Merge develop into master

.travis.yml

@@ -4,7 +4,7 @@
 
 language: cpp
 os: linux # Jobs are on Linux unless specified otherwise
-dist: trusty # Jobs are on Trusty unless specified otherwise
+dist: xenial
 sudo: false
 
 env:
@@ -22,39 +22,19 @@ matrix:
     # Note that we only use the memory checker on the main configuration to
     # speed up Travis builds.
     ##########################################################################
-    # Clang 3.9
-    - env: UNIT_TESTS=true COMPILER=clang++-3.9 BOOST_VERSION=default ENABLE_MEMCHECK=true
-      addons: { apt: { packages: ["clang-3.9", "valgrind"], sources: ["ubuntu-toolchain-r-test", "llvm-toolchain-trusty-3.9"] } }
-
-    # Clang 4.0
-    - env: UNIT_TESTS=true COMPILER=clang++-4.0 BOOST_VERSION=default ENABLE_MEMCHECK=true
-      addons: { apt: { packages: ["clang-4.0", "valgrind"], sources: ["ubuntu-toolchain-r-test", "llvm-toolchain-trusty-4.0"] } }
-
-    # Clang 5.0
-    - env: UNIT_TESTS=true COMPILER=clang++-5.0 BOOST_VERSION=default ENABLE_MEMCHECK=true
-      addons: { apt: { packages: ["clang-5.0", "valgrind"], sources: ["ubuntu-toolchain-r-test", "llvm-toolchain-trusty-5.0"] } }
-
-    # Clang 6.0
-    - env: UNIT_TESTS=true COMPILER=clang++-6.0 BOOST_VERSION=default ENABLE_MEMCHECK=true
-      addons: { apt: { packages: ["clang-6.0", "valgrind"], sources: ["ubuntu-toolchain-r-test", "llvm-toolchain-trusty-6.0"] } }
-
-    # Clang 7.0
+    # Clang 7
     - env: UNIT_TESTS=true COMPILER=clang++-7 BOOST_VERSION=default ENABLE_MEMCHECK=true
-      addons: &defaults { apt: { packages: ["clang-7", "valgrind"], sources: ["ubuntu-toolchain-r-test", "llvm-toolchain-trusty-7"] } }
+      addons: { apt: { packages: ["clang-7", "valgrind"], sources: ["ubuntu-toolchain-r-test", "llvm-toolchain-xenial-7"] } }
 
-    # GCC 6
-    - env: UNIT_TESTS=true COMPILER=g++-6 BOOST_VERSION=default ENABLE_MEMCHECK=true
-      addons: { apt: { packages: ["g++-6", "valgrind"], sources: ["ubuntu-toolchain-r-test"] } }
-
-    # GCC 7
-    - env: UNIT_TESTS=true COMPILER=g++-7 BOOST_VERSION=default ENABLE_MEMCHECK=true
-      addons: { apt: { packages: ["g++-7", "valgrind"], sources: ["ubuntu-toolchain-r-test"] } }
+    # Clang 8
+    - env: UNIT_TESTS=true COMPILER=clang++-8 BOOST_VERSION=default ENABLE_MEMCHECK=true
+      addons: &defaults { apt: { packages: ["clang-8", "valgrind"], sources: ["ubuntu-toolchain-r-test", "llvm-toolchain-xenial-8"] } }
 
     # GCC 8
     - env: UNIT_TESTS=true COMPILER=g++-8 BOOST_VERSION=default ENABLE_MEMCHECK=true
       addons: { apt: { packages: ["g++-8", "valgrind"], sources: ["ubuntu-toolchain-r-test"] } }
 
-    # Xcode 9.1
+    # Xcode 11
     - os: osx
       env: UNIT_TESTS=true BOOST_VERSION=default
       osx_image: xcode11
@@ -66,9 +46,17 @@ matrix:
     - env: UNIT_TESTS=true COMPILER=default BOOST_VERSION=default CMAKE_OPTIONS="-DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_STANDARD_REQUIRED=ON"
       addons: *defaults
 
+    # With C++20, on Clang
+    - env: UNIT_TESTS=true COMPILER=default BOOST_VERSION=default CMAKE_OPTIONS="-DCMAKE_CXX_STANDARD=20 -DCMAKE_CXX_STANDARD_REQUIRED=ON"
+      addons: *defaults
+
     # With C++17, on GCC
-    - env: UNIT_TESTS=true COMPILER=g++-6     BOOST_VERSION=default CMAKE_OPTIONS="-DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_STANDARD_REQUIRED=ON"
-      addons: { apt: { packages: ["g++-6", "valgrind"], sources: ["ubuntu-toolchain-r-test"] } }
+    - env: UNIT_TESTS=true COMPILER=g++-8     BOOST_VERSION=default CMAKE_OPTIONS="-DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_STANDARD_REQUIRED=ON"
+      addons: { apt: { packages: ["g++-8", "valgrind"], sources: ["ubuntu-toolchain-r-test"] } }
+
+    # With C++20, on GCC
+    - env: UNIT_TESTS=true COMPILER=g++-8     BOOST_VERSION=default CMAKE_OPTIONS="-DCMAKE_CXX_STANDARD=20 -DCMAKE_CXX_STANDARD_REQUIRED=ON"
+      addons: { apt: { packages: ["g++-8", "valgrind"], sources: ["ubuntu-toolchain-r-test"] } }
 
