Merge topic 'ExactVersionModeForVersionFile'

e390f87 WriteBasicConfigVersionFile: add test for ExactVersion mode
5d18223 write_basic_package_version_file: add ExactVersion mode
1c69cd8 write_basic_package_version_file(): improve documentation

2 files changed, 51 insertions, 1 deletions

diff --git a/Modules/BasicConfigVersion-ExactVersion.cmake.in b/Modules/BasicConfigVersion-ExactVersion.cmake.in
new file mode 100644
index 0000000..c610baa
--- /dev/null
+++ b/Modules/BasicConfigVersion-ExactVersion.cmake.in
@@ -0,0 +1,42 @@
+# 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 equal to the requested version.
+# The tweak version component is ignored.
+# The variable CVF_VERSION must be set before calling configure_file().
+
+
+set(PACKAGE_VERSION "@CVF_VERSION@")
+
+if("@CVF_VERSION@" MATCHES "^([0-9]+\\.[0-9]+\\.[0-9]+)\\..*") # strip the tweak version
+  set(CVF_VERSION_NO_TWEAK "${CMAKE_MATCH_1}")
+else()
+  set(CVF_VERSION_NO_TWEAK "@CVF_VERSION@")
+endif()
+
+if("${PACKAGE_FIND_VERSION}" MATCHES "^([0-9]+\\.[0-9]+\\.[0-9]+)\\..*") # strip the tweak version
+  set(REQUESTED_VERSION_NO_TWEAK "${CMAKE_MATCH_1}")
+else()
+  set(REQUESTED_VERSION_NO_TWEAK "${PACKAGE_FIND_VERSION}")
+endif()
+
+if("${REQUESTED_VERSION_NO_TWEAK}" STREQUAL "${CVF_VERSION_NO_TWEAK}")
+  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()
+
+
+# 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()
diff --git a/Modules/CMakePackageConfigHelpers.cmake b/Modules/CMakePackageConfigHelpers.cmake
index b174e98..98cd560 100644
--- a/Modules/CMakePackageConfigHelpers.cmake
+++ b/Modules/CMakePackageConfigHelpers.cmake
@@ -61,7 +61,7 @@
 # For an example see below the documentation for WRITE_BASIC_PACKAGE_VERSION_FILE().
 #
 #
-#  WRITE_BASIC_PACKAGE_VERSION_FILE( filename VERSION major.minor.patch COMPATIBILITY (AnyNewerVersion|SameMajorVersion) )
+#  WRITE_BASIC_PACKAGE_VERSION_FILE( filename VERSION major.minor.patch COMPATIBILITY (AnyNewerVersion|SameMajorVersion|ExactVersion) )
 #
 # Writes a file for use as <package>ConfigVersion.cmake file to <filename>.
 # See the documentation of FIND_PACKAGE() for details on this.
@@ -69,9 +69,17 @@
 #    major.minor.patch is the version number of the project to be installed
 # The COMPATIBILITY mode AnyNewerVersion means that the installed package version
 # will be considered compatible if it is newer or exactly the same as the requested version.
+# This mode should be used for packages which are fully backward compatible,
+# also across major versions.
 # If SameMajorVersion is used instead, then the behaviour differs from AnyNewerVersion
 # in that the major version number must be the same as requested, e.g. version 2.0 will
 # not be considered compatible if 1.0 is requested.
+# This mode should be used for packages which guarantee backward compatibility within the
+# same major version.
+# If ExactVersion is used, then the package is only considered compatible if the requested
+# version matches exactly its own version number (not considering the tweak version).
+# For example, version 1.2.3 of a package is only considered compatible to requested version 1.2.3.
+# This mode is for packages without compatibility guarantees.
 # If your project has more elaborated version matching rules, you will need to write your
 # own custom ConfigVersion.cmake file instead of using this macro.
 #