build!: Move to C++17 minimum

.github/workflows/ci.yml

@@ -34,29 +34,6 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - desc: gcc6/C++14 py2.7 boost1.66 exr2.4 ocio1.1
-            nametag: linux-vfx2019
-            runner: ubuntu-latest
-            container: aswf/ci-osl:2019
-            vfxyear: 2019
-            cxx_std: 14
-            openexr_ver: v2.4.3
-            python_ver: 2.7
-            simd: sse4.2
-            fmt_ver: 7.0.1
-            pybind11_ver: v2.4.2
-            setenvs: export PUGIXML_VERSION=v1.9 CMAKE_VERSION=3.15.5
-          - desc: gcc6/C++14 py3.7 boost1.70 exr2.4 ocio1.1
-            nametag: linux-vfx2020
-            runner: ubuntu-latest
-            container: aswf/ci-osl:2020
-            vfxyear: 2020
-            cxx_std: 14
-            python_ver: 3.7
-            simd: avx
-            fmt_ver: 7.0.1
-            pybind11_ver: v2.5.0
-            setenvs: export PUGIXML_VERSION=v1.9 WEBP_VERSION=v1.1.0
           - desc: gcc9/C++17 py3.7 boost1.73 exr2.5 ocio2.0
             nametag: linux-vfx2021
             runner: ubuntu-latest
@@ -68,14 +45,14 @@ jobs:
             fmt_ver: 7.1.0
             pybind11_ver: v2.7.0
             setenvs: export PUGIXML_VERSION=v1.9 WEBP_VERSION=v1.1.0
-          - desc: clang10/C++14 avx2 exr2.5 ocio2.0
+          - desc: clang10/C++17 avx2 exr2.5 ocio2.0
             nametag: linux-clang10-cpp14
             runner: ubuntu-latest
             container: aswf/ci-osl:2021-clang10
             vfxyear: 2021
             cc_compiler: clang
             cxx_compiler: clang++
-            cxx_std: 14
+            cxx_std: 17
             pybind11_ver: v2.6.2
             python_ver: 3.7
             simd: "avx2,f16c"
@@ -163,18 +140,18 @@ jobs:
             simd: "avx2,f16c"
             fmt_ver: 10.1.1
             pybind11_ver: v2.10.0
-          - desc: oldest/hobbled gcc6.3/C++14 py2.7 boost-1.66 exr-2.4 no-sse no-ocio
+          - desc: oldest/hobbled gcc9.3/C++17 py3.7 boost-1.66 exr-2.4 no-sse no-ocio
             # Oldest versions of the dependencies that we can muster, and various
             # things disabled (no SSE, OCIO, or OpenCV, don't embed plugins).
             nametag: linux-oldest
             runner: ubuntu-latest
-            container: aswf/ci-osl:2019
-            vfxyear: 2019
-            cxx_std: 14
+            container: aswf/ci-osl:2021
+            vfxyear: 2021
+            cxx_std: 17
             fmt_ver: 7.0.1
             openexr_ver: v2.4.0
             pybind11_ver: v2.4.2
-            python_ver: 2.7
+            python_ver: 3.7
             simd: 0
             setenvs: export  EMBEDPLUGINS=0
                              CMAKE_VERSION=3.15.5
@@ -352,13 +329,13 @@ jobs:
                             OPENCOLORIO_VERSION=v2.1.2
                             USE_OPENVDB=0
                             # The installed OpenVDB has a TLS conflict with Python 3.8
-          - desc: debug gcc7/C++14, sse4.2, exr2.4
-            nametag: linux-gcc7-cpp14-debug
+          - desc: debug gcc9/C++17, sse4.2, exr2.4
+            nametag: linux-gcc9-cpp17-debug
             runner: ubuntu-20.04
             container:
               image: ubuntu-18.04
-            cxx_compiler: g++-7
-            cxx_std: 14
+            cxx_compiler: g++-9
+            cxx_std: 17
             python_ver: 2.7
             simd: sse4.2
             openexr_ver: v2.4.3
@@ -367,25 +344,13 @@ jobs:
                             PUGIXML_VERSION=v1.9
                             CTEST_TEST_TIMEOUT=1200
 
