# [PATCH] clean: remove unnecessary variable 4 messages from 2021-05-06 to 2021-05-06. Participants: Matheus Tavares, Jeff King, Matheus Tavares Bernardino, Elijah Newren. Thread: https://gitlist.dev/t/55636 ## Matheus Tavares, 2021-05-06 19:33 Subject: [PATCH] clean: remove unnecessary variable Message-ID: <4f88ac58e46782c7cf335e13fabd14c8b4438267.1620329445.git.matheus.bernardino@usp.br> URL: https://gitlist.dev/e/4f88ac58e46782c7cf335e13fabd14c8b4438267.1620329445.git.matheus.bernardino%40usp.br ``` The variable `matches` used to hold the return of a `dir_path_match()` call that was removed in 95c11ecc73 ("Fix error-prone fill_directory() API; make it only return matches", 2020-04-01). Now `matches` will always hold 0, which is the value it's initialized with; and the condition `matches != MATCHED_EXACTLY` will always evaluate to true. So let's remove this unnecessary variable. Interestingly, it seems that `matches != MATCHED_EXACTLY` was already unnecessary before 95c11ecc73. That's because `remove_directories` is always set to 1 when we have pathspecs; So, in the condition `!remove_directories && matches != MATCHED_EXACTLY`, we would either: - have pathspecs (or have been given `-d`) and ignore `matches` because `remove_directories` is 1; or - not have pathspecs (nor `-d`) and end up just checking that `0 != MATCHED_EXACTLY`, as `matches` would never get reassigned after its zero initialization (because there is no pathspec to match). Signed-off-by: Matheus Tavares --- builtin/clean.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/builtin/clean.c b/builtin/clean.c index 995053b791..f6d7e8119c 100644 --- a/builtin/clean.c +++ b/builtin/clean.c @@ -1003,7 +1003,6 @@ int cmd_clean(int argc, const char **argv, const char *prefix) for (i = 0; i < dir.nr; i++) { struct dir_entry *ent = dir.entries[i]; - int matches = 0; struct stat st; const char *rel; @@ -1013,8 +1012,7 @@ int cmd_clean(int argc, const char **argv, const char *prefix) if (lstat(ent->name, &st)) die_errno("Cannot lstat '%s'", ent->name); - if (S_ISDIR(st.st_mode) && !remove_directories && - matches != MATCHED_EXACTLY) + if (S_ISDIR(st.st_mode) && !remove_directories) continue; rel = relative_path(ent->name, prefix, &buf); -- 2.30.1 ``` ## Jeff King, 2021-05-06 20:03 Subject: Re: [PATCH] clean: remove unnecessary variable Message-ID: URL: https://gitlist.dev/e/YJRLim10cznG5G3d%40coredump.intra.peff.net In-Reply-To: <4f88ac58e46782c7cf335e13fabd14c8b4438267.1620329445.git.matheus.bernardino@usp.br> ``` On Thu, May 06, 2021 at 04:33:15PM -0300, Matheus Tavares wrote: > The variable `matches` used to hold the return of a `dir_path_match()` > call that was removed in 95c11ecc73 ("Fix error-prone fill_directory() > API; make it only return matches", 2020-04-01). Now `matches` will > always hold 0, which is the value it's initialized with; and the > condition `matches != MATCHED_EXACTLY` will always evaluate to true. So > let's remove this unnecessary variable. > > Interestingly, it seems that `matches != MATCHED_EXACTLY` was already > unnecessary before 95c11ecc73. That's because `remove_directories` is > always set to 1 when we have pathspecs; So, in the condition > `!remove_directories && matches != MATCHED_EXACTLY`, we would either: > > - have pathspecs (or have been given `-d`) and ignore `matches` because > `remove_directories` is 1; or > > - not have pathspecs (nor `-d`) and end up just checking that > `0 != MATCHED_EXACTLY`, as `matches` would never get reassigned > after its zero initialization (because there is no pathspec to match). Thanks for this digging and the extra analysis. We can see from the patch that this variable can't possibly be doing anything, but it is always a comfort to see authors researching the source of the oddity and explaining what they found. I'm adding Elijah to the cc as an area expert, just in case he has any other insight. > diff --git a/builtin/clean.c b/builtin/clean.c > index 995053b791..f6d7e8119c 100644 > --- a/builtin/clean.c > +++ b/builtin/clean.c > @@ -1003,7 +1003,6 @@ int cmd_clean(int argc, const char **argv, const char *prefix) > > for (i = 0; i < dir.nr; i++) { > struct dir_entry *ent = dir.entries[i]; > - int matches = 0; > struct stat st; > const char *rel; > > @@ -1013,8 +1012,7 @@ int