     # Without concept checks
     - env: UNIT_TESTS=true COMPILER=default BOOST_VERSION=default CMAKE_OPTIONS="-DBOOST_HANA_ENABLE_CONCEPT_CHECKS=OFF"
@@ -87,12 +75,8 @@ matrix:
       env: UNIT_TESTS=true BOOST_VERSION=default CMAKE_OPTIONS="-DBOOST_HANA_ENABLE_EXCEPTIONS=OFF"
       osx_image: xcode11
 
-    # With Boost 1.64
-    - env: UNIT_TESTS=true COMPILER=default BOOST_VERSION=1.64.0
-      addons: *defaults
-
-    # With Boost 1.65.1
-    - env: UNIT_TESTS=true COMPILER=default BOOST_VERSION=1.65.1
+    # With Boost 1.76.0
+    - env: UNIT_TESTS=true COMPILER=default BOOST_VERSION=1.76.0
       addons: *defaults
 
     # Without Boost (make sure we don't depend on it)
@@ -113,6 +97,7 @@ matrix:
     ##########################################################################
     - os: osx
       env: DOCUMENTATION=true BOOST_VERSION=default
+      osx_image: xcode11
 
     ##########################################################################
     # Benchmarks
@@ -142,8 +127,8 @@ install:
   ############################################################################
   # Setup default versions and override CXX set by Travis if needed
   ############################################################################
-  - if [[ "${COMPILER}" == "default" ]]; then COMPILER=clang++-7; fi
-  - if [[ "${BOOST_VERSION}" == "default" ]]; then BOOST_VERSION=1.66.0; fi
+  - if [[ "${COMPILER}" == "default" ]]; then COMPILER=clang++-8; fi
+  - if [[ "${BOOST_VERSION}" == "default" ]]; then BOOST_VERSION=1.76.0; fi
 
   - if [[ "${COMPILER}" != "" ]]; then export CXX=${COMPILER}; fi
   - ${CXX} --version
@@ -159,7 +144,7 @@ install:
         travis_retry git clone --depth 1 --recursive ${BOOST_URL} ${BOOST_DIR} || exit 1
         (cd ${BOOST_DIR} && ./bootstrap.sh && ./b2 headers) || exit 1
       else
-        BOOST_URL="https://dl.bintray.com/boostorg/release/${BOOST_VERSION}/source/boost_${BOOST_VERSION//\./_}.tar.gz"
+        BOOST_URL="https://boostorg.jfrog.io/artifactory/main/release/${BOOST_VERSION}/source/boost_${BOOST_VERSION//\./_}.tar.gz"
         mkdir -p ${BOOST_DIR}
         { travis_retry wget -O - ${BOOST_URL} | tar --strip-components=1 -xz -C ${BOOST_DIR}; } || exit 1
       fi
@@ -174,7 +159,7 @@ install:
   ############################################################################
   - |
     if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then
-      CMAKE_URL="https://cmake.org/files/v3.10/cmake-3.10.0-Linux-x86_64.tar.gz"
+      CMAKE_URL="https://github.com/Kitware/CMake/releases/download/v3.20.2/cmake-3.20.2.tar.gz"
       mkdir cmake && travis_retry wget --no-check-certificate --quiet -O - ${CMAKE_URL} | tar --strip-components=1 -xz -C cmake
       export PATH=${DEPS_DIR}/cmake/bin:${PATH}
     else
@@ -192,35 +177,6 @@ install:
       b2 --version || true # b2 --version returns 1
     fi
 
-  ############################################################################
-  # Install libc++ and libc++abi if needed
-  ############################################################################
-  - |
-    if [[ "${CXX%%+*}" == "clang" ]]; then
-        if [[ "${CXX}" == "clang++-3.9" ]]; then LLVM_VERSION="3.9.1";
-      elif [[ "${CXX}" == "clang++-4.0" ]]; then LLVM_VERSION="4.0.1";
-      elif [[ "${CXX}" == "clang++-5.0" ]]; then LLVM_VERSION="5.0.2";
-      elif [[ "${CXX}" == "clang++-6.0" ]]; then LLVM_VERSION="6.0.1";
-      elif [[ "${CXX}" == "clang++-7" ]];   then LLVM_VERSION="7.0.1";
-      fi
-
-      LLVM_URL="http://llvm.org/releases/${LLVM_VERSION}/llvm-${LLVM_VERSION}.src.tar.xz"
-      LIBCXX_URL="http://llvm.org/releases/${LLVM_VERSION}/libcxx-${LLVM_VERSION}.src.tar.xz"
-      LIBCXXABI_URL="http://llvm.org/releases/${LLVM_VERSION}/libcxxabi-${LLVM_VERSION}.src.tar.xz"
-
-      mkdir -p llvm llvm/build llvm/projects/libcxx llvm/projects/libcxxabi
-      travis_retry wget -O - ${LLVM_URL} | tar --strip-components=1 -xJ -C llvm || exit 1
-      travis_retry wget -O - ${LIBCXX_URL} | tar --strip-components=1 -xJ -C llvm/projects/libcxx || exit 1
-      travis_retry wget -O - ${LIBCXXABI_URL} | tar --strip-components=1 -xJ -C llvm/projects/libcxxabi || exit 1
-      (cd llvm/build && cmake .. -DCMAKE_INSTALL_PREFIX=${DEPS_DIR}/llvm/install) || exit 1
-      (cd llvm/build/projects/libcxx && make install -j2) || exit 1
-      (cd llvm/build/projects/libcxxabi && make install -j2) || exit 1
-
-      export CXXFLAGS="-isystem ${DEPS_DIR}/llvm/install/include/c++/v1"
-      export LDFLAGS="-L ${DEPS_DIR}/llvm/install/lib -l c++ -l c++abi"
-      export LD_LIBRARY_PATH="${LD_LIBRARY_PATH}:${DEPS_DIR}/llvm/install/lib"
-    fi
-
   ############################################################################
   # Install a recent Doxygen
   ############################################################################
@@ -358,11 +314,7 @@ script:
 
