Re: plan shape work

CI is unhappy with v6 because:

[14:37:37.742] In function ‘show_result_replacement_info’,
[14:37:37.742]     inlined from ‘ExplainNode’ at explain.c:2240:4:
[14:37:37.742] explain.c:4849:33: error: ‘replacement_type’ may be
used uninitialized [-Werror=maybe-uninitialized]
[14:37:37.742]  4849 |                 char       *s = psprintf("%s on
%s", replacement_type, buf.data);
[14:37:37.742]       |
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[14:37:37.742] explain.c: In function ‘ExplainNode’:
[14:37:37.742] explain.c:4769:21: note: ‘replacement_type’ was declared here
[14:37:37.742]  4769 |         char       *replacement_type;
[14:37:37.742]       |                     ^~~~~~~~~~~~~~~~

So apparently an "enum" over every value of the switch is not good
enough for the value to be assigned.

I'm inclined to change the code like this to fix it:

    char       *replacement_type = "???";

...in the hopes of still producing a warning here if somebody adds
another label to the enum.

--
Robert Haas
EDB: http://www.enterprisedb.com