Vim change list behaviour

Question

I'm trying to grok the change list on vim and I'm having trouble understanding the following behavior:

As example I insert the following text:

I like chips and fish.

Realized I got the nouns in the wrong order, so I want to get:

I like fish and chips.

Starting with a fresh vim instance with no .vimrc (vim -u NONE) this is exactly what I do (# are just for explanation):

iI like chips and fish.<Esc>  # Insert text. Realize I want to switch the words
Fc                            # Jump back to 'chips'
de                            # Delete the word (and put it in anon register)
ff                            # Jump to the 'fish' word
vep                           # Select the word, and paste from anon register
g;                            # Try to jump back to the position where I change
                              # the word 'chips'. It doesn't work and I get:
E19: Mark has invalid line number

# To see what is going on i print the change list:
:changes
    change line  col text
        2     1   12 I like  and chips.
        1     2   12 -invalid-
    >

My first question is why the jump didn't work in the first place?

Second, the -invalid- entry of the change list doesn't make any sense to me. As you saw I never went beyond line 1. Why is an entry with line 2?

Im using Vim 7.4.52

Update: The -invalid- seems to be a bug. I already reported it:

https://code.google.com/p/vim/issues/detail?id=283

Answer 1

In the default Vim on Mac OS X (7.3 Normal version without GUI, no patches), g; moves the cursor to the c in chips and the output of :changes is different from yours:

change line  col text
>   0     1   16 I like fish and chops.

The fact that only one change is remembered is consistent with this paragraph from :help g;

When two undo-able changes are in the same line and at a column position less
than 'textwidth' apart only the last one is remembered.  This avoids that a
sequence of small changes in a line, for example "xxxxx", adds many positions
to the change list.  When 'textwidth' is zero 'wrapmargin' is used.  When that
also isn't set a fixed number of 79 is used.  Detail: For the computations
bytes are used, not characters, to avoid a speed penalty (this only matters
for multi-byte encodings).

so everything is normal (if a bit surprising).

With a reasonably recent MacVim (7.4.258), I get the behavior you describe for g; and a slightly different :changes output ("fish" is missing in yours):

change line  col text
    1     1   16 I like fish and chips.
>   0     2   16 -invalid-

It smells a lot like you discovered a bug and I strongly suggest you notify the vim_dev mailing list about it (if they are not already aware).