       # Build tests
       echo "using clang : : ${CXX} ;" > project-config.jam
-      if [[ "${LDFLAGS}" == "" ]]; then
-        (cd test && b2 toolset=clang cxxflags="-std=c++1y ${CXXFLAGS}" include="${BOOST_DIR}") || exit 1
-      else
-        (cd test && b2 toolset=clang cxxflags="-std=c++1y ${CXXFLAGS}" include="${BOOST_DIR}" linkflags="${LDFLAGS}") || exit 1
-      fi
+      (cd test && b2 toolset=clang cxxflags="-std=c++1y" include="${BOOST_DIR}") || exit 1
     fi
 
 

RELEASE_NOTES.md

@@ -1,4 +1,2 @@
-Release notes for Hana 1.7.0
+Release notes for Hana 1.6.2
 ============================
-- Disable the definition of traits::is_pod in C++20 and later, due to its
-  deprecation.

doc/tutorial.hpp

@@ -109,9 +109,9 @@ below, which are tested on an ongoing basis:
 
 Compiler/Toolchain | Status
 ------------------ | ------
-Clang >= 3.9.1     | Fully working; tested on each push to GitHub
-Xcode >= 9.1       | Fully working; tested on each push to GitHub
-GCC >= 6.0.0       | Fully working; tested on each push to GitHub
+Clang >= 7         | Fully working; tested on each push to GitHub
+Xcode >= 11        | Fully working; tested on each push to GitHub
+GCC >= 8           | Fully working; tested on each push to GitHub
 VS2017 >= Update 7 | Fully working; tested on each push to GitHub
 
 More specifically, Hana requires a compiler/standard library supporting the
@@ -2420,13 +2420,15 @@ for `Constant` and `IntegralConstant`.
 Hana's algorithms are `constexpr` function objects instead of being template
 functions. This allows passing them to higher-order algorithms, which is very
 useful. However, since those function objects are defined at namespace scope
-in the header files, this causes each translation unit to see a different
-algorithm object. Hence, the address of an algorithm function object is not
-guaranteed to be unique across translation units, which can cause an ODR
-violation if one relies on such an address. So, in short, do not rely on the
-uniqueness of the address of any global object provided by Hana, which does
-not make sense in the general case anyway because such objects are `constexpr`.
-See [issue #76](https://github.com/boostorg/hana/issues/76) for more information.
+in the header files, we require support for C++17 inline variables in order to
+avoid ODR violations (by means of the same object being defined twice in
+different translation units). When compiling in C++14 mode, where inline
+variables are not available, each translation unit will see a different
+algorithm object, so the address of an algorithm function object is not
+guaranteed to be unique across translation units. This is technically an ODR
+violation, but it shouldn't bite you unless you rely on the addresses being
+the same. So, in short, do not rely on the uniqueness of the address of any
+global object provided by Hana if you are compiling in C++14 mode.
 
 
 

include/boost/hana/config.hpp

@@ -104,6 +104,15 @@ Distributed under the Boost Software License, Version 1.0.
 #   define BOOST_HANA_CONSTEXPR_LAMBDA /* nothing */
 #endif
 
+// `BOOST_HANA_INLINE_VARIABLE` expands to `inline` when C++17 inline variables
+// are supported, and to nothing otherwise. This allows marking global variables
+// defined in a header as `inline` to avoid potential ODR violations.
+#if defined(__cplusplus) && __cplusplus > 201402L
+#   define BOOST_HANA_INLINE_VARIABLE inline
+#else
+#   define BOOST_HANA_INLINE_VARIABLE /* nothing */
+#endif
+
 //////////////////////////////////////////////////////////////////////////////
 // Namespace macros
 //////////////////////////////////////////////////////////////////////////////

include/boost/hana/detail/variadic/at.hpp

@@ -34,7 +34,7 @@ BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic {
     };
 
     template <std::size_t n>
-    constexpr at_type<n> at{};
+    BOOST_HANA_INLINE_VARIABLE constexpr at_type<n> at{};
 }} BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_DETAIL_VARIADIC_AT_HPP

include/boost/hana/detail/variadic/drop_into.hpp

@@ -41,7 +41,7 @@ BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic {
     };
 
     template <std::size_t n>
-    constexpr make_dropper<n> drop_into{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_dropper<n> drop_into{};
 }} BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_DETAIL_VARIADIC_DROP_INTO_HPP

include/boost/hana/detail/variadic/foldl1.hpp

@@ -207,8 +207,8 @@ BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic {
         }
     };
 
-    constexpr foldl1_t foldl1{};
-    constexpr auto foldl = foldl1;
+    BOOST_HANA_INLINE_VARIABLE constexpr foldl1_t foldl1{};
+    BOOST_HANA_INLINE_VARIABLE constexpr auto foldl = foldl1;
 }} BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_DETAIL_VARIADIC_FOLDL1_HPP

include/boost/hana/detail/variadic/foldr1.hpp

@@ -193,7 +193,7 @@ BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic {
         }
     };
 
-    constexpr foldr1_t foldr1{};
+    BOOST_HANA_INLINE_VARIABLE constexpr foldr1_t foldr1{};
 
     struct foldr_t {
         template <typename F, typename State, typename ...Xn>
@@ -204,7 +204,7 @@ BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic {
         }
     };
 
-    constexpr foldr_t foldr{};
+    BOOST_HANA_INLINE_VARIABLE constexpr foldr_t foldr{};
 }} BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_DETAIL_VARIADIC_FOLDR1_HPP

include/boost/hana/detail/variadic/reverse_apply.hpp

@@ -15,7 +15,7 @@ Distributed under the Boost Software License, Version 1.0.
 
