build: clean up obsolete logic for old compilers (AcademySoftwareFoundation#4849)

* Enforce gcc, clang, and apple clang minimum versions.

* Raise advertised minimum clang version to 10.0. Error for clang < 5,
  which we know is the true minimum because earlier than that won't
  support C++17 which we require. But in truth, we haven't tested
  versions older than 10.0 for a long time, so we should not be
  implying we know older versions will work or that we will support
  them.

* Simplify cases no longer relevant for older gcc and clang.

* Remove unneeded gcc guard in simd.h.  I think it was important only
  for gcc 5! But it was also preventing the slightly faster construct
  from activating for clang. Seems to pass all our CI jobs with this
  simplified.

Signed-off-by: Larry Gritz <lg@larrygritz.com>

Author: lgritz

.github/workflows/ci.yml

@@ -76,7 +76,7 @@ jobs:
             fmt_ver: 9.1.0
             setenvs: export FREETYPE_VERSION=VER-2-12-0
           - desc: oldest gcc9.3/C++17 py3.9 exr3.1 ocio2.3
-            # Oldest versions of the dependencies that we support.
+            # Oldest gcc and versions of the dependencies that we support.
             nametag: linux-oldest
             runner: ubuntu-latest
             container: aswf/ci-osl:2022
@@ -93,6 +93,26 @@ jobs:
                              WEBP_VERSION=v1.1.0
                              PUGIXML_VERSION=v1.8
             depcmds: sudo rm -rf /usr/local/include/OpenEXR
+          - desc: oldest clang10/C++17 py3.9 exr3.1 ocio2.3
+            # Oldest clang and versions of the dependencies that we support.
+            nametag: linux-oldest-clang
+            runner: ubuntu-latest
+            container: aswf/ci-osl:2022-clang10
+            vfxyear: 2021
+            old_node: 1
+            cc_compiler: clang
+            cxx_compiler: clang++
+            cxx_std: 17
+            fmt_ver: 7.0.1
+            opencolorio_ver: v2.3.0
+            openexr_ver: v3.1.0
+            pybind11_ver: v2.7.0
+            python_ver: 3.9
+            setenvs: export  CMAKE_VERSION=3.18.2
+                             PTEX_VERSION=v2.3.2
+                             WEBP_VERSION=v1.1.0
+                             PUGIXML_VERSION=v1.8
+            depcmds: sudo rm -rf /usr/local/include/OpenEXR
           - desc: hobbled gcc9.3/C++17 py3.9 exr-3.1 no-sse
             # Use the oldest supported versions of required dependencies, and
             # disable most optional dependencies and features (no SSE or

INSTALL.md

@@ -17,9 +17,8 @@ NEW or CHANGED MINIMUM dependencies since the last major release are **bold**.
  * C++17 or higher (also builds with C++20 and C++23)
      * The default build mode is C++17. This can be controlled by via the
        CMake configuration flag: `-DCMAKE_CXX_STANDARD=20`, etc.
- * Compilers: gcc 9.3 - 14.2, clang 5 - 20 (though we don't actively test
-   older than 11), MSVS 2017 - 2022 (v19.14 and up), Intel icc 19+, Intel
-   OneAPI C++ compiler 2022+.
+ * Compilers: gcc 9.3 - 14.2, **clang 10** - 20, MSVS 2017 - 2022 (v19.14
+   and up), Intel icc 19+, Intel OneAPI C++ compiler 2022+.
  * CMake >= 3.18.2 (tested through 4.1)
  * Imath >= 3.1 (tested through 3.2 and main)
  * OpenEXR >= 3.1 (tested through 3.4 and main)

