Re: [PATCH 1/4] gdb: add intern method to objfile_per_bfd_storage

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2021-03-23 10:47 a.m., Christian Biesinger via Gdb-patches wrote:
> On Mon, Mar 22, 2021 at 8:34 PM Simon Marchi via Gdb-patches
> <gdb-patches@sourceware.org> wrote:
>>
>> From: Simon Marchi <simon.marchi@polymtl.ca>
>>
>> This allows factoring out the internal implementation details that are
>> currently in the two objfile::intern methods.
>>
>> gdb/ChangeLog:
>>
>>         * objfiles.h (struct objfile_per_bfd_storage) <intern>: New
>>         method.
>>         (struct objfile) <intern>: Use
>>         objfile::objfile_per_bfd_storage::intern.
>>
>> Change-Id: Ifd54026c5efaeffafac9b84ff84c199acc7ce78a
>> ---
>>  gdb/objfiles.h | 13 ++++++++++---
>>  1 file changed, 10 insertions(+), 3 deletions(-)
>>
>> diff --git a/gdb/objfiles.h b/gdb/objfiles.h
>> index 41f8fc913d8..d9aa06636f5 100644
>> --- a/gdb/objfiles.h
>> +++ b/gdb/objfiles.h
>> @@ -270,6 +270,14 @@ struct objfile_per_bfd_storage
>>
>>    ~objfile_per_bfd_storage ();
>>
>> +  /* Intern STRING in this object's string cache and return the unique copy.
>> +     The copy has the same lifetime as this object.  */
>> +
>> +  const char *intern (gdb::string_view str)
>> +  {
>> +    return (const char *) string_cache.insert (str.data (), str.size () + 1);
> 
> Is this guaranteed to be nullterminated even without calling c_str()?
> 
> Christian

From what I remember from last time something like this came up (I can't
remember the context) is that we'd only use string_view for strings that
are null-terminated, even though string_view doesn't guarantee it.  Is
that the case?  Or is it a bad use case for string_view?

In this particular case, callers of this intern method have a C string
and an std::string, so we know they are null-terminated.

Simon