On Thu, Jan 28, 2021 at 11:24:30AM +0100, Tim Wiederhake wrote:
> clang-tidy is a static code analysis tool under the llvm umbrella. It is
> primarily meant to be used on C++ code bases, but some of the checks it
> provides also apply to C.
>
> The findings vary in severity and contain pseudo-false-positives, i.e.
> clang-tidy is flagging potential execution flows that could happen in
> theory but are virtually impossible in real life: In function
> `virGetUnprivSGIOSysfsPath`, variables `maj` and `min` would be read
> unintialized if `stat()` failed and set `errno` to a negative value, to name
> just one example.
>
> The main source of false positive findings is the lack of support for
> `__attribute__((cleanup))` in clang-tidy, which is heavily used in libvirt
> through glib's `g_autofree` and `g_auto()` macros:
>
> #include <stdlib.h>
>
> void freeptr(int** p) {
> if (*p)
> free(*p);
> }
>
> int main() {
> __attribute__((cleanup(freeptr))) int *ptr = NULL;
> ptr = calloc(sizeof(int), 1);
> return 0; /* flagged as memory leak of `ptr` */
> }
>
> This sadly renders clang-tidy's analysis of dynamic memory useless, hiding all
> real issues that it could otherwise find.
>
> Meson provides excellent integration for clang-tidy (a "clang-tidy" target is
> automatically generated if a ".clang-tidy" configuration file is present
> in the project's root directory). The amount of false-positives and the slow
> analysis, triggering time-outs in the CI, make this tool unfit for inclusion
> in libvirt's GitLab CI though.
Is it possible to make it viable for CI by disabling *all* checks by
default and then selectively re-enabling just the handful that are
useful and don't have false positives ?
Regards,
Daniel
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