 
 BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic {
-    BOOST_HANA_CONSTEXPR_LAMBDA auto reverse_apply =
+    BOOST_HANA_INLINE_VARIABLE BOOST_HANA_CONSTEXPR_LAMBDA auto reverse_apply =
         [](auto&& f, auto&& ...x) -> decltype(auto) {
             return detail::variadic::reverse_apply_unrolled(
                 static_cast<decltype(f)>(f),

include/boost/hana/detail/variadic/reverse_apply/unrolled.hpp

@@ -80,8 +80,7 @@ BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic {
         }
     };
 
-    constexpr reverse_apply_unrolled_impl reverse_apply_unrolled{};
-
+    BOOST_HANA_INLINE_VARIABLE constexpr reverse_apply_unrolled_impl reverse_apply_unrolled{};
 }} BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_DETAIL_VARIADIC_REVERSE_APPLY_UNROLLED_HPP

include/boost/hana/detail/variadic/split_at.hpp

@@ -147,7 +147,7 @@ BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic {
     };
 
     template <std::size_t n>
-    constexpr _makesplit_at_t<n> split_at{};
+    BOOST_HANA_INLINE_VARIABLE constexpr _makesplit_at_t<n> split_at{};
 }} BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_DETAIL_VARIADIC_SPLIT_AT_HPP

include/boost/hana/detail/variadic/take.hpp

@@ -45,7 +45,7 @@ BOOST_HANA_NAMESPACE_BEGIN namespace detail { namespace variadic {
     };
 
     template <std::size_t n>
-    constexpr take_t<n> take{};
+    BOOST_HANA_INLINE_VARIABLE constexpr take_t<n> take{};
 }} BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_DETAIL_VARIADIC_TAKE_HPP

include/boost/hana/experimental/printable.hpp

@@ -87,7 +87,7 @@ BOOST_HANA_NAMESPACE_BEGIN namespace experimental {
         }
     };
 
-    constexpr print_t print{};
+    BOOST_HANA_INLINE_VARIABLE constexpr print_t print{};
 #endif
 
     // Define the `Printable` concept

include/boost/hana/experimental/view.hpp

@@ -148,7 +148,7 @@ namespace experimental {
             return {s1, s2};
         }
     };
-    constexpr make_joined_view_t joined{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_joined_view_t joined{};
 
     namespace detail {
         template <typename Sequence1, typename Sequence2>

include/boost/hana/functional/always.hpp

@@ -57,7 +57,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         { return std::move(val_); }
     };
 
-    constexpr detail::create<_always> always{};
+    BOOST_HANA_INLINE_VARIABLE constexpr detail::create<_always> always{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/apply.hpp

@@ -78,7 +78,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr apply_t apply{};
+    BOOST_HANA_INLINE_VARIABLE constexpr apply_t apply{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/arg.hpp

@@ -134,7 +134,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     };
 
     template <std::size_t n>
-    constexpr arg_t<n> arg{};
+    BOOST_HANA_INLINE_VARIABLE constexpr arg_t<n> arg{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/capture.hpp

@@ -105,7 +105,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr make_capture_t capture{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_capture_t capture{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/compose.hpp

@@ -101,7 +101,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr _make_compose compose{};
+    BOOST_HANA_INLINE_VARIABLE constexpr _make_compose compose{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/curry.hpp

@@ -109,7 +109,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     };
 
     template <std::size_t n>
-    constexpr make_curry_t<n> curry{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_curry_t<n> curry{};
 
     namespace curry_detail { namespace {
         template <std::size_t n>

include/boost/hana/functional/demux.hpp

@@ -262,7 +262,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr make_pre_demux_t demux{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_pre_demux_t demux{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/fix.hpp

@@ -59,7 +59,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     template <typename F>
     struct fix_t;
 
-    constexpr detail::create<fix_t> fix{};
+    BOOST_HANA_INLINE_VARIABLE constexpr detail::create<fix_t> fix{};
 
     template <typename F>
     struct fix_t {

include/boost/hana/functional/flip.hpp

@@ -66,7 +66,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr detail::create<flip_t> flip{};
+    BOOST_HANA_INLINE_VARIABLE constexpr detail::create<flip_t> flip{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/id.hpp

@@ -31,7 +31,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr id_t id{};
+    BOOST_HANA_INLINE_VARIABLE constexpr id_t id{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/infix.hpp

@@ -178,7 +178,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     } // end namespace infix_detail
 
-    constexpr infix_detail::make_infix<false, false> infix{};
+    BOOST_HANA_INLINE_VARIABLE constexpr infix_detail::make_infix<false, false> infix{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/iterate.hpp

@@ -194,7 +194,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     };
 
     template <std::size_t n>
-    constexpr make_iterate_t<n> iterate{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_iterate_t<n> iterate{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/lockstep.hpp

@@ -107,7 +107,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr make_pre_lockstep_t lockstep{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_pre_lockstep_t lockstep{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/on.hpp

@@ -76,7 +76,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr auto on = infix(detail::create<on_t>{});
+    BOOST_HANA_INLINE_VARIABLE constexpr auto on = infix(detail::create<on_t>{});
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/overload.hpp

