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3095. strstreambuf refers to nonexistent member of fpos, fpos::offset

Section: 99 [depr.strstreambuf.virtuals] Status: New Submitter: Billy O'Neal III Opened: 2018-04-04 Last modified: 2020-09-06

Priority: 4

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Discussion:

strstreambuf refers to a nonexistent member function of fpos in the specification of the member function seekpos, 99 [depr.strstreambuf.virtuals]/18 (emphasize mine):

For a sequence to be positioned, if its next pointer is a null pointer, the positioning operation fails. Otherwise, the function determines newoff from sp.offset():

The intent is clearly to get the corresponding streamoff from the fpos, as p19 says "the resultant offset newoff (of type off_type)". The mechanism to make that conversion is a normal explicit conversion, as indicated in the last row of the table in [fpos.operations].

[2018-06-18 after reflector discussion]

Priority set to 4

Proposed resolution:

This wording is relative to N4727.

1. Edit 99 [depr.strstreambuf.virtuals] as indicated:

   pos_type seekpos(pos_type sp, ios_base::openmode which
                    = ios_base::in | ios_base::out) override;
   

   -17- Effects: […]

   -18- For a sequence to be positioned, if its next pointer is a null pointer, the positioning operation fails. Otherwise, the function determines newoff from static_cast<off_type>(sp).offset():

   […]