Fix the implementation of OnlyLiteralZero (#1420)
This patch changes the implementation of OnlyLiteralZero to only fail if the second overload is chosen, instead of failing during overload resolution.
This patch cherry-picks 2de126cc5826a8d464270ead65a7a9a7b012b741.
Fixes #1419
diff --git a/absl/base/config.h b/absl/base/config.h
index 573c9fd..0631ab6 100644
--- a/absl/base/config.h
+++ b/absl/base/config.h
@@ -112,7 +112,7 @@
// LTS releases can be obtained from
// https://github.com/abseil/abseil-cpp/releases.
#define ABSL_LTS_RELEASE_VERSION 20230125
-#define ABSL_LTS_RELEASE_PATCH_LEVEL 1
+#define ABSL_LTS_RELEASE_PATCH_LEVEL 2
// Helper macro to convert a CPP variable to a string literal.
#define ABSL_INTERNAL_DO_TOKEN_STR(x) #x
diff --git a/absl/types/compare.h b/absl/types/compare.h
index 78aa26d..1a965e9 100644
--- a/absl/types/compare.h
+++ b/absl/types/compare.h
@@ -44,29 +44,28 @@
using value_type = int8_t;
-template <typename T>
-struct Fail {
- static_assert(sizeof(T) < 0, "Only literal `0` is allowed.");
-};
+class OnlyLiteralZero {
+ // A private type which cannot be named to explicitly cast to it.
+ struct MatchLiteralZero;
-// We need the NullPtrT template to avoid triggering the modernize-use-nullptr
-// ClangTidy warning in user code.
-template <typename NullPtrT = std::nullptr_t>
-struct OnlyLiteralZero {
- constexpr OnlyLiteralZero(NullPtrT) noexcept {} // NOLINT
+ public:
+ // Accept only literal zero since it can be implicitly converted to a pointer
+ // type. nullptr constants will be caught by the other constructor which
+ // accepts a nullptr_t.
+ constexpr OnlyLiteralZero(MatchLiteralZero *) noexcept {} // NOLINT
// Fails compilation when `nullptr` or integral type arguments other than
// `int` are passed. This constructor doesn't accept `int` because literal `0`
// has type `int`. Literal `0` arguments will be implicitly converted to
// `std::nullptr_t` and accepted by the above constructor, while other `int`
// arguments will fail to be converted and cause compilation failure.
- template <
- typename T,
- typename = typename std::enable_if<
- std::is_same<T, std::nullptr_t>::value ||
- (std::is_integral<T>::value && !std::is_same<T, int>::value)>::type,
- typename = typename Fail<T>::type>
- OnlyLiteralZero(T); // NOLINT
+ template <typename T, typename = typename std::enable_if<
+ std::is_same<T, std::nullptr_t>::value ||
+ (std::is_integral<T>::value &&
+ !std::is_same<T, int>::value)>::type>
+ OnlyLiteralZero(T) { // NOLINT
+ static_assert(sizeof(T) < 0, "Only literal `0` is allowed.");
+ }
};
enum class eq : value_type {
@@ -163,18 +162,18 @@
// Comparisons
friend constexpr bool operator==(
- weak_equality v, compare_internal::OnlyLiteralZero<>) noexcept {
+ weak_equality v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ == 0;
}
friend constexpr bool operator!=(
- weak_equality v, compare_internal::OnlyLiteralZero<>) noexcept {
+ weak_equality v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ != 0;
}
- friend constexpr bool operator==(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator==(compare_internal::OnlyLiteralZero,
weak_equality v) noexcept {
return 0 == v.value_;
}
- friend constexpr bool operator!=(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator!=(compare_internal::OnlyLiteralZero,
weak_equality v) noexcept {
return 0 != v.value_;
}
@@ -214,18 +213,18 @@
}
// Comparisons
friend constexpr bool operator==(
- strong_equality v, compare_internal::OnlyLiteralZero<>) noexcept {
+ strong_equality v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ == 0;
}
friend constexpr bool operator!=(
- strong_equality v, compare_internal::OnlyLiteralZero<>) noexcept {
+ strong_equality v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ != 0;
}
- friend constexpr bool operator==(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator==(compare_internal::OnlyLiteralZero,
strong_equality v) noexcept {
return 0 == v.value_;
}
- friend constexpr bool operator!=(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator!=(compare_internal::OnlyLiteralZero,
strong_equality v) noexcept {
return 0 != v.value_;
}
@@ -277,50 +276,50 @@
}
// Comparisons
friend constexpr bool operator==(
- partial_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ partial_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.is_ordered() && v.value_ == 0;
}
friend constexpr bool operator!=(
- partial_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ partial_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return !v.is_ordered() || v.value_ != 0;
}
friend constexpr bool operator<(
- partial_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ partial_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.is_ordered() && v.value_ < 0;
}
friend constexpr bool operator<=(
- partial_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ partial_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.is_ordered() && v.value_ <= 0;
}
friend constexpr bool operator>(
- partial_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ partial_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.is_ordered() && v.value_ > 0;
}
friend constexpr bool operator>=(
- partial_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ partial_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.is_ordered() && v.value_ >= 0;
}
- friend constexpr bool operator==(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator==(compare_internal::OnlyLiteralZero,