@@ -81,7 +81,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr make_overload_t overload{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_overload_t overload{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/overload_linearly.hpp

@@ -103,7 +103,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr make_overload_linearly_t overload_linearly{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_overload_linearly_t overload_linearly{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/partial.hpp

@@ -98,7 +98,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr make_partial_t partial{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_partial_t partial{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/placeholder.hpp

@@ -256,7 +256,7 @@ BOOST_HANA_NAMESPACE_BEGIN
 #undef BOOST_HANA_BINARY_PLACEHOLDER_OP
     } // end namespace placeholder_detail
 
-    constexpr placeholder_detail::placeholder _{};
+    BOOST_HANA_INLINE_VARIABLE constexpr placeholder_detail::placeholder _{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/functional/reverse_partial.hpp

@@ -96,7 +96,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         }
     };
 
-    constexpr make_reverse_partial_t reverse_partial{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_reverse_partial_t reverse_partial{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/accessors.hpp

@@ -43,7 +43,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     struct accessors_t;
 
     template <typename S>
-    constexpr accessors_t<S> accessors{};
+    BOOST_HANA_INLINE_VARIABLE constexpr accessors_t<S> accessors{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/adjust.hpp

@@ -57,7 +57,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Value&& value, F&& f) const;
     };
 
-    constexpr adjust_t adjust{};
+    BOOST_HANA_INLINE_VARIABLE constexpr adjust_t adjust{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/adjust_if.hpp

@@ -62,7 +62,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Pred const& pred, F const& f) const;
     };
 
-    constexpr adjust_if_t adjust_if{};
+    BOOST_HANA_INLINE_VARIABLE constexpr adjust_if_t adjust_if{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/all.hpp

@@ -39,7 +39,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs) const;
     };
 
-    constexpr all_t all{};
+    BOOST_HANA_INLINE_VARIABLE constexpr all_t all{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/all_of.hpp

@@ -47,7 +47,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Pred&& pred) const;
     };
 
-    constexpr all_of_t all_of{};
+    BOOST_HANA_INLINE_VARIABLE constexpr all_of_t all_of{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/and.hpp

@@ -46,7 +46,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(X&& x, Y&& ...y) const;
     };
 
-    constexpr and_t and_{};
+    BOOST_HANA_INLINE_VARIABLE constexpr and_t and_{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/any.hpp

@@ -39,7 +39,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs) const;
     };
 
-    constexpr any_t any{};
+    BOOST_HANA_INLINE_VARIABLE constexpr any_t any{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/any_of.hpp

@@ -46,7 +46,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Pred&& pred) const;
     };
 
-    constexpr any_of_t any_of{};
+    BOOST_HANA_INLINE_VARIABLE constexpr any_of_t any_of{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/ap.hpp

@@ -74,7 +74,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(F&& f, Xs&& ...xs) const;
     };
 
-    constexpr ap_t ap{};
+    BOOST_HANA_INLINE_VARIABLE constexpr ap_t ap{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/append.hpp

@@ -61,7 +61,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, X&& x) const;
     };
 
-    constexpr append_t append{};
+    BOOST_HANA_INLINE_VARIABLE constexpr append_t append{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/at.hpp

@@ -59,7 +59,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Xs&& xs, N const& n) const;
     };
 
-    constexpr at_t at{};
+    BOOST_HANA_INLINE_VARIABLE constexpr at_t at{};
 #endif
 
     //! Equivalent to `at`; provided for convenience.

include/boost/hana/fwd/at_key.hpp

@@ -60,7 +60,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Xs&& xs, Key const& key) const;
     };
 
-    constexpr at_key_t at_key{};
+    BOOST_HANA_INLINE_VARIABLE constexpr at_key_t at_key{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/back.hpp

@@ -41,7 +41,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Xs&& xs) const;
     };
 
-    constexpr back_t back{};
+    BOOST_HANA_INLINE_VARIABLE constexpr back_t back{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/basic_tuple.hpp

@@ -64,7 +64,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     //! Example
     //! -------
     //! @include example/basic_tuple/make.cpp
-    constexpr auto make_basic_tuple = make<basic_tuple_tag>;
+    BOOST_HANA_INLINE_VARIABLE constexpr auto make_basic_tuple = make<basic_tuple_tag>;
 BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_FWD_BASIC_TUPLE_HPP

include/boost/hana/fwd/cartesian_product.hpp

@@ -55,7 +55,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs) const;
     };
 
-    constexpr cartesian_product_t cartesian_product{};
+    BOOST_HANA_INLINE_VARIABLE constexpr cartesian_product_t cartesian_product{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/chain.hpp

@@ -60,7 +60,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Xs&& xs, F&& f) const;
     };
 
-    constexpr chain_t chain{};
+    BOOST_HANA_INLINE_VARIABLE constexpr chain_t chain{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/comparing.hpp

@@ -58,7 +58,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(F&& f) const;
     };
 
-    constexpr comparing_t comparing{};
+    BOOST_HANA_INLINE_VARIABLE constexpr comparing_t comparing{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/concat.hpp

@@ -56,7 +56,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Ys&& ys) const;
     };
 
-    constexpr concat_t concat{};
+    BOOST_HANA_INLINE_VARIABLE constexpr concat_t concat{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/contains.hpp

@@ -51,7 +51,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Key&& key) const;
     };
 
-    constexpr auto contains = hana::infix(contains_t{});
+    BOOST_HANA_INLINE_VARIABLE constexpr auto contains = hana::infix(contains_t{});
 #endif
 
