The [cmath.syn] p1 wording about additional overloads sufficient to
handle any arithmetic types also applies to std::lerp. This adds a new
overload of std::lerp that does the required promotions to support
arguments of arbitrary arithmetic types.
A new __promoted_t alias template is added, which the C++17 function
templates std::hypot and std::lerp can use to avoid instantiating the
__promote_3 class template.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/101870
* include/c_global/cmath (hypot): Use __promoted_t.
(lerp): Add new overload accepting any arithmetic types.
* include/ext/type_traits.h (__promoted_t): New alias template.
* testsuite/26_numerics/lerp.cc: Moved to...
* testsuite/26_numerics/lerp/1.cc: ...here.
* testsuite/26_numerics/lerp/constexpr.cc: New test.
* testsuite/26_numerics/lerp/version.cc: New test.
9017326e19