Re: [PATCH 2/2] gdb: add SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT

[Tom Tromey <tom@tromey.com>]

>>>>> "Andrew" == Andrew Burgess via Gdb-patches <gdb-patches@sourceware.org> writes:

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

Andrew> The previous commit updated 'set debug symbol-lookup' to use the new
Andrew> debug scheme, however SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT still does
Andrew> not exist.  The reason for this is that 'set debug symbol-lookup'
Andrew> controls an integer variable, rather than a bool, and, depending on
Andrew> the value of this variable, different amounts of debug will be
Andrew> produced.

Andrew> Currently the *_SCOPED_DEBUG_ENTER_EXIT mechanism will only work for
Andrew> control variables of type bool, this is because the underlying
Andrew> scoped_debug_start_end class can only handle variables of type bool.

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

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

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

This seems fine.  I suppose inlining will make it not cost too much... ?

Andrew> +#define SYMBOL_LOOKUP_SCOPED_DEBUG_ENTER_EXIT \
Andrew> +  scoped_debug_enter_exit ([&] () -> bool { \
Andrew> +    return symbol_lookup_debug > 0; \
Andrew> +  }, "symbol-lookup")

I wonder whether the [&] is needed here.  I couldn't see what it is
capturing.

Tom