     //! Return whether the key occurs in the structure.
@@ -67,7 +67,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     //! Example
     //! -------
     //! @include example/in.cpp
-    constexpr auto in = hana::infix(hana::flip(hana::contains));
+    BOOST_HANA_INLINE_VARIABLE constexpr auto in = hana::infix(hana::flip(hana::contains));
 BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_FWD_CONTAINS_HPP

include/boost/hana/fwd/core/is_a.hpp

@@ -43,7 +43,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     struct is_a_t;
 
     template <typename Tag, typename ...T>
-    constexpr is_a_t<Tag, T...> is_a{};
+    BOOST_HANA_INLINE_VARIABLE constexpr is_a_t<Tag, T...> is_a{};
 #endif
 
     //! @ingroup group-core
@@ -54,7 +54,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     constexpr auto is_an = is_a<Tag, T...>;
 #else
     template <typename Tag, typename ...T>
-    constexpr is_a_t<Tag, T...> is_an{};
+    BOOST_HANA_INLINE_VARIABLE constexpr is_a_t<Tag, T...> is_an{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/core/make.hpp

@@ -63,7 +63,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     };
 
     template <typename Tag>
-    constexpr make_t<Tag> make{};
+    BOOST_HANA_INLINE_VARIABLE constexpr make_t<Tag> make{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/core/to.hpp

@@ -108,7 +108,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     };
 
     template <typename To>
-    constexpr to_t<To> to{};
+    BOOST_HANA_INLINE_VARIABLE constexpr to_t<To> to{};
 #endif
 
     //! @ingroup group-core

include/boost/hana/fwd/count.hpp

@@ -50,7 +50,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Value&& value) const;
     };
 
-    constexpr count_t count{};
+    BOOST_HANA_INLINE_VARIABLE constexpr count_t count{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/count_if.hpp

@@ -49,7 +49,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Pred&& pred) const;
     };
 
-    constexpr count_if_t count_if{};
+    BOOST_HANA_INLINE_VARIABLE constexpr count_if_t count_if{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/cycle.hpp

@@ -69,7 +69,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, N const& n) const;
     };
 
-    constexpr cycle_t cycle{};
+    BOOST_HANA_INLINE_VARIABLE constexpr cycle_t cycle{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/difference.hpp

@@ -26,7 +26,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&&, Ys&&) const;
     };
 
-    constexpr difference_t difference{};
+    BOOST_HANA_INLINE_VARIABLE constexpr difference_t difference{};
 BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_FWD_DIFFERENCE_HPP

include/boost/hana/fwd/div.hpp

@@ -52,7 +52,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(X&& x, Y&& y) const;
     };
 
-    constexpr div_t div{};
+    BOOST_HANA_INLINE_VARIABLE constexpr div_t div{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/drop_back.hpp

@@ -56,7 +56,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs) const;
     };
 
-    constexpr drop_back_t drop_back{};
+    BOOST_HANA_INLINE_VARIABLE constexpr drop_back_t drop_back{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/drop_front.hpp

@@ -59,7 +59,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs) const;
     };
 
-    constexpr drop_front_t drop_front{};
+    BOOST_HANA_INLINE_VARIABLE constexpr drop_front_t drop_front{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/drop_front_exactly.hpp

@@ -60,7 +60,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs) const;
     };
 
-    constexpr drop_front_exactly_t drop_front_exactly{};
+    BOOST_HANA_INLINE_VARIABLE constexpr drop_front_exactly_t drop_front_exactly{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/drop_while.hpp

@@ -53,7 +53,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Pred&& pred) const;
     };
 
-    constexpr drop_while_t drop_while{};
+    BOOST_HANA_INLINE_VARIABLE constexpr drop_while_t drop_while{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/duplicate.hpp

@@ -50,7 +50,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(W_&& w) const;
     };
 
-    constexpr duplicate_t duplicate{};
+    BOOST_HANA_INLINE_VARIABLE constexpr duplicate_t duplicate{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/empty.hpp

@@ -46,7 +46,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     };
 
     template <typename M>
-    constexpr empty_t<M> empty{};
+    BOOST_HANA_INLINE_VARIABLE constexpr empty_t<M> empty{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/equal.hpp

@@ -73,7 +73,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(X&& x, Y&& y) const;
     };
 
-    constexpr equal_t equal{};
+    BOOST_HANA_INLINE_VARIABLE constexpr equal_t equal{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/erase_key.hpp

@@ -26,7 +26,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Set&& set, Args&& ...args) const;
     };
 
-    constexpr erase_key_t erase_key{};
+    BOOST_HANA_INLINE_VARIABLE constexpr erase_key_t erase_key{};
 BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_FWD_ERASE_KEY_HPP

include/boost/hana/fwd/eval.hpp

@@ -51,7 +51,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Expr&& expr) const;
     };
 
-    constexpr eval_t eval{};
+    BOOST_HANA_INLINE_VARIABLE constexpr eval_t eval{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/eval_if.hpp

@@ -148,7 +148,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Cond&& cond, Then&& then, Else&& else_) const;
     };
 
-    constexpr eval_if_t eval_if{};
+    BOOST_HANA_INLINE_VARIABLE constexpr eval_if_t eval_if{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/extend.hpp

@@ -55,7 +55,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(W_&& w, F&& f) const;
     };
 
-    constexpr extend_t extend{};
+    BOOST_HANA_INLINE_VARIABLE constexpr extend_t extend{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/extract.hpp

@@ -51,7 +51,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(W_&& w) const;
     };
 