-          - desc: gcc8 C++17 avx exr2.5
-            nametag: linux-gcc8
-            runner: ubuntu-20.04
-            container:
-              image: ubuntu-18.04
-            cc_compiler: gcc-8
-            cxx_compiler: g++-8
-            cxx_std: 17
-            openexr_ver: v2.5.8
-            pybind11_ver: v2.5.0
-            simd: avx
-            setenvs: export EXTRA_DEP_PACKAGES=libjpeg-turbo8-dev
-          - desc: static libs gcc7 C++14 exr2.4
+          - desc: static libs gcc9 C++17 exr2.4
             nametag: linux-static
             runner: ubuntu-20.04
             container:
               image: ubuntu-18.04
-            cxx_compiler: g++-7
-            cxx_std: 14
+            cxx_compiler: g++-9
+            cxx_std: 17
             openexr_ver: v2.4.3
             pybind11_ver: v2.6.2
             setenvs: export BUILD_SHARED_LIBS=OFF

INSTALL.md

@@ -14,12 +14,11 @@ NEW or CHANGED MINIMUM dependencies since the last major release are **bold**.
 
 ### Required dependencies -- OIIO will not build at all without these
 
- * C++14 or higher (also builds with C++17, and C++20)
+ * **C++17 or higher** (also builds with C++20)
      * The default build mode is C++17. This can be controlled by via the
-       CMake configuration flag: `-DCMAKE_CXX_STANDARD=14`, etc.
-     * ADVISORY: We expect that OIIO 2.6 in 2024 will require C++17 or higher.
- * Compilers: gcc 6.1 - 13.1, clang 3.4 - 17, MSVS 2017 - 2019,
-   Intel icc 17+, Intel OneAPI C++ compiler 2022+.
+       CMake configuration flag: `-DCMAKE_CXX_STANDARD=20`, etc.
+ * Compilers: **gcc 9.3** - 13.1, **clang 5** - 17, MSVS 2017 - 2019 (**v19.14
+   and up**), **Intel icc 19+**, Intel OneAPI C++ compiler 2022+.
  * **CMake >= 3.15** (tested through 3.28)
  * **OpenEXR/Imath >= 2.4** (recommended: 3.1 or higher; tested through 3.2
    and main) (ADVISORY: We expect that OIIO 2.6 in 2024 will require OpenEXR >= 3.1)

Makefile

@@ -356,7 +356,7 @@ help:
 	@echo "      VERBOSE=1                Show all compilation commands"
 	@echo "      STOP_ON_WARNING=0        Do not stop building if compiler warns"
 	@echo "      MYCC=xx MYCXX=yy         Use custom compilers"
-	@echo "      CMAKE_CXX_STANDARD=14    C++ standard to build with (default is 17)"
+	@echo "      CMAKE_CXX_STANDARD=20    C++ standard to build with (default is 17)"
 	@echo "      USE_LIBCPLUSPLUS=1       For clang, use libc++"
 	@echo "      GLIBCXX_USE_CXX11_ABI=1  For gcc, use the new string ABI"
 	@echo "      EXTRA_CPP_ARGS=          Additional args to the C++ command"

src/build-scripts/ci-startup.bash

@@ -37,7 +37,7 @@ export OpenImageIO_CI=true
 export USE_NINJA=${USE_NINJA:=1}
 export CMAKE_GENERATOR=${CMAKE_GENERATOR:=Ninja}
 export CMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE:=Release}
-export CMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD:=14}
+export CMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD:=17}
 
 export LOCAL_DEPS_DIR=${LOCAL_DEPS_DIR:=$HOME/ext}
 export PATH=${LOCAL_DEPS_DIR}/dist/bin:$PATH