src/cmake/compiler.cmake

@@ -53,6 +53,9 @@ if (CMAKE_COMPILER_IS_GNUCC)
                      OUTPUT_VARIABLE GCC_VERSION
                      OUTPUT_STRIP_TRAILING_WHITESPACE)
     message (VERBOSE "Using gcc ${GCC_VERSION} as the compiler")
+    if (GCC_VERSION VERSION_LESS 9.0)
+        message (ERROR "gcc minimum version is 9.0")
+    endif ()
 else ()
     set (GCC_VERSION 0)
 endif ()
@@ -71,6 +74,11 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "Clang" OR CMAKE_CXX_COMPILER MATCHES "[Cc]lan
         string (REGEX REPLACE ".* version ([0-9]+\\.[0-9]+).*" "\\1" APPLECLANG_VERSION_STRING ${clang_full_version_string})
         set (ANY_CLANG_VERSION_STRING ${APPLECLANG_VERSION_STRING})
         message (VERBOSE "The compiler is Clang: ${CMAKE_CXX_COMPILER_ID} version ${APPLECLANG_VERSION_STRING}")
+        if (APPLECLANG_VERSION_STRING VERSION_LESS 5.0)
+            message (ERROR "Apple clang minimum version is 5.0")
+        elseif (APPLECLANG_VERSION_STRING VERSION_LESS 10.0)
+            message (WARNING "Apple clang minimum version is 10.0. Older versions might work, but we don't test or support them.")
+        endif ()
     elseif (CMAKE_CXX_COMPILER_ID MATCHES "IntelLLVM")
         set (CMAKE_COMPILER_IS_INTELCLANG 1)
         string (REGEX MATCH "[0-9]+(\\.[0-9]+)+" INTELCLANG_VERSION_STRING ${clang_full_version_string})
@@ -81,6 +89,11 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "Clang" OR CMAKE_CXX_COMPILER MATCHES "[Cc]lan
         string (REGEX REPLACE ".* version ([0-9]+\\.[0-9]+).*" "\\1" CLANG_VERSION_STRING ${clang_full_version_string})
         set (ANY_CLANG_VERSION_STRING ${CLANG_VERSION_STRING})
         message (VERBOSE "The compiler is Clang: ${CMAKE_CXX_COMPILER_ID} version ${CLANG_VERSION_STRING}")
+        if (CLANG_VERSION_STRING VERSION_LESS 5.0)
+            message (ERROR "clang minimum version is 5.0")
+        elseif (CLANG_VERSION_STRING VERSION_LESS 10.0)
+            message (WARNING "clang minimum version is 10.0. Older versions might work, but we don't test or support them.")
+        endif ()
     endif ()
 elseif (CMAKE_CXX_COMPILER_ID MATCHES "Intel")
     set (CMAKE_COMPILER_IS_INTEL 1)
@@ -157,11 +170,10 @@ if (CMAKE_COMPILER_IS_CLANG OR CMAKE_COMPILER_IS_APPLECLANG)
     add_compile_options ("-Qunused-arguments")
     # Don't warn if we ask it not to warn about warnings it doesn't know
     add_compile_options ("-Wunknown-warning-option")
-    if (CLANG_VERSION_STRING VERSION_GREATER_EQUAL 3.6 OR
-        APPLECLANG_VERSION_STRING VERSION_GREATER 6.1)
+    if (CLANG_VERSION_STRING OR APPLECLANG_VERSION_STRING VERSION_GREATER 6.1)
         add_compile_options ("-Wno-unused-local-typedefs")
     endif ()
-    if (CLANG_VERSION_STRING VERSION_GREATER_EQUAL 3.9)
+    if (CLANG_VERSION_STRING)
         # Don't warn about using unknown preprocessor symbols in `#if`
         add_compile_options ("-Wno-expansion-to-defined")
     endif ()
@@ -174,10 +186,8 @@ if (CMAKE_COMPILER_IS_GNUCC AND NOT (CMAKE_COMPILER_IS_CLANG OR CMAKE_COMPILER_I
     # gcc specific options
     add_compile_options ("-Wno-unused-local-typedefs")
     add_compile_options ("-Wno-unused-result")
-    if (NOT ${GCC_VERSION} VERSION_LESS 7.0)
-        add_compile_options ("-Wno-aligned-new")
-        add_compile_options ("-Wno-noexcept-type")
-    endif ()
+    add_compile_options ("-Wno-aligned-new")
+    add_compile_options ("-Wno-noexcept-type")
 endif ()
 
 if (INTELCLANG_VERSION_STRING VERSION_GREATER_EQUAL 2022.1.0)
@@ -284,10 +294,8 @@ endif ()
 # legit problem later.
 #
 set (GLIBCXX_USE_CXX11_ABI "" CACHE STRING "For gcc, use the new C++11 library ABI (0|1)")
-if (CMAKE_COMPILER_IS_GNUCC AND ${GCC_VERSION} VERSION_GREATER_EQUAL 5.0)
-    if (NOT ${GLIBCXX_USE_CXX11_ABI} STREQUAL "")
-        add_compile_definitions (_GLIBCXX_USE_CXX11_ABI=${GLIBCXX_USE_CXX11_ABI})
-    endif ()
+if (CMAKE_COMPILER_IS_GNUCC AND NOT ${GLIBCXX_USE_CXX11_ABI} STREQUAL "")
+    add_compile_definitions (_GLIBCXX_USE_CXX11_ABI=${GLIBCXX_USE_CXX11_ABI})
 endif ()
 
 

src/include/OpenImageIO/simd.h

@@ -3317,7 +3317,7 @@ OIIO_FORCEINLINE const vbool4 vbool4::False () {
 OIIO_FORCEINLINE const vbool4 vbool4::True () {
     // Fastest way to fill with all 1 bits is to cmp any value to itself.
 #if OIIO_SIMD_SSE
-# if OIIO_SIMD_AVX && (OIIO_GNUC_VERSION > 50000)
+# if OIIO_SIMD_AVX
     __m128i anyval = _mm_undefined_si128();
 # else
     __m128i anyval = _mm_setzero_si128();
@@ -3676,7 +3676,7 @@ OIIO_FORCEINLINE const vbool8 vbool8::False () {
 
