Export of internal Abseil changes.

--
441d1aa02483cdc510eb2fef012b31384fd8e3a6 by Eric Fiselier <ericwf@google.com>:

Fix str_format with non-POSIX libc implementations.

PiperOrigin-RevId: 218441122

--
da6190130e74222af6eb161a5593364341370370 by Jon Cohen <cohenjon@google.com>:

Refactor ExceptionSafetyTester::Test in order to remove the levels of indirection related to unpacking tuples.

PiperOrigin-RevId: 218403355
GitOrigin-RevId: 441d1aa02483cdc510eb2fef012b31384fd8e3a6
Change-Id: I6f6b978eb96fe261e8ee41ecdce185e5356a601d

5 files changed, 154 insertions, 136 deletions

diff --git a/absl/base/exception_safety_testing_test.cc b/absl/base/exception_safety_testing_test.cc
index 106bc34b00f7..7518264d2ec5 100644
--- a/absl/base/exception_safety_testing_test.cc
+++ b/absl/base/exception_safety_testing_test.cc
@@ -770,6 +770,18 @@ TEST(ExceptionCheckTest, ModifyingChecker) {
                   .Test(invoker));
 }
 
+TEST(ExceptionSafetyTesterTest, ResetsCountdown) {
+  auto test =
+      testing::MakeExceptionSafetyTester()
+          .WithInitialValue(ThrowingValue<>())
+          .WithContracts([](ThrowingValue<>*) { return AssertionSuccess(); })
+          .WithOperation([](ThrowingValue<>*) {});
+  ASSERT_TRUE(test.Test());
+  // If the countdown isn't reset because there were no exceptions thrown, then
+  // this will fail with a termination from an unhandled exception
+  EXPECT_TRUE(test.Test());
+}
+
 struct NonCopyable : public NonNegative {
   NonCopyable(const NonCopyable&) = delete;
   NonCopyable() : NonNegative{0} {}
diff --git a/absl/base/internal/exception_safety_testing.cc b/absl/base/internal/exception_safety_testing.cc
index f1d081f7e50d..8207b7d7b9ac 100644
--- a/absl/base/internal/exception_safety_testing.cc
+++ b/absl/base/internal/exception_safety_testing.cc
@@ -23,6 +23,10 @@ exceptions_internal::NoThrowTag nothrow_ctor;
 
 exceptions_internal::StrongGuaranteeTagType strong_guarantee;
 
+exceptions_internal::ExceptionSafetyTestBuilder<> MakeExceptionSafetyTester() {
+  return {};
+}
+
 namespace exceptions_internal {
 
 int countdown = -1;
diff --git a/absl/base/internal/exception_safety_testing.h b/absl/base/internal/exception_safety_testing.h
index 5665a1b67db2..429f5c2f1bb9 100644
--- a/absl/base/internal/exception_safety_testing.h
+++ b/absl/base/internal/exception_safety_testing.h
@@ -190,70 +190,6 @@ class TrackedObject {
 
