On Sun, Feb 21, 2016 at 6:22 PM, Moritz Neeb <lists@xxxxxxxxxxxxx> wrote:
> Thanks for your patch. Just to let you know, this will be my first
> review, but I hope it will be helpful anyway. I will mostly review your
> commit text. First some general remarks:
Thanks for taking on this review. I think you've covered everything I
was going to say (thus saving me a lot of time). I agree with pretty
much everything you said, with (I think) only one exception (below).
> The text you are submitting with you email is directly used as commit
> message (the email subject as well, as the first line). You might want
> to take care that the description is useful as a "bit of history", I
> will give examples of what I mean below. Some guidelines for that can be
> found in "Documentation/SubmittingPatches" section (2).
>
> On 02/21/2016 12:13 PM, Saurav Sachidanand wrote:
>> This is patch is for a suggested micro project for GSoC 2016; namely,
>> that of searching for a field of a struct that is of signed integral
>> type and used as a collection of multiple bits, and converting it to
>> an unsigned type if the MSB isn’t used in any special way.
>
> Especially, you might not want to include the fact that this is a GSoC
> project. You might want to add this kind of information in the
> "notes"-section of your email after the three dashes "---", this will be
> skipped when the patch is applied.
Correct. That this was a GSoC mini-project is not interesting in the
permanent project history, but it's helpful information for reviewers,
so you'd place it in the commentary section after the "---" just below
your sign-off.
>> Two structs, `pattern` defined in attr.c and `exclude` defined in dir.h,
>> have a `flags` field of signed int type.
>
> I have never seen the Markdown-style quotes ` in git.git commits. To be
> in the same style as previous git (which helps e.g. in readability
> because it is homogeneous), you can use the "-quote for code. Or even
> leave them out if its clear from context.
>
>> The fields of both structs take
>> on values from the same set of positive integers {1, 4, 8, 16},
>> enumerated through the marco EXC_FLAG_*.
>
> marco -> macro.
>
> I'd say this is a good observation to state.
>
> Maybe it's also helpful to further explain why the two structs are
> logically connected, or if that turns out to be false, to split up you
> changes into two commits. I am not fully convinced that it should be one
> commit.
If I'm reading the code correctly, I think these changes are
interconnected, thus they ought to remain together in a single patch.
Specifically, the change to the signature of parse_exclude_pattern()
in dir.h has an impact on both structs. Thus, it should not be
necessary to explain further that these structs are connected (they
aren't really); rather the changes to both are merely natural
consequence of the change to parse_exclude_pattern()'s signature.
>>`pattern` is used only in attr.c,
>> and `exclude` is used only in builtin/check-ignore.c and dir.c, and in
>> those files, either, the value of `flags` is checked using the `&` operator
>> (e.g.: flags & EXC_FLAG_NODIR), or the value of `flags` is first set to 0
>> and then set to any one of {1, 4, 8, 16} using the `|=` operator
>> (e.g.: flags |= EXC_FLAG_NODIR). And, so it does not appear that the MSB
>> of `flags` is used in any special way.
>
> This is the conclusion that is needed, but you might want state it more
> direct, like "the MSB is not used...".
>
>> Therefore, I thought to change the
>> type of `flags` in the definitions of both structs to `unsigned int`.
>> Furthermore, `flags` is passed by reference (of `pattern` in attr.c and of
>> `exclude` in dir.c) to the function `parse_exclude_pattern` defined in
>> dir.c, that accepts an `int *` type for `flags`.
>> When make was run, it gave
>> a warning for ‘converting between pointers to integer types of different
>> sign’, so I changed the type of that respective argument to `unsigned int *`.
>
> I think this explanation can be left out or has to be replaced by
> something less compiler-driven, i.e. why does it actually make sense for
> parse_exclude_pattern to have an unsigned int flags as parameter.
Right, the entire paragraph in the commit message could be collapsed
to something like:
Since the MSB of parse_exclude_pattern()'s 'flags' argument
is not special, change its type from 'int' to 'unsigned' to better
reflect this.
Everything else is implied by the above. The reader understands
implicitly that changing the types in the structs is a natural
consequence of changing the signature of parse_exclude_pattern(), thus
need not be stated explicitly. The bit about compiler warnings and
such is equally obvious and need not be mentioned.
One other comment: In this project, I think it is more common to give
these "flags" variables type "unsigned" rather than "unsigned int".
>> In the end, running make to build didn’t produce any more warnings, and
>> running make in t/ didn’t produce any breakage that wasn’t ‘#TODO known
>> breakage’.
>
> For the tests it is, from what I've seen, just assumed that you ran them
> (and the reviewers/the maintainer will confirm this for themselves), so
> no need to mention it. But it's good you ran them.
>
>> I also thought it’d be helpful to add the comment /* EXC_FLAG_* */ next
>> to `flags` of `exclude`, just like it exists for `flags` of `pattern`.
>
> I would reformulate this as well more direct to something like "when
> we're at it, document exclude->flags as EXC_FLAG".
Yep.
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