src/build-scripts/gh-installdeps.bash

@@ -118,20 +118,16 @@ else
 
     export CMAKE_PREFIX_PATH=/usr/lib/x86_64-linux-gnu:$CMAKE_PREFIX_PATH
 
-    if [[ "$CXX" == "g++-6" ]] ; then
-        time sudo apt-get install -y g++-6
-    elif [[ "$CXX" == "g++-7" ]] ; then
-        time sudo apt-get install -y g++-7
-    elif [[ "$CXX" == "g++-8" ]] ; then
-        time sudo apt-get install -y g++-8
-    elif [[ "$CXX" == "g++-9" ]] ; then
+    if [[ "$CXX" == "g++-9" ]] ; then
         time sudo apt-get install -y g++-9
     elif [[ "$CXX" == "g++-10" ]] ; then
         time sudo apt-get install -y g++-10
     elif [[ "$CXX" == "g++-11" ]] ; then
         time sudo apt-get install -y g++-11
     elif [[ "$CXX" == "g++-12" ]] ; then
         time sudo apt-get install -y g++-12
+    elif [[ "$CXX" == "g++-13" ]] ; then
+        time sudo apt-get install -y g++-13
     fi
 
     if [[ "$CXX" == "icpc" || "$CC" == "icc" || "$USE_ICC" != "" || "$USE_ICX" != "" ]] ; then

src/cmake/compiler.cmake

@@ -48,10 +48,10 @@ endmacro ()
 ###########################################################################
 # C++ language standard
 #
-set (CMAKE_CXX_MINIMUM 14)
+set (CMAKE_CXX_MINIMUM 17)
 set (CMAKE_CXX_STANDARD 17 CACHE STRING
      "C++ standard to build with (14, 17, 20, etc.) Minimum is ${CMAKE_CXX_MINIMUM}.")
-set (DOWNSTREAM_CXX_STANDARD 14 CACHE STRING
+set (DOWNSTREAM_CXX_STANDARD 17 CACHE STRING
      "C++ minimum standard to impose on downstream clients")
 set (CMAKE_CXX_STANDARD_REQUIRED ON)
 set (CMAKE_CXX_EXTENSIONS OFF)
@@ -389,29 +389,6 @@ if (NOT MSVC AND NOT APPLE AND NOT ANDROID)
 endif ()
 
 
-###########################################################################
-# Check if we need have std::filesystem on this platform.
-#
-cmake_push_check_state ()
-set (CMAKE_REQUIRED_DEFINITIONS ${CSTD_FLAGS})
-check_cxx_source_compiles("#include <filesystem>
-      int main() { std::filesystem::path p; return 0; }"
-      USE_STD_FILESYSTEM)
-if (USE_STD_FILESYSTEM AND GCC_VERSION AND GCC_VERSION VERSION_LESS 9.0)
-    message (STATUS "Excluding USE_STD_FILESYSTEM because gcc is ${GCC_VERSION}")
-    set (USE_STD_FILESYSTEM OFF)
-endif ()
-if (USE_STD_FILESYSTEM)
-    # Note: std::filesystem seems unreliable for gcc until 9
-    message (STATUS "Compiler supports std::filesystem")
-    proj_add_compile_definitions (-DUSE_STD_FILESYSTEM)
-else ()
-    message (STATUS "Using Boost::filesystem")
-    proj_add_compile_definitions (-DUSE_BOOST_FILESYSTEM)
-endif ()
-cmake_pop_check_state ()
-
-
 ###########################################################################
 # Code coverage options
 #

src/cmake/externalpackages.cmake

@@ -53,9 +53,6 @@ if (MSVC)
 endif ()
 
 set (Boost_COMPONENTS thread)
-if (NOT USE_STD_FILESYSTEM)
-    list (APPEND Boost_COMPONENTS filesystem)
-endif ()
 message (STATUS "Boost_COMPONENTS = ${Boost_COMPONENTS}")
 # The FindBoost.cmake interface is broken if it uses boost's installed
 # cmake output (e.g. boost 1.70.0, cmake <= 3.14). Specifically it fails
@@ -232,8 +229,8 @@ if (LibRaw_FOUND AND LibRaw_VERSION VERSION_LESS 0.20 AND CMAKE_CXX_STANDARD VER
     # Currently, we issue the above warning and let them take their chances.
     # If we wish to disable the LibRaw<0.20/C++17 combination that may fail,
     # just uncomment the following two lines.
-    # set (LibRaw_FOUND 0)
-    # set (LIBRAW_FOUND 0)
+    set (LibRaw_FOUND 0)
+    set (LIBRAW_FOUND 0)
 endif ()
 
