--function-context shows wrong function in chunk

Zach Riggle· Jul 10, 2020, 18:38 UTC · lore

$ git diff -b --function-context

diff --git i/example.c w/example.c
index d87b59b..346e2a7 100644
--- i/example.c
+++ w/example.c
@@ -4,5 +4,5 @@ int other_routine() {
 }

 int main() {
-
+    puts("Hello, world!");
 }

Zach Riggle

Junio C Hamano· Jul 10, 2020, 20:12 UTC · re: Zach Riggle · lore

Re: --function-context shows wrong function in chunk

Zach Riggle <zachriggle@gmail.com> writes:

> When using --function-context, the function that is claimed at the top
> of the diff does not match the actual function.
>
> Note that the change exists in main, but the hunk header
> (terminology?) shows other_routine.
>
> $ git --version
> git version 2.27.0
>
> $ git diff -b --function-context
> diff --git i/example.c w/example.c
> index d87b59b..346e2a7 100644
> --- i/example.c
> +++ w/example.c
> @@ -4,5 +4,5 @@ int other_routine() {
>  }
>
>  int main() {
> -
> +    puts("Hello, world!");
>  }
>
> Zach Riggle

        @@ ... @@ int other_routine() {
            return -1;
        }
        int main() {
        -   int i = other_routine();
        +   int i = other_routine() ? 1 : 0;
            printf("%d\n", i);
        }

it would be more informative than having "int main() {" there.

Zach Riggle· Jul 10, 2020, 20:14 UTC · re: Junio C Hamano · lore

Re: --function-context shows wrong function in chunk

$ git diff -U0 -b --function-context

diff --git i/example.c w/example.c
index d87b59b..346e2a7 100644
--- i/example.c
+++ w/example.c
@@ -6,3 +6,3 @@ int other_routine() {
 int main() {
-
+    puts("Hello, world!");
 }

Zach Riggle

On Fri, Jul 10, 2020 at 3:12 PM Junio C Hamano <gitster@pobox.com> wrote:
>
> Zach Riggle <zachriggle@gmail.com> writes:
>
> > When using --function-context, the function that is claimed at the top
> > of the diff does not match the actual function.
> >
> > Note that the change exists in main, but the hunk header
> > (terminology?) shows other_routine.
> >
> > $ git --version
> > git version 2.27.0
> >
> > $ git diff -b --function-context
> > diff --git i/example.c w/example.c
> > index d87b59b..346e2a7 100644
> > --- i/example.c
> > +++ w/example.c
> > @@ -4,5 +4,5 @@ int other_routine() {
> >  }
> >
> >  int main() {
> > -
> > +    puts("Hello, world!");
> >  }
> >
> > Zach Riggle
>
> I think it is possible to modify the "find the line that match
> xfuncname pattern" logic to start scanning backwards from the first
> actual change (i.e. the blank line in the preimage of the patch
> inside "int main() {" function in your example) and make the hunk
> header say "int main() {" instead of "int other_routine() {".
>
> I however doubt that such a change makes any sense.  In fact, I find
> the sample output above both quite logical and also even desirable.
>
> It is logical because the first thing we see in the hunk, "}", is at
> the end of "int other_routine() {" function; it does not conclude
> the "int main() {" function.  Saying "int main() {" there on the
> hunk header line would be misleading and confusing.  It sends a
> wrong signal that there was such a line _before_ the first line we
> see in this hunk, which is definitely not.
>
> It is desirable because it gives more information than saying the
> illogical "main".  The reader can see what the routine before the
> beginning of main function we see in the hunk is.  In the above
> example it may not matter, but if we see "return -1;" at the end of
> that function and a call to other_routine() from main(), e.g.
>
>         @@ ... @@ int other_routine() {
>             return -1;
>         }
>         int main() {
>         -   int i = other_routine();
>         +   int i = other_routine() ? 1 : 0;
>             printf("%d\n", i);
>         }
>
> it would be more informative than having "int main() {" there.

Junio C Hamano· Jul 10, 2020, 21:12 UTC · re: Zach Riggle · lore

Re: --function-context shows wrong function in chunk

Zach Riggle <zachriggle@gmail.com> writes:

[administrivia: do not top-post]

>> I think it is possible to modify the "find the line that match
>> xfuncname pattern" logic to start scanning backwards from the first
>> actual change (i.e. the blank line in the preimage of the patch
>> inside "int main() {" function in your example) and make the hunk
>> header say "int main() {" instead of "int other_routine() {".
>>
>> I however doubt that such a change makes any sense.  In fact, I find
>> the sample output above both quite logical and also even desirable.

> This happens even with -U0 which does not include the e.g. trailing
> bit of other_routine.

> $ git diff -U0 -b --function-context
> diff --git i/example.c w/example.c
> index d87b59b..346e2a7 100644
> --- i/example.c
> +++ w/example.c
> @@ -6,3 +6,3 @@ int other_routine() {
>  int main() {
> -
> +    puts("Hello, world!");
>  }