cppgc: Add SourceLocation class

SourceLocation is needed to track Persistents.

Bug: chromium:1056170
Change-Id: I4d5cf151a4d27b4c29582ff8195cdcb7453afe1c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2132790
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66974}

BUILD.gn

@@ -3948,6 +3948,7 @@ v8_source_set("cppgc_base") {
     "include/cppgc/heap.h",
     "include/cppgc/member.h",
     "include/cppgc/platform.h",
+    "include/cppgc/source-location.h",
     "include/cppgc/type_traits.h",
     "include/v8config.h",
     "src/heap/cppgc/allocation.cc",
@@ -3963,6 +3964,7 @@ v8_source_set("cppgc_base") {
     "src/heap/cppgc/member.cc",
     "src/heap/cppgc/platform.cc",
     "src/heap/cppgc/sanitizers.h",
+    "src/heap/cppgc/source-location.cc",
     "src/heap/cppgc/stack.cc",
     "src/heap/cppgc/stack.h",
   ]

include/cppgc/source-location.h

+// Copyright 2020 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef INCLUDE_CPPGC_SOURCE_LOCATION_H_
+#define INCLUDE_CPPGC_SOURCE_LOCATION_H_
+
+#include <string>
+
+#include "include/v8config.h"
+
+#if defined(__has_builtin)
+#define CPPGC_SUPPORTS_SOURCE_LOCATION                                   \
+  (__has_builtin(__builtin_FUNCTION) && __has_builtin(__builtin_FILE) && \
+   __has_builtin(__builtin_LINE))  // NOLINT
+#elif defined(V8_CC_GNU) && __GNUC__ >= 5
+#define CPPGC_SUPPORTS_SOURCE_LOCATION 1
+#elif defined(V8_CC_INTEL) && __ICC >= 1800
+#define CPPGC_SUPPORTS_SOURCE_LOCATION 1
+#else
+#define CPPGC_SUPPORTS_SOURCE_LOCATION 0
+#endif
+
+namespace cppgc {
+
+// Encapsulates source location information. Mimics C++20's
+// std::source_location.
+class V8_EXPORT SourceLocation final {
+ public:
+#if CPPGC_SUPPORTS_SOURCE_LOCATION
+  static constexpr SourceLocation Current(
+      const char* function = __builtin_FUNCTION(),
+      const char* file = __builtin_FILE(), size_t line = __builtin_LINE()) {
+    return SourceLocation(function, file, line);
+  }
+#else
+  static constexpr SourceLocation Current() { return SourceLocation(); }
+#endif  // CPPGC_SUPPORTS_SOURCE_LOCATION
+
+  constexpr SourceLocation() = default;
+
+  constexpr const char* Function() const { return function_; }
+  constexpr const char* FileName() const { return file_; }
+  constexpr size_t Line() const { return line_; }
+
+  std::string ToString() const;
+
+ private:
+  constexpr SourceLocation(const char* function, const char* file, size_t line)
+      : function_(function), file_(file), line_(line) {}
+
+  const char* function_ = nullptr;
+  const char* file_ = nullptr;
+  size_t line_ = 0u;
+};
+
+}  // namespace cppgc
+
+#endif  // INCLUDE_CPPGC_SOURCE_LOCATION_H_

src/heap/cppgc/source-location.cc

+// Copyright 2020 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "include/cppgc/source-location.h"
+
+namespace cppgc {
+
+std::string SourceLocation::ToString() const {
+  if (!file_) {
+    return {};
+  }
+  return std::string(function_) + "@" + file_ + ":" + std::to_string(line_);
+}
+
+}  // namespace cppgc

test/unittests/BUILD.gn

@@ -50,6 +50,7 @@ v8_source_set("cppgc_unittests_sources") {
     "heap/cppgc/gc-info_unittest.cc",
     "heap/cppgc/heap-object-header_unittest.cc",
     "heap/cppgc/member_unittests.cc",
+    "heap/cppgc/source-location_unittest.cc",
     "heap/cppgc/stack_unittest.cc",
     "heap/cppgc/tests.cc",
     "heap/cppgc/tests.h",

test/unittests/heap/cppgc/source-location_unittest.cc

+// Copyright 2020 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "include/cppgc/source-location.h"
+
+#include "src/base/macros.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cppgc {
+namespace internal {
+
+namespace {
+constexpr char kFileName[] = "source-location_unittest.cc";
+
+bool Contains(const std::string& base_string, const std::string& substring) {
+  return base_string.find(substring) != std::string::npos;
+}
+
+}  // namespace
+
+TEST(SourceLocationTest, DefaultCtor) {
+  constexpr SourceLocation loc;
+  EXPECT_EQ(nullptr, loc.Function());
+  EXPECT_EQ(nullptr, loc.FileName());
+  EXPECT_EQ(0u, loc.Line());
+}
+
+void TestSourceLocationCurrent() {
+  static constexpr char kFunctionName[] = "TestSourceLocationCurrent";
+  static constexpr size_t kNextLine = __LINE__ + 1;
+  constexpr auto loc = SourceLocation::Current();
+#if !CPPGC_SUPPORTS_SOURCE_LOCATION
+  EXPECT_EQ(nullptr, loc.Function());
+  EXPECT_EQ(nullptr, loc.FileName());
+  EXPECT_EQ(0u, loc.Line());
+  USE(kNextLine);
+  return;
+#endif
+  EXPECT_EQ(kNextLine, loc.Line());
+  EXPECT_TRUE(Contains(loc.FileName(), kFileName));
+  EXPECT_TRUE(Contains(loc.Function(), kFunctionName));
+}
+
+TEST(SourceLocationTest, Current) { TestSourceLocationCurrent(); }
+
+void TestToString() {
+  static const std::string kDescriptor = std::string(__func__) + "@" +
+                                         __FILE__ + ":" +
+                                         std::to_string(__LINE__ + 1);
+  constexpr auto loc = SourceLocation::Current();
+  const auto string = loc.ToString();
+  EXPECT_EQ(kDescriptor, string);
+}
+
+#if CPPGC_SUPPORTS_SOURCE_LOCATION
+TEST(SourceLocationTest, ToString) { TestToString(); }
+#endif
+
+}  // namespace internal
+}  // namespace cppgc