RSX and Props macro build times

# Effect of `rsx!` on Build Timing

The generated `rsx!` icon bodies were the dominant source of compile-time cost in
`dioxus-icons`, mostly because they produced a large amount of Rust for the
compiler to expand, resolve, and type-check for every generated icon.

Clean package-check timing for the `dioxus-icons` crate unit:

```text
rsx! generated icons: 23.8s
manual VDOM templates: 4.1s
manual VDOM + const builders: 2.3s
```

That is roughly a 10x reduction from the original generated `rsx!` version to
the current helper-based generated output.

Macro expansion itself was not the entire cost. In the current version, rustc
reports:

```text
total: 2.520s
macro_expand_crate: 0.212s
type_check_crate: 1.657s
generate_metadata: 0.129s
```

The bigger win came from avoiding the large expanded `rsx!` expression tree and
emitting compact release-style VDOM templates directly. That shrank the amount
of generated Rust that rustc has to resolve and type-check, which is why the
crate unit fell from about 23.8s to 2.3s.

## Trace with rsx:

```
time: 0.001; rss: 41MB -> 41MB ( +0MB) parse_crate
time: 0.001; rss: 42MB -> 42MB ( +0MB) incr_comp_prepare_session_directory
time: 0.000; rss: 42MB -> 42MB ( +0MB) incr_comp_garbage_collect_session_directories
time: 0.000; rss: 46MB -> 46MB ( +0MB) crate_injection
time: 10.357; rss: 46MB -> 1490MB (+1443MB) expand_crate
time: 10.357; rss: 46MB -> 1490MB (+1443MB) macro_expand_crate
time: 0.168; rss: 1490MB -> 1490MB ( +0MB) AST_validation
time: 0.041; rss: 1490MB -> 1572MB ( +82MB) finalize_imports
time: 0.037; rss: 1572MB -> 1574MB ( +3MB) compute_effective_visibilities
time: 0.009; rss: 1574MB -> 1574MB ( +0MB) lint_reexports
time: 0.089; rss: 1574MB -> 1576MB ( +1MB) finalize_macro_resolutions
time: 1.753; rss: 1576MB -> 1800MB ( +224MB) late_resolve_crate
time: 0.060; rss: 1800MB -> 1800MB ( +0MB) resolve_check_unused
time: 0.117; rss: 1800MB -> 1800MB ( +0MB) resolve_postprocess
time: 2.106; rss: 1490MB -> 1800MB ( +310MB) resolve_crate
time: 0.061; rss: 1611MB -> 1611MB ( +0MB) write_dep_info
time: 0.065; rss: 1611MB -> 1612MB ( +0MB) complete_gated_feature_checking
time: 0.253; rss: 2183MB -> 2183MB ( +0MB) drop_ast
time: 0.000; rss: 2017MB -> 2017MB ( +0MB) looking_for_entry_point
time: 0.000; rss: 2017MB -> 2017MB ( +0MB) check_externally_implementable_items
time: 0.022; rss: 2017MB -> 2013MB ( -3MB) looking_for_derive_registrar
time: 0.000; rss: 2014MB -> 2014MB ( +0MB) unused_lib_feature_checking
time: 0.544; rss: 2017MB -> 2037MB ( +20MB) misc_checking_1
time: 6.608; rss: 2037MB -> 2384MB ( +347MB) coherence_checking
time: 18.751; rss: 2037MB -> 2682MB ( +645MB) type_check_crate
time: 17.017; rss: 2682MB -> 2348MB ( -334MB) MIR_borrow_checking
time: 0.684; rss: 2190MB -> 2211MB ( +21MB) module_lints
time: 0.684; rss: 2190MB -> 2211MB ( +21MB) lint_checking
time: 0.489; rss: 2211MB -> 2217MB ( +6MB) privacy_checking_modules
time: 0.004; rss: 2217MB -> 2220MB ( +3MB) check_lint_expectations
time: 1.792; rss: 2348MB -> 2220MB ( -128MB) misc_checking_3
time: 0.011; rss: 3103MB -> 3102MB ( -2MB) monomorphization_collector_root_collections
time: 1.568; rss: 3102MB -> 3385MB ( +283MB) monomorphization_collector_graph_walk
time: 0.325; rss: 3385MB -> 3402MB ( +17MB) partition_and_assert_distinct_symbols
time: 4.139; rss: 2220MB -> 3272MB (+1051MB) generate_crate_metadata
time: 0.000; rss: 3272MB -> 3272MB ( +0MB) codegen_crate
time: 0.000; rss: 3272MB -> 3272MB ( +0MB) assert_dep_graph
time: 0.648; rss: 3272MB -> 3414MB ( +142MB) encode_query_results
time: 0.744; rss: 3272MB -> 3358MB ( +86MB) incr_comp_serialize_result_cache
time: 0.744; rss: 3272MB -> 3358MB ( +86MB) incr_comp_persist_result_cache
time: 0.744; rss: 3272MB -> 3358MB ( +86MB) serialize_dep_graph
time: 0.000; rss: 1217MB -> 1217MB ( +0MB) finish_ongoing_codegen
time: 0.000; rss: 1217MB -> 1217MB ( +0MB) serialize_work_products
time: 0.237; rss: 1217MB -> 1370MB ( +153MB) link_rlib
time: 0.240; rss: 1217MB -> 1370MB ( +153MB) link_binary
time: 0.241; rss: 1217MB -> 1218MB ( +1MB) link_crate
time: 0.241; rss: 1217MB -> 1218MB ( +1MB) link
time: 59.437; rss: 25MB -> 87MB ( +62MB) total
```

