Export of internal Abseil changes

--
9e8b4a286d70df9487bff080816bd07ae38af5f8 by Evan Brown <ezb@google.com>:

Add btree_node::transfer_n/transfer_n_backward and replace usage of uninitialized_move_n and value_destroy_n.

PiperOrigin-RevId: 314600027

--
6c452aa1ee7e46ab941ba7d1fa636da8ea3d7370 by Laramie Leavitt <lar@google.com>:

Remove the MockingBitGenBase base class in favor of type-erasure in BitGenRef.

In Abseil random, mocking was split across two different classes,
MockingBitGenBase and MockingBitGen. This split existed because Google Mock is a
test-only library that we don't link into production, so MockingBitGenBase
provided a low-overhead scaffold used to lookup mocks when in test code, but
which is unused in production code.

That has been replaced by type-erasure which looks for a method named
CallImpl with the correct signature.

Weaken the coupling between MockingBitGen, DistributionCaller, and MockOverloadSet.

Rename CallImpl to InvokeMock()

Previously, the implementation of DistributionCaller was also split across different files using explicit instantiation of the DistributionCaller struct and some details in the Mocking classes. Now Distribution caller uses the presence of the InvokeMock() method to choose whether to use the mockable call path or the default call path.

PiperOrigin-RevId: 314584095

--
07853c47dc98698d67d65a3b9b662a65ab9def0a by Abseil Team <absl-team@google.com>:

Add PC / backtrace / symbolization support for Apple platforms.

Full backtrace support requires iOS 9+

PiperOrigin-RevId: 314415072

--
43889f17a132b31f6558c6482721cbbc776128fd by Gennadiy Rozental <rogeeff@google.com>:

Consolidate all reflection interface in the new module 'reflection' and expose interface to locate reflection handle by name.

PiperOrigin-RevId: 314390358
GitOrigin-RevId: 9e8b4a286d70df9487bff080816bd07ae38af5f8
Change-Id: I8e0910437740cf9ea9da5000adddfcef127e1158

8 files changed, 170 insertions, 2 deletions

diff --git a/absl/debugging/BUILD.bazel b/absl/debugging/BUILD.bazel
index 8f521bec..ff627924 100644
--- a/absl/debugging/BUILD.bazel
+++ b/absl/debugging/BUILD.bazel
@@ -55,6 +55,7 @@ cc_library(
     name = "symbolize",
     srcs = [
         "symbolize.cc",
+        "symbolize_darwin.inc",
         "symbolize_elf.inc",
         "symbolize_unimplemented.inc",
         "symbolize_win32.inc",
@@ -77,6 +78,7 @@ cc_library(
         "//absl/base:dynamic_annotations",
         "//absl/base:malloc_internal",
         "//absl/base:raw_logging_internal",
+        "//absl/strings",
     ],
 )
 
diff --git a/absl/debugging/CMakeLists.txt b/absl/debugging/CMakeLists.txt
index 77336159..995e8887 100644
--- a/absl/debugging/CMakeLists.txt
+++ b/absl/debugging/CMakeLists.txt
@@ -46,6 +46,7 @@ absl_cc_library(
     "internal/symbolize.h"
   SRCS
     "symbolize.cc"
+    "symbolize_darwin.inc"
     "symbolize_elf.inc"
     "symbolize_unimplemented.inc"
     "symbolize_win32.inc"
@@ -63,6 +64,7 @@ absl_cc_library(
     absl::dynamic_annotations
     absl::malloc_internal
     absl::raw_logging_internal
+    absl::strings
   PUBLIC
 )
 
diff --git a/absl/debugging/internal/examine_stack.cc b/absl/debugging/internal/examine_stack.cc
index a3dd893a..6e5ff1fb 100644
--- a/absl/debugging/internal/examine_stack.cc
+++ b/absl/debugging/internal/examine_stack.cc
@@ -20,6 +20,10 @@
 #include <unistd.h>
 #endif
 
+#ifdef __APPLE__
+#include <sys/ucontext.h>
+#endif
+
 #include <csignal>
 #include <cstdio>
 