 checked_find_package (OpenJPEG VERSION_MIN 2.0

src/doc/Doxyfile

@@ -2164,7 +2164,6 @@ PREDEFINED             = DOXYGEN_SHOULD_SKIP_THIS \
                          OIIO_HOSTDEVICE= \
                          OIIO_NAMESPACE_BEGIN="namespace OIIO {" \
                          OIIO_NAMESPACE_END="}" \
-                         OIIO_CONSTEXPR14=constexpr \
                          OIIO_CONSTEXPR17=constexpr \
                          OIIO_CONSTEXPR20=constexpr \
                          OIIO_INLINE_CONSTEXPR="inline constexpr" \

src/include/OpenImageIO/detail/farmhash.h

@@ -83,19 +83,13 @@
 // Make static inline 'const expr, if possible.  Also, try to make CUDA friendly
 // for device code.
 #undef STATIC_INLINE
-#if OIIO_CPLUSPLUS_VERSION >= 14
-#  define HASH_CAN_USE_CONSTEXPR 1
-#endif
-#define STATIC_INLINE OIIO_HOSTDEVICE inline OIIO_CONSTEXPR14
+#define HASH_CAN_USE_CONSTEXPR 1
+#define STATIC_INLINE OIIO_HOSTDEVICE inline constexpr
 
 // FARMHASH PORTABILITY LAYER: Runtime error if misconfigured
 
 #ifndef FARMHASH_DIE_IF_MISCONFIGURED
-#ifdef HASH_CAN_USE_CONSTEXPR
 #define FARMHASH_DIE_IF_MISCONFIGURED
-#else
-#define FARMHASH_DIE_IF_MISCONFIGURED do { *(char*)(len % 17) = 0; } while (0)
-#endif
 #endif
 
 // FARMHASH PORTABILITY LAYER: endianness and byteswapping functions

src/include/OpenImageIO/oiioversion.h.in

@@ -185,7 +185,7 @@ namespace @PROJ_NAME@ = @PROJ_NAMESPACE_V@;
 #define OIIO_USING_IMATH_VERSION_MAJOR @Imath_VERSION_MAJOR@
 #define OIIO_USING_IMATH_VERSION_MINOR @Imath_VERSION_MINOR@
 
-// Which CPP standard (11, 14, etc.) was this copy of OIIO *built* with?
+// Which CPP standard (17, 20, etc.) was this copy of OIIO *built* with?
 #define OIIO_BUILD_CPP @CMAKE_CXX_STANDARD@
 
 // DEPRECATED(2.1): old macros separately giving compatibility.

src/include/OpenImageIO/platform.h

@@ -64,7 +64,7 @@
 // OIIO_INLINE_CONSTEXPR : inline constexpr variables, added in C++17. For
 //                         older C++, static constexpr.
 //
-// Note: oiioversion.h defines OIIO_BUILD_CPP (set to 14, 17, etc.)
+// Note: oiioversion.h defines OIIO_BUILD_CPP (set to 17, 20, etc.)
 // reflecting what OIIO itself was *built* with.  In contrast,
 // OIIO_CPLUSPLUS_VERSION defined below will be set to the right number for
 // the C++ standard being compiled RIGHT NOW. These two things may be the
@@ -77,18 +77,13 @@
 #    define OIIO_CONSTEXPR17 constexpr
 #    define OIIO_CONSTEXPR20 constexpr
 #    define OIIO_INLINE_CONSTEXPR inline constexpr
-#elif (__cplusplus >= 201703L)
+#elif (__cplusplus >= 201703L) || (defined(_MSC_VER) && _MSC_VER >= 1914)
 #    define OIIO_CPLUSPLUS_VERSION 17
 #    define OIIO_CONSTEXPR17 constexpr
 #    define OIIO_CONSTEXPR20 /* not constexpr before C++20 */
 #    define OIIO_INLINE_CONSTEXPR inline constexpr
-#elif (__cplusplus >= 201402L) || (defined(_MSC_VER) && _MSC_VER >= 1914)
-#    define OIIO_CPLUSPLUS_VERSION 14
-#    define OIIO_CONSTEXPR17 /* not constexpr before C++17 */
-#    define OIIO_CONSTEXPR20 /* not constexpr before C++20 */
-#    define OIIO_INLINE_CONSTEXPR static constexpr
 #else
-#    error "This version of OIIO is meant to work only with C++14 and above"
+#    error "This version of OIIO is meant to work only with C++17 and above"
 #endif
 