   ~TrackedObject() noexcept { ConstructorTracker::ObjectDestructed(this); }
 };
-
-template <typename Factory, typename Operation, typename Contract>
-absl::optional<testing::AssertionResult> TestSingleContractAtCountdownImpl(
-    const Factory& factory, const Operation& operation, int count,
-    const Contract& contract) {
-  auto t_ptr = factory();
-  absl::optional<testing::AssertionResult> current_res;
-  SetCountdown(count);
-  try {
-    operation(t_ptr.get());
-  } catch (const exceptions_internal::TestException& e) {
-    current_res.emplace(contract(t_ptr.get()));
-    if (!current_res.value()) {
-      *current_res << e.what() << " failed contract check";
-    }
-  }
-  UnsetCountdown();
-  return current_res;
-}
-
-template <typename Factory, typename Operation>
-absl::optional<testing::AssertionResult> TestSingleContractAtCountdownImpl(
-    const Factory& factory, const Operation& operation, int count,
-    StrongGuaranteeTagType) {
-  using TPtr = typename decltype(factory())::pointer;
-  auto t_is_strong = [&](TPtr t) { return *t == *factory(); };
-  return TestSingleContractAtCountdownImpl(factory, operation, count,
-                                           t_is_strong);
-}
-
-template <typename Factory, typename Operation, typename Contract>
-int TestSingleContractAtCountdown(
-    const Factory& factory, const Operation& operation, int count,
-    const Contract& contract,
-    absl::optional<testing::AssertionResult>* reduced_res) {
-  // If reduced_res is empty, it means the current call to
-  // TestSingleContractAtCountdown(...) is the first test being run so we do
-  // want to run it. Alternatively, if it's not empty (meaning a previous test
-  // has run) we want to check if it passed. If the previous test did pass, we
-  // want to contine running tests so we do want to run the current one. If it
-  // failed, we want to short circuit so as not to overwrite the AssertionResult
-  // output. If that's the case, we do not run the current test and instead we
-  // simply return.
-  if (!reduced_res->has_value() || reduced_res->value()) {
-    *reduced_res =
-        TestSingleContractAtCountdownImpl(factory, operation, count, contract);
-  }
-  return 0;
-}
-
-template <typename Factory, typename Operation, typename... Contracts>
-inline absl::optional<testing::AssertionResult> TestAllContractsAtCountdown(
-    const Factory& factory, const Operation& operation, int count,
-    const Contracts&... contracts) {
-  absl::optional<testing::AssertionResult> reduced_res;
-
-  // Run each checker, short circuiting after the first failure
-  int dummy[] = {
-      0, (TestSingleContractAtCountdown(factory, operation, count, contracts,
-                                        &reduced_res))...};
-  static_cast<void>(dummy);
-  return reduced_res;
-}
-
 }  // namespace exceptions_internal
 
 extern exceptions_internal::NoThrowTag nothrow_ctor;
@@ -871,7 +807,7 @@ testing::AssertionResult TestNothrowOp(const Operation& operation) {
 
 namespace exceptions_internal {
 
-// Dummy struct for ExceptionSafetyTester<> partial state.
+// Dummy struct for ExceptionSafetyTestBuilder<> partial state.
 struct UninitializedT {};
 
 template <typename T>
@@ -893,20 +829,97 @@ using EnableIfTestable = typename absl::enable_if_t<
 
 template <typename Factory = UninitializedT,
           typename Operation = UninitializedT, typename... Contracts>
-class ExceptionSafetyTester;
+class ExceptionSafetyTestBuilder;
 
 }  // namespace exceptions_internal
 
-exceptions_internal::ExceptionSafetyTester<> MakeExceptionSafetyTester();
+/*
+ * Constructs an empty ExceptionSafetyTestBuilder. All
+ * ExceptionSafetyTestBuilder objects are immutable and all With[thing] mutation
+ * methods return new instances of ExceptionSafetyTestBuilder.
+ *
+ * In order to test a T for exception safety, a factory for that T, a testable
+ * operation, and at least one contract callback returning an assertion
+ * result must be applied using the respective methods.
+ */
+exceptions_internal::ExceptionSafetyTestBuilder<> MakeExceptionSafetyTester();
 
