Re: [PATCH] guile/: Add enum casts

[Pedro Alves <palves@redhat.com>]

On 10/28/2015 07:38 PM, Pedro Alves wrote:
> On 10/28/2015 07:36 PM, Pedro Alves wrote:
>> On 10/28/2015 07:29 PM, Simon Marchi wrote:
>>
>>> The status comes from gdbscm_disasm_read_memory returning TARGET_XFER_E_IO:
>>>
>>>   return status != NULL ? TARGET_XFER_E_IO : 0;
>>>
>>> Does it make sense that this function returns TARGET_XFER_E_IO, and
>>> not just -1 (or any other non-zero value) on error?  It's an
>>> all-or-nothing memory read function, unlike those of the xfer_partial
>>> interface.
>>>
>>> I would have done a change similar to what you have done in
>>> target_read_memory&co: make gdbscm_disasm_read_memory return -1 on
>>> error, and change
>>>   memory_error (status, memaddr);
>>> to
>>>   memory_error (TARGET_XFER_E_IO, memaddr);
>>>
>>> Would it make sense?
>>
>> I had the same thoughts when I did the target_read_memory&co patch,
>> and went through all the memory_error callers.  In the end I left
>> it be because of the IWBN comment:
>>
>>   /* TODO: IWBN to distinguish problems reading target memory versus problems
>>      with the port (e.g., EOF).
>>      We return TARGET_XFER_E_IO here as that's what memory_error looks for.  */
>>   return status != NULL ? TARGET_XFER_E_IO : 0;
>>
>> Either way is fine with me.  Doug, what would you prefer?
>>
>> Cast?
>> Hardcode TARGET_XFER_E_IO in the memory_error call?
>> Other?
> 
> Hmm, reading the comment back, I actually agree with Simon.
> The comment refers to distinguishing memory errors from something
> else not memory errors.  In that "something else" case, sounds like
> we wouldn't end up calling memory_error at all.  So sounds like Simon's
> suggestion would be the clearer way to go.  WDYT?

Like this?

From: Pedro Alves <palves@redhat.com>
Date: 2015-10-27 17:25:12 +0000

guile disassembly hardcode TARGET_XFER_E_IO

Instead of adding a cast at the memory_error call, as needed for C++,
and have the reader understand the indirection, make it simple and
hardcode the generic memory error at the memory_error call site.

gdb/ChangeLog:
2015-10-28  Pedro Alves  <palves@redhat.com>

	* guile/scm-disasm.c (gdbscm_disasm_read_memory): Return -1 on
	error instead of TARGET_XFER_E_IO.
	(gdbscm_disasm_memory_error): Always pass TARGET_XFER_E_IO to
	memory_error.
---

 gdb/guile/scm-disasm.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/gdb/guile/scm-disasm.c b/gdb/guile/scm-disasm.c
index 78b38df..c9e940d 100644
--- a/gdb/guile/scm-disasm.c
+++ b/gdb/guile/scm-disasm.c
@@ -119,9 +119,8 @@ gdbscm_disasm_read_memory (bfd_vma memaddr, bfd_byte *myaddr,
   status = gdbscm_with_guile (gdbscm_disasm_read_memory_worker, &data);
 
   /* TODO: IWBN to distinguish problems reading target memory versus problems
-     with the port (e.g., EOF).
-     We return TARGET_XFER_E_IO here as that's what memory_error looks for.  */
-  return status != NULL ? TARGET_XFER_E_IO : 0;
+     with the port (e.g., EOF).  */
+  return status != NULL ? -1 : 0;
 }
 
 /* disassemble_info.memory_error_func for gdbscm_print_insn_from_port.
@@ -133,7 +132,7 @@ static void
 gdbscm_disasm_memory_error (int status, bfd_vma memaddr,
 			    struct disassemble_info *info)
 {
-  memory_error (status, memaddr);
+  memory_error (TARGET_XFER_E_IO, memaddr);
 }
 
 /* disassemble_info.print_address_func for gdbscm_print_insn_from_port.