# [php-src] PR #20903: GH-10497 (const obj->prop write) - language change notes - Thread: https://externals.io/message/129757 - Original archive: https://news-web.php.net/php.internals/129757 - Started by Khaled Alam on 2026-01-15T06:36:03+00:00 - Messages: 17 - Reply by email to internals@lists.php.net - More for agents: search with https://externals.io/search.md?q={query} · JSON API at https://externals.io/api · documentation at https://externals.io/llms.txt --- ## #129757 — Khaled Alam — 2026-01-15T06:36:03+00:00 URL: https://externals.io/message/129757#129757 Hi internals, I opened PR #20903 to address GH-10497 by allowing writes to properties of objects referenced by consts (const binding stays immutable, referenced objects can be mutable). class C { public int $x = 0; } const OBJ = new C(); OBJ->x = 1; // currently rejected, PR makes it valid var_dump(OBJ->x); // 1 Notes: - This is a language/semantics change and may overlap with / impact GH-13800 . - A potentially surprising case: some newly-valid writes can be a no-op when they target a temporary const value, e.g. - const X = [1,2,3]; X[] = 4; - const Y = ['a' => 1]; Y['b'] = 2; These become valid syntax but have no effect because the write happens on a temporary basis. Feedback on semantics + expected behavior for the temporary-write case is appreciated. Thanks, __ *Khaled Alam* --- ## #129779 — tim@bastelstu.be — 2026-01-18T12:28:22+00:00 URL: https://externals.io/message/129757#129779 · In reply to: #129757 Hi > A potentially surprising case: some newly-valid writes can be a no-op > when they target a temporary const value, e.g. > - const X = [1,2,3]; X[] = 4; > - const Y = ['a' => 1]; Y['b'] = 2; > > These become valid syntax but have no effect because the write happens on a > temporary basis. > > Feedback on semantics + expected behavior for the temporary-write case is > appreciated. This is too unexpected / error-prone for me. Trying to write into arrays should remain disallowed / an Error, since this is never (?) useful. For objects, I don't have a strong opinion, but I expect objects in constants to be so rare that it probably isn't worth it to make a change at all. Best regards Tim Düsterhus --- ## #129835 — Ilija Tovilo — 2026-01-21T23:33:06+00:00 URL: https://externals.io/message/129757#129835 · In reply to: #129779 Hi Tim > > > > […] > > This is too unexpected / error-prone for me. Trying to write into arrays > should remain disallowed / an Error, since this is never (?) useful. No strong opinions on my part, but I'd like to point out that similar situations already exist. https://3v4l.org/ARMMS#v8.4.14 const C = [1, 2, 3]; function foo(): array { return C; } foo()[] = 4; var_dump(C); PHP will happily duplicate the array returned from foo() to append 4, without warning. The original array in C remains unmodified. It might make sense for ASSIGN_DIM to warn/throw if OP1 is not a "pointer" (indirect, reference or object), as then the operation will never have an effect. But it seems to me this is a distinct issue. Ilija --- ## #129839 — tim@bastelstu.be — 2026-01-22T08:31:16+00:00 URL: https://externals.io/message/129757#129839 · In reply to: #129835 Hi Am 2026-01-22 00:33, schrieb Ilija Tovilo: > No strong opinions on my part, but I'd like to point out that similar > situations already exist. > > https://3v4l.org/ARMMS#v8.4.14 > > const C = [1, 2, 3]; > function foo(): array { > return C; > } > foo()[] = 4; > var_dump(C); > > PHP will happily duplicate the array returned from foo() to append 4, > without warning. The original array in C remains unmodified. It might I'm aware. However to me this situation is a little different, intuition-wise: A return value already looks and feels like a temporary value to me (unless a by-ref return is used, of course, but those are rare). An access on a const does not. > make sense for ASSIGN_DIM to warn/throw if OP1 is not a "pointer" > (indirect, reference or object), as then the operation will never have > an effect. But it seems to me this is a distinct issue. That makes sense to me and IMO is a necessary precursor for this. Best regards Tim Düsterhus --- ## #130557 — Khaled Alam — 2026-04-04T00:52:34+00:00 URL: https://externals.io/message/129757#130557 · In reply to: #129839 Hi internals, I'd like to bring attention back to this RFC, which has