julia

7239fecd - inference: Model always-throwing `modifyfield!`/`replacefield!` as `Bottom` (#62235)

inference: Model always-throwing `modifyfield!`/`replacefield!` as `Bottom` (#62235) `setfield!_tfunc`, `swapfield!_tfunc` and `setfieldonce!_tfunc` already return `Bottom` when the targeted field can never be written, namely a `const` field or a field of an immutable type, since the underlying store always throws. `modifyfield!_tfunc` and `replacefield!_tfunc` did not perform that check and instead reported a `Pair`/cmpswap result type, so an operation that can only ever throw was not recognized as such. Guard both tfuncs through `setfield!_tfunc`. `modifyfield!` stores `op(o.f, v)` rather than `v`, so the simple tfunc only consults field writability (passing `Any` as the value; the result is refined precisely in `abstract_modifyop!`, the direct-call path that derives its return type from `modifyfield!_tfunc`). `replacefield!` type-checks the replacement `v` before the comparison and therefore throws even when the comparison would have failed, so `v` is consulted as well — this also models a replacement value that can never be stored into the field. Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>