-    constexpr extract_t extract{};
+    BOOST_HANA_INLINE_VARIABLE constexpr extract_t extract{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/fill.hpp

@@ -50,7 +50,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Value&& value) const;
     };
 
-    constexpr fill_t fill{};
+    BOOST_HANA_INLINE_VARIABLE constexpr fill_t fill{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/filter.hpp

@@ -74,7 +74,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Pred&& pred) const;
     };
 
-    constexpr filter_t filter{};
+    BOOST_HANA_INLINE_VARIABLE constexpr filter_t filter{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/find.hpp

@@ -53,7 +53,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Key const& key) const;
     };
 
-    constexpr find_t find{};
+    BOOST_HANA_INLINE_VARIABLE constexpr find_t find{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/find_if.hpp

@@ -50,7 +50,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Pred&& pred) const;
     };
 
-    constexpr find_if_t find_if{};
+    BOOST_HANA_INLINE_VARIABLE constexpr find_if_t find_if{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/first.hpp

@@ -42,7 +42,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Pair&& pair) const;
     };
 
-    constexpr first_t first{};
+    BOOST_HANA_INLINE_VARIABLE constexpr first_t first{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/flatten.hpp

@@ -56,7 +56,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs) const;
     };
 
-    constexpr flatten_t flatten{};
+    BOOST_HANA_INLINE_VARIABLE constexpr flatten_t flatten{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/fold.hpp

@@ -32,7 +32,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     //! Example
     //! -------
     //! @include example/fold.cpp
-    constexpr auto fold = fold_left;
+    BOOST_HANA_INLINE_VARIABLE constexpr auto fold = fold_left;
 BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_FWD_FOLD_HPP

include/boost/hana/fwd/fold_left.hpp

@@ -81,7 +81,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Xs&& xs, F&& f) const;
     };
 
-    constexpr fold_left_t fold_left{};
+    BOOST_HANA_INLINE_VARIABLE constexpr fold_left_t fold_left{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/fold_right.hpp

@@ -85,7 +85,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Xs&& xs, F&& f) const;
     };
 
-    constexpr fold_right_t fold_right{};
+    BOOST_HANA_INLINE_VARIABLE constexpr fold_right_t fold_right{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/for_each.hpp

@@ -48,7 +48,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr void operator()(Xs&& xs, F&& f) const;
     };
 
-    constexpr for_each_t for_each{};
+    BOOST_HANA_INLINE_VARIABLE constexpr for_each_t for_each{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/front.hpp

@@ -41,7 +41,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Xs&& xs) const;
     };
 
-    constexpr front_t front{};
+    BOOST_HANA_INLINE_VARIABLE constexpr front_t front{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/fuse.hpp

@@ -48,7 +48,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(F&& f) const;
     };
 
-    constexpr fuse_t fuse{};
+    BOOST_HANA_INLINE_VARIABLE constexpr fuse_t fuse{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/greater.hpp

@@ -46,7 +46,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(X&& x, Y&& y) const;
     };
 
-    constexpr greater_t greater{};
+    BOOST_HANA_INLINE_VARIABLE constexpr greater_t greater{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/greater_equal.hpp

@@ -47,7 +47,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(X&& x, Y&& y) const;
     };
 
-    constexpr greater_equal_t greater_equal{};
+    BOOST_HANA_INLINE_VARIABLE constexpr greater_equal_t greater_equal{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/group.hpp

@@ -96,7 +96,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Predicate&& pred) const;
     };
 
-    constexpr group_t group{};
+    BOOST_HANA_INLINE_VARIABLE constexpr group_t group{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/hash.hpp

@@ -61,7 +61,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(X const& x) const;
     };
 
-    constexpr hash_t hash{};
+    BOOST_HANA_INLINE_VARIABLE constexpr hash_t hash{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/if.hpp

@@ -50,7 +50,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Cond&& cond, Then&& then, Else&& else_) const;
     };
 
-    constexpr if_t if_{};
+    BOOST_HANA_INLINE_VARIABLE constexpr if_t if_{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/index_if.hpp

@@ -52,7 +52,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Pred&& pred) const;
     };
 
-    constexpr index_if_t index_if{};
+    BOOST_HANA_INLINE_VARIABLE constexpr index_if_t index_if{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/insert.hpp

@@ -26,7 +26,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr decltype(auto) operator()(Set&& set, Args&& ...args) const;
     };
 
-    constexpr insert_t insert{};
+    BOOST_HANA_INLINE_VARIABLE constexpr insert_t insert{};
 
 
     //! Insert a value at a given index in a sequence.

include/boost/hana/fwd/insert_range.hpp

@@ -50,7 +50,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, N&& n, Elements&& elements) const;
     };
 
-    constexpr insert_range_t insert_range{};
+    BOOST_HANA_INLINE_VARIABLE constexpr insert_range_t insert_range{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/integral_constant.hpp

@@ -36,7 +36,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     //! -------
     //! @snippet example/integral_constant.cpp integral_c
     template <typename T, T v>
-    constexpr integral_constant<T, v> integral_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr integral_constant<T, v> integral_c{};
 
 
     //! @relates hana::integral_constant
@@ -45,19 +45,19 @@ BOOST_HANA_NAMESPACE_BEGIN
 
     //! @relates hana::integral_constant
     template <bool b>
-    constexpr bool_<b> bool_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr bool_<b> bool_c{};
 
     //! @relates hana::integral_constant
     using true_ = bool_<true>;
 
     //! @relates hana::integral_constant
-    constexpr auto true_c = bool_c<true>;
+    BOOST_HANA_INLINE_VARIABLE constexpr auto true_c = bool_c<true>;
 
