Reland "Abseil component build (default symbols visibility)."

This is a reland of 5906c258

This CL adds .def files for release builds (and changes the
generator script to generate them at roll time).

The issue was that release component builds (is_debug=false) were
trying to link symbols that were not available in release mode
.obj files.

Original change's description:
> Abseil component build (default symbols visibility).
>
> This CL introduces an Abseil component on which all Chromium Abseil
> clients will have to depend on.
>
> Abseil doesn't export symbols explicitly, so for the moment Chromium
> exports all of them when is_component_build=true. On Android, Linux and
> Mac -fvisibility=default is used while on Windows a .def file is
> generated at Abseil roll time.
>
> Bug: 1046390
> Change-Id: I1697eb9e0179cee01badcf1b687acd94160e5f6d
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2174434
> Commit-Queue: Mirko Bonadei <mbonadei@chromium.org>
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#781225}

Bug: 1046390
Change-Id: Ieb48ec9eff6d08a0770c4b22521536bb29a76121
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2264062
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782701}

BUILD.gn

@@ -79,7 +79,6 @@ group("gn_all") {
     "//services/service_manager/public/cpp",
     "//skia:skia_unittests",
     "//sql:sql_unittests",
-    "//third_party/abseil-cpp:absl_tests",
     "//third_party/flatbuffers:flatbuffers_unittests",
     "//tools/binary_size:binary_size_trybot_py",
     "//tools/ipc_fuzzer:ipc_fuzzer_all",
@@ -90,6 +89,12 @@ group("gn_all") {
     "//url:url_unittests",
   ]
 
+  if (!is_component_build) {
+    deps += [
+      "//third_party/abseil-cpp:absl_tests",
+    ]
+  }
+
   if (!is_android && !is_chromecast) {
     deps += [
       "//crypto:crypto_unittests",

third_party/abseil-cpp/BUILD.gn

@@ -9,13 +9,42 @@
 import("//build/toolchain/toolchain.gni")
 import("//testing/test.gni")
 
+config("absl_component_build") {
+  defines = [ "ABSL_CONSUME_DLL" ]
+}
+
+# TODO(mbonadei): WebRTC tests and binaries use absl flags but they are
+# marked testonly because we don't want them to be usable in Chromium.
+# Add an absl_flags component which depends on the main absl component.
+component("absl") {
+  if (is_component_build) {
+    public_configs = [ ":absl_component_build" ]
+
+    if (is_win) {
+      if (target_cpu == "x64") {
+        if (is_debug) {
+          sources = [ "symbols_x64_dbg.def" ]
+        } else {
+          sources = [ "symbols_x64_rel.def" ]
+        }
+      }
+      if (target_cpu == "x86") {
+        if (is_debug) {
+          sources = [ "symbols_x86_dbg.def" ]
+        } else {
+          sources = [ "symbols_x86_rel.def" ]
+        }
+      }
+      if (target_cpu == "arm64") {
+        if (is_debug) {
+          sources = [ "symbols_arm64_dbg.def" ]
+        } else {
+          sources = [ "symbols_arm64_rel.def" ]
+        }
+      }
+    }
+  }
 
-# This is a placeholder target (that will become a "component" in a follow up
-# CL) to allow both WebRTC and OpenScreen to depend on
-# //third_party/abseil-cpp:absl. This is beneficial for the
-# migration from an always statically linked Abseil to an Abseil that
-# will respect the value of is_component_build.
-group("absl") {
   public_deps = [
     "//third_party/abseil-cpp/absl/algorithm:container",
     "//third_party/abseil-cpp/absl/base:config",
@@ -103,25 +132,27 @@ config("absl_test_cflags_cc") {
   }
 }
 
