breaking: Remove the FromArgs impl on T: TryFromJs and add cx.arg() and cx.arg_opt().

[kjvalencik]

A blanket impl was added to avoid duplicate methods or a confusing let (n,) = cx.args()?; syntax for unary functions. However, this does not work well with the #[neon::export] macro where functions with zero arguments end up unnecessarily deserializing undefined.

Removing the blanket impl and replacing it with a specialized version for () allows the proc macros to be more efficient without unneeded complexity.

In order to make these changes more ergonomic, I added Context::arg and Context::arg_opt for unary functions.

Attention: This is a breaking change, but the API has not landed in a stable version yet.

In the future, we could unify these APIs if Rust ships specialization.

[codecov]

Codecov Report

Attention: Patch coverage is 87.50000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 83.42%. Comparing base (7f08b76) to head (ac8603c).

Files with missing lines	Patch %	Lines
crates/neon/src/types_impl/extract/mod.rs	50.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1096   +/-   ##
=======================================
  Coverage   83.42%   83.42%           
=======================================
  Files          74       74           
  Lines        5537     5546    +9     
  Branches     5537     5546    +9     
=======================================
+ Hits         4619     4627    +8     
- Misses        803      806    +3     
+ Partials      115      113    -2     

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[github-actions]

Bencher Report

Branch	kv/no-args
Testbed	ubuntu-latest

🚨 10 Alerts

Benchmark	Measure Units	View	Benchmark Result (Result Δ%)	Lower Boundary (Limit %)	Upper Boundary (Limit %)
JsFunction::bind	Latency nanoseconds (ns)	📈 plot 🚷 threshold 🚨 alert (🔔)	198.67 ns (-5.78%) Baseline: 210.86 ns	208.75 ns (105.07%)	421.73 ns (47.11%)
JsFunction::bind	Throughput operations / second (ops/s)	📈 plot 🚷 threshold 🚨 alert (🔔)	4,914,643.21 ops/s (+4.69%) Baseline: 4,694,405.32 ops/s	0.00 ops/s (0.00%)	4,741,349.37 ops/s (103.65%)
JsFunction::call_with	Latency nanoseconds (ns)	📈 plot 🚷 threshold 🚨 alert (🔔)	202.07 ns (-3.39%) Baseline: 209.17 ns	207.07 ns (102.48%)	418.33 ns (48.30%)
JsFunction::call_with	Throughput operations / second (ops/s)	📈 plot 🚷 threshold 🚨 alert (🔔)	4,861,292.81 ops/s (+2.69%) Baseline: 4,733,974.83 ops/s	0.00 ops/s (0.00%)	4,781,314.58 ops/s (101.67%)
auto-exported-noop	Latency nanoseconds (ns)	📈 plot 🚷 threshold 🚨 alert (🔔)	28.04 ns (-27.32%) Baseline: 38.58 ns	38.20 ns (136.22%)	77.16 ns (36.34%)
auto-exported-noop	Throughput operations / second (ops/s)	📈 plot 🚷 threshold 🚨 alert (🔔)	34,981,675.55 ops/s (+26.84%) Baseline: 27,578,719.75 ops/s	0.00 ops/s (0.00%)	27,854,506.95 ops/s (125.59%)
hello-world	Latency nanoseconds (ns)	📈 plot 🚷 threshold 🚨 alert (🔔)	54.01 ns (-2.51%) Baseline: 55.40 ns	54.85 ns (101.55%)	110.81 ns (48.75%)
hello-world	Throughput operations / second (ops/s)	📈 plot 🚷 threshold 🚨 alert (🔔)	18,471,275.47 ops/s (+3.25%) Baseline: 17,889,450.26 ops/s	0.00 ops/s (0.00%)	18,068,344.76 ops/s (102.23%)
manually-exported-noop	Latency nanoseconds (ns)	📈 plot 🚷 threshold 🚨 alert (🔔)	28.15 ns (-3.36%) Baseline: 29.13 ns	28.84 ns (102.45%)	58.26 ns (48.32%)
manually-exported-noop	Throughput operations / second (ops/s)	📈 plot 🚷 threshold 🚨 alert (🔔)	34,707,426.02 ops/s (+2.21%) Baseline: 33,958,166.60 ops/s	0.00 ops/s (0.00%)	34,297,748.27 ops/s (101.19%)

Click to view all benchmark results

Benchmark	Latency	Benchmark Result nanoseconds (ns) (Result Δ%)	Lower Boundary nanoseconds (ns) (Limit %)	Upper Boundary nanoseconds (ns) (Limit %)	Throughput	Benchmark Result operations / second (ops/s) (Result Δ%)	Lower Boundary operations / second (ops/s) (Limit %)	Upper Boundary operations / second (ops/s) (Limit %)
JsFunction::bind	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	198.67 ns (-5.78%) Baseline: 210.86 ns	208.75 ns (105.07%)	421.73 ns (47.11%)	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	4,914,643.21 ops/s (+4.69%) Baseline: 4,694,405.32 ops/s	0.00 ops/s (0.00%)	4,741,349.37 ops/s (103.65%)
JsFunction::call	📈 view plot 🚷 view threshold	226.99 ns (+0.63%) Baseline: 225.57 ns	223.31 ns (98.38%)	451.14 ns (50.32%)	📈 view plot 🚷 view threshold	4,402,536.07 ops/s (-0.65%) Baseline: 4,431,529.03 ops/s	0.00 ops/s (0.00%)	4,475,844.32 ops/s (98.36%)
JsFunction::call_with	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	202.07 ns (-3.39%) Baseline: 209.17 ns	207.07 ns (102.48%)	418.33 ns (48.30%)	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	4,861,292.81 ops/s (+2.69%) Baseline: 4,733,974.83 ops/s	0.00 ops/s (0.00%)	4,781,314.58 ops/s (101.67%)
auto-exported-noop	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	28.04 ns (-27.32%) Baseline: 38.58 ns	38.20 ns (136.22%)	77.16 ns (36.34%)	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	34,981,675.55 ops/s (+26.84%) Baseline: 27,578,719.75 ops/s	0.00 ops/s (0.00%)	27,854,506.95 ops/s (125.59%)
hello-world	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	54.01 ns (-2.51%) Baseline: 55.40 ns	54.85 ns (101.55%)	110.81 ns (48.75%)	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	18,471,275.47 ops/s (+3.25%) Baseline: 17,889,450.26 ops/s	0.00 ops/s (0.00%)	18,068,344.76 ops/s (102.23%)
manually-exported-noop	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	28.15 ns (-3.36%) Baseline: 29.13 ns	28.84 ns (102.45%)	58.26 ns (48.32%)	📈 view plot 🚷 view threshold 🚨 view alert (🔔)	34,707,426.02 ops/s (+2.21%) Baseline: 33,958,166.60 ops/s	0.00 ops/s (0.00%)	34,297,748.27 ops/s (101.19%)

🐰 View full continuous benchmarking report in Bencher