been updated to v0.2 based on prior feedback: https://wiki.php.net/rfc/const_object_property_write Summary: This RFC proposes allowing property write operations (->) on objects referenced by constants. Currently, CONST_OBJ->prop = value produces "Cannot use temporary expression in write context", even though the operation mutates the object, not the constant binding. What changed since the initial discussion (Jan 2026): - Addressed Tim Düsterhus's and Ilija Tovilo's feedback regarding array constant dim writes. The RFC now explicitly scopes out dim/array writes and documents the "silent no-op" concern in a dedicated section. A future RFC can address whether ASSIGN_DIM on non-pointer OP1 should warn/throw — this is acknowledged as a valid but distinct issue. - Added by-reference passing support (BP_VAR_FUNC_ARG path), with tests. - Added guardrail tests confirming that dim writes on constants, dim writes on constant objects, and constant rebinding all remain unchanged. - Updated the gh12102_3.phpt test: passing an array constant element by-ref now correctly throws an Error instead of silently operating on a temporary copy. PR: https://github.com/php/php-src/pull/20903 I'd appreciate any feedback before moving this to a formal vote. Best regards, __ *Khaled Alam* > Hi > > Am 2026-01-22 00:33, schrieb Ilija Tovilo: > > […] > > I'm aware. However to me this situation is a little different, > intuition-wise: A return value already looks and feels like a temporary > value to me (unless a by-ref return is used, of course, but those are > rare). An access on a const does not. > > > […] > > That makes sense to me and IMO is a necessary precursor for this. > > Best regards > Tim Düsterhus --- ## #130593 — tim@bastelstu.be — 2026-04-09T08:39:21+00:00 URL: https://externals.io/message/129757#130593 · In reply to: #130557 Hi Am 2026-04-04 02:52, schrieb Khaled Alam: > I'd like to bring attention back to this RFC, which has been updated to > v0.2 based on prior feedback: > > https://wiki.php.net/rfc/const_object_property_write Thank you. The updated RFC makes sense to me and with the removal of the `FOO[123] = 'bar';` support I don't have any further technical concerns. With regard to the RFC policy, I just added the necessary “Abstain” option to the vote. I'm also noting some rendering issues in the RFC, particularly in the Proposal section, where the “bullet point list” does not render properly, due to the line-breaks in the markup. I'm also seeing that you try to use the markdown syntax for inline code. That doesn't work in the Wiki, since it doesn't speak markdown. When showcasing PHP code, I recommend using isset() tags ( XML tag). For non-PHP-Code ''BP_VAR_FUNC_ARG'' (two single-quotes works). You might want to clean-up both of these, it will make the RFC look much nicer and more approachable. Please note that your RFC update is considered a major change, so it needs 14 days of “cooldown” for discussion, before the RFC can go to vote. Best regards Tim Düsterhus --- ## #130606 — Khaled Alam — 2026-04-11T08:14:22+00:00 URL: https://externals.io/message/129757#130606 · In reply to: #130593 Hi Tim, > With regard to the RFC policy, I just added the necessary “Abstain” > option to the vote. > > I'm also noting some rendering issues in the RFC, particularly in the > Proposal section, where the “bullet point list” does not render > properly, due to the line-breaks in the markup. I'm also seeing that you > try to use the markdown syntax for inline code. That doesn't work in the > Wiki, since it doesn't speak markdown. When showcasing PHP code, I > recommend using isset() tags ( XML tag). For > non-PHP-Code ''BP_VAR_FUNC_ARG'' (two single-quotes works). You might > want to clean-up both of these, it will make the RFC look much nicer and > more approachable. > > Please note that your RFC update is considered a major change, so it > needs 14 days of “cooldown” for discussion, before the RFC can go to > vote. Thanks for the feedback, I just fixed the RFC rendering issues. Best regards, __ *Khaled Alam* > Hi > > Am 2026-04-04 02:52, schrieb Khaled Alam: > > […] > > Thank you. The updated RFC makes sense to me and with the removal of the > `FOO[123] = 'bar';` support I don't have any further technical concerns. > > With regard to the RFC policy, I just added the necessary “Abstain” > option to the vote. > > I'm also noting some rendering issues in the RFC, particularly in the > Proposal section, where the “bullet point list” does not render > properly, due to the line-breaks in the markup. I'm also seeing that you > try to use the markdown syntax for inline code. That doesn't work in the > Wiki, since it doesn't speak markdown. When showcasing PHP code, I > recommend using isset() tags ( XML tag). For > non-PHP-Code ''BP_VAR_FUNC_ARG'' (two single-quotes works). You might > want to clean-up both of these, it will make the RFC look much nicer and > more approachable. > > Please note that your RFC update is considered a major change, so it > needs 14 days of “cooldown” for discussion, before the RFC can go to > vote. > > Best regards > Tim Düsterhus --- ## #131440 — Khaled Alam — 2026-06-21T18:28:12+00:00 URL: https://externals.io/message/129757#131440 · In reply to: #130606 Hi all, Reviving this thread. The v0.2 RFC (object property writes on constants only; array/dim writes removed) addressed Tim's concerns, and the 14-day cooldown has long passed. Unless there are further objections, I intend to open voting on Monday, 29 June 2026. 2/3 majority, targets PHP 8.6, two-week vote. RFC: https://wiki.php.net/rfc/const_object_property_write PR: https://github.com/php/php-src/pull/20903 Best regards, __ *Khaled Alam* On Sat, Apr 11, 2026 at 3:14 PM Khaled Alam wrote: > Hi Tim, > > > > […] > > Thanks for the feedback, I just fixed the RFC > rendering issues. > > Best regards, > __ > > *Khaled Alam* > > > > > > […] --- ## #131441 — Claude Pache — 2026-06-21T20:01:18+00:00 URL: https://externals.io/message/129757#131441 · In reply to: #131440 > Le 21 juin 2026 à 20:33, Khaled Alam a écrit : > >  > Hi all, > > Reviving this thread. The v0.2 RFC (object property writes on constants only; > array/dim writes removed) addressed Tim's concerns, and the 14-day cooldown has long passed. > > Unless there are further objections, I intend to open voting on Monday, 29 June 2026. 2/3 majority, > targets PHP 8.6, two-week vote. > > RFC: https://wiki.php.net/rfc/const_object_property_write > PR: https://github.com/php/php-src/pull/20903 > > Best regards, > __ > Khaled Alam Hi, The RFC talks only about global constants. What about class constants? It is somewhat cumbersome to get a mutable object in this position, but it is nevertheless possible, and, at least for consistency, it should be ensured that they are treated the same way as global constants: https://3v4l.org/QhM1L —Claude --- ## #131550 — Khaled Alam — 2026-06-28T07:50:45+00:00 URL: https://externals.io/message/129757#131550 · In reply to: #131441 > Hi, > The RFC talks only about global constants. What about class constants? It is somewhat > cumbersome to get a mutable object in this position, but it is nevertheless possible, and, > at least for consistency, it should be ensured that they are treated the same way as global constants: > https://3v4l.org/QhM1L Hi Claude, Good point, thanks. I've extended the implementation so they're handled the same way; both forms from your example now work: c::o->b = 42; $c::o->b = 42; One consequence worth flagging: enum cases are class constants, so unset(Enum::Case->value) (and writes to readonly case properties) now raise the regular runtime readonly-property Error instead of the old compile-time "temporary expression" error, i.e. identical to $x = Enum::Case; unset($x->value);. Enum case properties remain immutable. I've updated the PR (#20903) and bumped the RFC to v0.3 to cover this. Since it widens the scope, I'll restart the discussion cooldown and push the vote date back accordingly. Best regards, __ *Khaled Alam* On Mon, Jun 22, 2026 at 12:01 AM Claude Pache wrote: > > > Le 21 juin 2026 à 20:33, Khaled Alam a écrit : > >  > Hi all, > > Reviving this thread. The v0.2 RFC > (object property > writes on constants only; > array/dim writes removed) addressed Tim's concerns, and the 14-day > cooldown has long passed. > > Unless there are further objections, I intend to open voting on Monday, 29 > June 2026. 