build: add non-cmake version header fallback

Author: Pierre-Luc Gagné

README.md

@@ -150,10 +150,10 @@ find_package(ds_mysql CONFIG REQUIRED)
 target_link_libraries(my_target PRIVATE ds_mysql::ds_mysql)
 ```
 
-If you are not using CMake, prefer the release archive (`ds_mysql-v<version>.tar.gz`):
-it already contains generated `ds_mysql/version.hpp`. Cloning the raw repository
-and copying headers directly will not provide `version.hpp` unless you run CMake
-configure first.
+If you are not using CMake, you can consume headers directly from either the
+release archive or a git checkout: `ds_mysql/version.hpp` is checked in as a
+fallback. In CMake builds, a generated `version.hpp` (from `version.hpp.in`) is
+preferred so `project(VERSION ...)` remains the authoritative source.
 
 ## Key API
 

lib/CMakeLists.txt

@@ -16,8 +16,8 @@ option(DSMYSQL_ENABLE_INSTALL "Enable install targets" ${PROJECT_IS_TOP_LEVEL})
 
 target_include_directories(ds_mysql
     INTERFACE
-        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
         $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/include>
+        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
         $<INSTALL_INTERFACE:include>
     "$<BUILD_INTERFACE:${MYSQL_INCLUDE_DIRS}>"
 )

lib/include/ds_mysql/version.hpp

@@ -0,0 +1,25 @@
+#pragma once
+
+#include <cstdint>
+#include <string_view>
+
+namespace ds_mysql {
+
+/// Compile-time version information for DSMySQL.
+///
+/// This checked-in header is a fallback for non-CMake consumption.
+/// In CMake builds, `version.hpp.in` is configured into the build tree and
+/// should be preferred so `project(VERSION ...)` stays authoritative.
+struct version {
+    static constexpr std::uint32_t major  = 1;
+    static constexpr std::uint32_t minor  = 0;
+    static constexpr std::uint32_t patch  = 0;
+
+    /// Packed integer: major * 10000 + minor * 100 + patch.
+    static constexpr std::uint32_t value  = major * 10'000u + minor * 100u + patch;
+
+    /// Canonical "major.minor.patch" string.
+    static constexpr std::string_view string = "1.0.0";
+};
+
+}  // namespace ds_mysql