cmd_clean(int argc, const char **argv, const char *prefix) > if (lstat(ent->name, &st)) > die_errno("Cannot lstat '%s'", ent->name); > > - if (S_ISDIR(st.st_mode) && !remove_directories && > - matches != MATCHED_EXACTLY) > + if (S_ISDIR(st.st_mode) && !remove_directories) > continue; > > rel = relative_path(ent->name, prefix, &buf); Definitely not necessary, but on a patch like this I'll sometimes manually specify "-U4" (and I always have diff.interhunkcontext set to "1") to show the complete code between the declaration and use. It makes it even more obvious that the result is correct (though obviously applying and compiling shows it, too). #gitlifehacks -Peff ``` ## Matheus Tavares Bernardino, 2021-05-06 21:14 Subject: Re: [PATCH] clean: remove unnecessary variable Message-ID: URL: https://gitlist.dev/e/CAHd-oW6oN7%3D8DwzEFmCXdSWRcvzpqGEKFDkTMzN3uP1M9Cphrg%40mail.gmail.com In-Reply-To: ``` On Thu, May 6, 2021 at 5:03 PM Jeff King wrote: > > Definitely not necessary, but on a patch like this I'll sometimes > manually specify "-U4" (and I always have diff.interhunkcontext set to > "1") to show the complete code between the declaration and use. It makes > it even more obvious that the result is correct (though obviously > applying and compiling shows it, too). #gitlifehacks That's a good idea, thanks for the advice :) ``` ## Elijah Newren, 2021-05-06 21:35 Subject: Re: [PATCH] clean: remove unnecessary variable Message-ID: URL: https://gitlist.dev/e/CABPp-BGj5AmWrQLfU7u1MZbcjGiytCMkAXwutEZG1tjfJYWDTQ%40mail.gmail.com In-Reply-To: ``` On Thu, May 6, 2021 at 1:03 PM Jeff King wrote: > > On Thu, May 06, 2021 at 04:33:15PM -0300, Matheus Tavares wrote: > > > The variable `matches` used to hold the return of a `dir_path_match()` > > call that was removed in 95c11ecc73 ("Fix error-prone fill_directory() > > API; make it only return matches", 2020-04-01). Now `matches` will > > always hold 0, which is the value it's initialized with; and the > > condition `matches != MATCHED_EXACTLY` will always evaluate to true. So > > let's remove this unnecessary variable. > > > > Interestingly, it seems that `matches != MATCHED_EXACTLY` was already > > unnecessary before 95c11ecc73. That's because `remove_directories` is > > always set to 1 when we have pathspecs; So, in the condition > > `!remove_directories && matches != MATCHED_EXACTLY`, we would either: > > > > - have pathspecs (or have been given `-d`) and ignore `matches` because > > `remove_directories` is 1; or > > > > - not have pathspecs (nor `-d`) and end up just checking that > > `0 != MATCHED_EXACTLY`, as `matches` would never get reassigned > > after its zero initialization (because there is no pathspec to match). > > Thanks for this digging and the extra analysis. We can see from the > patch that this variable can't possibly be doing anything, but it is > always a comfort to see authors researching the source of the oddity and > explaining what they found. > > I'm adding Elijah to the cc as an area expert, just in case he has any > other insight. Thanks for catching this Matheus, and digging in a bit on the analysis. This change looks good to me: Reviewed-by: Elijah Newren > > > diff --git a/builtin/clean.c b/builtin/clean.c > > index 995053b791..f6d7e8119c 100644 > > --- a/builtin/clean.c > > +++ b/builtin/clean.c > > @@ -1003,7 +1003,6 @@ int cmd_clean(int argc, const char **argv, const char *prefix) > > > > for (i = 0; i < dir.nr; i++) { > > struct dir_entry *ent = dir.entries[i]; > > - int matches = 0; > > struct stat st; > > const char *rel; > > > > @@ -1013,8 +1012,7 @@ int cmd_clean(int argc, const char **argv, const char *prefix) > > if (lstat(ent->name, &st)) > > die_errno("Cannot lstat '%s'", ent->name); > > > > - if (S_ISDIR(st.st_mode) && !remove_directories && > > - matches != MATCHED_EXACTLY) > > + if (S_ISDIR(st.st_mode) && !remove_directories) > > continue; > > > > rel = relative_path(ent->name, prefix, &buf); > > Definitely not necessary, but on a patch like this I'll sometimes > manually specify "-U4" (and I always have diff.interhunkcontext set to > "1") to show the complete code between the declaration and use. It makes > it even more obvious that the result is correct (though obviously > applying and compiling shows it, too). #gitlifehacks > > -Peff ```