build(cmake): add versioning for unstable builds

New SemVer compatible scheme:
Following a stable release the hard-coded version will be bumped to
the next patch.
Builds from untagged revisions will have "-dev" version suffix added.
If Git metadata is present it will be added to the version string as well.

cmake/GetVersionFromGit.cmake

@@ -0,0 +1,93 @@
+# Based on https://github.com/fakenmc/cmake-git-semver by Nuno Fachada.
+# This module is public domain, use it as it fits you best.
+#
+# This cmake module sets the project version and partial version
+# variables by analysing the git tag and commit history. It expects git
+# tags defined with semantic versioning 2.0.0 (http://semver.org/).
+#
+# The module expects the PROJECT_NAME variable to be set, and recognizes
+# the GIT_FOUND, GIT_EXECUTABLE and VERSION_UPDATE_FROM_GIT variables.
+# If Git is found and VERSION_UPDATE_FROM_GIT is set to boolean TRUE,
+# the project version will be updated using information fetched from the
+# most recent git tag and commit. Otherwise, the module will try to read
+# a VERSION file containing the full and partial versions. The module
+# will update this file each time the project version is updated.
+#
+# Once done, this module will define the following variables:
+#
+# ${PROJECT_NAME}_GIT_VERSION_STRING - Version string without metadata
+# such as "v2.0.0" or "v1.2.41-beta.1". This should correspond to the
+# most recent git tag.
+# ${PROJECT_NAME}_GIT_VERSION_STRING_FULL - Version string with metadata
+# such as "v2.0.0+3.a23fbc" or "v1.3.1-alpha.2+4.9c4fd1"
+# ${PROJECT_NAME}_GIT_VERSION_MAJOR - Major version integer (e.g. 2 in v2.3.1-RC.2+21.ef12c8)
+# ${PROJECT_NAME}_GIT_VERSION_MINOR - Minor version integer (e.g. 3 in v2.3.1-RC.2+21.ef12c8)
+# ${PROJECT_NAME}_GIT_VERSION_PATCH - Patch version integer (e.g. 1 in v2.3.1-RC.2+21.ef12c8)
+# ${PROJECT_NAME}_GIT_VERSION_TWEAK - Tweak version string (e.g. "RC.2" in v2.3.1-RC.2+21.ef12c8)
+# ${PROJECT_NAME}_GIT_VERSION_AHEAD - How many commits ahead of last tag (e.g. 21 in v2.3.1-RC.2+21.ef12c8)
+# ${PROJECT_NAME}_GIT_VERSION_SHA - The git sha1 of the most recent commit (e.g. the "ef12c8" in v2.3.1-RC.2+21.ef12c8)
+# Only if VERSION_UPDATE_FROM_GIT is TRUE:
+# ${PROJECT_NAME}_VERSION - Same as ${PROJECT_NAME}_GIT_VERSION_STRING,
+# without the preceding 'v', e.g. "2.0.0" or "1.2.41-beta.1"
+
+# Check if git is found...
+find_package(Git)
+if(NOT GIT_FOUND)
+    return()
+endif()
+
+# Get last tag from git
+execute_process(COMMAND ${GIT_EXECUTABLE} describe --abbrev=0 --tags
+    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+    OUTPUT_VARIABLE ${PROJECT_NAME}_GIT_VERSION_STRING
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+# How many commits since the last tag
+execute_process(COMMAND ${GIT_EXECUTABLE} rev-list master ${${PROJECT_NAME}_GIT_VERSION_STRING}^..HEAD --count
+    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+    OUTPUT_VARIABLE ${PROJECT_NAME}_GIT_VERSION_AHEAD
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+# Get current commit SHA from git
+execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse --short HEAD
+    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+    OUTPUT_VARIABLE ${PROJECT_NAME}_GIT_VERSION_SHA
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+# Get partial versions into a list
+string(REGEX MATCHALL "-.*$|[0-9]+" ${PROJECT_NAME}_PARTIAL_VERSION_LIST
+    ${${PROJECT_NAME}_GIT_VERSION_STRING})
+
+# Set the version numbers
+list(GET ${PROJECT_NAME}_PARTIAL_VERSION_LIST
+    0 ${PROJECT_NAME}_GIT_VERSION_MAJOR)
+list(GET ${PROJECT_NAME}_PARTIAL_VERSION_LIST
+    1 ${PROJECT_NAME}_GIT_VERSION_MINOR)
+list(GET ${PROJECT_NAME}_PARTIAL_VERSION_LIST
+    2 ${PROJECT_NAME}_GIT_VERSION_PATCH)
+
+# Calculate next patch version.
+math(EXPR ${PROJECT_NAME}_GIT_VERSION_PATCH_NEXT ${${PROJECT_NAME}_GIT_VERSION_PATCH}+1)
+
+# The tweak part is optional, so check if the list contains it
+list(LENGTH ${PROJECT_NAME}_PARTIAL_VERSION_LIST
+    ${PROJECT_NAME}_PARTIAL_VERSION_LIST_LEN)
+if (${PROJECT_NAME}_PARTIAL_VERSION_LIST_LEN GREATER 3)
+    list(GET ${PROJECT_NAME}_PARTIAL_VERSION_LIST 3 ${PROJECT_NAME}_GIT_VERSION_TWEAK)
+    string(SUBSTRING ${${PROJECT_NAME}_GIT_VERSION_TWEAK} 1 -1 ${PROJECT_NAME}_GIT_VERSION_TWEAK)
+endif()
+
+# Unset the list
+unset(${PROJECT_NAME}_PARTIAL_VERSION_LIST)
+
+# Set full project version string
+set(${PROJECT_NAME}_GIT_VERSION_STRING_FULL
+    ${${PROJECT_NAME}_GIT_VERSION_STRING}+${${PROJECT_NAME}_GIT_VERSION_AHEAD}.${${PROJECT_NAME}_GIT_VERSION_SHA})
+
+if(VERSION_UPDATE_FROM_GIT)
+    # Set project version (without the preceding 'v')
+    set(${PROJECT_NAME}_VERSION ${${PROJECT_NAME}_GIT_VERSION_MAJOR}.${${PROJECT_NAME}_GIT_VERSION_MINOR}.${${PROJECT_NAME}_GIT_VERSION_PATCH})
+    if (${PROJECT_NAME}_GIT_VERSION_TWEAK)
+        set(${PROJECT_NAME}_VERSION ${${PROJECT_NAME}_VERSION}-${${PROJECT_NAME}_GIT_VERSION_TWEAK})
+    endif()
+endif()