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Problem Report 0747 Details

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Report 0747 Actions

    Problem Report Number 0747
    Submitter's Classification Specification problem
    State Resolved
    Resolution Temporary Interpretation (TIN)
    Problem Resolution ID TIN.X.0038
    Raised 1970-01-01 08:00
    Updated 2003-03-13 08:00
    Published 1995-10-23 08:00
    Product Standard Commands and Utilities V2 (UNIX 95)
    Certification Program The Open Brand certification program
    Test Suite VSC version 4.1.4
    Test Identification POSIX.upe/vi 272,273,274,277
    Specification Commands and Utilities Issue 4 Version 2
    Location in Spec See Problem Text
    Problem Summary TIN4C.00023 The tests may fail on implementations that conform to POSIX 1003.2b/D11 and position the cursor at the beginning of the change.
    Problem Text
    The tests may fail on implementations that adhere to historic practice
    and position the cursor at the beginning of the change. Although
    POSIX.2 interpretation #64 reaffirms the behavior, the POSIX.2b draft
    reinstates the historic behavior.

    The tests in question verify the following assertions:

    272:
    When u is entered in command mode and the reversal only affects one
    line, then vi positions the cursor at the first non-blank character of
    the changed line.

    273:
    When u is entered in command mode and the reversal represents an
    addition or change, then vi positions the cursor at the first non-blank
    character of the first line changed.

    274:
    When u is entered in command mode and more than one line is deleted and
    an addition or change is not represented, then vi moves to the first
    non-blank character on the line preceding the deleted text.

    277:
    When U is entered in command mode and the autoindent option is set,
    then vi restores the line to its state before the cursor was last moved
    to it and positions the cursor as indicated by the previous line's
    indentation.

    None of these describe the historical cursor-positioning behavior of
    vi. The assertions are based on the following language for the u command
    in XCU4 Issue 2, p. 799:

    Undo

    Synopsis: u

    Reverse the last change made to the current buffer. ...

    Current line: Move to the position of the first line changed, if the
    reversal affects only one line or represents an addition or change;
    otherwise, move to the line preceding the deleted text.

    and corresponding language for the U command on p. 800:

    Undo Current Line

    Synopsis: U

    Restore the current line to its state before the cursor was last
    moved to it.

    Current line: Unchanged.

    Current column: Set to column position 1 or to the position indicated
    by the previous line if autoindent is set.

    This language is taken directly from POSIX.2. However, IEEE
    interpretation pasc-1003.2-064 addresses a large number of issues
    regarding vi and ex, including this one. This interpretation request
    is too long to cite here in its entirety, but it states in part:

    #68 vi Command Descriptions
    Section 5.35.7.1, page 629, line 4903

    General reworking, trying to get the discussion of the current
    line and column to work. The major change is that the current
    specification doesn't handle characters that take up more than
    a single screen column. The intent of this fix is to require
    that the current column be a screen column where some part of
    the correct character is displayed, and then rely on the
    adjustment rules to get it on the exact correct column.

    Historically, each time the window is redrawn, only the window
    option number of lines are displayed.

    Historically, the window option could not be set to any value
    larger than LINES - 1.

    This change should include the deletion of the paragraph on
    page 632, lines 5051-5058, and adding appropriate wording to
    the paragraphs on page 629, around lines 4903. The fact that
    the current line has changed, and the screen is required to
    display the current line should cause the update to happen.

    This change should include the deletion of the paragraph on
    page 632, lines 5059-5078, and adding appropriate wording to
    the paragraphs on page 629, around lines 4903. More
    specifically, as noted in Request for Interpretation #64(43),
    this has to be specified on a command-by-command basis,
    there simply aren't any general rules.

    This change also includes a large number of changes, which
    are NOT individually identified, throughout the standard, for
    the Current line/column lines.

    ...
    Note particularly the last cited paragraph. The response to this section
    was:

    #68:

    The standard states the behavior for lines and columns in vi, and
    conforming implementations must conform to this. However, concerns
    have been raised about this which are being referred to the sponsor.

