* doc/observer.texi (executable_changed): New observer.

* symtab.c: Include "observer.h".
        (find_main_name): New function.
        (main_name): If name_of_main is unset, then compute it
        using find_main_name.
        (symtab_observer_executable_changed): New function.
        (_initialize_symtab): Attach executable_changed observer.
        * exec.c: Include "observer.h".
        (exec_file_attach): Emit executable_changed notification.
        * symfile.c: Include "observer.h".
        (reread_symbols): Send an executable_changed if appropriate.
        * Makefile.in (exec.o): Add dependency on observer.h.
        (symfile.o): Likewise.
        (symtab.o): Likewise.

gdb/ChangeLog

@@ -1,3 +1,20 @@
+2005-03-07  Joel Brobecker  <brobecker@adacore.com>
+
+	* doc/observer.texi (executable_changed): New observer.
+	* symtab.c: Include "observer.h".
+	(find_main_name): New function.
+	(main_name): If name_of_main is unset, then compute it
+	using find_main_name.
+	(symtab_observer_executable_changed): New function.
+	(_initialize_symtab): Attach executable_changed observer.
+	* exec.c: Include "observer.h".
+	(exec_file_attach): Emit executable_changed notification.
+	* symfile.c: Include "observer.h".
+	(reread_symbols): Send an executable_changed if appropriate.
+	* Makefile.in (exec.o): Add dependency on observer.h.
+	(symfile.o): Likewise.
+	(symtab.o): Likewise.
+
 2005-03-07  Daniel Jacobowitz  <dan@codesourcery.com>
 
 	* findvar.c (read_var_value): Don't allocate V when it will not

gdb/Makefile.in

@@ -1903,7 +1903,7 @@ exceptions.o: exceptions.c $(defs_h) $(exceptions_h) $(breakpoint_h) \
 exec.o: exec.c $(defs_h) $(frame_h) $(inferior_h) $(target_h) $(gdbcmd_h) \
 	$(language_h) $(symfile_h) $(objfiles_h) $(completer_h) $(value_h) \
 	$(exec_h) $(readline_h) $(gdb_string_h) $(gdbcore_h) $(gdb_stat_h) \
-	$(xcoffsolib_h)
+	$(xcoffsolib_h) $(observer_h)
 expprint.o: expprint.c $(defs_h) $(symtab_h) $(gdbtypes_h) $(expression_h) \
 	$(value_h) $(language_h) $(parser_defs_h) $(user_regs_h) $(target_h) \
 	$(gdb_string_h) $(block_h)
@@ -2614,7 +2614,7 @@ symfile.o: symfile.c $(defs_h) $(bfdlink_h) $(symtab_h) $(gdbtypes_h) \
 	$(complaints_h) $(demangle_h) $(inferior_h) $(filenames_h) \
 	$(gdb_stabs_h) $(gdb_obstack_h) $(completer_h) $(bcache_h) \
 	$(hashtab_h) $(readline_h) $(gdb_assert_h) $(block_h) \
-	$(gdb_string_h) $(gdb_stat_h)
+	$(gdb_string_h) $(gdb_stat_h) $(observer_h)
 symfile-mem.o: symfile-mem.c $(defs_h) $(symtab_h) $(gdbcore_h) \
 	$(objfiles_h) $(exceptions_h) $(gdbcmd_h) $(target_h) $(value_h) \
 	$(symfile_h) $(observer_h) $(auxv_h) $(elf_common_h)
@@ -2629,7 +2629,7 @@ symtab.o: symtab.c $(defs_h) $(symtab_h) $(gdbtypes_h) $(gdbcore_h) \
 	$(language_h) $(demangle_h) $(inferior_h) $(linespec_h) $(source_h) \
 	$(filenames_h) $(objc_lang_h) $(ada_lang_h) $(hashtab_h) \
 	$(gdb_obstack_h) $(block_h) $(dictionary_h) $(gdb_string_h) \
-	$(gdb_stat_h) $(cp_abi_h)
+	$(gdb_stat_h) $(cp_abi_h) $(observer_h)
 target.o: target.c $(defs_h) $(gdb_string_h) $(target_h) $(gdbcmd_h) \
 	$(symtab_h) $(inferior_h) $(bfd_h) $(symfile_h) $(objfiles_h) \
 	$(gdb_wait_h) $(dcache_h) $(regcache_h) $(gdb_assert_h) $(gdbcore_h)

gdb/doc/observer.texi

@@ -83,6 +83,13 @@ The inferior has stopped for real.
 The target's register contents have changed.
 @end deftypefun
 