 OIIO_FORCEINLINE const vbool8 vbool8::True () {
 #if OIIO_SIMD_AVX
-# if OIIO_SIMD_AVX >= 2 && (OIIO_GNUC_VERSION > 50000)
+# if OIIO_SIMD_AVX >= 2
     // Fastest way to fill with all 1 bits is to cmp any value to itself.
     __m256i anyval = _mm256_undefined_si256();
     return _mm256_castsi256_ps (_mm256_cmpeq_epi8 (anyval, anyval));
@@ -4413,7 +4413,7 @@ OIIO_FORCEINLINE const vint4 vint4::NegOne () {
 #if OIIO_SIMD_SSE
     // Fastest way to fill an __m128 with all 1 bits is to cmpeq_epi8
     // any value to itself.
-# if OIIO_SIMD_AVX && (OIIO_GNUC_VERSION > 50000)
+# if OIIO_SIMD_AVX
     __m128i anyval = _mm_undefined_si128();
 # else
     __m128i anyval = _mm_setzero_si128();

src/libOpenImageIO/CMakeLists.txt

@@ -15,7 +15,7 @@ if (NOT USE_EXTERNAL_PUGIXML)
           ../include/OpenImageIO/detail/pugixml/pugixml.hpp
           ../include/OpenImageIO/detail/pugixml/pugixml.cpp
     )
-    if (CMAKE_COMPILER_IS_GNUCC AND NOT ${GCC_VERSION} VERSION_LESS 6.0)
+    if (CMAKE_COMPILER_IS_GNUCC)
         set_source_files_properties (formatspec.cpp xmp.cpp
                                      PROPERTIES COMPILE_FLAGS -Wno-error=placement-new)
     endif ()
@@ -30,17 +30,11 @@ if (NOT MSVC)
                              PROPERTIES COMPILE_FLAGS "-Wno-deprecated-declarations")
 endif()
 
-if (CMAKE_COMPILER_IS_GNUCC AND ${GCC_VERSION} VERSION_GREATER_EQUAL 9.0)
+if (CMAKE_COMPILER_IS_GNUCC)
     set_source_files_properties (../libutil/SHA1.cpp
                                  PROPERTIES COMPILE_FLAGS -Wno-stringop-truncation)
 endif ()
 
-if (CMAKE_COMPILER_IS_GNUCC AND ${GCC_VERSION} VERSION_GREATER_EQUAL 6.0
-    AND ${GCC_VERSION} VERSION_LESS 7.0)
-    set_source_files_properties (../openvdb.imageio/openvdbinput.cpp
-                                 PROPERTIES COMPILE_FLAGS -Wno-error=strict-overflow)
-endif ()
-
 set (libOpenImageIO_srcs
                           imagebufalgo.cpp
                           imagebufalgo_pixelmath.cpp

src/libutil/CMakeLists.txt

@@ -9,7 +9,7 @@ set (libOpenImageIO_Util_srcs argparse.cpp benchmark.cpp
                   strutil.cpp sysutil.cpp thread.cpp timer.cpp
                   typedesc.cpp ustring.cpp xxhash.cpp)
 
-if (CMAKE_COMPILER_IS_GNUCC AND NOT ${GCC_VERSION} VERSION_LESS 9.0)
+if (CMAKE_COMPILER_IS_GNUCC)
     set_property (SOURCE SHA1.cpp
                   APPEND PROPERTY COMPILE_OPTIONS -Wno-stringop-truncation)
 endif ()

src/raw.imageio/rawinput.cpp

@@ -17,14 +17,13 @@
 #include <OpenImageIO/sysutil.h>
 #include <OpenImageIO/tiffutils.h>
 
-#if OIIO_GNUC_VERSION || OIIO_CLANG_VERSION >= 50000
+#if OIIO_GNUC_VERSION || OIIO_CLANG_VERSION
 // fix warnings in libraw headers: use of auto_ptr
 #    pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 #endif
 
-#if OIIO_CPLUSPLUS_VERSION >= 17                            \
-    && ((OIIO_CLANG_VERSION && OIIO_CLANG_VERSION < 110000) \
-        || OIIO_APPLE_CLANG_VERSION)
+#if (OIIO_CLANG_VERSION && OIIO_CLANG_VERSION < 110000) \
+    || OIIO_APPLE_CLANG_VERSION
 // libraw uses auto_ptr, which is not in C++17 at all for clang, though
 // it does seem to be for gcc. So for clang, alias it to unique_ptr.
 namespace std {