 namespace exceptions_internal {
+template <typename T>
+struct IsUniquePtr : std::false_type {};
+
+template <typename T, typename D>
+struct IsUniquePtr<std::unique_ptr<T, D>> : std::true_type {};
+
+template <typename Factory>
+struct FactoryPtrTypeHelper {
+  using type = decltype(std::declval<const Factory&>()());
+
+  static_assert(IsUniquePtr<type>::value, "Factories must return a unique_ptr");
+};
+
+template <typename Factory>
+using FactoryPtrType = typename FactoryPtrTypeHelper<Factory>::type;
+
+template <typename Factory>
+using FactoryElementType = typename FactoryPtrType<Factory>::element_type;
+
+template <typename T>
+class ExceptionSafetyTest {
+  using Factory = std::function<std::unique_ptr<T>()>;
+  using Operation = std::function<void(T*)>;
+  using Contract = std::function<AssertionResult(T*)>;
+
+ public:
+  template <typename... Contracts>
+  explicit ExceptionSafetyTest(const Factory& f, const Operation& op,
+                               const Contracts&... contracts)
+      : factory_(f), operation_(op), contracts_{WrapContract(contracts)...} {}
+
+  AssertionResult Test() const {
+    for (int count = 0;; ++count) {
+      exceptions_internal::ConstructorTracker ct(count);
+
+      for (const auto& contract : contracts_) {
+        auto t_ptr = factory_();
+        try {
+          SetCountdown(count);
+          operation_(t_ptr.get());
+          // Unset for the case that the operation throws no exceptions, which
+          // would leave the countdown set and break the *next* exception safety
+          // test after this one.
+          UnsetCountdown();
+          return AssertionSuccess();
+        } catch (const exceptions_internal::TestException& e) {
+          if (!contract(t_ptr.get())) {
+            return AssertionFailure() << e.what() << " failed contract check";
+          }
+        }
+      }
+    }
+  }
+
+ private:
+  template <typename ContractFn>
+  Contract WrapContract(const ContractFn& contract) {
+    return [contract](T* t_ptr) { return AssertionResult(contract(t_ptr)); };
+  }
+
+  Contract WrapContract(StrongGuaranteeTagType) {
+    return [this](T* t_ptr) { return AssertionResult(*factory_() == *t_ptr); };
+  }
+
+  Factory factory_;
+  Operation operation_;
+  std::vector<Contract> contracts_;
+};
 
 /*
  * Builds a tester object that tests if performing a operation on a T follows
  * exception safety guarantees. Verification is done via contract assertion
  * callbacks applied to T instances post-throw.
  *
- * Template parameters for ExceptionSafetyTester:
+ * Template parameters for ExceptionSafetyTestBuilder:
  *
  * - Factory: The factory object (passed in via tester.WithFactory(...) or
  *   tester.WithInitialValue(...)) must be invocable with the signature
@@ -933,13 +946,13 @@ namespace exceptions_internal {
  *   please.
  */
 template <typename Factory, typename Operation, typename... Contracts>
-class ExceptionSafetyTester {
+class ExceptionSafetyTestBuilder {
  public:
   /*
-   * Returns a new ExceptionSafetyTester with an included T factory based on the
-   * provided T instance. The existing factory will not be included in the newly
-   * created tester instance. The created factory returns a new T instance by
-   * copy-constructing the provided const T& t.
+   * Returns a new ExceptionSafetyTestBuilder with an included T factory based
+   * on the provided T instance. The existing factory will not be included in
+   * the newly created tester instance. The created factory returns a new T
+   * instance by copy-constructing the provided const T& t.
    *
    * Preconditions for tester.WithInitialValue(const T& t):
    *
@@ -948,41 +961,41 @@ class ExceptionSafetyTester {
    *   tester.WithFactory(...).
    */
   template <typename T>
-  ExceptionSafetyTester<DefaultFactory<T>, Operation, Contracts...>
+  ExceptionSafetyTestBuilder<DefaultFactory<T>, Operation, Contracts...>
   WithInitialValue(const T& t) const {
     return WithFactory(DefaultFactory<T>(t));
   }
 
   /*
-   * Returns a new ExceptionSafetyTester with the provided T factory included.
-   * The existing factory will not be included in the newly-created tester
-   * instance. This method is intended for use with types lacking a copy
+   * Returns a new ExceptionSafetyTestBuilder with the provided T factory
+   * included. The existing factory will not be included in the newly-created
+   * tester instance. This method is intended for use with types lacking a copy
    * constructor. Types that can be copy-constructed should instead use the
    * method tester.WithInitialValue(...).
    */
   template <typename NewFactory>
-  ExceptionSafetyTester<absl::decay_t<NewFactory>, Operation, Contracts...>
+  ExceptionSafetyTestBuilder<absl::decay_t<NewFactory>, Operation, Contracts...>
   WithFactory(const NewFactory& new_factory) const {
     return {new_factory, operation_, contracts_};
   }
 
