Add --version flag with -V alias via QCommandLineParser

CMakeLists.txt

@@ -118,6 +118,18 @@ target_link_libraries(fstl Qt5::Widgets Qt5::Core Qt5::Gui Qt5::OpenGL ${OPENGL_
 # Add version definitions to use within the code. 
 target_compile_definitions(fstl PRIVATE -DFSTL_VERSION="${PROJECT_VERSION}")
 
+# Enable a simple test that validates the CLI `--version` output is exact.
+# Escape dots in PROJECT_VERSION so version is matched literally in the regex. Use character class to avoid backslash escaping issues.
+string(REPLACE "." "[.]" PROJECT_VERSION_ESCAPED "${PROJECT_VERSION}")
+
+enable_testing()
+add_test(NAME version_check COMMAND $<TARGET_FILE:fstl> --version)
+set_tests_properties(version_check PROPERTIES PASS_REGULAR_EXPRESSION "fstl ${PROJECT_VERSION_ESCAPED}")
+
+# Also validate the POSIX-compliant short alias `-V` produces the same output.
+add_test(NAME version_check_V COMMAND $<TARGET_FILE:fstl> -V)
+set_tests_properties(version_check_V PROPERTIES PASS_REGULAR_EXPRESSION "fstl ${PROJECT_VERSION_ESCAPED}")
+
 #installer information that is platform independent
 set(CPACK_PACKAGE_DESCRIPTION_SUMMARY "Fast .stl file viewer.")
 set(CPACK_PACKAGE_VERSION_MAJOR ${FSTL_VERSION_MAJOR})

src/main.cpp

@@ -1,4 +1,6 @@
+#include <iostream>
 #include <QApplication>
+#include <QCommandLineParser>
 
 #include "app.h"
 
@@ -11,7 +13,27 @@ int main(int argc, char* argv[])
     QCoreApplication::setOrganizationDomain("https://github.com/fstl-app/fstl");
     QCoreApplication::setApplicationName("fstl");
     QCoreApplication::setApplicationVersion(FSTL_VERSION);
+
     App a(argc, argv);
 
+    // Set up QCommandLineParser to handle --help, --version, and file argument
+    QCommandLineParser parser;
+    parser.setApplicationDescription("Fast .stl file viewer");
+    parser.addHelpOption();
+
+    // Add custom version option with both -V (uppercase, POSIX) and --version
+    QCommandLineOption versionOption(QStringList{"V", "version"}, "Displays version information.");
+    parser.addOption(versionOption);
+
+    parser.addPositionalArgument("file", "STL file to open (optional)", "[file]");
+    parser.process(a);
+
+    // Handle version option manually since we use custom -V
+    if (parser.isSet(versionOption)) {
+        std::cout << QCoreApplication::applicationName().toStdString() << " "
+                  << QCoreApplication::applicationVersion().toStdString() << "\n";
+        return 0;
+    }
+
     return a.exec();
 }