partial_ordering v) noexcept {
return v.is_ordered() && 0 == v.value_;
}
- friend constexpr bool operator!=(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator!=(compare_internal::OnlyLiteralZero,
partial_ordering v) noexcept {
return !v.is_ordered() || 0 != v.value_;
}
- friend constexpr bool operator<(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator<(compare_internal::OnlyLiteralZero,
partial_ordering v) noexcept {
return v.is_ordered() && 0 < v.value_;
}
- friend constexpr bool operator<=(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator<=(compare_internal::OnlyLiteralZero,
partial_ordering v) noexcept {
return v.is_ordered() && 0 <= v.value_;
}
- friend constexpr bool operator>(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator>(compare_internal::OnlyLiteralZero,
partial_ordering v) noexcept {
return v.is_ordered() && 0 > v.value_;
}
- friend constexpr bool operator>=(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator>=(compare_internal::OnlyLiteralZero,
partial_ordering v) noexcept {
return v.is_ordered() && 0 >= v.value_;
}
@@ -369,50 +368,50 @@
}
// Comparisons
friend constexpr bool operator==(
- weak_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ weak_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ == 0;
}
friend constexpr bool operator!=(
- weak_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ weak_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ != 0;
}
friend constexpr bool operator<(
- weak_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ weak_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ < 0;
}
friend constexpr bool operator<=(
- weak_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ weak_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ <= 0;
}
friend constexpr bool operator>(
- weak_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ weak_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ > 0;
}
friend constexpr bool operator>=(
- weak_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ weak_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ >= 0;
}
- friend constexpr bool operator==(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator==(compare_internal::OnlyLiteralZero,
weak_ordering v) noexcept {
return 0 == v.value_;
}
- friend constexpr bool operator!=(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator!=(compare_internal::OnlyLiteralZero,
weak_ordering v) noexcept {
return 0 != v.value_;
}
- friend constexpr bool operator<(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator<(compare_internal::OnlyLiteralZero,
weak_ordering v) noexcept {
return 0 < v.value_;
}
- friend constexpr bool operator<=(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator<=(compare_internal::OnlyLiteralZero,
weak_ordering v) noexcept {
return 0 <= v.value_;
}
- friend constexpr bool operator>(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator>(compare_internal::OnlyLiteralZero,
weak_ordering v) noexcept {
return 0 > v.value_;
}
- friend constexpr bool operator>=(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator>=(compare_internal::OnlyLiteralZero,
weak_ordering v) noexcept {
return 0 >= v.value_;
}
@@ -468,50 +467,50 @@
}
// Comparisons
friend constexpr bool operator==(
- strong_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ strong_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ == 0;
}
friend constexpr bool operator!=(
- strong_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ strong_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ != 0;
}
friend constexpr bool operator<(
- strong_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ strong_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ < 0;
}
friend constexpr bool operator<=(
- strong_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ strong_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ <= 0;
}
friend constexpr bool operator>(
- strong_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ strong_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ > 0;
}
friend constexpr bool operator>=(
- strong_ordering v, compare_internal::OnlyLiteralZero<>) noexcept {
+ strong_ordering v, compare_internal::OnlyLiteralZero) noexcept {
return v.value_ >= 0;
}
- friend constexpr bool operator==(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator==(compare_internal::OnlyLiteralZero,
strong_ordering v) noexcept {
return 0 == v.value_;
}
- friend constexpr bool operator!=(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator!=(compare_internal::OnlyLiteralZero,
strong_ordering v) noexcept {
return 0 != v.value_;
}
- friend constexpr bool operator<(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator<(compare_internal::OnlyLiteralZero,
strong_ordering v) noexcept {
return 0 < v.value_;
}
- friend constexpr bool operator<=(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator<=(compare_internal::OnlyLiteralZero,
strong_ordering v) noexcept {
return 0 <= v.value_;
}
- friend constexpr bool operator>(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator>(compare_internal::OnlyLiteralZero,
strong_ordering v) noexcept {
return 0 > v.value_;
}
- friend constexpr bool operator>=(compare_internal::OnlyLiteralZero<>,
+ friend constexpr bool operator>=(compare_internal::OnlyLiteralZero,
strong_ordering v) noexcept {
return 0 >= v.value_;
}
