Add version number to plugin

Like in linuxdeploy, it's always printed, so every log should contain a version number from now on.

Author: TheAssassin

src/CMakeLists.txt

@@ -1,5 +1,31 @@
 find_package(Threads)
 
+# read Git revision ID
+# WARNING: this value will be stored in the CMake cache
+# to update it, you will have to reset the CMake cache
+# (doesn't matter for CI builds like Travis for instance, where there's no permanent CMake cache)
+execute_process(
+    COMMAND git rev-parse --short HEAD
+    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+    OUTPUT_VARIABLE GIT_COMMIT
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+
+# set version and build number
+set(VERSION 1-alpha)
+if(DEFINED ENV{GITHUB_RUN_NUMBER})
+    set(BUILD_NUMBER "GitHub actions build $ENV{GITHUB_RUN_NUMBER}")
+else()
+    set(BUILD_NUMBER "<local dev build>")
+endif()
+
+# get current date
+execute_process(
+    COMMAND env LC_ALL=C date -u "+%Y-%m-%d %H:%M:%S %Z"
+    OUTPUT_VARIABLE DATE
+    OUTPUT_STRIP_TRAILING_WHITESPACE
+)
+
 # TODO: CMake <= 3.7 (at least!) doesn't allow for using OBJECT libraries with target_link_libraries
 add_library(linuxdeploy-plugin-qt_util STATIC util.cpp util.h)
 target_include_directories(linuxdeploy-plugin-qt_util PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
@@ -8,6 +34,12 @@ target_link_libraries(linuxdeploy-plugin-qt_util linuxdeploy_core args Threads::
 add_executable(linuxdeploy-plugin-qt main.cpp qt-modules.h qml.cpp qml.h deployment.h)
 target_link_libraries(linuxdeploy-plugin-qt linuxdeploy_core args nlohmann_json::nlohmann_json linuxdeploy-plugin-qt_util Threads::Threads)
 set_target_properties(linuxdeploy-plugin-qt PROPERTIES RUNTIME_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/bin")
+target_compile_definitions(linuxdeploy-plugin-qt
+    PRIVATE -DLD_GIT_COMMIT="${GIT_COMMIT}"
+    PRIVATE -DLD_VERSION="${VERSION}"
+    PRIVATE -DLD_BUILD_NUMBER="${BUILD_NUMBER}"
+    PRIVATE -DLD_BUILD_DATE="${DATE}"
+)
 
 if(STATIC_BUILD)
     message(WARNING "static builds enabled")

src/main.cpp

@@ -42,6 +42,8 @@ int main(const int argc, const char *const *const argv) {
     args::Flag pluginType(parser, "", "Print plugin type and exit", {"plugin-type"});
     args::Flag pluginApiVersion(parser, "", "Print plugin API version and exit", {"plugin-api-version"});
 
+    args::Flag printVersion(parser, "", "Print plugin version and exit", {"plugin-version"});
+
     try {
         parser.ParseCLI(argc, argv);
     } catch (const args::ParseError &) {
@@ -59,6 +61,15 @@ int main(const int argc, const char *const *const argv) {
         return 0;
     }
 
+    // always show version statement
+    std::cerr << "linuxdeploy-plugin-qt version " << LD_VERSION
+              << " (git commit ID " << LD_GIT_COMMIT << "), "
+              << LD_BUILD_NUMBER << " built on " << LD_BUILD_DATE << std::endl;
+
+    if (printVersion) {
+        return 0;
+    }
+
     if (!appDirPath) {
         ldLog() << LD_ERROR << "--appdir parameter required" << std::endl;
         std::cout << std::endl << parser;