fix: allow bare None for Option props in html! macro

[Madoshakalaka]

Fixes #3747
Unblocks #4020

• Properties derive: for props whose type is Option<_>, generates an additional {name}_none() setter that assigns Some(None) directly, bypassing IntoPropValue
• html! macro: detects when a prop value is literally None and routes to the _none setter instead of the normal one

This means None never goes through trait resolution, so it works regardless of how many IntoPropValue<Option<T>> impls exist.

Caveat

If a user passes None to a non-Option prop (e.g. foo: String with foo={None}), the error changes from a type inference failure to no method named foo_none found. It might be a bit cryptic to the user but both are compile errors pointing to the correct line, only the message text differs. I think this is acceptible as it is an uncommon mistake.

checklist

• I have reviewed my own code
• I have added tests

[github-actions]

Visit the preview URL for this PR (updated for commit 81efe92):

https://yew-rs-api--pr4021-fix-none-value-senti-m40zxj84.web.app

_{(expires Sat, 07 Mar 2026 22:36:07 GMT)}

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[github-actions]

Benchmark - core

Yew Master

vnode           fastest       │ slowest       │ median        │ mean          │ samples │ iters
╰─ vnode_clone  2.403 ns      │ 3.681 ns      │ 2.407 ns      │ 2.714 ns      │ 100     │ 1000000000

Pull Request

vnode           fastest       │ slowest       │ median        │ mean          │ samples │ iters
╰─ vnode_clone  2.403 ns      │ 3.653 ns      │ 2.407 ns      │ 2.491 ns      │ 100     │ 1000000000

[github-actions]

Size Comparison

Details

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
async_clock	100.197	100.197	0	0.000%
boids	168.081	168.081	0	0.000%
communication_child_to_parent	93.469	93.469	0	0.000%
communication_grandchild_with_grandparent	105.248	105.248	0	0.000%
communication_grandparent_to_grandchild	101.606	101.606	0	0.000%
communication_parent_to_child	90.899	90.899	0	0.000%
contexts	105.149	105.149	0	0.000%
counter	86.282	86.282	0	0.000%
counter_functional	88.273	88.273	0	0.000%
dyn_create_destroy_apps	90.323	90.323	0	0.000%
file_upload	99.346	99.346	0	0.000%
function_delayed_input	94.373	94.373	0	0.000%
function_memory_game	172.935	172.935	0	0.000%
function_router	405.536	405.536	0	0.000%
function_todomvc	164.148	164.148	0	0.000%
futures	235.159	235.159	0	0.000%
game_of_life	104.718	104.718	0	0.000%
immutable	255.688	255.688	0	0.000%
inner_html	80.803	80.803	0	0.000%
js_callback	109.376	109.376	0	0.000%
keyed_list	179.725	179.725	0	0.000%
mount_point	84.145	84.145	0	0.000%
nested_list	113.057	113.057	0	0.000%
node_refs	91.526	91.526	0	0.000%
password_strength	1728.825	1728.825	0	0.000%
portals	93.032	93.032	0	0.000%
router	376.132	376.132	0	0.000%
suspense	113.454	113.454	0	0.000%
timer	88.634	88.634	0	0.000%
timer_functional	98.874	98.874	0	0.000%
todomvc	142.088	142.088	0	0.000%
two_apps	86.146	86.146	0	0.000%
web_worker_fib	136.219	136.219	0	0.000%
web_worker_prime	187.441	187.441	0	0.000%
webgl	83.222	83.222	0	0.000%

✅ None of the examples has changed their size significantly.

[github-actions]

Benchmark - SSR

Yew Master

Details

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	291.102	292.513	291.433	0.422
Hello World	10	463.162	469.128	464.943	1.689
Function Router	10	32421.639	32815.794	32619.656	133.329
Concurrent Task	10	1005.877	1007.855	1006.866	0.621
Many Providers	10	1052.043	1096.928	1071.351	15.299

Pull Request

Details

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	291.026	292.446	291.448	0.504
Hello World	10	477.192	501.938	482.455	7.229
Function Router	10	33778.071	34626.689	34216.423	236.237
Concurrent Task	10	1005.909	1007.497	1007.066	0.500
Many Providers	10	1097.093	1136.013	1117.441	14.690