   /*
-   * Returns a new ExceptionSafetyTester with the provided testable operation
-   * included. The existing operation will not be included in the newly created
-   * tester.
+   * Returns a new ExceptionSafetyTestBuilder with the provided testable
+   * operation included. The existing operation will not be included in the
+   * newly created tester.
    */
   template <typename NewOperation>
-  ExceptionSafetyTester<Factory, absl::decay_t<NewOperation>, Contracts...>
+  ExceptionSafetyTestBuilder<Factory, absl::decay_t<NewOperation>, Contracts...>
   WithOperation(const NewOperation& new_operation) const {
     return {factory_, new_operation, contracts_};
   }
 
   /*
-   * Returns a new ExceptionSafetyTester with the provided MoreContracts...
+   * Returns a new ExceptionSafetyTestBuilder with the provided MoreContracts...
    * combined with the Contracts... that were already included in the instance
    * on which the method was called. Contracts... cannot be removed or replaced
-   * once added to an ExceptionSafetyTester instance. A fresh object must be
-   * created in order to get an empty Contracts... list.
+   * once added to an ExceptionSafetyTestBuilder instance. A fresh object must
+   * be created in order to get an empty Contracts... list.
    *
    * In addition to passing in custom contract assertion callbacks, this method
    * accepts `testing::strong_guarantee` as an argument which checks T instances
@@ -991,8 +1004,8 @@ class ExceptionSafetyTester {
    * properly rolled back.
    */
   template <typename... MoreContracts>
-  ExceptionSafetyTester<Factory, Operation, Contracts...,
-                        absl::decay_t<MoreContracts>...>
+  ExceptionSafetyTestBuilder<Factory, Operation, Contracts...,
+                             absl::decay_t<MoreContracts>...>
   WithContracts(const MoreContracts&... more_contracts) const {
     return {
         factory_, operation_,
@@ -1039,48 +1052,27 @@ class ExceptionSafetyTester {
       typename LazyOperation = Operation,
       typename = EnableIfTestable<sizeof...(Contracts), Factory, LazyOperation>>
   testing::AssertionResult Test() const {
-    return TestImpl(operation_, absl::index_sequence_for<Contracts...>());
+    return Test(operation_);
   }
 
  private:
   template <typename, typename, typename...>
-  friend class ExceptionSafetyTester;
+  friend class ExceptionSafetyTestBuilder;
 
-  friend ExceptionSafetyTester<> testing::MakeExceptionSafetyTester();
+  friend ExceptionSafetyTestBuilder<> testing::MakeExceptionSafetyTester();
 
-  ExceptionSafetyTester() {}
+  ExceptionSafetyTestBuilder() {}
 
-  ExceptionSafetyTester(const Factory& f, const Operation& o,
-                        const std::tuple<Contracts...>& i)
+  ExceptionSafetyTestBuilder(const Factory& f, const Operation& o,
+                             const std::tuple<Contracts...>& i)
       : factory_(f), operation_(o), contracts_(i) {}
 
   template <typename SelectedOperation, size_t... Indices>
-  testing::AssertionResult TestImpl(const SelectedOperation& selected_operation,
+  testing::AssertionResult TestImpl(SelectedOperation selected_operation,
                                     absl::index_sequence<Indices...>) const {
-    // Starting from 0 and counting upwards until one of the exit conditions is
-    // hit...
-    for (int count = 0;; ++count) {
-      exceptions_internal::ConstructorTracker ct(count);
-
-      // Run the full exception safety test algorithm for the current countdown
-      auto reduced_res =
-          TestAllContractsAtCountdown(factory_, selected_operation, count,
-                                      std::get<Indices>(contracts_)...);
-      // If there is no value in the optional, no contracts were run because no
-      // exception was thrown. This means that the test is complete and the loop
-      // can exit successfully.
-      if (!reduced_res.has_value()) {
-        return testing::AssertionSuccess();
-      }
-      // If the optional is not empty and the value is falsy, an contract check
-      // failed so the test must exit to propegate the failure.
-      if (!reduced_res.value()) {
-        return reduced_res.value();
-      }
-      // If the optional is not empty and the value is not falsy, it means
-      // exceptions were thrown but the contracts passed so the test must
-      // continue to run.
-    }
+    return ExceptionSafetyTest<FactoryElementType<Factory>>(
+               factory_, selected_operation, std::get<Indices>(contracts_)...)
+        .Test();
   }
 
