cmake: Add FindCMath to handle libm linking portably

2 files changed, 72 insertions, 0 deletions

diff --git a/cmake/FindCMath.cmake b/cmake/FindCMath.cmake
new file mode 100644
index 00000000..b094c920
--- /dev/null
+++ b/cmake/FindCMath.cmake
@@ -0,0 +1,72 @@
+# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+# file Copyright.txt or https://cmake.org/licensing for details.
+
+#[=======================================================================[.rst:
+FindCMath
+--------
+
+Find the native CMath includes and library.
+
+IMPORTED Targets
+^^^^^^^^^^^^^^^^
+
+This module defines :prop_tgt:`IMPORTED` target ``CMath::CMath``, if
+CMath has been found.
+
+Result Variables
+^^^^^^^^^^^^^^^^
+
+This module defines the following variables:
+
+::
+
+  CMath_INCLUDE_DIRS   - where to find CMath.h, etc.
+  CMath_LIBRARIES      - List of libraries when using CMath.
+  CMath_FOUND          - True if CMath found.
+
+#]=======================================================================]
+
+
+include(CheckSymbolExists)
+include(CheckLibraryExists)
+
+check_symbol_exists(pow "math.h" CMath_HAVE_LIBC_POW)
+if(NOT CMath_HAVE_LIBC_POW)
+    find_library(CMath_LIBRARY NAMES m)
+
+    set(CMAKE_REQUIRED_INCLUDES_SAVE ${CMAKE_REQUIRED_INCLUDES})
+    set(CMAKE_REQUIRED_INCLUDES ${CMAKE_REQUIRED_INCLUDES} ${ZSTD_INCLUDE_DIRS})
+    set(CMAKE_REQUIRED_LIBRARIES_SAVE ${CMAKE_REQUIRED_LIBRARIES})
+    set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES} ${CMath_LIBRARY})
+    check_symbol_exists(pow "math.h" CMath_HAVE_LIBM_POW)
+    set(CMAKE_REQUIRED_INCLUDES ${CMAKE_REQUIRED_INCLUDES_SAVE})
+    set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES_SAVE})
+endif()
+
+set(CMath_pow FALSE)
+if(CMath_HAVE_LIBC_POW OR CMath_HAVE_LIBM_POW)
+    set(CMath_pow TRUE)
+endif()
+
+set(CMath_INCLUDE_DIRS)
+
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(CMath REQUIRED_VARS CMath_pow)
+
+if(CMath_FOUND)
+    if(NOT CMath_LIBRARIES)
+        if (CMath_LIBRARY)
+            set(CMath_LIBRARIES ${CMath_LIBRARY})
+        endif()
+    endif()
+
+    if(NOT TARGET CMath::CMath)
+        if(CMath_LIBRARIES)
+            add_library(CMath::CMath UNKNOWN IMPORTED)
+            set_target_properties(CMath::CMath PROPERTIES
+                  IMPORTED_LOCATION "${CMath_LIBRARY}")
+        else()
+            add_library(CMath::CMath INTERFACE IMPORTED)
+        endif()
+    endif()
+endif()
diff --git a/cmake/FindM.cmake b/cmake/FindM.cmake
deleted file mode 100644
index e69de29b..00000000
--- a/cmake/FindM.cmake
+++ /dev/null