2/3 majority, > targets PHP 8.6, two-week vote. > > RFC: https://wiki.php.net/rfc/const_object_property_write > PR: https://github.com/php/php-src/pull/20903 > > Best regards, > __ > *Khaled Alam* > > > Hi, > > The RFC talks only about global constants. What about class constants? It > is somewhat cumbersome to get a mutable object in this position, but it is > nevertheless possible, and, at least for consistency, it should be ensured > that they are treated the same way as global constants: > > https://3v4l.org/QhM1L > > > > —Claude --- ## #131618 — tim@bastelstu.be — 2026-06-29T19:55:13+00:00 URL: https://externals.io/message/129757#131618 · In reply to: #131550 Hi Am 2026-06-28 09:50, schrieb Khaled Alam: > I've updated the PR (#20903) and bumped the RFC > to v0.3 to cover > this. Since it widens the scope, > I'll restart the discussion cooldown and push the vote date back > accordingly. Thank you. I've had a look at the changes you made and I'm noticing that you added a second voting widget by accident. Can you double-check the diff and revert the accidental changes? https://wiki.php.net/rfc/const_object_property_write?do=diff&rev2%5B0%5D=1775894869&rev2%5B1%5D=1782632547&difftype=sidebyside I'm also noticing just now that the RFC is not listed in the RFC overview at https://wiki.php.net/rfc (and itself has the status “Draft”). Can you make sure to list the RFC in “Under Discussion”? It could technically be argued that the discussion didn't properly happen, but as you made a recent change that resets the cooldown anyway and there's still a bit of time until feature freeze that shouldn't be an issue. Best regards Tim Düsterhus --- ## #131867 — Khaled Alam — 2026-07-11T10:38:19+00:00 URL: https://externals.io/message/129757#131867 · In reply to: #131618 > Hi > Thank you. I've had a look at the changes you made and I'm noticing that > you added a second voting widget by accident. Can you double-check the > diff and revert the accidental changes? > https://wiki.php.net/rfc/const_object_property_write?do=diff&rev2%5B0%5D=1775894869&rev2%5B1%5D=1782632547&difftype=sidebyside > I'm also noticing just now that the RFC is not listed in the RFC > overview at https://wiki.php.net/rfc (and itself has the status > “Draft”). Can you make sure to list the RFC in “Under Discussion”? It > could technically be argued that the discussion didn't properly happen, > but as you made a recent change that resets the cooldown anyway and > there's still a bit of time until feature freeze that shouldn't be an > issue. Hi Tim, Thanks for catching these. I removed the accidental duplicate voting content and added the RFC to the “Under Discussion” section of the RFC overview page. Best regards, __ *Khaled Alam* > Hi > > Am 2026-06-28 09:50, schrieb Khaled Alam: > > […] > > Thank you. I've had a look at the changes you made and I'm noticing that > you added a second voting widget by accident. Can you double-check the > diff and revert the accidental changes? > > > https://wiki.php.net/rfc/const_object_property_write?do=diff&rev2%5B0%5D=1775894869&rev2%5B1%5D=1782632547&difftype=sidebyside > > I'm also noticing just now that the RFC is not listed in the RFC > overview at https://wiki.php.net/rfc (and itself has the status > “Draft”). Can you make sure to list the RFC in “Under Discussion”? It > could technically be argued that the discussion didn't properly happen, > but as you made a recent change that resets the cooldown anyway and > there's still a bit of time until feature freeze that shouldn't be an > issue. > > Best regards > Tim Düsterhus --- ## #131883 — tim@bastelstu.be — 2026-07-13T14:09:38+00:00 URL: https://externals.io/message/129757#131883 · In reply to: #131867 Hi > Thanks for catching these. I removed the accidental duplicate voting > content and added the RFC to the “Under Discussion” section of the RFC > overview page. Thank you. You missed the status in the RFC itself, which I have now done for you: https://wiki.php.net/rfc/const_object_property_write?do=diff&rev2%5B0%5D=1783766078&rev2%5B1%5D=1783951590&difftype=sidebyside I consider your change on Saturday to be the last (major) change to the RFC. You may then open the vote on on July 25th. Vote must start no later than July 28th to meet the deadline for PHP 8.6. Don't forget to send the “intent to vote” 2-7 days before actually starting the vote. Best regards Tim Düsterhus --- ## #132006 — Khaled Alam — 2026-07-17T23:39:24+00:00 URL: https://externals.io/message/129757#132006 · In reply to: #131883 Hi Tim and internals, Thank you all for the feedback and