   Factory factory_;
@@ -1090,20 +1082,6 @@ class ExceptionSafetyTester {
 
 }  // namespace exceptions_internal
 
-/*
- * Constructs an empty ExceptionSafetyTester. All ExceptionSafetyTester
- * objects are immutable and all With[thing] mutation methods return new
- * instances of ExceptionSafetyTester.
- *
- * In order to test a T for exception safety, a factory for that T, a testable
- * operation, and at least one contract callback returning an assertion
- * result must be applied using the respective methods.
- */
-inline exceptions_internal::ExceptionSafetyTester<>
-MakeExceptionSafetyTester() {
-  return {};
-}
-
 }  // namespace testing
 
 #endif  // ABSL_BASE_INTERNAL_EXCEPTION_SAFETY_TESTING_H_
diff --git a/absl/strings/internal/str_format/output.cc b/absl/strings/internal/str_format/output.cc
index 5c3795b737ca..d7fef69b4cf9 100644
--- a/absl/strings/internal/str_format/output.cc
+++ b/absl/strings/internal/str_format/output.cc
@@ -20,6 +20,16 @@
 namespace absl {
 namespace str_format_internal {
 
+namespace {
+struct ClearErrnoGuard {
+  ClearErrnoGuard() : old_value(errno) { errno = 0; }
+  ~ClearErrnoGuard() {
+    if (!errno) errno = old_value;
+  }
+  int old_value;
+};
+}  // namespace
+
 void BufferRawSink::Write(string_view v) {
   size_t to_write = std::min(v.size(), size_);
   std::memcpy(buffer_, v.data(), to_write);
@@ -30,14 +40,27 @@ void BufferRawSink::Write(string_view v) {
 
 void FILERawSink::Write(string_view v) {
   while (!v.empty() && !error_) {
+    // Reset errno to zero in case the libc implementation doesn't set errno
+    // when a failure occurs.
+    ClearErrnoGuard guard;
+
     if (size_t result = std::fwrite(v.data(), 1, v.size(), output_)) {
       // Some progress was made.
       count_ += result;
       v.remove_prefix(result);
     } else {
-      // Some error occurred.
-      if (errno != EINTR) {
+      if (errno == EINTR) {
+        continue;
+      } else if (errno) {
         error_ = errno;
+      } else if (std::ferror(output_)) {
+        // Non-POSIX compliant libc implementations may not set errno, so we
+        // have check the streams error indicator.
+        error_ = EBADF;
+      } else {
+        // We're likely on a non-POSIX system that encountered EINTR but had no
+        // way of reporting it.
+        continue;
       }
     }
   }
diff --git a/absl/strings/str_format_test.cc b/absl/strings/str_format_test.cc
index ea9a3a176612..87ed234fe825 100644
--- a/absl/strings/str_format_test.cc
+++ b/absl/strings/str_format_test.cc
@@ -242,6 +242,7 @@ class TempFile {
   std::string ReadFile() {
     std::fseek(file_, 0, SEEK_END);
     int size = std::ftell(file_);
+    EXPECT_GT(size, 0);
     std::rewind(file_);
     std::string str(2 * size, ' ');
     int read_bytes = std::fread(&str[0], 1, str.size(), file_);
@@ -270,7 +271,7 @@ TEST_F(FormatEntryPointTest, FPrintFError) {
   EXPECT_EQ(errno, EBADF);
 }
 
-#if __GNUC__
+#if __GLIBC__
 TEST_F(FormatEntryPointTest, FprintfTooLarge) {
   std::FILE* f = std::fopen("/dev/null", "w");
   int width = 2000000000;
@@ -297,7 +298,7 @@ TEST_F(FormatEntryPointTest, PrintF) {
   EXPECT_EQ(result, 30);
   EXPECT_EQ(tmp.ReadFile(), "STRING: ABC NUMBER: -000000019");
 }
-#endif  // __GNUC__
+#endif  // __GLIBC__
 
 TEST_F(FormatEntryPointTest, SNPrintF) {
   char buffer[16];