Add AST logging

[martong]

Summary

Log the AST of the TU associated with LLDB's expr command, once a declaration
is completed

[JDevlieghere]

lldb/source/Symbol/ClangASTImporter.cpp

956

Why not if (Log* log_ast = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_AST))

963

You can use the LLDB_LOG macro which provides a much nicer interface.

[martong]

• Change to if(Log *log = ...)
• Use LLDB_LOG

lldb/source/Symbol/ClangASTImporter.cpp

956

Sure, changed that.

963

Ok thanks for pointing it out. Changed to use it.

[JDevlieghere]

lldb/source/Symbol/ClangASTImporter.cpp

968

The macro uses llvm's format library, so you can omit the calls to .cstr().

974

Same here

[shafik]

LGTM outside of Jonas's comments.

[martong]

• Remove superflous '.c_str()'

lldb/include/lldb/Utility/Logging.h

 #define LIBLLDB_LOG_MMAP (1u << 23)
 #define LIBLLDB_LOG_OS (1u << 24)
 #define LIBLLDB_LOG_PLATFORM (1u << 25)
 #define LIBLLDB_LOG_SYSTEM_RUNTIME (1u << 26)
 #define LIBLLDB_LOG_JIT_LOADER (1u << 27)
 #define LIBLLDB_LOG_LANGUAGE (1u << 28)
 #define LIBLLDB_LOG_DATAFORMATTERS (1u << 29)
 #define LIBLLDB_LOG_DEMANGLE (1u << 30)
+#define LIBLLDB_LOG_AST (1u << 31)
 #define LIBLLDB_LOG_ALL (UINT32_MAX)
 #define LIBLLDB_LOG_DEFAULT                                                    \
   (LIBLLDB_LOG_PROCESS | LIBLLDB_LOG_THREAD | LIBLLDB_LOG_DYNAMIC_LOADER |     \
    LIBLLDB_LOG_BREAKPOINTS | LIBLLDB_LOG_WATCHPOINTS | LIBLLDB_LOG_STEP |      \
    LIBLLDB_LOG_STATE | LIBLLDB_LOG_SYMBOLS | LIBLLDB_LOG_TARGET |              \
    LIBLLDB_LOG_COMMANDS)
 
 namespace lldb_private {

lldb/source/Symbol/ClangASTImporter.cpp

if (llvm::Error err = ImportDefinition(from)) {
     LLDB_LOG_ERROR(log, std::move(err),
                    "[ClangASTImporter] Error during importing definition: {0}");
     return;
   }
 
   if (clang::TagDecl *to_tag = dyn_cast<clang::TagDecl>(to)) {
     if (clang::TagDecl *from_tag = dyn_cast<clang::TagDecl>(from)) {
       to_tag->setCompleteDefinition(from_tag->isCompleteDefinition());
+
+      if (Log *log_ast =
+              lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_AST)) {
+        std::string name_string;
+        if (NamedDecl *from_named_decl = dyn_cast<clang::NamedDecl>(from)) {
+          llvm::raw_string_ostream name_stream(name_string);
+          from_named_decl->printName(name_stream);
+          name_stream.flush();
+        }
+        LLDB_LOG(log_ast, "==== [ClangASTImporter][TUDecl: {0}] Imported "
+                          "({1}Decl*){2}, named {3} (from "
+                          "(Decl*){4})",
+                 static_cast<void *>(to->getTranslationUnitDecl()),
+                 from->getDeclKindName(), static_cast<void *>(to), name_string,
+                 static_cast<void *>(from));
+
+        // Log the AST of the TU.
+        std::string ast_string;
+        llvm::raw_string_ostream ast_stream(ast_string);
+        to->getTranslationUnitDecl()->dump(ast_stream);
+        LLDB_LOG(log_ast, "{0}", ast_string);
+      }
     }
   }
 
   // If we're dealing with an Objective-C class, ensure that the inheritance
   // has been set up correctly.  The ASTImporter may not do this correctly if
   // the class was originally sourced from symbols.
 
   if (ObjCInterfaceDecl *to_objc_interface = dyn_cast<ObjCInterfaceDecl>(to)) {

lldb/source/Utility/Logging.cpp

 #include "llvm/ADT/ArrayRef.h"
 
 #include <stdarg.h>
 
 using namespace lldb_private;
 
 static constexpr Log::Category g_categories[] = {
   {{"api"}, {"log API calls and return values"}, LIBLLDB_LOG_API},
+  {{"ast"}, {"log AST"}, LIBLLDB_LOG_AST},
   {{"break"}, {"log breakpoints"}, LIBLLDB_LOG_BREAKPOINTS},
   {{"commands"}, {"log command argument parsing"}, LIBLLDB_LOG_COMMANDS},
   {{"comm"}, {"log communication activities"}, LIBLLDB_LOG_COMMUNICATION},
   {{"conn"}, {"log connection details"}, LIBLLDB_LOG_CONNECTION},
   {{"demangle"}, {"log mangled names to catch demangler crashes"}, LIBLLDB_LOG_DEMANGLE},
   {{"dyld"}, {"log shared library related activities"}, LIBLLDB_LOG_DYNAMIC_LOADER},
   {{"event"}, {"log broadcaster, listener and event queue activities"}, LIBLLDB_LOG_EVENTS},
   {{"expr"}, {"log expressions"}, LIBLLDB_LOG_EXPRESSIONS},