discussion on the "Const object property write" RFC over the past weeks The RFC text has been stable since last weekend, and I believe the remaining questions have been addressed. I therefore intend to open the vote on Saturday, July 25th. The voting period will run for the standard two weeks. This gives us time to complete the vote and merge in time for the PHP 8.6 feature freeze. RFC: https://wiki.php.net/rfc/const_object_property_write If there are any final objections or concerns that should be resolved before the vote opens, please raise them in the next few days so I can address them before Saturday. Best regards, __ *Khaled Alam* > Hi > > > > […] > > Thank you. You missed the status in the RFC itself, which I have now > done for you: > > https://wiki.php.net/rfc/const_object_property_write?do=diff&rev2%5B0%5D=1783766078&rev2%5B1%5D=1783951590&difftype=sidebyside > > I consider your change on Saturday to be the last (major) change to the > RFC. You may then open the vote on on July 25th. Vote must start no > later than July 28th to meet the deadline for PHP 8.6. Don't forget to > send the “intent to vote” 2-7 days before actually starting the vote. > > Best regards > Tim Düsterhus --- ## #132099 — Khaled Alam — 2026-07-25T13:48:56+00:00 URL: https://externals.io/message/129757#132099 · In reply to: #132006 Hi internals, As announced previously, I am now opening the vote for the RFC *“Allow Object Property Writes on Objects Referenced by Constants.”* RFC and voting: https://wiki.php.net/rfc/const_object_property_write The vote will remain open for the standard two-week period and will close on *Saturday, August 8, 2026, at 23:59 UTC*. I would like to thank everyone who participated in the discussion and provided feedback. The comments and suggestions helped improve the proposal considerably. Best regards, __ *Khaled Alam* On Sat, Jul 18, 2026 at 2:39 AM Khaled Alam wrote: > Hi Tim and internals, > > Thank you all for the feedback and discussion on the "Const object > property write" RFC over the past weeks > > The RFC text has been stable since last weekend, and I believe the > remaining questions have been addressed. > > I therefore intend to open the vote on Saturday, July 25th. The voting > period will run for the standard two weeks. > > This gives us time to complete the vote and merge in time for the PHP 8.6 > feature freeze. > > RFC: https://wiki.php.net/rfc/const_object_property_write > > If there are any final objections or concerns that should be resolved > before the vote opens, please raise them in the next few days so I can > address them before Saturday. > > Best regards, > __ > > *Khaled Alam* > > > > > > […] --- ## #132100 — Bob Weinand — 2026-07-25T14:22:01+00:00 URL: https://externals.io/message/129757#132100 · In reply to: #132099 Hey Khaled Am 25.07.2026 um 15:48 schrieb Khaled Alam : Hi internals, As announced previously, I am now opening the vote for the RFC “Allow Object Property Writes on Objects Referenced by Constants.” RFC and voting: https://wiki.php.net/rfc/const_object_property_write The vote will remain open for the standard two-week period and will close on Saturday, August 8, 2026, at 23:59 UTC. I would like to thank everyone who participated in the discussion and provided feedback. The comments and suggestions helped improve the proposal considerably. Best regards, __ Khaled Alam Could you please re-submit this mail in its own thread? Titled "[RFC][VOTE] Allow Object Property Writes on Objects Referenced by Constants" This gives it the correct visibility. Thank you! Bob --- ## #132101 — Ilija Tovilo — 2026-07-25T15:07:19+00:00 URL: https://externals.io/message/129757#132101 · In reply to: #132099 Hi Khaled > > As announced previously, I am now opening the vote for the RFC *“Allow > Object Property Writes on Objects Referenced by Constants.”* > > RFC and voting: https://wiki.php.net/rfc/const_object_property_write > > The vote will remain open for the standard two-week period and will > close on *Saturday, August 8, 2026, at 23:59 UTC*. > > I would like to thank everyone who participated in the discussion and > provided feedback. The comments and suggestions helped improve the > proposal considerably. > You seem to be missing the abstain option, which is mandatory since https://wiki.php.net/rfc/rfc_vote_abstain. Ilija