get_maintainer: lazy load JSON::PP only when --json is used

After commit 09d8b39563e8 ("get_maintainer: add --json output mode"), I can no longer use get_maintainer.pl; it fails at compile time

if JSON::PP is not installed even when --json is not requested.

This module is only needed with the --json option. Use "require" to load this module dynamically inside the "if ($json)" block instead.

scripts/get_maintainer.pl +0 -0

     my $json_encoder = JSON::PP->new->canonical->utf8;
     print($json_encoder->encode(\%result) . "\n");
 } else {

```

Quoted 2 lines · Oleg Nesterov

After commit 09d8b39563e8 ("get_maintainer: add --json output mode"), I can no longer use get_maintainer.pl; it fails at compile time

?

Just verifying that you mean when using perl directly and not something like perlcc.

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if JSON::PP is not installed even when --json is not requested.

What version of perl are you using?

I believe JSON is bundled since perl 5.14

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This module is only needed with the --json option. Use "require" to load this module dynamically inside the "if ($json)" block instead.

The patch may be sensible but could fail the same way if you used the --json option with your version.

scripts/get_maintainer.pl

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scripts/get_maintainer.pl +0 -0

[]

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scripts/get_maintainer.pl +0 -1

@@ -21,7 +21,6 @@ use Cwd;
 use File::Find;
 use File::Spec::Functions;
 use open qw(:std :encoding(UTF-8));
-use JSON::PP;
 
 my $cur_path = fastgetcwd() . '/';
 my $lk_path = "./";

@@ -685,6 +684,7 @@ if ($json) {
     $result{web} = \@web if ($web);
     $result{bug} = \@bug if ($bug);
 

scripts/get_maintainer.pl if ($json) { · line 687

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scripts/get_maintainer.pl +1 -0

+    require JSON::PP;

style nit:
I likely would have placed this require immediately after the if ($json) {

Quoted 1 line · Joe Perches

On Fri, 2026-10-30 at 16:43 +0100, Oleg Nesterov wrote:

After commit 09d8b39563e8 ("get_maintainer: add --json output mode"),

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I can no longer use get_maintainer.pl; it fails at compile time

Just verifying that you mean when using perl directly and not something like perlcc.

Yes,

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if JSON::PP is not installed even when --json is not requested.

What version of perl are you using?

v5.42.3

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I believe JSON is bundled since perl 5.14

Well, JSON::PP is not installed on my Fedora release 44

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This module is only needed with the --json option. Use "require" to load this module dynamically inside the "if ($json)" block instead.

The patch may be sensible but could fail the same way if you used the --json option with your version.

Of course, "./scripts/get_maintainer.pl --json ..." will still fail the same way without JSON::PP. But with this patch get_maintainer.pl works without the --json option.

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scripts/get_maintainer.pl

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scripts/get_maintainer.pl +0 -0

[]

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scripts/get_maintainer.pl +0 -1

@@ -21,7 +21,6 @@ use Cwd;
 use File::Find;
 use File::Spec::Functions;
 use open qw(:std :encoding(UTF-8));
-use JSON::PP;
 
 my $cur_path = fastgetcwd() . '/';
 my $lk_path = "./";

@@ -685,6 +684,7 @@ if ($json) {
     $result{web} = \@web if ($web);
     $result{bug} = \@bug if ($bug);
 

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scripts/get_maintainer.pl if ($json) { · line 687

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scripts/get_maintainer.pl +1 -0

+    require JSON::PP;

style nit:
I likely would have placed this require immediately after the if ($json) {

I am fine either way... should I send V2 ?

Quoted 3 lines · Oleg Nesterov

Quoted 2 lines · Joe Perches

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This module is only needed with the --json option. Use "require" to load this module dynamically inside the "if ($json)" block instead.

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The patch may be sensible but could fail the same way if you used the --json option with your version.

Of course, "./scripts/get_maintainer.pl --json ..." will still fail the same way without JSON::PP. But with this patch get_maintainer.pl works without the --json option.

What does that failure output?

Dunno. Depending on the current failure output
maybe adding something like the below is better:

use Module::Load::Conditional qw(check_install);

if (!check_install(module => 'JSON:PP')) {
    die "$P: --json not available - missing perl module JSON:PP\n";
}

Quoted 8 lines · Joe Perches

Dunno. Depending on the current failure output
maybe adding something like the below is better:

use Module::Load::Conditional qw(check_install);

if (!check_install(module => 'JSON:PP')) {
    die "$P: --json not available - missing perl module JSON:PP\n";
}

But why? Why make get_maintainer.pl depend on yet another module? FYI, on my Fedora 44

	$ perl -we 'use Module::Load::Conditional qw(check_install);'
	Can't locate Module/Load/Conditional.pm in @INC (you may need to install the Module::Load::Conditional module) (@INC entries checked: /usr/local/lib64/perl5/5.42 /usr/local/share/perl5/5.42 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5) at -e line 1.
