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59. Ambiguity in specification of gbump

Section: 31.6.3.4.2[streambuf.get.area]Status:TC1Submitter: Matt AusternOpened: 1998-07-28Last modified: 2016-01-28

Priority:Not Prioritized

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Discussion:

27.5.2.3.1 says that basic_streambuf::gbump() "Advances thenext pointer for the input sequence by n."

The straightforward interpretation is that it is just gptr() +=n. An alternative interpretation, though, is that it behaves as if itcalls sbumpc n times. (The issue, of course, is whether it might evercall underflow.) There is a similar ambiguity in the case ofpbump.

(The "classic" AT&T implementation used theformer interpretation.)

Proposed resolution:

Change 31.6.3.4.2[streambuf.get.area] paragraph 4 gbump effects from:

Effects: Advances the next pointer for the input sequence by n.

to:

Effects: Addsn to the next pointer for the input sequence.

Make the same change to 31.6.3.4.3[streambuf.put.area] paragraph 4 pbumpeffects.