[v2] devtools: allow variable declaration inside for loop
Checks
Commit Message
Declaring variable inside for loop is not supported via C89 and it was
checked in checkpatch.sh via commit [1].
But as DPDK supported C standard is becoming C99/C11 [2], declaring
variable inside loop can be allowed.
[1]
Commit 43e73483a4b8 ("devtools: forbid variable declaration inside for")
[2]
https://dpdk.org/patch/121912
Signed-off-by: Ferruh Yigit <ferruh.yigit@amd.com>
---
Cc: Bruce Richardson <bruce.richardson@intel.com>
Cc: David Marchand <david.marchand@redhat.com>
v2:
* Update coding convention too
---
devtools/checkpatches.sh | 8 --------
doc/guides/contributing/coding_style.rst | 1 +
2 files changed, 1 insertion(+), 8 deletions(-)
Comments
On Wed, May 03, 2023 at 11:30:53AM +0100, Ferruh Yigit wrote:
> Declaring variable inside for loop is not supported via C89 and it was
> checked in checkpatch.sh via commit [1].
> But as DPDK supported C standard is becoming C99/C11 [2], declaring
> variable inside loop can be allowed.
>
> [1]
> Commit 43e73483a4b8 ("devtools: forbid variable declaration inside for")
>
> [2]
> https://dpdk.org/patch/121912
>
> Signed-off-by: Ferruh Yigit <ferruh.yigit@amd.com>
> ---
> Cc: Bruce Richardson <bruce.richardson@intel.com>
> Cc: David Marchand <david.marchand@redhat.com>
>
> v2:
> * Update coding convention too
> ---
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> devtools/checkpatches.sh | 8 --------
> doc/guides/contributing/coding_style.rst | 1 +
> 2 files changed, 1 insertion(+), 8 deletions(-)
>
> diff --git a/devtools/checkpatches.sh b/devtools/checkpatches.sh
> index 15d5d6709445..b5baf6f2b161 100755
> --- a/devtools/checkpatches.sh
> +++ b/devtools/checkpatches.sh
> @@ -78,14 +78,6 @@ check_forbidden_additions() { # <patch>
> -f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
> "$1" || res=1
>
> - # forbid variable declaration inside "for" loop
> - awk -v FOLDERS='.' \
> - -v EXPRESSIONS='for[[:space:]]*\\((char|u?int|unsigned|s?size_t)' \
> - -v RET_ON_FAIL=1 \
> - -v MESSAGE='Declaring a variable inside for()' \
> - -f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
> - "$1" || res=1
> -
> # refrain from new additions of 16/32/64 bits rte_atomicNN_xxx()
> awk -v FOLDERS="lib drivers app examples" \
> -v EXPRESSIONS="rte_atomic[0-9][0-9]_.*\\\(" \
> diff --git a/doc/guides/contributing/coding_style.rst b/doc/guides/contributing/coding_style.rst
> index 89db6260cfbf..e18b8d4439ea 100644
> --- a/doc/guides/contributing/coding_style.rst
> +++ b/doc/guides/contributing/coding_style.rst
> @@ -558,6 +558,7 @@ Local Variables
>
> * Variables should be declared at the start of a block of code rather than in the middle.
I'd love to see this restriction removed in future too. Having a variable
declared on first use in the middle of block I find a far easier way of
working as a) it saves scrolling to look for variable definitions and b) it
makes it far easier when adding/removing blocks of code e.g. commenting out
for testing, to have all the code together rather than having variables at
the top to add/remove also.
> The exception to this is when the variable is ``const`` in which case the declaration must be at the point of first use/assignment.
> + Declaring variable inside a for loop is OK.
> * When declaring variables in functions, multiple variables per line are OK.
> However, if multiple declarations would cause the line to exceed a reasonable line length, begin a new set of declarations on the next line rather than using a line continuation.
> * Be careful to not obfuscate the code by initializing variables in the declarations, only the last variable on a line should be initialized.
> --
> 2.34.1
>
> From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> Sent: Wednesday, 3 May 2023 12.57
>
> On Wed, May 03, 2023 at 11:30:53AM +0100, Ferruh Yigit wrote:
> > Declaring variable inside for loop is not supported via C89 and it was
> > checked in checkpatch.sh via commit [1].
> > But as DPDK supported C standard is becoming C99/C11 [2], declaring
> > variable inside loop can be allowed.
> >
> > [1]
> > Commit 43e73483a4b8 ("devtools: forbid variable declaration inside
> for")
> >
> > [2]
> > https://dpdk.org/patch/121912
> >
> > Signed-off-by: Ferruh Yigit <ferruh.yigit@amd.com>
> > ---
> > Cc: Bruce Richardson <bruce.richardson@intel.com>
> > Cc: David Marchand <david.marchand@redhat.com>
> >
> > v2:
> > * Update coding convention too
> > ---
>
> Acked-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
[...]