     //! @relates hana::integral_constant
     using false_ = bool_<false>;
 
     //! @relates hana::integral_constant
-    constexpr auto false_c = bool_c<false>;
+    BOOST_HANA_INLINE_VARIABLE constexpr auto false_c = bool_c<false>;
 
 
     //! @relates hana::integral_constant
@@ -66,7 +66,7 @@ BOOST_HANA_NAMESPACE_BEGIN
 
     //! @relates hana::integral_constant
     template <char c>
-    constexpr char_<c> char_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr char_<c> char_c{};
 
 
     //! @relates hana::integral_constant
@@ -75,7 +75,7 @@ BOOST_HANA_NAMESPACE_BEGIN
 
     //! @relates hana::integral_constant
     template <short i>
-    constexpr short_<i> short_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr short_<i> short_c{};
 
 
     //! @relates hana::integral_constant
@@ -84,7 +84,7 @@ BOOST_HANA_NAMESPACE_BEGIN
 
     //! @relates hana::integral_constant
     template <unsigned short i>
-    constexpr ushort_<i> ushort_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr ushort_<i> ushort_c{};
 
 
     //! @relates hana::integral_constant
@@ -93,7 +93,7 @@ BOOST_HANA_NAMESPACE_BEGIN
 
     //! @relates hana::integral_constant
     template <int i>
-    constexpr int_<i> int_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr int_<i> int_c{};
 
 
     //! @relates hana::integral_constant
@@ -102,7 +102,7 @@ BOOST_HANA_NAMESPACE_BEGIN
 
     //! @relates hana::integral_constant
     template <unsigned int i>
-    constexpr uint<i> uint_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr uint<i> uint_c{};
 
 
     //! @relates hana::integral_constant
@@ -111,7 +111,7 @@ BOOST_HANA_NAMESPACE_BEGIN
 
     //! @relates hana::integral_constant
     template <long i>
-    constexpr long_<i> long_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr long_<i> long_c{};
 
 
     //! @relates hana::integral_constant
@@ -120,7 +120,7 @@ BOOST_HANA_NAMESPACE_BEGIN
 
     //! @relates hana::integral_constant
     template <unsigned long i>
-    constexpr ulong<i> ulong_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr ulong<i> ulong_c{};
 
 
     //! @relates hana::integral_constant
@@ -129,7 +129,7 @@ BOOST_HANA_NAMESPACE_BEGIN
 
     //! @relates hana::integral_constant
     template <long long i>
-    constexpr llong<i> llong_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr llong<i> llong_c{};
 
 
     //! @relates hana::integral_constant
@@ -138,7 +138,7 @@ BOOST_HANA_NAMESPACE_BEGIN
 
     //! @relates hana::integral_constant
     template <unsigned long long i>
-    constexpr ullong<i> ullong_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr ullong<i> ullong_c{};
 
 
     //! @relates hana::integral_constant
@@ -147,7 +147,7 @@ BOOST_HANA_NAMESPACE_BEGIN
 
     //! @relates hana::integral_constant
     template <std::size_t i>
-    constexpr size_t<i> size_c{};
+    BOOST_HANA_INLINE_VARIABLE constexpr size_t<i> size_c{};
 
 
     namespace literals {

include/boost/hana/fwd/intersection.hpp

@@ -26,7 +26,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&&, Ys&&) const;
     };
 
-    constexpr intersection_t intersection{};
+    BOOST_HANA_INLINE_VARIABLE constexpr intersection_t intersection{};
 BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_FWD_INTERSECTION_HPP

include/boost/hana/fwd/intersperse.hpp

@@ -50,7 +50,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Z&& z) const;
     };
 
-    constexpr intersperse_t intersperse{};
+    BOOST_HANA_INLINE_VARIABLE constexpr intersperse_t intersperse{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/is_disjoint.hpp

@@ -43,7 +43,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Ys&& ys) const;
     };
 
-    constexpr is_disjoint_t is_disjoint{};
+    BOOST_HANA_INLINE_VARIABLE constexpr is_disjoint_t is_disjoint{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/is_empty.hpp

@@ -42,7 +42,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs const& xs) const;
     };
 
-    constexpr is_empty_t is_empty{};
+    BOOST_HANA_INLINE_VARIABLE constexpr is_empty_t is_empty{};
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/is_subset.hpp

@@ -72,7 +72,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Xs&& xs, Ys&& ys) const;
     };
 
-    constexpr auto is_subset = hana::infix(is_subset_t{});
+    BOOST_HANA_INLINE_VARIABLE constexpr auto is_subset = hana::infix(is_subset_t{});
 #endif
 BOOST_HANA_NAMESPACE_END
 

include/boost/hana/fwd/keys.hpp

@@ -26,7 +26,7 @@ BOOST_HANA_NAMESPACE_BEGIN
         constexpr auto operator()(Map&& map) const;
     };
 
-    constexpr keys_t keys{};
+    BOOST_HANA_INLINE_VARIABLE constexpr keys_t keys{};
 
     //! Returns a `Sequence` containing the name of the members of
     //! the data structure.

include/boost/hana/fwd/lazy.hpp

@@ -118,7 +118,7 @@ BOOST_HANA_NAMESPACE_BEGIN
     //! Example
     //! -------
     //! @include example/lazy/make.cpp
-    constexpr auto make_lazy = make<lazy_tag>;
+    BOOST_HANA_INLINE_VARIABLE constexpr auto make_lazy = make<lazy_tag>;
 BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_FWD_LAZY_HPP