Add length property to cartesianProduct for finite forward ranges

[manavgupta26]

Adds a length property to cartesianProduct when all input ranges
are finite forward ranges supporting length.

The length is computed as the product of the input ranges' lengths.

Fixes https://issues.dlang.org/show_bug.cgi?id=9871

[dlang-bot]

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If your PR contains non-trivial changes, please reference a Bugzilla issue or create a manual changelog.

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + phobos#10960"

[pbackus]

1. Please remove all changes to the indentation of existing code.
2. 9871 is the Github issue number, not the issues.dlang.org number. Please change the relevant line in the commit PR description to Fixes issue 9871 .

[pbackus]

Closing because the author has resubmitted in #10961.

[manavgupta26]

Hi, Can you check now Added the unit tests with proper indentation

…

On Sat, Feb 21, 2026 at 9:07 PM Paul Backus ***@***.***> wrote: *pbackus* left a comment (dlang/phobos#10960) <#10960 (comment)> Closing because the author has resubmitted in #10961 <#10961>. — Reply to this email directly, view it on GitHub <#10960 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/A5VYG3TCKFP4AHDC5LE7NGT4NB3TDAVCNFSM6AAAAACV3KZY7OVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTSMZYHE3TCNBWGI> . You are receiving this because you authored the thread.Message ID: ***@***.***>