[#BloombergLP-bslstl-SharedPtr_TestIsCallable-test-08]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::xref:BloombergLP/bslstl/SharedPtr_TestIsCallable.adoc[SharedPtr_TestIsCallable]::test
:relfileprefix: ../../../
:mrdocs:

This function is never defined. It provides a property‐checker that an entity of (template parameter) type `FACTORY` can be called like a function with a single argument, which is a pointer to an object of (template parameter) type `ARG`. The `sizeof()` expression provides an unevaluated context to check the validity of the enclosed expression, and the `, 0` ensures that the `sizeof` check remains valid, even if the expression returns `void`. Similarly, the cast to `void` ensures that there are no surprises with types that overload the comma operator. Note that the cast to `void` is elided for Clang compilers using versions of LLVM prior to 12, which fail to evaluate the trait properly. Note that `sizeof(decltype())` is required for MSVC due to a compiler bug in MSVC 17.6 and later (at least including 17.7.0 Preview 2.0).

== Synopsis

Declared in `<bslstl_sharedptr.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class ARG>
static
xref:BloombergLP/bslstl/SharedPtr_TestIsCallable.adoc[FalseType]
test(...);
----


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