	BEGIN failed--compilation aborted at -e line 1.

And for what ???

If we want to "improve" the errmsg, we can use "eval { require JSON::PP; }; die ... if $@" but this looks absolutely pointless to me.

Let me repeat. If JSON::PP is not installed, then get_maintainer.pl with --json:

fails the same way before or after this patch, I see nothing to improve.

without --json:

fails before this patch, works after this patch

Sorry, I really can't understand your concerns.

Quoted 9 lines · Joe Perches

Quoted 7 lines · Oleg Nesterov

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This module is only needed with the --json option. Use "require" to load this module dynamically inside the "if ($json)" block instead.

The patch may be sensible but could fail the same way if you used the --json option with your version.

Of course, "./scripts/get_maintainer.pl --json ..." will still fail the same way without JSON::PP. But with this patch get_maintainer.pl works without the --json option.

What does that failure output?

Hmm. I am not sure I understand you concerns. Let me add more details. So, I think this patch makes no difference if JSON::PP is installed. Do you agree?

Now lets see what happens on my machine where JSON::PP is NOT installed. Without --json:

Before this patch:

	$ ./scripts/get_maintainer.pl ./scripts/get_maintainer.pl
	Can't locate JSON/PP.pm in @INC (you may need to install the JSON::PP module) (@INC entries checked: /usr/local/lib64/perl5/5.42 /usr/local/share/perl5/5.42 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5) at ./scripts/get_maintainer.pl line 24.
	BEGIN failed--compilation aborted at ./scripts/get_maintainer.pl line 24.

After:

	$ ./scripts/get_maintainer.pl ./scripts/get_maintainer.pl
	Joe Perches <[[email protected]](mailto:[email protected])> (maintainer:GET_MAINTAINER SCRIPT)
	[[email protected]](mailto:[email protected]) (open list)

With --json:

Before this patch:

	$ ./scripts/get_maintainer.pl --json ./scripts/get_maintainer.pl
	Can't locate JSON/PP.pm in @INC (you may need to install the JSON::PP module) (@INC entries checked: /usr/local/lib64/perl5/5.42 /usr/local/share/perl5/5.42 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5) at ./scripts/get_maintainer.pl line 24.
	BEGIN failed--compilation aborted at ./scripts/get_maintainer.pl line 24.

After:

	$ ./scripts/get_maintainer.pl --json ./scripts/get_maintainer.pl
	Can't locate JSON/PP.pm in @INC (you may need to install the JSON::PP module) (@INC entries checked: /usr/local/lib64/perl5/5.42 /usr/local/share/perl5/5.42 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5) at ./scripts/get_maintainer.pl line 665.

Same failure. Sorry, I don't understand what is not clear for you :(

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Dunno. Depending on the current failure output
maybe adding something like the below is better:

use Module::Load::Conditional qw(check_install);

if (!check_install(module => 'JSON:PP')) {
    die "$P: --json not available - missing perl module JSON:PP\n";
}

But why? Why make get_maintainer.pl depend on yet another module? FYI, on my Fedora 44

	$ perl -we 'use Module::Load::Conditional qw(check_install);'
	Can't locate Module/Load/Conditional.pm in @INC (you may need to install the Module::Load::Conditional module) (@INC entries checked: /usr/local/lib64/perl5/5.42 /usr/local/share/perl5/5.42 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5) at -e line 1.
	BEGIN failed--compilation aborted at -e line 1.

And for what ???

If we want to "improve" the errmsg, we can use "eval { require JSON::PP; }; die ... if $@" but this looks absolutely pointless to me.

Quoted 13 lines · Oleg Nesterov

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Dunno. Depending on the current failure output
maybe adding something like the below is better:

use Module::Load::Conditional qw(check_install);

if (!check_install(module => 'JSON:PP')) {
    die "$P: --json not available - missing perl module JSON:PP\n";
}

But why? Why make get_maintainer.pl depend on yet another module? FYI, on my Fedora 44

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	$ perl -we 'use Module::Load::Conditional qw(check_install);'
	Can't locate Module/Load/Conditional.pm in @INC (you may need to install the Module::Load::Conditional module) (@INC entries checked: /usr/local/lib64/perl5/5.42 /usr/local/share/perl5/5.42 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5) at -e line 1.
	BEGIN failed--compilation aborted at -e line 1.

Module::Load is a core perl module since 5.10 and

I think you are using a broken version of a perl installation

and I think you should:

$ sudo dnf install perl-core

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And for what ???

My idea is to make it more obvious _why_ something fails and not like get_maintainer itself is broken.

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If we want to "improve" the errmsg, we can use "eval { require JSON::PP; }; die ... if $@" but this looks absolutely pointless to me.

We disagree. I prefer output errors to look less broken.

Quoted 1 line · Joe Perches

On Fri, 2026-10-30 at 22:44 +0100, Oleg Nesterov wrote:

Dunno. Depending on the current failure output

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maybe adding something like the below is better:

use Module::Load::Conditional qw(check_install);

if (!check_install(module => 'JSON:PP')) {
    die "$P: --json not available - missing perl module JSON:PP\n";
}

But why? Why make get_maintainer.pl depend on yet another module? FYI, on my Fedora 44