## Trace without rsx:

```text
time: 0.000; rss: 41MB -> 41MB ( +0MB) parse_crate
time: 0.000; rss: 42MB -> 42MB ( +0MB) incr_comp_prepare_session_directory
time: 0.000; rss: 42MB -> 42MB ( +0MB) incr_comp_garbage_collect_session_directories
time: 0.000; rss: 46MB -> 47MB ( +0MB) crate_injection
time: 0.225; rss: 47MB -> 136MB ( +89MB) expand_crate
time: 0.225; rss: 47MB -> 136MB ( +89MB) macro_expand_crate
time: 0.006; rss: 136MB -> 136MB ( +0MB) AST_validation
time: 0.017; rss: 136MB -> 141MB ( +5MB) finalize_imports
time: 0.012; rss: 141MB -> 142MB ( +1MB) compute_effective_visibilities
time: 0.001; rss: 142MB -> 142MB ( +0MB) lint_reexports
time: 0.001; rss: 142MB -> 143MB ( +1MB) finalize_macro_resolutions
time: 0.026; rss: 143MB -> 159MB ( +17MB) late_resolve_crate
time: 0.007; rss: 159MB -> 159MB ( +0MB) resolve_check_unused
time: 0.002; rss: 159MB -> 160MB ( +0MB) resolve_postprocess
time: 0.065; rss: 136MB -> 160MB ( +24MB) resolve_crate
time: 0.002; rss: 160MB -> 160MB ( +0MB) write_dep_info
time: 0.001; rss: 160MB -> 160MB ( +0MB) complete_gated_feature_checking
time: 0.012; rss: 173MB -> 173MB ( +0MB) drop_ast
time: 0.000; rss: 173MB -> 173MB ( +0MB) looking_for_entry_point
time: 0.000; rss: 173MB -> 173MB ( +0MB) check_externally_implementable_items
time: 0.004; rss: 173MB -> 173MB ( +0MB) looking_for_derive_registrar
time: 0.000; rss: 173MB -> 173MB ( +0MB) unused_lib_feature_checking
time: 0.031; rss: 173MB -> 173MB ( +0MB) misc_checking_1
time: 0.116; rss: 173MB -> 191MB ( +18MB) coherence_checking
time: 1.634; rss: 173MB -> 281MB ( +108MB) type_check_crate
time: 0.129; rss: 281MB -> 294MB ( +14MB) MIR_borrow_checking
time: 0.055; rss: 298MB -> 299MB ( +0MB) module_lints
time: 0.055; rss: 298MB -> 299MB ( +0MB) lint_checking
time: 0.020; rss: 299MB -> 299MB ( +0MB) privacy_checking_modules
time: 0.106; rss: 294MB -> 299MB ( +5MB) misc_checking_3
time: 0.002; rss: 321MB -> 322MB ( +1MB) monomorphization_collector_root_collections
time: 0.034; rss: 322MB -> 331MB ( +9MB) monomorphization_collector_graph_walk
time: 0.031; rss: 331MB -> 333MB ( +2MB) partition_and_assert_distinct_symbols
time: 0.129; rss: 299MB -> 327MB ( +29MB) generate_crate_metadata
time: 0.000; rss: 327MB -> 328MB ( +0MB) codegen_crate
time: 0.000; rss: 328MB -> 328MB ( +0MB) assert_dep_graph
time: 0.027; rss: 328MB -> 335MB ( +8MB) encode_query_results
time: 0.033; rss: 328MB -> 331MB ( +3MB) incr_comp_serialize_result_cache
time: 0.033; rss: 328MB -> 331MB ( +3MB) incr_comp_persist_result_cache
time: 0.034; rss: 328MB -> 331MB ( +3MB) serialize_dep_graph
time: 0.000; rss: 272MB -> 272MB ( +0MB) finish_ongoing_codegen
time: 0.000; rss: 272MB -> 272MB ( +0MB) serialize_work_products
time: 0.008; rss: 272MB -> 280MB ( +8MB) link_rlib
time: 0.008; rss: 272MB -> 280MB ( +8MB) link_binary
time: 0.008; rss: 272MB -> 273MB ( +0MB) link_crate
time: 0.009; rss: 272MB -> 273MB ( +0MB) link
time: 2.499; rss: 25MB -> 78MB ( +53MB) total
```

