Hi,
Paul J. Lucas wrote:
> The getopt.c file generates the following warnings from Apple’s gcc (Apple
> clang version 11.0.3 (clang-1103.0.32.62)):
>
> --------------------------------------------------------------------------------
> getopt.c:208:21: warning: implicit conversion changes signedness: 'long' to
> 'size_t' (aka 'unsigned long') [-Wsign-conversion]
> namelen = nameend - d->__nextchar;
> ~ ~~~~~~~~^~~~~~~~~~~~~~~
> getopt.c:255:34: warning: implicit conversion changes signedness: 'int' to
> 'unsigned long' [-Wsign-conversion]
> else if ((ambig_set = malloc (n_options)) == NULL)
> ~~~~~~ ^~~~~~~~~
The obvious "fix" for these warnings is to introduce a cast. But such casts
would decrease the robustness of the code. As I wrote in [1], such explicit
casts introduce bugs when the standards change or some platform is not 100%
standards compliant.
Therefore it is best to ignore warnings of this type. That's what gnulib does,
through the file build-aux/gcc-warning.spec, when you use the
gl_MANYWARN_ALL_GCC macro.
> getopt.c:369:16: warning: variable 'option_index' may be uninitialized when
> used
> here [-Wconditional-uninitialized]
> *longind = option_index;
> ^~~~~~~~~~~~
> getopt.c:204:19: note: initialize the variable 'option_index' to silence this
> warning
> int option_index;
> ^
> = 0
Here the code is copying an uninitialized value, if pfound == NULL. But this is
harmless, because
1) The documentation of _getopt_internal_r says that
"LONGIND returns the index in LONGOPT of the long-named option found.
It is only valid when a long-named option has been found by the most
recent call."
2) valgrind does not complain about copying an uninitialized value, if it ends
up being unused.
Bruno
[1] https://bugs.llvm.org/show_bug.cgi?id=46025
