throw_exception_fmt_format

Summary: A variation of the `throw_exception` and `terminate_with` functions which wraps throwing an exception constructed with a single argument returned from `fmt::format`. Reviewed By: vitaut Differential Revision: D64835338 fbshipit-source-id: 64830616cc3c9076f5df7deb0327d94527c3cd8b
facebook · Nov 8, 2024 · cf549a4 · cf549a4
1 parent 3ccdcba
commit cf549a4
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diff --git a/folly/lang/BUCK b/folly/lang/BUCK
@@ -138,6 +138,7 @@ cpp_library(
         ":new",
     ],
     exported_deps = [
+        "fbsource//third-party/fmt:fmt",
         ":assume",
         ":safe_assert",
         ":thunk",

diff --git a/folly/lang/Exception.h b/folly/lang/Exception.h
@@ -18,10 +18,15 @@
 
 #include <atomic>
 #include <exception>
+#include <functional>
 #include <string>
 #include <type_traits>
 #include <utility>
 
+#if __has_include(<fmt/format.h>)
+#include <fmt/format.h>
+#endif
+
 #include <folly/CPortability.h>
 #include <folly/CppAttributes.h>
 #include <folly/Likely.h>
@@ -86,6 +91,9 @@ using throw_exception_arg_ = //
 template <typename R>
 using throw_exception_arg_t =
     typename throw_exception_arg_<R>::template apply<R>;
+template <typename R>
+using throw_exception_arg_fmt_t =
+    remove_cvref_t<typename throw_exception_arg_<R>::template apply<R>>;
 
 template <typename Ex, typename... Args>
 [[noreturn, FOLLY_ATTR_GNU_COLD]] FOLLY_NOINLINE void throw_exception_(
@@ -129,6 +137,56 @@ template <typename Ex, typename... Args>
       static_cast<Args&&>(args)...);
 }
 
+#if __has_include(<fmt/format.h>)
+
+namespace detail {
+
+template <typename Ex, typename... Args, typename Str>
+[[noreturn, FOLLY_ATTR_GNU_COLD]] FOLLY_NOINLINE void
+throw_exception_fmt_format_(Str str, Args&&... args) {
+  auto what = [&] { return fmt::format(str, static_cast<Args&&>(args)...); };
+  if constexpr (std::is_constructible_v<Ex, std::string&&>) {
+    throw_exception<Ex>(what());
+  } else {
+    throw_exception<Ex>(what().c_str());
+  }
+}
+
+template <typename Ex, typename... Args, typename Str>
+[[noreturn, FOLLY_ATTR_GNU_COLD]] FOLLY_NOINLINE void
+terminate_with_fmt_format_(Str str, Args&&... args) noexcept {
+  auto what = [&] { return fmt::format(str, static_cast<Args&&>(args)...); };
+  if constexpr (std::is_constructible_v<Ex, std::string&&>) {
+    throw_exception<Ex>(what());
+  } else {
+    throw_exception<Ex>(what().c_str());
+  }
+}
+
+} // namespace detail
+
+template <typename Ex, typename... Args>
+[[noreturn]] FOLLY_ERASE void throw_exception_fmt_format(
+    fmt::format_string<detail::throw_exception_arg_fmt_t<Args&&>...> str,
+    Args&&... args) {
+  detail::throw_exception_fmt_format_< //
+      Ex,
+      detail::throw_exception_arg_t<Args&&>...>(
+      str, static_cast<Args&&>(args)...);
+}
+
+template <typename Ex, typename... Args>
+[[noreturn]] FOLLY_ERASE void terminate_with_fmt_format(
+    fmt::format_string<detail::throw_exception_arg_fmt_t<Args&&>...> str,
+    Args&&... args) {
+  detail::terminate_with_fmt_format_< //
+      Ex,
+      detail::throw_exception_arg_t<Args&&>...>(
+      str, static_cast<Args&&>(args)...);
+}
+
+#endif
+
 /// invoke_cold
 ///
 /// Invoke the provided function with the provided arguments.

diff --git a/folly/lang/test/ExceptionTest.cpp b/folly/lang/test/ExceptionTest.cpp
@@ -136,6 +136,22 @@ class MyException : public std::exception {
   char const* what() const noexcept override { return what_; }
 };
 
+struct MyFmtFormatCStrException : std::exception {
+  std::runtime_error inner;
+  explicit MyFmtFormatCStrException(char const* const what) noexcept
+      : inner{what} {}
+  char const* what() const noexcept override { return inner.what(); }
+};
+
+struct MyFmtFormatStringException : std::exception {
+  std::runtime_error inner;
+  explicit MyFmtFormatStringException(std::string&& what) : inner{what} {}
+  explicit MyFmtFormatStringException(char const*) : inner{""} {
+    ADD_FAILURE();
+  }
+  char const* what() const noexcept override { return inner.what(); }
+};
+
 class ExceptionTest : public testing::Test {};
 
 TEST_F(ExceptionTest, throw_exception_direct) {
@@ -156,6 +172,26 @@ TEST_F(ExceptionTest, throw_exception_variadic) {
   }
 }
 
+TEST_F(ExceptionTest, throw_exception_fmt_format_c_str) {
+  try {
+    folly::throw_exception_fmt_format<MyFmtFormatCStrException>(
+        "{} {}", "hello", "world");
+    ADD_FAILURE();
+  } catch (MyFmtFormatCStrException const& ex) {
+    EXPECT_STREQ("hello world", ex.what());
+  }
+}
+
+TEST_F(ExceptionTest, throw_exception_fmt_format_string_view) {
+  try {
+    folly::throw_exception_fmt_format<MyFmtFormatStringException>(
+        "{} {}", "hello", "world");
+    ADD_FAILURE();
+  } catch (MyFmtFormatStringException const& ex) {
+    EXPECT_STREQ("hello world", ex.what());
+  }
+}
+
 TEST_F(ExceptionTest, terminate_with_direct) {
   EXPECT_DEATH(
       folly::terminate_with<MyException>("hello world"),
@@ -168,6 +204,20 @@ TEST_F(ExceptionTest, terminate_with_variadic) {
       message_for_terminate_with<MyException>("world"));
 }
 
+TEST_F(ExceptionTest, terminate_with_fmt_format_c_str) {
+  EXPECT_DEATH(
+      folly::terminate_with_fmt_format<MyFmtFormatCStrException>(
+          "{} {}", "hello", "world"),
+      message_for_terminate_with<MyFmtFormatCStrException>("hello world"));
+}
+
+TEST_F(ExceptionTest, terminate_with_fmt_format_string_view) {
+  EXPECT_DEATH(
+      folly::terminate_with_fmt_format<MyFmtFormatStringException>(
+          "{} {}", "hello", "world"),
+      message_for_terminate_with<MyFmtFormatStringException>("hello world"));
+}
+
 TEST_F(ExceptionTest, invoke_cold) {
   EXPECT_THROW(
       folly::invoke_cold([] { throw std::runtime_error("bad"); }),