From b5d925de98720a8a8e6f03d482bab8a22903d30a Mon Sep 17 00:00:00 2001
From: jzmaddock <john@johnmaddock.co.uk>
Date: Mon, 6 Jul 2020 19:29:28 +0100
Subject: [PATCH] Minor update for pow<N>(): Add a few more constexpr tests for
 the corner cases. Document the constexpr-ness. See
 https://github.com/boostorg/math/issues/354.

---
 doc/sf/pow.qbk    | 8 ++++++--
 test/pow_test.cpp | 4 ++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/doc/sf/pow.qbk b/doc/sf/pow.qbk
index b349ace09..db021978e 100644
--- a/doc/sf/pow.qbk
+++ b/doc/sf/pow.qbk
@@ -10,10 +10,10 @@ power of a run-time base.
     namespace boost { namespace math {
 
     template <int N, typename T>
-    ``__sf_result`` pow(T base);
+    constexpr ``__sf_result`` pow(T base);
 
     template <int N, typename T, class Policy>
-    ``__sf_result`` pow(T base, const Policy& policy);
+    constexpr ``__sf_result`` pow(T base, const Policy& policy);
 
     }}
 
@@ -60,6 +60,10 @@ For example:
 * If T is a `long double`, the return type is a `long double`.
 * Otherwise, the return type is a `double`.
 
+[h4 constexpr]
+
+This function is usable in `constexpr` contexts from C++14 onwards.
+
 [h4 Policies]
 
 [optional_policy]
diff --git a/test/pow_test.cpp b/test/pow_test.cpp
index eef8e3e6d..6c45d893b 100644
--- a/test/pow_test.cpp
+++ b/test/pow_test.cpp
@@ -196,6 +196,10 @@ BOOST_AUTO_TEST_CASE( test_main )
 
     #ifndef BOOST_NO_CXX14_CONSTEXPR
     static_assert(boost::math::pow<8>(2)==256, "Pow is not constexpr");
+    static_assert(boost::math::pow<9>(2)==512, "Pow is not constexpr");
+    static_assert(boost::math::pow<2>(2)==4,   "Pow is not constexpr");
+    static_assert(boost::math::pow<1>(2)==2,   "Pow is not constexpr");
+    static_assert(boost::math::pow<0>(2)==1,   "Pow is not constexpr");
     #endif
 
     test_return_types();