-test("absl_tests") {
-  testonly = true
-  deps = [
-    "absl/algorithm:algorithm_test",
-    "absl/algorithm:container_test",
-    "absl/base:config_test",
-    "absl/container:inlined_vector_test",
-    "absl/memory:memory_test",
-    "absl/meta:type_traits_test",
-    "absl/strings:ascii_test",
-    "absl/strings:match_test",
-    "absl/strings:str_replace_test",
-    "absl/strings:string_view_test",
-
-    # TODO(mbonadei): On iOS, gtest doesn't support death tests. Fix upstream
-    # Abseil to use EXPECT_DEATH_IF_SUPPORTED instead of EXPECT_DEATH.
-    # "absl/types:optional_test",
-    # "absl/types:variant_test",
-
-    "//third_party/googletest:gtest_main",
-  ]
+if (!is_component_build) {
+  test("absl_tests") {
+    testonly = true
+    deps = [
+      "absl/algorithm:algorithm_test",
+      "absl/algorithm:container_test",
+      "absl/base:config_test",
+      "absl/container:inlined_vector_test",
+      "absl/memory:memory_test",
+      "absl/meta:type_traits_test",
+      "absl/strings:ascii_test",
+      "absl/strings:match_test",
+      "absl/strings:str_replace_test",
+      "absl/strings:string_view_test",
+
+      # TODO(mbonadei): On iOS, gtest doesn't support death tests. Fix upstream
+      # Abseil to use EXPECT_DEATH_IF_SUPPORTED instead of EXPECT_DEATH.
+      # "absl/types:optional_test",
+      # "absl/types:variant_test",
+
+      "//third_party/googletest:gtest_main",
+    ]
+  }
 }

third_party/abseil-cpp/absl.gni

@@ -60,6 +60,14 @@ template("absl_source_set") {
       "//third_party/abseil-cpp:absl_default_cflags_cc",
     ]
 
+    if (is_component_build) {
+      defines = [ "ABSL_BUILD_DLL" ]
+      if (!is_win) {
+        configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
+        configs += [ "//build/config/gcc:symbol_visibility_default" ]
+      }
+    }
+
     if (!defined(public_configs)) {
       public_configs = []
     }

third_party/abseil-cpp/absl/base/internal/raw_logging.cc

@@ -227,7 +227,7 @@ bool RawLoggingFullySupported() {
 #endif  // !ABSL_LOW_LEVEL_WRITE_SUPPORTED
 }
 
-ABSL_DLL ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES
+ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES ABSL_DLL
     absl::base_internal::AtomicHook<InternalLogFunction>
         internal_log_function(DefaultInternalLog);
 

third_party/abseil-cpp/absl/base/internal/raw_logging.h

@@ -170,7 +170,7 @@ using InternalLogFunction = void (*)(absl::LogSeverity severity,
                                      const char* file, int line,
                                      const std::string& message);
 
-ABSL_DLL ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES extern base_internal::AtomicHook<
+ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES ABSL_DLL extern base_internal::AtomicHook<
     InternalLogFunction>
     internal_log_function;
 

third_party/abseil-cpp/absl/strings/string_view.h

@@ -586,7 +586,7 @@ constexpr bool operator>=(string_view x, string_view y) noexcept {
 }
 
 // IO Insertion Operator
-std::ostream& operator<<(std::ostream& o, string_view piece);
+ABSL_DLL std::ostream& operator<<(std::ostream& o, string_view piece);
 
