From 4dd2fb5d969eaf45e66f584684705b9cf5842e28 Mon Sep 17 00:00:00 2001
From: Jonas Bushart <jonas@bushart.org>
Date: Thu, 12 Sep 2024 21:50:26 +0200
Subject: [PATCH] WIP

---
 Cargo.lock                       |  1 +
 serde_with/Cargo.toml            |  1 +
 serde_with/src/chrono_0_4.rs     | 10 +++++++---
 serde_with/src/utils.rs          | 23 +++++++++++------------
 serde_with/src/utils/duration.rs |  3 ++-
 5 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index a969cd0a..871c1544 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1022,6 +1022,7 @@ dependencies = [
  "indexmap 2.7.0",
  "jsonschema",
  "mime",
+ "num-traits",
  "pretty_assertions",
  "regex",
  "rmp-serde",
diff --git a/serde_with/Cargo.toml b/serde_with/Cargo.toml
index 1f0034ed..b335ba80 100644
--- a/serde_with/Cargo.toml
+++ b/serde_with/Cargo.toml
@@ -136,6 +136,7 @@ hashbrown_0_15 = { package = "hashbrown", version = "0.15.0", optional = true, d
 hex = { version = "0.4.3", optional = true, default-features = false }
 indexmap_1 = { package = "indexmap", version = "1.8", optional = true, default-features = false, features = ["serde-1"] }
 indexmap_2 = { package = "indexmap", version = "2.0", optional = true, default-features = false, features = ["serde"] }
+num-traits = { version = "0.2.19", features = ["std"] }
 schemars_0_8 = { package = "schemars", version = "0.8.16", optional = true, default-features = false }
 serde = { version = "1.0.152", default-features = false }
 serde_derive = "1.0.152"
diff --git a/serde_with/src/chrono_0_4.rs b/serde_with/src/chrono_0_4.rs
index 7be9c136..7e8f4c93 100644
--- a/serde_with/src/chrono_0_4.rs
+++ b/serde_with/src/chrono_0_4.rs
@@ -62,6 +62,7 @@ fn unix_epoch_naive() -> NaiveDateTime {
 #[cfg(feature = "std")]
 pub mod datetime_utc_ts_seconds_from_any {
     use super::*;
+    use num_traits::ToPrimitive as _;
 
     /// Deserialize a Unix timestamp with optional subsecond precision into a `DateTime<Utc>`.
     pub fn deserialize<'de, D>(deserializer: D) -> Result<DateTime<Utc>, D::Error>
@@ -110,9 +111,12 @@ pub mod datetime_utc_ts_seconds_from_any {
             where
                 E: DeError,
             {
-                let seconds = value.trunc() as i64;
-                let nsecs = (value.fract() * 1_000_000_000_f64).abs() as u32;
-                DateTime::from_timestamp(seconds, nsecs).ok_or_else(|| {
+                fn f64_to_value(value: f64) -> Option<DateTime<Utc>> {
+                    let seconds = value.trunc().to_i64()?;
+                    let nsecs = (value.fract() * 1_000_000_000_f64).abs().to_u32()?;
+                    DateTime::from_timestamp(seconds, nsecs)
+                }
+                f64_to_value(value).ok_or_else(|| {
                     DeError::custom(format_args!(
                         "a timestamp which can be represented in a DateTime but received '{value}'"
                     ))
diff --git a/serde_with/src/utils.rs b/serde_with/src/utils.rs
index 6d895ef7..8ce65c4b 100644
--- a/serde_with/src/utils.rs
+++ b/serde_with/src/utils.rs
@@ -1,6 +1,7 @@
 pub(crate) mod duration;
 
 use crate::prelude::*;
+use num_traits::ToPrimitive as _;
 
 /// Re-Implementation of `serde::private::de::size_hint::cautious`
 #[cfg(feature = "alloc")]
@@ -40,7 +41,10 @@ pub(crate) const NANOS_PER_SEC_F64: f64 = 1_000_000_000.0;
 // pub(crate) const NANOS_PER_MICRO: u32 = 1_000;
 // pub(crate) const MILLIS_PER_SEC: u64 = 1_000;
 // pub(crate) const MICROS_PER_SEC: u64 = 1_000_000;
+#[expect(clippy::as_conversions)]
 pub(crate) const U64_MAX: u128 = u64::MAX as u128;
+#[expect(clippy::as_conversions)]
+pub(crate) const U64_MAX_FLOAT: f64 = u64::MAX as f64;
 
 pub(crate) struct MapIter<'de, A, K, V> {
     pub(crate) access: A,
@@ -115,27 +119,22 @@ where
     }
 }
 
-pub(crate) fn duration_signed_from_secs_f64(secs: f64) -> Result<DurationSigned, &'static str> {
-    const MAX_NANOS_F64: f64 = ((U64_MAX + 1) * NANOS_PER_SEC) as f64;
-    // TODO why are the seconds converted to nanoseconds first?
-    // Does it make sense to just truncate the value?
-    let mut nanos = secs * NANOS_PER_SEC_F64;
-    if !nanos.is_finite() {
+pub(crate) fn duration_signed_from_secs_f64(mut secs: f64) -> Result<DurationSigned, &'static str> {
+    if !secs.is_finite() {
         return Err("got non-finite value when converting float to duration");
     }
-    if nanos >= MAX_NANOS_F64 {
+    if secs.trunc() > U64_MAX_FLOAT {
         return Err("overflow when converting float to duration");
     }
     let mut sign = Sign::Positive;
-    if nanos < 0.0 {
-        nanos = -nanos;
+    if secs < 0.0 {
+        secs = -secs;
         sign = Sign::Negative;
     }
-    let nanos = nanos as u128;
     Ok(DurationSigned::new(
         sign,
-        (nanos / NANOS_PER_SEC) as u64,
-        (nanos % NANOS_PER_SEC) as u32,
+        secs.trunc() as u64,
+        (secs.fract() * NANOS_PER_SEC_F64) as u32,
     ))
 }
 
diff --git a/serde_with/src/utils/duration.rs b/serde_with/src/utils/duration.rs
index dca876ad..0b6f834b 100644
--- a/serde_with/src/utils/duration.rs
+++ b/serde_with/src/utils/duration.rs
@@ -9,6 +9,7 @@ use crate::{
     formats::{Flexible, Format, Strict, Strictness},
     prelude::*,
 };
+use num_traits::ToPrimitive as _;
 
 #[derive(Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(test, derive(Debug))]
@@ -212,7 +213,7 @@ where
     where
         S: Serializer,
     {
-        let mut secs = source
+        let mut secs: i64 = source
             .sign
             .apply_i64(i64::try_from(source.duration.as_secs()).map_err(|_| {
                 SerError::custom("The Duration of Timestamp is outside the supported range.")