[PATCH] Remove a warning from symtab.c

[PATCH] Remove a warning from symtab.c

[Tom Tromey]

When building symtab.c, I get:

../../binutils-gdb/gdb/language.h: In function ‘void print_symbol_info(search_domain, symbol*, int, const char*)’:
../../binutils-gdb/gdb/language.h:738:20: warning: ‘*((void*)& l +4)’ may be used uninitialized in this function [-Wmaybe-uninitialized]
       set_language (m_lang);
       ~~~~~~~~~~~~~^~~~~~~~
../../binutils-gdb/gdb/symtab.c:4613:41: note: ‘*((void*)& l +4)’ was declared here
   scoped_switch_to_sym_language_if_auto l (sym);
                                         ^

This is another instance of the std::optional problem, see
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80635.

However, it seemed straightforward and inexpensive to me to silence
this one, which is what this patch does.

gdb/ChangeLog
2019-01-18  Tom Tromey  <tom@tromey.com>

	* language.h (class scoped_switch_to_sym_language_if_auto):
	Initialize m_lang in both cases.
---
 gdb/ChangeLog  | 5 +++++
 gdb/language.h | 7 ++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/gdb/language.h b/gdb/language.h
index 1b880979a8..d56ec20020 100644
--- a/gdb/language.h
+++ b/gdb/language.h
@@ -726,7 +726,12 @@ public:
 	set_language (SYMBOL_LANGUAGE (sym));
       }
     else
-      m_switched = false;
+      {
+	m_switched = false;
+	/* Assign to m_lang to silence a GCC warning.  See
+	   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80635.  */
+	m_lang = language_unknown;
+      }
   }
 
   ~scoped_switch_to_sym_language_if_auto ()
-- 
2.17.2

Re: [PATCH] Remove a warning from symtab.c

[Pedro Alves]

On 01/18/2019 02:46 PM, Tom Tromey wrote:
> When building symtab.c, I get:
> 
> ../../binutils-gdb/gdb/language.h: In function ‘void print_symbol_info(search_domain, symbol*, int, const char*)’:
> ../../binutils-gdb/gdb/language.h:738:20: warning: ‘*((void*)& l +4)’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>        set_language (m_lang);
>        ~~~~~~~~~~~~~^~~~~~~~
> ../../binutils-gdb/gdb/symtab.c:4613:41: note: ‘*((void*)& l +4)’ was declared here
>    scoped_switch_to_sym_language_if_auto l (sym);
>                                          ^
> 
> This is another instance of the std::optional problem, see
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80635.
> 
> However, it seemed straightforward and inexpensive to me to silence
> this one, which is what this patch does.

Yeah, seems harmless.  OK.

Thanks,
Pedro Alves