 ABSL_NAMESPACE_END
 }  // namespace absl

third_party/abseil-cpp/generate_def_file.py

+"""Script to generate Chromium's Abseil .def file at roll time.
+
+This script generates //third_party/abseil-app/absl/symbols_x64.def at Abseil
+roll time.
+
+Since Abseil doesn't export symbols, Chromium is forced to consider all
+Abseil's symbols as publicly visible. On POSIX it is possible to use
+-fvisibility=default but on Windows a .def file with all the symbols
+is needed.
+
+Unless you are on a Windows machine, you need to set up your Chromium
+checkout for cross-compilation by following the instructions at
+https://chromium.googlesource.com/chromium/src.git/+/master/docs/win_cross.md.
+"""
+
+import fnmatch
+import logging
+import os
+import re
+import subprocess
+import tempfile
+import time
+
+# Matches a mangled symbol that has 'absl' in it, this should be a good
+# enough heuristic to select Abseil symbols to list in the .def file.
+ABSL_SYM_RE = re.compile(r'0* [BT] (?P<symbol>\?{1}[^\?].*absl.*)')
+
+
+def _DebugOrRelease(is_debug):
+  return 'dbg' if is_debug else 'rel'
+
+
+def _GenerateDefFile(cpu, is_debug):
+  """Generates a .def file for the absl component build on the specified CPU."""
+  flavor = _DebugOrRelease(is_debug)
+  gn_args = [
+      'ffmpeg_branding = "Chrome"',
+      'is_component_build = false',
+      'is_debug = {}'.format(str(is_debug).lower()),
+      'proprietary_codecs = true',
+      'symbol_level = 0',
+      'target_cpu = "{}"'.format(cpu),
+      'target_os = "win"',
+  ]
+
+  with tempfile.TemporaryDirectory() as out_dir:
+    logging.info('[%s - %s] Creating tmp out dir in %s', cpu, flavor, out_dir)
+    subprocess.check_call(['gn', 'gen', out_dir, '--args=' + ' '.join(gn_args)],
+                          cwd=os.getcwd())
+    logging.info('[%s - %s] gn gen completed', cpu, flavor)
+    subprocess.check_call(
+        ['autoninja', '-C', out_dir, 'third_party/abseil-cpp:absl'],
+        cwd=os.getcwd())
+    logging.info('[%s - %s] autoninja completed', cpu, flavor)
+
+    obj_files = []
+    for root, _dirnames, filenames in os.walk(
+        os.path.join(out_dir, 'obj', 'third_party', 'abseil-cpp')):
+      matched_files = fnmatch.filter(filenames, '*.obj')
+      obj_files.extend((os.path.join(root, f) for f in matched_files))
+
+    logging.info('[%s - %s] Found %d object files.', cpu, flavor, len(obj_files))
+
+    absl_symbols = set()
+    for f in obj_files:
+      stdout = subprocess.check_output(['llvm-nm-9', f], cwd=os.getcwd())
+      for line in stdout.splitlines():
+        match = re.match(ABSL_SYM_RE, line.decode('utf-8'))
+        if match:
+          absl_symbols.add(match.group('symbol'))
+
+    logging.info('[%s - %s] Found %d absl symbols.', cpu, flavor, len(absl_symbols))
+
+    def_file = os.path.join('third_party', 'abseil-cpp',
+                            'symbols_{}_{}.def'.format(cpu, flavor))
+    with open(def_file, 'w') as f:
+      f.write('EXPORTS\n')
+      for s in sorted(absl_symbols):
+        f.write('    {}\n'.format(s))
+
+    # Hack, it looks like there is a race in the directory cleanup.
+    time.sleep(3)
+
+  logging.info('[%s - %s] .def file successfully generated.', cpu, flavor)
+
+
+if __name__ == '__main__':
+  logging.getLogger().setLevel(logging.INFO)
+
+  if not os.getcwd().endswith('chromium/src'):
+    logging.error('Run this script from Chromium\'s src/ directory.')
+    exit(1)
+
+  _GenerateDefFile('x86', True)
+  _GenerateDefFile('x86', False)
+  _GenerateDefFile('x64', True)
+  _GenerateDefFile('x64', False)
+  _GenerateDefFile('arm64', True)
+  _GenerateDefFile('arm64', False)

