gdb: add SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT

After the previous commit converted symbol-lookup debug to use the new
debug scheme, this commit adds SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT.

The previous commit didn't add SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT
because symbol-lookup debug is controlled by an 'unsigned int' rather
than a 'bool' control variable, we use the numeric value to offer
different levels of verbosity for symbol-lookup debug.

The *_SCOPED_DEBUG_ENTER_EXIT mechanism currently relies on capturing
a reference to the bool control variable, and evaluating the variable
both on entry, and at exit, this is done in the scoped_debug_start_end
class (see gdbsupport/common-debug.h).

This commit templates scoped_debug_start_end so that the class can
accept either a 'bool &' or an invokable object, e.g. a lambda
function, or a function pointer.

The existing scoped_debug_start_end and scoped_debug_enter_exit macros
in common-debug.h are updated to support scoped_debug_enter_exit being
templated, however, nothing outside of common-debug.h needs to change.

I've then added SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT in symtab.h, and
added a couple of token uses in symtab.c.  I didn't want to add too
much in this first commit, this is really about updating
common-debug.h to support this new functionality.

Within symtab.h I created a couple of global functions that can be
used to query the status of the symbol_lookup_debug control variable,
these functions are then used within the two existing macros:

  symbol_lookup_debug_printf
  symbol_lookup_debug_printf_v

and also in the new SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT macro.

1 files changed, 4 insertions, 0 deletions

diff --git a/gdb/symtab.c b/gdb/symtab.c
index 14d81f5468d..a7a54159b6d 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -1950,6 +1950,8 @@ lookup_symbol_in_language (const char *name, const struct block *block,
 			   const domain_enum domain, enum language lang,
 			   struct field_of_this_result *is_a_field_of_this)
 {
+  SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT;
+
   demangle_result_storage storage;
   const char *modified_name = demangle_for_lookup (name, lang, storage);
 
@@ -2072,6 +2074,8 @@ lookup_symbol_aux (const char *name, symbol_name_match_type match_type,
 		   const domain_enum domain, enum language language,
 		   struct field_of_this_result *is_a_field_of_this)
 {
+  SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT;
+
   struct block_symbol result;
   const struct language_defn *langdef;