	$ perl -we 'use Module::Load::Conditional qw(check_install);'
	Can't locate Module/Load/Conditional.pm in @INC (you may need to install the Module::Load::Conditional module) (@INC entries checked: /usr/local/lib64/perl5/5.42 /usr/local/share/perl5/5.42 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5) at -e line 1.
	BEGIN failed--compilation aborted at -e line 1.

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Module::Load is a core perl module since 5.10 and
I think you are using a broken version of a perl installation

And how do you think it is broken? my laptop runs the fresh Fedora 44.

I used ./scripts/get_maintainer.pl many years, almost every day, and I never needed to install the additional modules. Until ("get_maintainer: add --json output mode")

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and I think you should:

$ sudo dnf install perl-core

Oh. I LOVE perl. Damn I still consider myself as a perl programmer ;)

But why do you think I should install the additional modules (which I will never use) on my machine???

Again, again, again. AFAICS, this patch makes no difference if JSON::PP is installed. Please correct me.

It just allows to use get_maintainer.pl without --json in the case when JSON::PP is NOT installed. This is the ONLY difference afaics.

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And for what ???

My idea is to make it more obvious _why_ something fails and not like get_maintainer itself is broken.

Good idea! But again, again, again, if JSON::PP is not installed, then the failure message is the same with or without my patch. Just get_maintainer.pl does NOT fail without --json.

Although to be honest "Can't locate JSON/PP.pm ..." looks very clear to me, but you can make it more obvious with or without my patch.

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If we want to "improve" the errmsg, we can use "eval { require JSON::PP; }; die ... if $@" but this looks absolutely pointless to me.

We disagree. I prefer output errors to look less broken.

less broken than what? see above.

It's not that we disagree... Worse, we can't understand each other :( Perhaps is this my fault.

Quoted 8 lines · Oleg Nesterov

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But why? Why make get_maintainer.pl depend on yet another module? FYI, on my Fedora 44

	$ perl -we 'use Module::Load::Conditional qw(check_install);'
	Can't locate Module/Load/Conditional.pm in @INC (you may need to install the Module::Load::Conditional module) (@INC entries checked: /usr/local/lib64/perl5/5.42 /usr/local/share/perl5/5.42 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5) at -e line 1.
	BEGIN failed--compilation aborted at -e line 1.

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Module::Load is a core perl module since 5.10 and
I think you are using a broken version of a perl installation

And how do you think it is broken? my laptop runs the fresh Fedora 44.

It doesn't include perl-core ;)

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I used ./scripts/get_maintainer.pl many years, almost every day, and I never needed to install the additional modules. Until ("get_maintainer: add --json output mode")

I think that was added in Linus' 7.2 in mid August and in -next since April

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It's not that we disagree... Worse, we can't understand each other :( Perhaps is this my fault.

I don't disagree with the concept of the patch.

I think we understand each other fine, you just care less about the output error message.

Quoted 3 lines · Joe Perches

Quoted 2 lines · Oleg Nesterov

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But why? Why make get_maintainer.pl depend on yet another module? FYI, on my Fedora 44

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Module::Load is a core perl module since 5.10 and
I think you are using a broken version of a perl installation

And how do you think it is broken? my laptop runs the fresh Fedora 44.

It doesn't include perl-core ;)

you can blame the Fedora maintainers, not me ;)

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I used ./scripts/get_maintainer.pl many years, almost every day, and I never needed to install the additional modules. Until ("get_maintainer: add --json output mode")

I think that was added in Linus' 7.2 in mid August and in -next since April

Yes, I hit this problem months ago, but didn't have time to send the fix.

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I don't disagree with the concept of the patch.

Great, then perhaps you can ACK my trivial patch? Then we can discuss the possible improvements.

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I think we understand each other fine, you just care less about the output error message.

Yes, it is true in that I don't really care about the output error message.

But then again. This error message can only happen if JSON::PP is not installed, and my patch doesn't make it worse?

Quoted 5 lines · Oleg Nesterov

Quoted 2 lines · Joe Perches

I think that was added in Linus' 7.2 in mid August and in -next since April

Yes, I hit this problem months ago, but didn't have time to send the fix.

Nor apparently have time to send an email to the get_maintainer maintainer about it either.

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Great, then perhaps you can ACK my trivial patch? Then we can discuss the possible improvements.

Maybe when it's done without needing updates.

In the meantime, you have an easy workaround with dnf install perl-core.