third_party/abseil-cpp/patches/0002-Manual-ABSL_DLL-fixes.patch

+From 330cb7c7a62ab3187a6a2a3dc3a7b92f3690677c Mon Sep 17 00:00:00 2001
+From: Mirko Bonadei <mbonadei@chromium.org>
+Date: Wed, 17 Jun 2020 21:37:18 +0200
+Subject: [PATCH] Manual ABSL_DLL fixes.
+
+---
+ third_party/abseil-cpp/absl/base/internal/raw_logging.cc | 2 +-
+ third_party/abseil-cpp/absl/base/internal/raw_logging.h  | 2 +-
+ third_party/abseil-cpp/absl/strings/string_view.h        | 2 +-
+ 3 files changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/third_party/abseil-cpp/absl/base/internal/raw_logging.cc b/third_party/abseil-cpp/absl/base/internal/raw_logging.cc
+index 40cea5506172..f27e2838d72b 100644
+--- a/third_party/abseil-cpp/absl/base/internal/raw_logging.cc
++++ b/third_party/abseil-cpp/absl/base/internal/raw_logging.cc
+@@ -227,7 +227,7 @@ bool RawLoggingFullySupported() {
+ #endif  // !ABSL_LOW_LEVEL_WRITE_SUPPORTED
+ }
+ 
+-ABSL_DLL ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES
++ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES ABSL_DLL
+     absl::base_internal::AtomicHook<InternalLogFunction>
+         internal_log_function(DefaultInternalLog);
+ 
+diff --git a/third_party/abseil-cpp/absl/base/internal/raw_logging.h b/third_party/abseil-cpp/absl/base/internal/raw_logging.h
+index 418d6c856feb..51551bafff48 100644
+--- a/third_party/abseil-cpp/absl/base/internal/raw_logging.h
++++ b/third_party/abseil-cpp/absl/base/internal/raw_logging.h
+@@ -170,7 +170,7 @@ using InternalLogFunction = void (*)(absl::LogSeverity severity,
+                                      const char* file, int line,
+                                      const std::string& message);
+ 
+-ABSL_DLL ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES extern base_internal::AtomicHook<
++ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES ABSL_DLL extern base_internal::AtomicHook<
+     InternalLogFunction>
+     internal_log_function;
+ 
+diff --git a/third_party/abseil-cpp/absl/strings/string_view.h b/third_party/abseil-cpp/absl/strings/string_view.h
+index 8a9db8c3d796..7fb033300338 100644
+--- a/third_party/abseil-cpp/absl/strings/string_view.h
++++ b/third_party/abseil-cpp/absl/strings/string_view.h
+@@ -586,7 +586,7 @@ constexpr bool operator>=(string_view x, string_view y) noexcept {
+ }
+ 
+ // IO Insertion Operator
+-std::ostream& operator<<(std::ostream& o, string_view piece);
++ABSL_DLL std::ostream& operator<<(std::ostream& o, string_view piece);
+ 
+ ABSL_NAMESPACE_END
+ }  // namespace absl
+-- 
+2.27.0.290.gba653c62da-goog
+

third_party/blink/renderer/modules/peerconnection/BUILD.gn

@@ -170,7 +170,7 @@ blink_modules_sources("peerconnection") {
   ]
 
   public_deps = [ "//third_party/webrtc_overrides:webrtc_component" ]
-  deps = [ "//third_party/abseil-cpp/absl/types:optional" ]
+  deps = [ "//third_party/abseil-cpp:absl" ]
 }
 
 jumbo_source_set("test_support") {

third_party/blink/renderer/platform/BUILD.gn

@@ -1586,7 +1586,7 @@ jumbo_component("platform") {
     "//skia",
     "//skia:skcms",
     "//third_party:freetype_harfbuzz",
-    "//third_party/abseil-cpp/absl/types:optional",
+    "//third_party/abseil-cpp:absl",
     "//third_party/blink/public:image_resources",
     "//third_party/blink/public/common",
     "//third_party/blink/public/mojom:embedded_frame_sink_mojo_bindings_blink",

third_party/googletest/BUILD.gn

@@ -134,12 +134,7 @@ source_set("gtest") {
     ]
     if (gtest_enable_absl_printers) {
       public_deps += [
-        "//third_party/abseil-cpp/absl/debugging:failure_signal_handler",
-        "//third_party/abseil-cpp/absl/debugging:stacktrace",
-        "//third_party/abseil-cpp/absl/debugging:symbolize",
-        "//third_party/abseil-cpp/absl/strings",
-        "//third_party/abseil-cpp/absl/types:optional",
-        "//third_party/abseil-cpp/absl/types:variant",
+        "//third_party/abseil-cpp:absl",
       ]
     }
   } else {