ext/intl: Guard Spoofchecker restriction-level APIs at ICU 53 (fix build on ICU 50.x)

[GrahamCampbell]

PHP 8.4.22 fails to compile the intl extension when the system ICU is older than 53 — on Amazon Linux 2 (system ICU 50.2) the build breaks with USPOOF_ASCII, the other Spoofchecker restriction-level constants, and URestrictionLevel undeclared. The cause is GH-22055 (fixing #22053), which removed the #if U_ICU_VERSION_MAJOR_NUM >= 58 guards around the Spoofchecker restriction-level constants and the setRestrictionLevel() method, so they are now referenced unconditionally.

This is fine on master and PHP-8.5 (icu-uc >= 57.1) but not on PHP-8.4, which still accepts icu-uc >= 50.1. The symbols have existed since ICU 51 except USPOOF_SINGLE_SCRIPT_RESTRICTIVE (ICU 53, used in the setRestrictionLevel() body); since 50.2 satisfies the 50.1 minimum, configure passes and only the compile fails. ICU 53 is therefore the right floor: guarding at >= 53 builds on every ICU PHP-8.4 supports while still exposing the API on ICU 53+ — which is what GH-22055 wanted, since its >= 58 guard was too strict and hid the API on ICU 57.x.

The fix restores the guard at #if U_ICU_VERSION_MAJOR_NUM >= 53 around the constants and setRestrictionLevel() in spoofchecker.stub.php (regenerating spoofchecker_arginfo.h) and around the setRestrictionLevel() body in spoofchecker_main.c. The unrelated setAllowedChars() message change is kept.

[LamentXU123]

Indeed correct analysis. I wasn't aware PHP 8.4 has a different minimum ICU version than 8.5 and 8.6. Thank you for this PR!

[LamentXU123]

@GrahamCampbell We may need to add this into the PHP 8.4 NEWS file to notice others that we fix this.
This should only be merged into 8.4 so I will create 2 blank commit on upper branches (i.e. 8.5 and master)
For hardening reasons this can also be merged into upper branches (PHP 8.5 and master) without NEWS just in case if in the future we lower the minimum supported version.

[GrahamCampbell]

Added a news entry.

[LamentXU123]

@GrahamCampbell Thank you. The PR looks good and we will merge it if @devnexen has no opinions :)

[devnexen]

none I just wanted to see how you do :)

[LamentXU123]

Ideally, we may still want to support ICU 51 since it is technically >50.1, which is our minimum supported version in 8.4. So I'd suggest to only guard USPOOF_SINGLE_SCRIPT_RESTRICTIVE under ICU 53 and guard the rest under ICU 51. This benefit people who are using 51 < ICU version < 53 that they should have access to these const that exists since ICU 51

That is, I suggest to change this guard to >= 51 and specifically list USPOOF_SINGLE_SCRIPT_RESTRICTIVE out and put it in a ICU >= 53 guard.

[GrahamCampbell]

I dug into the ICU headers and php-src history, and I think >= 53 is intentional here.

In ICU 51/52, URestrictionLevel, uspoof_setRestrictionLevel(), and the restriction-level constants are still draft API behind U_HIDE_DRAFT_API. PHP does not force U_SHOW_DRAFT_API, so guarding only on U_ICU_VERSION_MAJOR_NUM >= 51 would rely on ICU draft APIs being visible. The enum values also changed in ICU 53 when USPOOF_SINGLE_SCRIPT_RESTRICTIVE was added.

Since PHP’s setRestrictionLevel() implementation validates against USPOOF_SINGLE_SCRIPT_RESTRICTIVE, and the tests exercise that constant, ICU 53 is the first version where the PHP-visible API is consistent and stable enough to expose as a group.

What do you think?

[LamentXU123]

Fair :) Sounds reasonable I will have a closer look later today. Thank you for your work!