Re: [php-src] PR #20903: GH-10497 (const obj->prop write) - language change notes

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* On Thu, Jan 22, 2026 at 10:33 AM Tim Düsterhus <tim@bastelstu.be> wrote: > 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 >