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src: simplify is_callable by making it a concept #58169

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Merged
merged 1 commit into from
Sep 20, 2025
+3 −7
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src: simplify is_callable by making it a concept #58169

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2 changes: 1 addition & 1 deletion src/req_wrap-inl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -111,7 +111,7 @@ struct CallLibuvFunction<ReqT, void(*)(ReqT*, Args...)> {
template <typename ReqT, typename T>
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Suggested change
template <typename ReqT, typename T>
template <typename ReqT, is_callable T>

struct MakeLibuvRequestCallback {
static T For(ReqWrap<ReqT>* req_wrap, T v) {
static_assert(!is_callable<T>::value,
static_assert(!is_callable<T>,
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You can change type name T to is_callable T and remove this static_assertion.

"MakeLibuvRequestCallback missed a callback");
Comment on lines +114 to 115
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Suggested change
static_assert(!is_callable<T>,
"MakeLibuvRequestCallback missed a callback");

return v;
}
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8 changes: 2 additions & 6 deletions src/util.h
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Expand Up @@ -689,13 +689,9 @@ class NonCopyableMaybe {
};

// Test whether some value can be called with ().
template <typename T, typename = void>
struct is_callable : std::is_function<T> { };

template <typename T>
struct is_callable<T, typename std::enable_if<
std::is_same<decltype(void(&T::operator())), void>::value
>::type> : std::true_type { };
concept is_callable =
std::is_function<T>::value || requires { &T::operator(); };
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For concepts like this, I'd prefer if we adopted a naming scheme like IsCallable


template <typename T, void (*function)(T*)>
struct FunctionDeleter {
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