read fmt version from fmt/core.h

Signed-off-by: Dominik Wójt <[email protected]>

Author: domin144

src/cmake/externalpackages.cmake

@@ -350,7 +350,12 @@ macro (find_or_download_fmt)
         endif ()
         set (FMT_INCLUDE_DIR "${FMT_INSTALL_DIR}/include")
         set (OIIO_USING_FMT_LOCAL TRUE)
-        set (fmt_VERSION ${BUILD_FMT_VERSION})
+        file (STRINGS "${FMT_INCLUDE_DIR}/fmt/core.h" TMP REGEX "^#define FMT_VERSION .*$")
+        string (REGEX MATCHALL "[0-9]+" FMT_VERSION_NUMERIC ${TMP})
+        math(EXPR FMT_VERSION_PATCH "${FMT_VERSION_NUMERIC} % 100")
+        math(EXPR FMT_VERSION_MINOR "(${FMT_VERSION_NUMERIC} / 100) % 100")
+        math(EXPR FMT_VERSION_MAJOR "${FMT_VERSION_NUMERIC} / 10000")
+        set (fmt_VERSION "${FMT_VERSION_MAJOR}.${FMT_VERSION_MINOR}.${FMT_VERSION_PATCH}")
     else ()
         get_target_property(FMT_INCLUDE_DIR fmt::fmt-header-only INTERFACE_INCLUDE_DIRECTORIES)
         set (OIIO_USING_FMT_LOCAL FALSE)