feat: Add compiled version info

Core/ActsVersion.hpp.in

@@ -1,6 +1,6 @@
 // This file is part of the Acts project.
 //
-// Copyright (C) 2016-2020 CERN for the benefit of the Acts project
+// Copyright (C) 2016-2023 CERN for the benefit of the Acts project
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -13,6 +13,8 @@
 //  will cause a recompile every time a new Acts version is
 //  used.
 
+#include <iosfwd>
+
 namespace Acts {
 
 // clang-format does not like the CMake @...@ replacement variables
@@ -26,4 +28,26 @@ constexpr unsigned int Version =
 constexpr const char* const CommitHash = "@_acts_commit_hash@";
 constexpr const char* const CommitHashShort = "@_acts_commit_hash_short@";
 
+struct VersionInfo {
+  unsigned int versionMajor;
+  unsigned int versionMinor;
+  unsigned int versionPatch;
+  const char* const commitHash;
+
+  static VersionInfo fromHeader() {
+    return VersionInfo(VersionMajor, VersionMinor, VersionPatch, CommitHash);
+  }
+
+  static VersionInfo fromLibrary();
+
+  bool operator==(const VersionInfo& other) const;
+  bool operator!=(const VersionInfo& other) const { return !(*this == other); }
+
+  friend std::ostream& operator<<(std::ostream& os, const VersionInfo& vi);
+
+ private:
+  VersionInfo(unsigned int majorIn, unsigned int minorIn, unsigned int patchIn,
+              const char* const commitHashIn);
+};
+
 }  // namespace Acts

Core/CMakeLists.txt

@@ -6,6 +6,11 @@ configure_file(
 add_library(
   ActsCore SHARED "")
 
+target_sources(
+  ActsCore
+  PRIVATE
+    src/ActsVersion.cpp)
+
 target_compile_features(
   ActsCore
   PUBLIC ${ACTS_CXX_STANDARD_FEATURE})

Core/src/ActsVersion.cpp

@@ -0,0 +1,41 @@
+// This file is part of the Acts project.
+//
+// Copyright (C) 2023 CERN for the benefit of the Acts project
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#include "Acts/ActsVersion.hpp"
+
+#include <ostream>
+#include <string_view>
+
+namespace Acts {
+
+VersionInfo::VersionInfo(unsigned int majorIn, unsigned int minorIn,
+                         unsigned int patchIn, const char* const commitHashIn)
+    : versionMajor(majorIn),
+      versionMinor(minorIn),
+      versionPatch(patchIn),
+      commitHash(commitHashIn) {}
+
+VersionInfo VersionInfo::fromLibrary() {
+  // this is filled by the Core shared library
+  // while the constants below depend on the include
+  return VersionInfo{VersionMajor, VersionMinor, VersionPatch, CommitHash};
+}
+
+bool VersionInfo::operator==(const VersionInfo& other) const {
+  return versionMajor == other.versionMajor &&
+         versionMinor == other.versionMinor &&
+         versionPatch == other.versionPatch &&
+         std::string_view{commitHash} == std::string_view{other.commitHash};
+}
+
+std::ostream& operator<<(std::ostream& os, const VersionInfo& vi) {
+  os << vi.versionMajor << "." << vi.versionMinor << "." << vi.versionPatch
+     << " (commit " << vi.commitHash << ")";
+  return os;
+}
+}  // namespace Acts

Tests/DownstreamProject/ShowActsVersion.cpp

@@ -8,11 +8,19 @@
 
 #include <Acts/ActsVersion.hpp>
 
-#include <cstdio>
-#include <cstdlib>
+#include <iostream>
 
 int main(void) {
-  printf("Using Acts version %u.%u.%u commit %s\n", Acts::VersionMajor,
-         Acts::VersionMinor, Acts::VersionPatch, Acts::CommitHash);
+  std::cout << "Using Acts version " << Acts::VersionMajor << "."
+            << Acts::VersionMinor << "." << Acts::VersionPatch << " commit "
+            << Acts::CommitHash << std::endl;
+
+  if (Acts::VersionInfo::fromHeader() != Acts::VersionInfo::fromLibrary()) {
+    std::cout << "WARNING: The version information is inconsistent!"
+              << std::endl;
+    std::cout << "Header: " << Acts::VersionInfo::fromHeader() << std::endl;
+    std::cout << "Library: " << Acts::VersionInfo::fromLibrary() << std::endl;
+    return EXIT_FAILURE;
+  }
   return EXIT_SUCCESS;
 }