Add SameMajorVersionWithPreleases compat option to ecm_setup_version.

SameMajorVersionWithPreleases is intended implement the versioning
scheme followed by many KDE projects: minor releases after some high
number (eg: 90) are considered to be pre-releases of the next major
version, and are not compatible with the current major version. This
allows alpha and beta releases to be ordered correctly by
version-number-aware software like package managers (an alpha of version
2 should have a higher number than any release of version 1, but less
than version 2.0).

So a request for version 2.1.0 of a piece of software should not be
satisfied by 2.93.4, because that is actually a pre-release of version
3. On the other hand, a request for version 2.91.0 should be satisfied
by version 3.1.0.

Note that prereleases are not considered unless explicitly requested, so
2.93.4 will not satisfy requests for version 3 (or version 2) of a piece
of software.

1 files changed, 64 insertions, 0 deletions

diff --git a/modules/BasicConfigVersion-SameMajorVersionWithPrereleases.cmake.in b/modules/BasicConfigVersion-SameMajorVersionWithPrereleases.cmake.in
new file mode 100644
index 00000000..6d4e16f4
--- /dev/null
+++ b/modules/BasicConfigVersion-SameMajorVersionWithPrereleases.cmake.in
@@ -0,0 +1,64 @@
+# This is a basic version file for the Config-mode of find_package().
+# It is used by write_basic_package_version_file() as input file for configure_file()
+# to create a version-file which can be installed along a config.cmake file.
+#
+# The created file sets PACKAGE_VERSION_EXACT if the current version string and
+# the requested version string are exactly the same and it sets
+# PACKAGE_VERSION_COMPATIBLE if the current version is >= requested version,
+# but only if the requested major version is the same as the current one EXCEPT
+# that all minor releases after (and including) @CVF_FIRST_PRERELEASE_VERSION@
+# are considered to be part of the next major release.
+#
+# The variables CVF_VERSION and CVF_FIRST_PRERELEASE_VERSION must be set before
+# calling configure_file().
+
+
+set(PACKAGE_VERSION "@CVF_VERSION@")
+
+if("${PACKAGE_VERSION}" VERSION_LESS "${PACKAGE_FIND_VERSION}" )
+  set(PACKAGE_VERSION_COMPATIBLE FALSE)
+else()
+
+  if("@CVF_VERSION@" MATCHES "^([0-9]+)\\.([0-9]+)(\\.|$)")
+    set(CVF_VERSION_MAJOR "${CMAKE_MATCH_1}")
+    set(CVF_VERSION_MINOR "${CMAKE_MATCH_2}")
+  else()
+    set(CVF_VERSION_MAJOR "@CVF_VERSION@")
+    set(CVF_VERSION_MINOR "0")
+  endif()
+
+  set(_real_version_major "${CVF_VERSION_MAJOR}")
+  if(NOT "${CVF_VERSION_MINOR}" LESS "@CVF_FIRST_PRERELEASE_VERSION@")
+    math(EXPR _real_version_major "${CVF_VERSION_MAJOR}+1")
+  endif()
+
+  set(_real_find_version_major "${PACKAGE_FIND_VERSION_MAJOR}")
+  if("${PACKAGE_FIND_VERSION_COUNT}" GREATER 1)
+    if(NOT "${PACKAGE_FIND_VERSION_MINOR}" LESS "@CVF_FIRST_PRERELEASE_VERSION@")
+      math(EXPR _real_find_version_major "${PACKAGE_FIND_VERSION_MAJOR}+1")
+    endif()
+  endif()
+
+  if("${_real_find_version_major}" STREQUAL "${_real_version_major}")
+    set(PACKAGE_VERSION_COMPATIBLE TRUE)
+  else()
+    set(PACKAGE_VERSION_COMPATIBLE FALSE)
+  endif()
+
+  if( "${PACKAGE_FIND_VERSION}" STREQUAL "${PACKAGE_VERSION}")
+      set(PACKAGE_VERSION_EXACT TRUE)
+  endif()
+endif()
+
+
+# if the installed or the using project don't have CMAKE_SIZEOF_VOID_P set, ignore it:
+if("${CMAKE_SIZEOF_VOID_P}"  STREQUAL ""  OR "@CMAKE_SIZEOF_VOID_P@" STREQUAL "")
+   return()
+endif()
+
+# check that the installed version has the same 32/64bit-ness as the one which is currently searching:
+if(NOT "${CMAKE_SIZEOF_VOID_P}" STREQUAL "@CMAKE_SIZEOF_VOID_P@")
+  math(EXPR installedBits "@CMAKE_SIZEOF_VOID_P@ * 8")
+  set(PACKAGE_VERSION "${PACKAGE_VERSION} (${installedBits}bit)")
+  set(PACKAGE_VERSION_UNSUITABLE TRUE)
+endif()