> > @@ -558,6 +558,7 @@ Local Variables
> >
> > * Variables should be declared at the start of a block of code rather
> than in the middle.
>
> I'd love to see this restriction removed in future too. Having a
> variable
> declared on first use in the middle of block I find a far easier way of
> working as a) it saves scrolling to look for variable definitions and b)
> it
> makes it far easier when adding/removing blocks of code e.g. commenting
> out
> for testing, to have all the code together rather than having variables
> at
> the top to add/remove also.
And c) Initializing the variables close to where they are used the first time reduces the risk of initializing them incorrectly. Especially when modifying a block of code, initialization of its variables might be missed if out of sight. (Although this is probably a consequence of "a)".)
I consider it old style to only declare variables at the start of a block of code, and this style of coding should be considered obsolete.
If you are really old (like me?), you might remember when function parameters were provided like this:
int main(argc, argv)
int argc;
char *argv[];
{
return(0);
}
We have moved on from that to a more modern coding style a long time ago. We should also move on to a more modern coding style regarding variable declarations.
>
> > The exception to this is when the variable is ``const`` in which
> case the declaration must be at the point of first use/assignment.
> > + Declaring variable inside a for loop is OK.
> > * When declaring variables in functions, multiple variables per line
> are OK.
> > However, if multiple declarations would cause the line to exceed a
> reasonable line length, begin a new set of declarations on the next line
> rather than using a line continuation.
> > * Be careful to not obfuscate the code by initializing variables in
> the declarations, only the last variable on a line should be
> initialized.
> > --
> > 2.34.1
> >
03/05/2023 14:19, Morten Brørup:
> > From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> > Sent: Wednesday, 3 May 2023 12.57
> >
> > On Wed, May 03, 2023 at 11:30:53AM +0100, Ferruh Yigit wrote:
> > > Declaring variable inside for loop is not supported via C89 and it was
> > > checked in checkpatch.sh via commit [1].
> > > But as DPDK supported C standard is becoming C99/C11 [2], declaring
> > > variable inside loop can be allowed.
> > >
> > > [1]
> > > Commit 43e73483a4b8 ("devtools: forbid variable declaration inside
> > for")
> > >
> > > [2]
> > > https://dpdk.org/patch/121912
> > >
> > > Signed-off-by: Ferruh Yigit <ferruh.yigit@amd.com>
> > > ---
> > > Cc: Bruce Richardson <bruce.richardson@intel.com>
> > > Cc: David Marchand <david.marchand@redhat.com>
> > >
> > > v2:
> > > * Update coding convention too
> > > ---
> >
> > Acked-by: Bruce Richardson <bruce.richardson@intel.com>
>
> Acked-by: Morten Brørup <mb@smartsharesystems.com>
>
> [...]
>
> > > @@ -558,6 +558,7 @@ Local Variables
> > >
> > > * Variables should be declared at the start of a block of code rather
> > than in the middle.
> >
> > I'd love to see this restriction removed in future too. Having a
> > variable
> > declared on first use in the middle of block I find a far easier way of
> > working as a) it saves scrolling to look for variable definitions and b)
> > it
> > makes it far easier when adding/removing blocks of code e.g. commenting
> > out
> > for testing, to have all the code together rather than having variables
> > at
> > the top to add/remove also.
>
> And c) Initializing the variables close to where they are used the first time reduces the risk of initializing them incorrectly. Especially when modifying a block of code, initialization of its variables might be missed if out of sight. (Although this is probably a consequence of "a)".)
>
> I consider it old style to only declare variables at the start of a block of code, and this style of coding should be considered obsolete.
>
> If you are really old (like me?), you might remember when function parameters were provided like this:
>
> int main(argc, argv)
> int argc;
> char *argv[];
> {
> return(0);
> }
>
> We have moved on from that to a more modern coding style a long time ago. We should also move on to a more modern coding style regarding variable declarations.
Old men are used to look for variable types at the beginning of functions.
Having only new code adopting a different style may be confusing a little.
Note I'm not against it, just asking for more feedbacks.
On Wed, May 03, 2023 at 05:01:01PM +0200, Thomas Monjalon wrote:
> 03/05/2023 14:19, Morten Brørup:
> > > From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> > > Sent: Wednesday, 3 May 2023 12.57
> > >
> > > On Wed, May 03, 2023 at 11:30:53AM +0100, Ferruh Yigit wrote:
> > > > Declaring variable inside for loop is not supported via C89 and it was
> > > > checked in checkpatch.sh via commit [1].