## Trace with rsx and git Dioxus

This was measured from a temporary worktree at commit `5bcbc1a1` (`use rsx
rosetta`) with `dioxus` and `dioxus-signals` pointed at
`https://github.com/DioxusLabs/dioxus`. Cargo resolved the git dependency to
Dioxus commit `2bce0692`.

Command:

```text
cargo clean -p dioxus-icons
env RUSTC_BOOTSTRAP=1 cargo rustc -p dioxus-icons --lib -- -Z time-passes -Z no-codegen
```

Summary against the crates.io `rsx!` trace:

```text
rsx! + crates.io 0.7.7 rsx! + git Dioxus
total 59.437s 57.257s
macro_expand_crate 10.357s 10.602s
type_check_crate 18.751s 19.212s
MIR_borrow_checking 17.017s 13.637s
generate_crate_metadata 4.139s 4.450s
peak-ish RSS ~3.4GB ~3.7GB
```

The git version is only slightly faster overall for the generated `rsx!` shape:
about 3.7% faster by total rustc time. Macro expansion and type checking were
slightly slower; the improvement came mostly from MIR borrow checking.

```text
time: 0.000; rss: 39MB -> 40MB ( +0MB) parse_crate
time: 0.000; rss: 41MB -> 41MB ( +0MB) incr_comp_prepare_session_directory
time: 0.000; rss: 41MB -> 41MB ( +0MB) incr_comp_garbage_collect_session_directories
time: 0.000; rss: 45MB -> 45MB ( +0MB) crate_injection
time: 10.602; rss: 45MB -> 1504MB (+1459MB) expand_crate
time: 10.602; rss: 45MB -> 1504MB (+1459MB) macro_expand_crate
time: 0.180; rss: 1504MB -> 1504MB ( +0MB) AST_validation
time: 0.050; rss: 1504MB -> 1587MB ( +83MB) finalize_imports
time: 0.036; rss: 1587MB -> 1587MB ( +0MB) compute_effective_visibilities
time: 0.010; rss: 1587MB -> 1587MB ( +0MB) lint_reexports
time: 0.074; rss: 1587MB -> 1581MB ( -6MB) finalize_macro_resolutions
time: 1.696; rss: 1581MB -> 1810MB ( +229MB) late_resolve_crate
time: 0.062; rss: 1810MB -> 1810MB ( +0MB) resolve_check_unused
time: 0.111; rss: 1810MB -> 1810MB ( +0MB) resolve_postprocess
time: 2.041; rss: 1504MB -> 1810MB ( +306MB) resolve_crate
time: 0.062; rss: 1621MB -> 1621MB ( +0MB) write_dep_info
time: 0.072; rss: 1621MB -> 1622MB ( +0MB) complete_gated_feature_checking
time: 0.273; rss: 2192MB -> 2192MB ( +0MB) drop_ast
time: 0.000; rss: 2026MB -> 2026MB ( +0MB) looking_for_entry_point
time: 0.000; rss: 2026MB -> 2026MB ( +0MB) check_externally_implementable_items
time: 0.019; rss: 2026MB -> 2023MB ( -3MB) looking_for_derive_registrar
time: 0.000; rss: 2024MB -> 2024MB ( +0MB) unused_lib_feature_checking
time: 0.584; rss: 2026MB -> 2052MB ( +25MB) misc_checking_1
time: 7.250; rss: 2052MB -> 2400MB ( +349MB) coherence_checking
time: 19.212; rss: 2052MB -> 2691MB ( +639MB) type_check_crate
time: 13.637; rss: 2691MB -> 3183MB ( +492MB) MIR_borrow_checking
