[#BSLSTL_OPTIONAL_USES_STD_ALIASES]
= BSLSTL_OPTIONAL_USES_STD_ALIASES
:mrdocs:

The following macro `BSLSTL_OPTIONAL_USES_STD_ALIASES` controls whether platform standard library is used as a basis for `bsl` types in the following ways: ‐ `bsl::nullopt` is an alias to `std::nullopt`

== Synopsis

Declared in `<bslstl_optional.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
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#define BSLSTL_OPTIONAL_USES_STD_ALIASES

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== Description

* `bsl::optional<T>` inherits from `std::optional<T>` when `T` is not allocator‐aware.

This macro does _not_ control whether there are conversions and comparisons between `std::optional` and `bsl::optional`, that is conditioned only on whether `std::optional` is available (i.e., `BSLS_LIBRARYFEATURES_HAS_CPP17_BASELINE_LIBRARY` is defined).


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