro.
+//
 // When annotating a function, it must appear as the first part of the
 // declaration or definition. The compiler will warn if the return value from
 // such a function is unused:
@@ -427,9 +430,10 @@
 // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66425
 //
 // Note: past advice was to place the macro after the argument list.
-#if ABSL_HAVE_ATTRIBUTE(nodiscard)
-#define ABSL_MUST_USE_RESULT [[nodiscard]]
-#elif defined(__clang__) && ABSL_HAVE_ATTRIBUTE(warn_unused_result)
+//
+// TODO(b/176172494): Use ABSL_HAVE_CPP_ATTRIBUTE(nodiscard) when all code is
+// compliant with the stricter [[nodiscard]].
+#if defined(__clang__) && ABSL_HAVE_ATTRIBUTE(warn_unused_result)
 #define ABSL_MUST_USE_RESULT __attribute__((warn_unused_result))
 #else
 #define ABSL_MUST_USE_RESULT
diff --git a/absl/debugging/internal/stacktrace_aarch64-inl.inc b/absl/debugging/internal/stacktrace_aarch64-inl.inc
index f4859d7c..4f9db9d6 100644
--- a/absl/debugging/internal/stacktrace_aarch64-inl.inc
+++ b/absl/debugging/internal/stacktrace_aarch64-inl.inc
@@ -176,12 +176,17 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
     // Implementation detail: we clamp the max of frames we are willing to
     // count, so as not to spend too much time in the loop below.
     const int kMaxUnwind = 200;
-    int j = 0;
-    for (; frame_pointer != nullptr && j < kMaxUnwind; j++) {
+    int num_dropped_frames = 0;
+    for (int j = 0; frame_pointer != nullptr && j < kMaxUnwind; j++) {
+      if (skip_count > 0) {
+        skip_count--;
+      } else {
+        num_dropped_frames++;
+      }
       frame_pointer =
           NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
     }
-    *min_dropped_frames = j;
+    *min_dropped_frames = num_dropped_frames;
   }
   return n;
 }
diff --git a/absl/debugging/internal/stacktrace_arm-inl.inc b/absl/debugging/internal/stacktrace_arm-inl.inc
index 2a1bf2e8..102a2a12 100644
--- a/absl/debugging/internal/stacktrace_arm-inl.inc
+++ b/absl/debugging/internal/stacktrace_arm-inl.inc
@@ -112,11 +112,16 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
     // Implementation detail: we clamp the max of frames we are willing to
     // count, so as not to spend too much time in the loop below.
     const int kMaxUnwind = 200;
-    int j = 0;
-    for (; sp != nullptr && j < kMaxUnwind; j++) {
+    int num_dropped_frames = 0;
+    for (int j = 0; sp != nullptr && j < kMaxUnwind; j++) {
+      if (skip_count > 0) {
+        skip_count--;
+      } else {
+        num_dropped_frames++;
+      }
       sp = NextStackFrame<!IS_STACK_FRAMES>(sp);
     }
-    *min_dropped_frames = j;
+    *min_dropped_frames = num_dropped_frames;
   }
   return n;
 }
diff --git a/absl/debugging/internal/stacktrace_powerpc-inl.inc b/absl/debugging/internal/stacktrace_powerpc-inl.inc
index cf8c0516..085cef67 100644
--- a/absl/debugging/internal/stacktrace_powerpc-inl.inc
+++ b/absl/debugging/internal/stacktrace_powerpc-inl.inc
@@ -231,11 +231,16 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
     // Implementation detail: we clamp the max of frames we are willing to
     // count, so as not to spend too much time in the loop below.
     const int kMaxUnwind = 1000;
-    int j = 0;
-    for (; next_sp != nullptr && j < kMaxUnwind; j++) {
+    int num_dropped_frames = 0;
+    for (int j = 0; next_sp != nullptr && j < kMaxUnwind; j++) {
+      if (skip_count > 0) {
+        skip_count--;
+      } else {
+        num_dropped_frames++;
+      }
       next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(next_sp, ucp);
     }
-    *min_dropped_frames = j;
+    *min_dropped_frames = num_dropped_frames;
   }
   return n;
 }
diff --git a/absl/debugging/internal/stacktrace_riscv-inl.inc b/absl/debugging/internal/stacktrace_riscv-inl.inc
index 8cbc7854..b4bdb5f1 100644
--- a/absl/debugging/internal/stacktrace_riscv-inl.inc
+++ b/absl/debugging/internal/stacktrace_riscv-inl.inc
@@ -213,12 +213,17 @@ static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
     // Implementation detail: we clamp the max of frames we are willing to
     // count, so as not to spend too much time in the loop below.
     const int kMaxUnwind = 200;
-    int j = 0;
-    for (; frame_pointer != nullptr && j < kMaxUnwind; j++) {
+    int num_dropped_frames = 0;
+    for (int j = 0; frame_pointer != nullptr && j < kMaxUnwind; j++) {
+      if (skip_count > 0) {
+        skip_count--;
+      } else {
+        num_dropped_frames++;
+      }
       frame_pointer =
           NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
     }
-    *min_dropped_frames = j;
+    *min_dropped_frames = num_dropped_frames;
   }
   return n;
 }
diff --git a/absl/debugging/internal/stacktrace_x86-inl.inc b/absl/debugging/internal/stacktrace_x86-inl.inc
index 847a5473..1b5d8235 100644
--- a/absl/debugging/internal/stacktrace_x86-inl.inc
+++ b/absl/debugging/internal/stacktrace_x86-inl.inc
@@ -341,12 +341,17 @@ static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
     // Implementation detail: we clamp the max of frames we are willing to
     // count, so as not to spend too much time in the loop below.
     const int kMaxUnwind = 1000;
-    int j = 0;
-    for (; fp != nullptr && j < kMaxUnwind; j++) {
+    int num_dropped_frames = 0;
+    for (int j = 0; fp != nullptr && j < kMaxUnwind; j++) {
+      if (skip_count > 0) {
+        skip_count--;
+      } else {
+        num_dropped_frames++;
+      }
       fp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(fp, ucp, stack_low,
                                                              stack_high);
     }
-    *min_dropped_frames = j;
+    *min_dropped_frames = num_dropped_frames;
   }
   return n;
 }
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index 2d0a7e9c..6154638c 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -303,7 +303,9 @@ constexpr FlagDefaultArg DefaultArg(char) {
 ///////////////////////////////////////////////////////////////////////////////
 // Flag current value auxiliary structs.
 
