[lldb] Avoid global constructor in LLDBLog.cpp

[JDevlieghere]

Summary

Avoid a static initializer for Log::Channel in LLDBLog.cpp

[labath]

The class has a constexpr constructor. I thought that would be enough to avoid runtime initialization. Is this being flagged by something?

[JDevlieghere]

In D121161#3367806, @labath wrote:

The class has a constexpr constructor. I thought that would be enough to avoid runtime initialization. Is this being flagged by something?

It is getting flagged by -Wglobal-constructor but you're right, it's constexpr and therefore shouldn't. Might be a bug in clang. I'll try to repro with ToT.

[shafik]

In D121161#3368117, @JDevlieghere wrote:

In D121161#3367806, @labath wrote:

The class has a constexpr constructor. I thought that would be enough to avoid runtime initialization. Is this being flagged by something?

It is getting flagged by -Wglobal-constructor but you're right, it's constexpr and therefore shouldn't. Might be a bug in clang. I'll try to repro with ToT.

I wonder if for ArrayRef the copy constructor does not look constexpr and so if you change it to constexpr static if it will be ill-formed, that would mean it is not really constant initialization and therefore that would make it dynamic since it also not static initialization since you are calling a constructor.

[labath]

Amusingly enough, the problem is the custom operator| used for bitmask enums. D121281 ought to fix that (by making the function constexpr).

[JDevlieghere]

In D121161#3369641, @labath wrote:

Amusingly enough, the problem is the custom operator| used for bitmask enums. D121281 ought to fix that (by making the function constexpr).

Great, thanks!

lldb/source/Utility/LLDBLog.cpp

static constexpr Log::Category g_categories[] = {
     {{"target"}, {"log target events and activities"}, LLDBLog::Target},
     {{"temp"}, {"log internal temporary debug messages"}, LLDBLog::Temporary},
     {{"thread"}, {"log thread events and activities"}, LLDBLog::Thread},
     {{"types"}, {"log type system related activities"}, LLDBLog::Types},
     {{"unwind"}, {"log stack unwind activities"}, LLDBLog::Unwind},
     {{"watch"}, {"log watchpoint related activities"}, LLDBLog::Watchpoints},
 };
 
-static Log::Channel g_log_channel(g_categories,
-                                  LLDBLog::Process | LLDBLog::Thread |
-                                      LLDBLog::DynamicLoader |
-                                      LLDBLog::Breakpoints |
-                                      LLDBLog::Watchpoints | LLDBLog::Step |
-                                      LLDBLog::State | LLDBLog::Symbols |
-                                      LLDBLog::Target | LLDBLog::Commands);
 
 template <> Log::Channel &lldb_private::LogChannelFor<LLDBLog>() {
+  static Log::Channel g_log_channel(
+      g_categories, LLDBLog::Process | LLDBLog::Thread |
+                        LLDBLog::DynamicLoader | LLDBLog::Breakpoints |
+                        LLDBLog::Watchpoints | LLDBLog::Step | LLDBLog::State |
+                        LLDBLog::Symbols | LLDBLog::Target | LLDBLog::Commands);
   return g_log_channel;
 }
 
 void lldb_private::InitializeLldbChannel() {
-  Log::Register("lldb", g_log_channel);
+  Log::Register("lldb", lldb_private::LogChannelFor<LLDBLog>());
 }