> > > > But as DPDK supported C standard is becoming C99/C11 [2], declaring
> > > > variable inside loop can be allowed.
> > > >
> > > > [1]
> > > > Commit 43e73483a4b8 ("devtools: forbid variable declaration inside
> > > for")
> > > >
> > > > [2]
> > > > https://dpdk.org/patch/121912
> > > >
> > > > Signed-off-by: Ferruh Yigit <ferruh.yigit@amd.com>
> > > > ---
> > > > Cc: Bruce Richardson <bruce.richardson@intel.com>
> > > > Cc: David Marchand <david.marchand@redhat.com>
> > > >
> > > > v2:
> > > > * Update coding convention too
> > > > ---
> > >
> > > Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> >
> > Acked-by: Morten Brørup <mb@smartsharesystems.com>
> >
> > [...]
> >
> > > > @@ -558,6 +558,7 @@ Local Variables
> > > >
> > > > * Variables should be declared at the start of a block of code rather
> > > than in the middle.
> > >
> > > I'd love to see this restriction removed in future too. Having a
> > > variable
> > > declared on first use in the middle of block I find a far easier way of
> > > working as a) it saves scrolling to look for variable definitions and b)
> > > it
> > > makes it far easier when adding/removing blocks of code e.g. commenting
> > > out
> > > for testing, to have all the code together rather than having variables
> > > at
> > > the top to add/remove also.
> >
> > And c) Initializing the variables close to where they are used the first time reduces the risk of initializing them incorrectly. Especially when modifying a block of code, initialization of its variables might be missed if out of sight. (Although this is probably a consequence of "a)".)
> >
> > I consider it old style to only declare variables at the start of a block of code, and this style of coding should be considered obsolete.
> >
> > If you are really old (like me?), you might remember when function parameters were provided like this:
> >
> > int main(argc, argv)
> > int argc;
> > char *argv[];
> > {
> > return(0);
> > }
heh, k&r C
> >
> > We have moved on from that to a more modern coding style a long time ago. We should also move on to a more modern coding style regarding variable declarations.
>
> Old men are used to look for variable types at the beginning of functions.
> Having only new code adopting a different style may be confusing a little.
> Note I'm not against it, just asking for more feedbacks.
Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
+1 for declare in minimum necessary scope
+1 for declare at first use (enables more use of const)
thank you!
> > > > > Declaring variable inside for loop is not supported via C89 and it was
> > > > > checked in checkpatch.sh via commit [1].
> > > > > But as DPDK supported C standard is becoming C99/C11 [2], declaring
> > > > > variable inside loop can be allowed.
> > > > >
> > > > > [1]
> > > > > Commit 43e73483a4b8 ("devtools: forbid variable declaration inside
> > > > for")
> > > > >
> > > > > [2]
> > > > > https://dpdk.org/patch/121912
> > > > >
> > > > > Signed-off-by: Ferruh Yigit <ferruh.yigit@amd.com>
> > > > > ---
> > > > > Cc: Bruce Richardson <bruce.richardson@intel.com>
> > > > > Cc: David Marchand <david.marchand@redhat.com>
> > > > >
> > > > > v2:
> > > > > * Update coding convention too
> > > > > ---
> > > >
> > > > Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> > >
> > > Acked-by: Morten Brørup <mb@smartsharesystems.com>
>
> Acked-by: Tyler Retzlaff <roretzla@linux.microsoft.com>
Applied, thanks.
@@ -78,14 +78,6 @@ check_forbidden_additions() { # <patch>
-f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
"$1" || res=1
- # forbid variable declaration inside "for" loop
- awk -v FOLDERS='.' \
- -v EXPRESSIONS='for[[:space:]]*\\((char|u?int|unsigned|s?size_t)' \
- -v RET_ON_FAIL=1 \
- -v MESSAGE='Declaring a variable inside for()' \
- -f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
- "$1" || res=1
-
# refrain from new additions of 16/32/64 bits rte_atomicNN_xxx()
awk -v FOLDERS="lib drivers app examples" \
-v EXPRESSIONS="rte_atomic[0-9][0-9]_.*\\\(" \
@@ -558,6 +558,7 @@ Local Variables
* Variables should be declared at the start of a block of code rather than in the middle.
The exception to this is when the variable is ``const`` in which case the declaration must be at the point of first use/assignment.
+ Declaring variable inside a for loop is OK.
* When declaring variables in functions, multiple variables per line are OK.
However, if multiple declarations would cause the line to exceed a reasonable line length, begin a new set of declarations on the next line rather than using a line continuation.
* Be careful to not obfuscate the code by initializing variables in the declarations, only the last variable on a line should be initialized.