-constexpr int64_t UninitializedFlagValue() { return 0xababababababababll; }
+constexpr int64_t UninitializedFlagValue() {
+  return static_cast<int64_t>(0xababababababababll);
+}
 
 template <typename T>
 using FlagUseValueAndInitBitStorage = std::integral_constant<
@@ -755,8 +757,8 @@ void* FlagOps(FlagOp op, const void* v1, void* v2, void* v3) {
     case FlagOp::kValueOffset: {
       // Round sizeof(FlagImp) to a multiple of alignof(FlagValue<T>) to get the
       // offset of the data.
-      ptrdiff_t round_to = alignof(FlagValue<T>);
-      ptrdiff_t offset =
+      size_t round_to = alignof(FlagValue<T>);
+      size_t offset =
           (sizeof(FlagImpl) + round_to - 1) / round_to * round_to;
       return reinterpret_cast<void*>(offset);
     }
diff --git a/absl/strings/internal/str_format/arg.h b/absl/strings/internal/str_format/arg.h
index 3c91be70..b9dda909 100644
--- a/absl/strings/internal/str_format/arg.h
+++ b/absl/strings/internal/str_format/arg.h
@@ -144,7 +144,7 @@ StringConvertResult FormatConvertImpl(const AbslCord& value,
   size_t space_remaining = 0;
 
   int width = conv.width();
-  if (width >= 0) space_remaining = width;
+  if (width >= 0) space_remaining = static_cast<size_t>(width);
 
   size_t to_write = value.size();
 
diff --git a/absl/strings/internal/str_format/extension.h b/absl/strings/internal/str_format/extension.h
index 55cbb56d..c47536d6 100644
--- a/absl/strings/internal/str_format/extension.h
+++ b/absl/strings/internal/str_format/extension.h
@@ -70,7 +70,7 @@ class FormatSinkImpl {
   ~FormatSinkImpl() { Flush(); }
 
   void Flush() {
-    raw_.Write(string_view(buf_, pos_ - buf_));
+    raw_.Write(string_view(buf_, static_cast<size_t>(pos_ - buf_)));
     pos_ = buf_;
   }
 
@@ -120,7 +120,9 @@ class FormatSinkImpl {
   }
 
  private:
-  size_t Avail() const { return buf_ + sizeof(buf_) - pos_; }
+  size_t Avail() const {
+    return static_cast<size_t>(buf_ + sizeof(buf_) - pos_);
+  }
 
   FormatRawSinkImpl raw_;
   size_t size_ = 0;
diff --git a/absl/strings/internal/str_format/output.h b/absl/strings/internal/str_format/output.h
index 8030dae0..15e751ab 100644
--- a/absl/strings/internal/str_format/output.h
+++ b/absl/strings/internal/str_format/output.h
@@ -22,6 +22,7 @@
 #define ABSL_STRINGS_INTERNAL_STR_FORMAT_OUTPUT_H_
 
 #include <cstdio>
+#include <ios>
 #include <ostream>
 #include <string>
 
@@ -71,7 +72,7 @@ inline void AbslFormatFlush(std::string* out, string_view s) {
   out->append(s.data(), s.size());
 }
 inline void AbslFormatFlush(std::ostream* out, string_view s) {
-  out->write(s.data(), s.size());
+  out->write(s.data(), static_cast<std::streamsize>(s.size()));
 }
 
 inline void AbslFormatFlush(FILERawSink* sink, string_view v) {
diff --git a/absl/strings/internal/str_format/parser.h b/absl/strings/internal/str_format/parser.h
index ad8646ed..32b91d03 100644
--- a/absl/strings/internal/str_format/parser.h
+++ b/absl/strings/internal/str_format/parser.h
@@ -151,7 +151,8 @@ bool ParseFormatString(string_view src, Consumer consumer) {
   const char* p = src.data();
   const char* const end = p + src.size();
   while (p != end) {
-    const char* percent = static_cast<const char*>(memchr(p, '%', end - p));
+    const char* percent =
+        static_cast<const char*>(memchr(p, '%', static_cast<size_t>(end - p)));
     if (!percent) {
       // We found the last substring.
       return consumer.Append(string_view(p, end - p));
@@ -242,7 +243,8 @@ class ParsedFormatBase {
     string_view text(base, 0);
     for (const auto& item : items_) {
       const char* const end = text.data() + text.size();
-      text = string_view(end, (base + item.text_end) - end);
+      text =
+          string_view(end, static_cast<size_t>((base + item.text_end) - end));
       if (item.is_conversion) {
         if (!consumer.ConvertOne(item.conv, text)) return false;
       } else {