@@ -66,6 +70,32 @@ void* GetProgramCounter(void* vuc) {
 #error "Undefined Architecture."
 #endif
   }
+#elif defined(__APPLE__)
+  if (vuc != nullptr) {
+    ucontext_t* signal_ucontext = reinterpret_cast<ucontext_t*>(vuc);
+#if defined(__aarch64__)
+    return reinterpret_cast<void*>(
+        __darwin_arm_thread_state64_get_pc(signal_ucontext->uc_mcontext->__ss));
+#elif defined(__arm__)
+#if __DARWIN_UNIX03
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__pc);
+#else
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.pc);
+#endif
+#elif defined(__i386__)
+#if __DARWIN_UNIX03
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__eip);
+#else
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.eip);
+#endif
+#elif defined(__x86_64__)
+#if __DARWIN_UNIX03
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->__ss.__rip);
+#else
+    return reinterpret_cast<void*>(signal_ucontext->uc_mcontext->ss.rip);
+#endif
+#endif
+  }
 #elif defined(__akaros__)
   auto* ctx = reinterpret_cast<struct user_context*>(vuc);
   return reinterpret_cast<void*>(get_user_ctx_pc(ctx));
diff --git a/absl/debugging/internal/stacktrace_config.h b/absl/debugging/internal/stacktrace_config.h
index d4e8480a..8caa97c0 100644
--- a/absl/debugging/internal/stacktrace_config.h
+++ b/absl/debugging/internal/stacktrace_config.h
@@ -28,6 +28,27 @@
 #define ABSL_STACKTRACE_INL_HEADER \
     "absl/debugging/internal/stacktrace_win32-inl.inc"
 
+#elif defined(__APPLE__)
+// Thread local support required for UnwindImpl.
+// Notes:
+// * Xcode's clang did not support `thread_local` until version 8, and
+//   even then not for all iOS < 9.0.
+// * Xcode 9.3 started disallowing `thread_local` for 32-bit iOS simulator
+//   targeting iOS 9.x.
+// * Xcode 10 moves the deployment target check for iOS < 9.0 to link time
+//   making __has_feature unreliable there.
+//
+// Otherwise, `__has_feature` is only supported by Clang so it has be inside
+// `defined(__APPLE__)` check.
+#if __has_feature(cxx_thread_local) && \
+    !(TARGET_OS_IPHONE && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_9_0)
+#define ABSL_STACKTRACE_INL_HEADER \
+  "absl/debugging/internal/stacktrace_generic-inl.inc"
+#else
+#define ABSL_STACKTRACE_INL_HEADER \
+  "absl/debugging/internal/stacktrace_unimplemented-inl.inc"
+#endif
+
 #elif defined(__linux__) && !defined(__ANDROID__)
 
 #if !defined(NO_FRAME_POINTER)
diff --git a/absl/debugging/internal/symbolize.h b/absl/debugging/internal/symbolize.h
index 5d0858b5..8789e69a 100644
--- a/absl/debugging/internal/symbolize.h
+++ b/absl/debugging/internal/symbolize.h
@@ -59,6 +59,12 @@ ABSL_NAMESPACE_END
 