 // DEPRECATED(2.3): use C++14 constexpr
@@ -113,12 +108,6 @@
 #    define __has_attribute(x) 0
 #endif
 
-// In C++17 (and some compilers before that), __has_include("blah.h") or
-// __has_include(<blah.h>) can test for presence of an include file.
-#ifndef __has_include
-#    define __has_include(x) 0
-#endif
-
 
 
 // Detect which compiler and version we're using
@@ -389,7 +378,7 @@
 #endif
 
 
-// OIIO_FORCELINE is a function attribute that attempts to make the function
+// OIIO_FORCEINLINE is a function attribute that attempts to make the function
 // always inline. On many compilers regular 'inline' is only advisory. Put
 // this attribute before the function return type, just like you would use
 // 'inline'.
@@ -431,15 +420,11 @@
 #    define OIIO_CONST_FUNC
 #endif
 
-// OIIO_MAYBE_UNUSED is a function or variable attribute that assures the
-// compiler that it's fine for the item to appear to be unused.
-#if OIIO_CPLUSPLUS_VERSION >= 17 || __has_cpp_attribute(maybe_unused)
-#    define OIIO_MAYBE_UNUSED [[maybe_unused]]
-#elif defined(__GNUC__) || defined(__clang__) || defined(__INTEL_COMPILER) || __has_attribute(unused)
-#    define OIIO_MAYBE_UNUSED __attribute__((unused))
-#else
-#    define OIIO_MAYBE_UNUSED
-#endif
+// OIIO_MAYBE_UNUSED is an annotator for function or variable attribute that
+// assures the compiler that it's fine for the item to appear to be unused.
+// Consider this deprecated (as of OIIO 3.0), you should favor C++17's
+// [[maybe_unused]] attribute.
+#define OIIO_MAYBE_UNUSED [[maybe_unused]]
 
 // DEPRECATED(1.9) name:
 #define OIIO_UNUSED_OK OIIO_MAYBE_UNUSED
@@ -455,26 +440,18 @@
 
 
 // OIIO_DEPRECATED before a function declaration marks it as deprecated in
-// a way that will generate compile warnings if it is called.
-#if OIIO_CPLUSPLUS_VERSION >= 14 || __has_cpp_attribute(deprecated)
-#    define OIIO_DEPRECATED(msg) [[deprecated(msg)]]
-#elif defined(__GNUC__) || defined(__clang__) || __has_attribute(deprecated)
-#    define OIIO_DEPRECATED(msg) __attribute__((deprecated(msg)))
-#elif defined(_MSC_VER)
-#    define OIIO_DEPRECATED(msg) __declspec(deprecated(msg))
-#else
-#    define OIIO_DEPRECATED(msg)
-#endif
+// a way that will generate compile warnings if it is called. This should
+// itself be considered deprecated (as of OIIO 3.0) and code should use
+// [[deprecated(msg)]] instead.
+#define OIIO_DEPRECATED(msg) [[deprecated(msg)]]
 
 
 // OIIO_FALLTHROUGH at the end of a `case` label's statements documents that
 // the switch statement case is intentionally falling through to the code
 // for the next case.
-#if OIIO_CPLUSPLUS_VERSION >= 17 || __has_cpp_attribute(fallthrough)
-#    define OIIO_FALLTHROUGH [[fallthrough]]
-#else
-#    define OIIO_FALLTHROUGH
-#endif
+// Consider this deprecated (as of OIIO 3.0), you should favor C++17's
+// [[fallthrough]] attribute.
+#define OIIO_FALLTHROUGH [[fallthrough]]
 
 
 // OIIO_NODISCARD following a function declaration documents that the