+@deftypefun void executable_changed (void *@var{unused_args})
+The executable being debugged by GDB has changed: The user decided
+to debug a different program, or the program he was debugging has
+been modified since being loaded by the debugger (by being recompiled,
+for instance).
+@end deftypefun
+
 @deftypefun void inferior_created (struct target_ops *@var{objfile}, int @var{from_tty})
 @value{GDBN} has just connected to an inferior.  For @samp{run},
 @value{GDBN} calls this observer while the inferior is still stopped

gdb/exec.c

@@ -32,6 +32,7 @@
 #include "completer.h"
 #include "value.h"
 #include "exec.h"
+#include "observer.h"
 
 #include <fcntl.h>
 #include "readline/readline.h"
@@ -276,6 +277,7 @@ exec_file_attach (char *filename, int from_tty)
 	(*deprecated_exec_file_display_hook) (filename);
     }
   bfd_cache_close_all ();
+  observer_notify_executable_changed (NULL);
 }
 
 /*  Process the first arg in ARGS as the new exec file.

gdb/symfile.c

@@ -48,6 +48,7 @@
 #include "readline/readline.h"
 #include "gdb_assert.h"
 #include "block.h"
+#include "observer.h"
 
 #include <sys/types.h>
 #include <fcntl.h>
@@ -2013,7 +2014,13 @@ reread_symbols (void)
     }
 
   if (reread_one)
-    clear_symtab_users ();
+    {
+      clear_symtab_users ();
+      /* At least one objfile has changed, so we can consider that
+         the executable we're debugging has changed too.  */
+      observer_notify_executable_changed (NULL);
+    }
+      
 }
 
 

gdb/symtab.c

@@ -55,6 +55,7 @@
 #include "gdb_stat.h"
 #include <ctype.h>
 #include "cp-abi.h"
+#include "observer.h"
 
 /* Prototypes for local functions */
 
@@ -4092,15 +4093,59 @@ set_main_name (const char *name)
     }
 }
 
+/* Deduce the name of the main procedure, and set NAME_OF_MAIN
+   accordingly.  */
+
+static void
+find_main_name (void)
+{
+  char *new_main_name;
+
+  /* Try to see if the main procedure is in Ada.  */
+  /* FIXME: brobecker/2005-03-07: Another way of doing this would
+     be to add a new method in the language vector, and call this
+     method for each language until one of them returns a non-empty
+     name.  This would allow us to remove this hard-coded call to
+     an Ada function.  It is not clear that this is a better approach
+     at this point, because all methods need to be written in a way
+     such that false positives never be returned. For instance, it is
+     important that a method does not return a wrong name for the main
+     procedure if the main procedure is actually written in a different
+     language.  It is easy to guaranty this with Ada, since we use a
+     special symbol generated only when the main in Ada to find the name
+     of the main procedure. It is difficult however to see how this can
+     be guarantied for languages such as C, for instance.  This suggests
+     that order of call for these methods becomes important, which means
+     a more complicated approach.  */
+  new_main_name = ada_main_name ();
+  if (new_main_name != NULL)
+    { 
+      set_main_name (new_main_name);
+      return;
+    }
+
+  /* The languages above didn't identify the name of the main procedure.
+     Fallback to "main".  */
+  set_main_name ("main");
+}
+
 char *
 main_name (void)
 {
-  if (name_of_main != NULL)
-    return name_of_main;
-  else
-    return "main";
+  if (name_of_main == NULL)
+    find_main_name ();
+
+  return name_of_main;
 }
 
+/* Handle ``executable_changed'' events for the symtab module.  */
+
+static void
+symtab_observer_executable_changed (void *unused)
+{
+  /* NAME_OF_MAIN may no longer be the same, so reset it for now.  */
+  set_main_name (NULL);
+}
 
 void
 _initialize_symtab (void)
@@ -4143,4 +4188,6 @@ All global and static variable names, or those matching REGEXP."));
   /* Initialize the one built-in type that isn't language dependent... */
   builtin_type_error = init_type (TYPE_CODE_ERROR, 0, 0,
 				  "<unknown type>", (struct objfile *) NULL);
+
+  observer_attach_executable_changed (symtab_observer_executable_changed);
 }