Re: [PATCH] Fix ptype problem printing typedefs defined differently in different compilation units

[Fred Fish <fnf@specifix.com>]

On Monday 23 January 2006 11:12, Daniel Jacobowitz wrote:
> I don't understand.  What doesn't work?  Is it something that works
> without the patch, or not?

Doesn't work without the patch, as it uses the type for the first
symtab it happens to find that has a definition for that type.

> I don't understand how your examples relate
> to your description of the problem anymore.

OK, I've attached a typescript at the bottom of this mail showing how
it fails in the presence of a core and/or running executable.

> > So something like the following, which currently produces an error:
> > 
> >   (gdb) ptype 'main.c'::foo
> >   Cannot look up value of a typedef
> 
> Well that seems like a reasonable thing to fix anyway; ptype (and
> sizeof!) should be using a non-side-effects evaluation anyway.

I can look at this, though it may be a week or so.

-Fred

============================================================================

Here is a simple testcase

$ cat main.c
typedef long foo;
foo longfoo;

main ()
{
  extern charfoo (char);
  extern intfoo (int);
  int a = 5;

  a = intfoo (a);
  a = charfoo (a);
  printf ("a = %d (should be 20)\n", a);
  *(char *)0 = 0;
}

$ cat int.c
typedef int foo;

intfoo (foo a)
{
  return (2 * a);
}

$ cat char.c
typedef char foo;

charfoo (foo a)
{
  return (2 * a);
}

============================================================================

Build testcase on Fedora Core 4 and generate corefile

$ make
gcc -g  --save-temps   -c -o main.o main.c
main.c: In function ‘main’:
main.c:12: warning: incompatible implicit declaration of built-in function ‘printf’
gcc -g  --save-temps   -c -o char.o char.c
gcc -g  --save-temps   -c -o int.o int.c
gcc -o main main.o char.o int.o 

$ ./main
a = 20 (should be 20)
Segmentation fault (core dumped)
$ mv core.* core

============================================================================

Use gdb to examine just the executable file

$ ../gdb main
(gdb) list main
1	typedef long foo;
2	foo longfoo;
3	
4	main ()
5	{
6	  extern charfoo (char);
7	  extern intfoo (int);
8	  int a = 5;
9	
10	  a = intfoo (a);
(gdb) ptype foo
type = long int			<===== OK
(gdb) list charfoo
1	typedef char foo;
2	
3	charfoo (foo a)
4	{
5	  return (2 * a);
6	}
(gdb) ptype foo
type = char			<===== OK
(gdb) list intfoo
1	typedef int foo;
2	
3	intfoo (foo a)
4	{
5	  return (2 * a);
6	}
(gdb) ptype foo
type = int			<===== OK
(gdb) quit

============================================================================

Use gdb to examine the executable file and core file

$ ../gdb main core
#0  0x080483de in main () at main.c:13
13	  *(char *)0 = 0;
(gdb) list main
1	typedef long foo;
2	foo longfoo;
3	
4	main ()
5	{
6	  extern charfoo (char);
7	  extern intfoo (int);
8	  int a = 5;
9	
10	  a = intfoo (a);
(gdb) ptype foo
type = long int			<===== OK
(gdb) list charfoo
1	typedef char foo;
2	
3	charfoo (foo a)
4	{
5	  return (2 * a);
6	}
(gdb) ptype foo
type = long int			<===== Prints using frame context
(gdb) list intfoo
1	typedef int foo;
2	
3	intfoo (foo a)
4	{
5	  return (2 * a);
6	}
(gdb) ptype foo
type = long int			<===== Prints using frame context
(gdb) quit

============================================================================