time: 0.604; rss: 3100MB -> 3116MB ( +16MB) module_lints
time: 0.604; rss: 3100MB -> 3116MB ( +16MB) lint_checking
time: 0.455; rss: 3116MB -> 3119MB ( +3MB) privacy_checking_modules
time: 0.004; rss: 3119MB -> 3122MB ( +3MB) check_lint_expectations
time: 1.493; rss: 3183MB -> 3122MB ( -61MB) misc_checking_3
time: 0.013; rss: 3564MB -> 3564MB ( +0MB) monomorphization_collector_root_collections
time: 1.609; rss: 3564MB -> 3733MB ( +169MB) monomorphization_collector_graph_walk
time: 0.341; rss: 3733MB -> 3749MB ( +16MB) partition_and_assert_distinct_symbols
time: 4.450; rss: 3122MB -> 3610MB ( +488MB) generate_crate_metadata
time: 0.000; rss: 3610MB -> 3610MB ( +0MB) codegen_crate
time: 0.000; rss: 3610MB -> 3610MB ( +0MB) assert_dep_graph
time: 0.729; rss: 3610MB -> 3706MB ( +96MB) encode_query_results
time: 0.857; rss: 3610MB -> 3650MB ( +40MB) incr_comp_serialize_result_cache
time: 0.857; rss: 3610MB -> 3650MB ( +40MB) incr_comp_persist_result_cache
time: 0.857; rss: 3610MB -> 3650MB ( +40MB) serialize_dep_graph
time: 0.000; rss: 1356MB -> 1356MB ( +0MB) finish_ongoing_codegen
time: 0.000; rss: 1356MB -> 1356MB ( +0MB) serialize_work_products
time: 0.339; rss: 1347MB -> 1500MB ( +153MB) link_rlib
time: 0.342; rss: 1347MB -> 1500MB ( +153MB) link_binary
time: 0.344; rss: 1347MB -> 1348MB ( +1MB) link_crate
time: 0.345; rss: 1356MB -> 1348MB ( -8MB) link
time: 57.257; rss: 25MB -> 87MB ( +62MB) total
```

## Props macro

The refactor that fixed this also cut down on 1000s of generated `Props` which contribute to the type checking time. We could explore const generics instead of type state to keep track of what props are built:
```rust
struct PropsBuilder {
propa: String, // Either Default or the real value depending on ABuilt
propb: String, // Either Default or the real value depending on BBuilt
}
```

This may have more runtime overhead depending on if LLVM can skip the default value initialization which may be difficult if it has non local side effects (like `ReadSignal::new`)

## Next Steps

There is some optimization we can do in the expansion, but a good chunk of the compile time is just dealing with that much expanded code. It would be nice to have more granular benchmarks of different builder strategies on compile times and debug-only-hot-reload expansion. Seems like a fairly automatable task. Very sloppy start in [this branch](https://github.com/ealmloff/dioxus/tree/rsx-macro-build-times).

One thing that would be fairly simple to expose and could help libraries a lot is opting out of the hot reload only expansion in debug mode since the release expansion has less code to type check and bundled libraries will not be changed