"warning: ‘kind’ may be used uninitialized" in longobject.c #116592
Description
Bug report
New CI worker identified two possible problems: https://buildbot.python.org/all/#/builders/1379/builds/1
Objects/longobject.c: In function ‘long_format_binary’:
Objects/longobject.c:2321:13: warning: ‘kind’ may be used uninitialized [-Wmaybe-uninitialized]
2321 | else if (kind == PyUnicode_1BYTE_KIND) {
| ^
Objects/longobject.c:2197:9: note: ‘kind’ was declared here
2197 | int kind;
| ^~~~
Objects/longobject.c: In function ‘long_to_decimal_string_internal’:
Objects/longobject.c:2144:13: warning: ‘kind’ may be used uninitialized [-Wmaybe-uninitialized]
2144 | else if (kind == PyUnicode_1BYTE_KIND) {
| ^
Objects/longobject.c:1968:9: note: ‘kind’ was declared here
1968 | int kind;
| ^~~~
I don't think that this can ever happen, but, because of how code is written, static analysis is unsure about it:
Lines 2076 to 2097 in 1cc02ca
Notice how if (bytes_writer) does not have kind = part.
I think it is safe to assign kind as 0 by default. Because it is expected to be 1, 2, or 4.
And it is asserted to be in this range with ifs and assert (kind == PyUnicode_4BYTE_KIND);
One more thing: right now it is possible to pass both writer and bytes_writer or both NULLs.
I think that we should also an assert: only one of them can be present.