 #endif  // ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
 
+#ifdef ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE
+#error ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE cannot be directly set
+#elif defined(__APPLE__)
+#define ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE 1
+#endif
+
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace debugging_internal {
diff --git a/absl/debugging/symbolize.cc b/absl/debugging/symbolize.cc
index 54ed9700..eec7a6e8 100644
--- a/absl/debugging/symbolize.cc
+++ b/absl/debugging/symbolize.cc
@@ -20,6 +20,8 @@
 // The Windows Symbolizer only works if PDB files containing the debug info
 // are available to the program at runtime.
 #include "absl/debugging/symbolize_win32.inc"
+#elif defined(__APPLE__)
+#include "absl/debugging/symbolize_darwin.inc"
 #else
 #include "absl/debugging/symbolize_unimplemented.inc"
 #endif
diff --git a/absl/debugging/symbolize_darwin.inc b/absl/debugging/symbolize_darwin.inc
new file mode 100644
index 00000000..cdadd40e
--- /dev/null
+++ b/absl/debugging/symbolize_darwin.inc
@@ -0,0 +1,101 @@
+// Copyright 2020 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <cxxabi.h>
+#include <execinfo.h>
+
+#include <algorithm>
+#include <cstring>
+
+#include "absl/base/internal/raw_logging.h"
+#include "absl/debugging/internal/demangle.h"
+#include "absl/strings/numbers.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+void InitializeSymbolizer(const char*) {}
+
+namespace debugging_internal {
+namespace {
+
+static std::string GetSymbolString(absl::string_view backtrace_line) {
+  // Example Backtrace lines:
+  // 0   libimaging_shared.dylib             0x018c152a
+  // _ZNSt11_Deque_baseIN3nik7mediadb4PageESaIS2_EE17_M_initialize_mapEm + 3478
+  //
+  // or
+  // 0   libimaging_shared.dylib             0x0000000001895c39
+  // _ZN3nik4util19register_shared_ptrINS_3gpu7TextureEEEvPKvS5_ + 39
+  //
+  // or
+  // 0   mysterious_app                      0x0124000120120009 main + 17
+  auto address_pos = backtrace_line.find(" 0x");
+  if (address_pos == absl::string_view::npos) return std::string();
+  absl::string_view symbol_view = backtrace_line.substr(address_pos + 1);
+
+  auto space_pos = symbol_view.find(" ");
+  if (space_pos == absl::string_view::npos) return std::string();
+  symbol_view = symbol_view.substr(space_pos + 1);  // to mangled symbol
+
+  auto plus_pos = symbol_view.find(" + ");
+  if (plus_pos == absl::string_view::npos) return std::string();
+  symbol_view = symbol_view.substr(0, plus_pos);  // strip remainng
+
+  return std::string(symbol_view);
+}
+
+}  // namespace
+}  // namespace debugging_internal
+
+bool Symbolize(const void* pc, char* out, int out_size) {
+  if (out_size <= 0 || pc == nullptr) {
+    out = nullptr;
+    return false;
+  }
+
+  // This allocates a char* array.
+  char** frame_strings = backtrace_symbols(const_cast<void**>(&pc), 1);
+
+  if (frame_strings == nullptr) return false;
+
+  std::string symbol = debugging_internal::GetSymbolString(frame_strings[0]);
+  free(frame_strings);
+
+  char tmp_buf[1024];
+  if (debugging_internal::Demangle(symbol.c_str(), tmp_buf, sizeof(tmp_buf))) {
+    int len = strlen(tmp_buf);
+    if (len + 1 <= out_size) {  // +1 for '\0'
+      assert(len < sizeof(tmp_buf));
+      memmove(out, tmp_buf, len + 1);
+    }
+  } else {
+    strncpy(out, symbol.c_str(), out_size);
+  }
+
+  if (out[out_size - 1] != '\0') {
+    // strncpy() does not '\0' terminate when it truncates.
+    static constexpr char kEllipsis[] = "...";
+    int ellipsis_size = std::min<int>(sizeof(kEllipsis) - 1, out_size - 1);
+    memcpy(out + out_size - ellipsis_size - 1, kEllipsis, ellipsis_size);
+    out[out_size - 1] = '\0';
+  }
+
+  return true;
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl
diff --git a/absl/debugging/symbolize_test.cc b/absl/debugging/symbolize_test.cc
index a1d03aab..e476d82a 100644
--- a/absl/debugging/symbolize_test.cc
+++ b/absl/debugging/symbolize_test.cc
@@ -144,7 +144,8 @@ static const char *TrySymbolize(void *pc) {
   return TrySymbolizeWithLimit(pc, sizeof(try_symbolize_buffer));
 }
 
-#ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
+#if defined(ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE) || \
+    defined(ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE)
 
 TEST(Symbolize, Cached) {
   // Compilers should give us pointers to them.
@@ -258,6 +259,7 @@ TEST(Symbolize, SymbolizeWithDemanglingStackConsumption) {
 
 #endif  // ABSL_INTERNAL_HAVE_DEBUGGING_STACK_CONSUMPTION
 
+#ifndef ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE
 // Use a 64K page size for PPC.
 const size_t kPageSize = 64 << 10;
 // We place a read-only symbols into the .text section and verify that we can
@@ -413,6 +415,7 @@ TEST(Symbolize, ForEachSection) {
 
   close(fd);
 }
+#endif  // !ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE
 
 // x86 specific tests.  Uses some inline assembler.
 extern "C" {
@@ -541,7 +544,8 @@ int main(int argc, char **argv) {
   absl::InitializeSymbolizer(argv[0]);
   testing::InitGoogleTest(&argc, argv);
 
-#ifdef ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE
+#if defined(ABSL_INTERNAL_HAVE_ELF_SYMBOLIZE) || \
+    defined(ABSL_INTERNAL_HAVE_DARWIN_SYMBOLIZE)
   TestWithPCInsideInlineFunction();
   TestWithPCInsideNonInlineFunction();
   TestWithReturnAddress();