expected.h - fix bugprone-forwarding-reference-overload warnings
Fixes:
system/core/base/include/android-base/expected.h:
186:13: warning: constructor accepting a forwarding reference can hide the copy and move constructors [bugprone-forwarding-reference-overload]
195:22: warning: constructor accepting a forwarding reference can hide the copy and move constructors [bugprone-forwarding-reference-overload]
611:13: warning: constructor accepting a forwarding reference can hide the copy and move constructors [bugprone-forwarding-reference-overload]
To quote Tom Cherry:
I'm a bit confused at what's happening there.
I think it's a bug in the linter itself.
The general solution to that problem is a heavy dose of std::enable_if<>
to hide that constructor when the 'U' parameter is the same class,
but those constructors do have the necessarily std::enable_if<> lines.
I think the problem is that the linter doesn't check that the macro
_ENABLE_IF() expands into std::enable_if<>. Let me try explicitly
putting the std::enable_if<> instead of the macro and check if it
goes away.
I expanded the macro but the linter doesn't still doesn't accept
the format of `std::enable_if_t<(condition_here)>* = nullptr`.
It does accept `typename Enable = std::enable_if_t<(condition_here), void>`,
which is the syntax used on their example here:
https://clang.llvm.org/extra/clang-tidy/checks/bugprone-forwarding-reference-overload.html.
That latter syntax doesn't work for us.
See the Notes section on
https://en.cppreference.com/w/cpp/types/enable_if
as a reference for why what we're doing is correct.
Test: builds
Bug: 153035880
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I493ff19208cc104f5f176a36ec23fbcb914388f7
Merged-In: I493ff19208cc104f5f176a36ec23fbcb914388f7
diff --git a/base/include/android-base/expected.h b/base/include/android-base/expected.h
index 38f0d6f..9470344 100644
--- a/base/include/android-base/expected.h
+++ b/base/include/android-base/expected.h
@@ -182,7 +182,7 @@
!std::is_same_v<unexpected<E>, std::remove_cv_t<std::remove_reference_t<U>>> &&
std::is_convertible_v<U&&, T> /* non-explicit */
)>
- // NOLINTNEXTLINE(google-explicit-constructor)
+ // NOLINTNEXTLINE(google-explicit-constructor,bugprone-forwarding-reference-overload)
constexpr expected(U&& v) : var_(std::in_place_index<0>, std::forward<U>(v)) {}
template <class U = T _ENABLE_IF(
@@ -192,6 +192,7 @@
!std::is_same_v<unexpected<E>, std::remove_cv_t<std::remove_reference_t<U>>> &&
!std::is_convertible_v<U&&, T> /* explicit */
)>
+ // NOLINTNEXTLINE(bugprone-forwarding-reference-overload)
constexpr explicit expected(U&& v) : var_(std::in_place_index<0>, T(std::forward<U>(v))) {}
template<class G = E _ENABLE_IF(
@@ -607,7 +608,7 @@
std::is_constructible_v<E, Err> &&
!std::is_same_v<std::remove_cv_t<std::remove_reference_t<E>>, std::in_place_t> &&
!std::is_same_v<std::remove_cv_t<std::remove_reference_t<E>>, unexpected>)>
- // NOLINTNEXTLINE(google-explicit-constructor)
+ // NOLINTNEXTLINE(google-explicit-constructor,bugprone-forwarding-reference-overload)
constexpr unexpected(Err&& e) : val_(std::forward<Err>(e)) {}
template<class U, class... Args _ENABLE_IF(