    The language on which the assertions were based is no longer present in
    the most recent draft (Draft 11) of POSIX.2b. Rather, language
    describing the historical behavior of vi (which is also the behavior of
    our system) has replaced it. As can be seen in the output of the test
    tests shown above, the test suite itself contains comments written to
    the journal to the effect that these assertions appear to be errors and
    will change. In view of this, the assertion is clearly a grey area.

    Test Output
    -----------------start of test output------------------

    ************************************************************************
    /tset/POSIX.upe/vi/vi_05.ex 1 Failed


    Test Information:
    Assertion #272 (C): u moves to start of line
    Note: The behavior associated with this assertion is expected
    to change in a future revision of POSIX.2.
    Standard output isn't the same as file 'vi_exp_2'
    diff of "out.stdout" and "vi_exp_2":
    *** out.stdout Thu Sep 21 11:39:02 1995
    --- vi_exp_2 Thu Sep 21 11:38:27 1995
    ***************
    *** 1,5 ****
    first
    ! se1cond
    third
    fourth
    penultimate
    --- 1,5 ----
    first
    ! 1second
    third
    fourth
    penultimate
    ************************************************************************


    ************************************************************************
    /tset/POSIX.upe/vi/vi_05.ex 1 Failed


    Test Information:
    Assertion #273 (C): u moves to start of first line
    Note: The behavior associated with this assertion is expected
    to change in a future revision of POSIX.2.
    Standard output isn't the same as file 'vi_exp_2'
    diff of "out.stdout" and "vi_exp_2":
    *** out.stdout Thu Sep 21 11:39:42 1995
    --- vi_exp_2 Thu Sep 21 11:39:07 1995
    ***************
    *** 1,5 ****
    first
    ! se1cond
    third
    fourth
    penultimate
    --- 1,5 ----
    first
    ! 1second
    third
    fourth
    penultimate
    ************************************************************************


    ************************************************************************
    /tset/POSIX.upe/vi/vi_05.ex 1 Failed


    Test Information:
    Assertion #274 (C): u moves to start of first line added
    Note: The behavior associated with this assertion is expected
    to change in a future revision of POSIX.2.
    Standard output isn't the same as file 'vi_exp_2'
    diff of "out.stdout" and "vi_exp_2":
    *** out.stdout Thu Sep 21 11:40:25 1995
    --- vi_exp_2 Thu Sep 21 11:39:47 1995
    ***************
    *** 1,5 ****
    first
    ! se1cond
    third
    fourth
    penultimate
    --- 1,5 ----
    first
    ! 1second
    third
    fourth
    penultimate
    ************************************************************************


    ************************************************************************
    /tset/POSIX.upe/vi/vi_05.ex 1 Failed


    Test Information:
    Assertion #277 (C): U with autoindent set
    Note: The behavior associated with this assertion is expected
    to change in a future revision of POSIX.2.
    Standard output isn't the same as file 'vi_exp_1'
    diff of "out.stdout" and "vi_exp_1":
    *** out.stdout Thu Sep 21 11:42:38 1995
    --- vi_exp_1 Thu Sep 21 11:41:58 1995
    ***************
    *** 1,5 ****
    first
    second
    ! 1 third
    penultimate
    2last
    --- 1,5 ----
    first
    second
    ! 1third
    penultimate
    2last
    ************************************************************************
    ------------------end of test output-------------------

    Note: this output was from the vrpt report.

    Review Information

    Review Type TSMA Review
    Start Date null
    Completed null
    Status Complete
    Review Recommendation No Resolution Given
    Review Response
    Anticipating acceptance of the completely rewritten vi specification
    in POSIX 2003.2b/D11 and the eventual alignment of the tests with it
    a temporary interpretation is recommended.

    Review Type SA Review
    Start Date null
    Completed null
    Status Complete
    Review Resolution Temporary Interpretation (TIN)
    Review Conclusion
    A Temporary Interpretation is granted.

    Problem Reporting System Options:

     

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