fix compile issues on clang with cxxstd=latest

added tests of clang with cxxstd=latest to detect issue

.appveyor.yml

@@ -47,7 +47,7 @@ test_script:
   - sh:
       ../../b2 $B2_OPTS cxxstd=14 exception-handling=off rtti=off test//minimal &&
       ../../b2 $B2_OPTS toolset=gcc-9 cxxstd=latest examples test//all &&
-      ../../b2 $B2_OPTS toolset=clang cxxstd=14 variant=histogram_ubasan test//all
+      ../../b2 $B2_OPTS toolset=clang cxxstd=latest variant=histogram_ubasan test//all
 
 on_failure:
   # Uncomment the following line to stop VM and enable interactive login

.travis.yml

@@ -14,8 +14,11 @@ branches:
     - develop
 
 matrix:
+  fast_finish: true
+
   include:
-    - os: osx
+    - name: osx and cmake
+      os: osx
       language: cpp
       before_script:
         - mkdir build
@@ -24,6 +27,30 @@ matrix:
       script:
         ctest -j2
 
+    - name: osx and b2
+      os: osx
+      language: cpp
+      before_script:
+        # clone minimal set of Boost libraries
+        - cd ..
+        - git clone -b $TRAVIS_BRANCH --depth 5 https://github.com/boostorg/boost.git
+        - cd boost
+        - git submodule update --init --depth 5 tools/build tools/boostdep
+
+        # replace library with this version and install dependencies
+        - rm -rf libs/histogram
+        - mv $TRAVIS_BUILD_DIR libs/histogram
+        - python tools/boostdep/depinst/depinst.py --git_args "--depth 5 --jobs 3" histogram
+
+        # prepare build
+        - ./bootstrap.sh
+        - ./b2 headers
+        - cd libs/histogram
+        - B2="../../b2 -q -j2 warnings-as-errors=on"        
+      script:
+        $B2 cxxstd=latest exception-handling=off test//minimal &&
+        $B2 cxxstd=latest test//all
+
     - os: linux
       language: python
       python: "3.6"
@@ -55,7 +82,7 @@ matrix:
         $B2 toolset=gcc-5 cxxstd=14 examples test//all &&
         $B2 toolset=gcc-5 cxxstd=14 exception-handling=off rtti=off test//minimal &&
         $B2 toolset=gcc-8 cxxstd=latest coverage=on test//all &&
-        GCOV=gcov-8 tools/cov.sh
+        GCOV=gcov-8 tools/cov.sh  
-
+  
 notifications:
   email: false

include/boost/histogram/detail/span.hpp

@@ -32,6 +32,8 @@ namespace boost {
 namespace histogram {
 namespace detail {
 
+namespace dtl = ::boost::histogram::detail;
+
 static constexpr std::size_t dynamic_extent = ~static_cast<std::size_t>(0);
 
 template <class T, std::size_t N>
@@ -105,31 +107,30 @@ public:
   constexpr span(pointer ptr, index_type count) : base(ptr, count) {}
 
   template <std::size_t N>
-  constexpr span(element_type (&arr)[N]) noexcept : span(data(arr), N) {
+  constexpr span(element_type (&arr)[N]) noexcept : span(dtl::data(arr), N) {
     static_assert(extent == dynamic_extent || extent == N, "static sizes do not match");
   }
 
   template <std::size_t N,
             class = std::enable_if_t<(extent == dynamic_extent || extent == N)> >
-  constexpr span(std::array<value_type, N>& arr) noexcept : span(data(arr), N) {}
+  constexpr span(std::array<value_type, N>& arr) noexcept : span(dtl::data(arr), N) {}
 
   template <std::size_t N,
             class = std::enable_if_t<(extent == dynamic_extent || extent == N)> >
-  constexpr span(const std::array<value_type, N>& arr) noexcept : span(data(arr), N) {}
+  constexpr span(const std::array<value_type, N>& arr) noexcept
+      : span(dtl::data(arr), N) {}
 
-  template <
+  template <class Container, class = std::enable_if_t<std::is_convertible<
-      class Container,
+                                 decltype(dtl::size(std::declval<Container>()),
-      class = std::enable_if_t<std::is_convertible<
+                                          dtl::data(std::declval<Container>())),
-          decltype(size(std::declval<Container>()), data(std::declval<Container>())),
+                                 pointer>::value> >
-          pointer>::value> >
+  constexpr span(const Container& cont) : span(dtl::data(cont), dtl::size(cont)) {}
-  constexpr span(const Container& cont) : span(data(cont), size(cont)) {}
 
-  template <
+  template <class Container, class = std::enable_if_t<std::is_convertible<
-      class Container,
+                                 decltype(dtl::size(std::declval<Container>()),
-      class = std::enable_if_t<std::is_convertible<
+                                          dtl::data(std::declval<Container>())),
-          decltype(size(std::declval<Container>()), data(std::declval<Container>())),
+                                 pointer>::value> >
-          pointer>::value> >
+  constexpr span(Container& cont) : span(dtl::data(cont), dtl::size(cont)) {}
-  constexpr span(Container& cont) : span(data(cont), size(cont)) {}
 
   template <class U, std::size_t N,
             class = std::enable_if_t<((extent == dynamic_extent || extent == N) &&
@@ -229,10 +230,10 @@ span<T> make_span(T* begin, std::size_t size) {
   return span<T>{begin, size};
 }
 
-template <class Container, class = decltype(size(std::declval<Container>()),
+template <class Container, class = decltype(dtl::size(std::declval<Container>()),
-                                            data(std::declval<Container>()))>
+                                            dtl::data(std::declval<Container>()))>
 auto make_span(const Container& cont) {
-  return make_span(data(cont), size(cont));
+  return make_span(dtl::data(cont), dtl::size(cont));
 }
 
 template <class T, std::size_t N>

test/histogram_fill_test.cpp

@@ -4,6 +4,7 @@
 // (See accompanying file LICENSE_1_0.txt
 // or copy at http://www.boost.org/LICENSE_1_0.txt)
 
+#include <array>
 #include <boost/config.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <boost/histogram/accumulators.hpp>
@@ -92,11 +93,14 @@ void run_tests(const std::vector<int>& x, const std::vector<int>& y,
 
     BOOST_TEST_EQ(h, h2);
 
-    BOOST_TEST_THROWS(h2.fill(std::array<std::vector<int>, 2>(
+#ifndef BOOST_NO_EXCEPTIONS
-                          {std::vector<int>(2), std::vector<int>(3)})),
+    // wrong rank
-                      std::invalid_argument);
-
     BOOST_TEST_THROWS(h.fill(x), std::invalid_argument);
+
+    // not rectangular
+    std::array<std::vector<int>, 2> bad = {{std::vector<int>(2), std::vector<int>(3)}};
+    BOOST_TEST_THROWS(h2.fill(bad), std::invalid_argument);
+#endif
   }
 
   // 1D variant and weight