Base: Impl has to be the second data member after base_guard to be de…

…stroyed last

SolvRepo relies on the fact that pointers in libsolv repos are always
valid.
c8e26cb

include/libdnf/base/base.hpp

@@ -104,8 +104,6 @@ class Base {
     friend class libdnf::advisory::AdvisoryQuery;
     friend class libdnf::repo::SolvRepo;
 
-    WeakPtrGuard<Base, false> base_guard;
-
     /// Loads the default configuration. To load distribution-specific configuration.
     void load_defaults();
 
@@ -123,6 +121,12 @@ class Base {
     /// The files in the directory are read in alphabetical order.
     void load_config_from_dir();
 
+    WeakPtrGuard<Base, false> base_guard;
+    // Impl has to be the second data member (right after base_guard which is needed for its construction) because it
+    // contains Pool and that has be destructed last.
+    // See commit: https://github.com/rpm-software-management/dnf5/commit/c8e26cb545aed0d6ca66545d51eda7568efdf232
+    ImplPtr<Impl> p_impl;
+
     LogRouter log_router;
     ConfigMain config;
     repo::RepoSack repo_sack;
@@ -136,8 +140,6 @@ class Base {
 
     WeakPtrGuard<LogRouter, false> log_router_gurad;
     WeakPtrGuard<Vars, false> vars_gurad;
-
-    ImplPtr<Impl> p_impl;
 };
 
 }  // namespace libdnf

libdnf/base/base.cpp

@@ -41,12 +41,12 @@ static std::atomic<Base *> locked_base{nullptr};
 static std::mutex locked_base_mutex;
 
 Base::Base(std::vector<std::unique_ptr<Logger>> && loggers)
-    : log_router(std::move(loggers)),
+    : p_impl(new Impl(get_weak_ptr())),
+      log_router(std::move(loggers)),
       repo_sack(get_weak_ptr()),
       rpm_package_sack(get_weak_ptr()),
       transaction_history(get_weak_ptr()),
-      vars(get_weak_ptr()),
-      p_impl(new Impl(get_weak_ptr())) {
+      vars(get_weak_ptr()) {
     load_defaults();
 }
 

libdnf/base/base_impl.hpp

@@ -51,6 +51,7 @@ class Base::Impl {
     friend class Base;
     Impl(const libdnf::BaseWeakPtr & base);
 
+    // Pool as the owner of underlying libsolv data, has to be the first member so that it is destroyed last.
     std::unique_ptr<solv::Pool> pool;
 
     std::optional<libdnf::system::State> system_state;