Remove Utc::now() and dependents without wasmbind

std::time::SystemTime::now() panics in WASM environments other than
Emscripten (i.e., wasm32-unknown-emscripten) and WASI (e.g.,
wasm32-wasi). Since compilation errors are preferable to unexpected
runtime panics, this PR removes the `Utc::now()` function from this
crate's public interface altogether in unsupported WASM environments
unless the `wasmbind` feature is enabled. This catches the case in
which a user of the crate forgets to enable the `wasmbind` feature
(see ramosbugs/openidconnect-rs#127 and ramosbugs/oauth2-rs#230) in
build targets that require it.

Fixes chronotope#1301.

src/offset/local/mod.rs

@@ -12,9 +12,6 @@ use rkyv::{Archive, Deserialize, Serialize};
 use super::fixed::FixedOffset;
 use super::{MappedLocalTime, TimeZone};
 use crate::naive::{NaiveDate, NaiveDateTime, NaiveTime};
-#[allow(deprecated)]
-use crate::Date;
-use crate::{DateTime, Utc};
 
 #[cfg(unix)]
 #[path = "unix.rs"]
@@ -123,18 +120,24 @@ pub struct Local;
 
 impl Local {
     /// Returns a `Date` which corresponds to the current date.
+    #[cfg(any(
+        not(target_arch = "wasm32"),
+        feature = "wasmbind",
+        target_os = "emscripten",
+        target_os = "wasi",
+    ))]
     #[deprecated(since = "0.4.23", note = "use `Local::now()` instead")]
     #[allow(deprecated)]
     #[must_use]
-    pub fn today() -> Date<Local> {
+    pub fn today() -> crate::Date<Local> {
         Local::now().date()
     }
 
     /// Returns a `DateTime<Local>` which corresponds to the current date, time and offset from
     /// UTC.
     ///
-    /// See also the similar [`Utc::now()`] which returns `DateTime<Utc>`, i.e. without the local
-    /// offset.
+    /// See also the similar [`Utc::now()`](crate::Utc) which returns `DateTime<Utc>`, i.e. without
+    /// the local offset.
     ///
     /// # Example
     ///
@@ -157,8 +160,14 @@ impl Local {
     /// let offset = FixedOffset::east_opt(5 * 60 * 60).unwrap();
     /// let now_with_offset = Local::now().with_timezone(&offset);
     /// ```
-    pub fn now() -> DateTime<Local> {
-        Utc::now().with_timezone(&Local)
+    #[cfg(any(
+        not(target_arch = "wasm32"),
+        feature = "wasmbind",
+        target_os = "emscripten",
+        target_os = "wasi",
+    ))]
+    pub fn now() -> crate::DateTime<Local> {
+        crate::Utc::now().with_timezone(&Local)
     }
 }
 

src/offset/utc.rs

@@ -4,24 +4,12 @@
 //! The UTC (Coordinated Universal Time) time zone.
 
 use core::fmt;
-#[cfg(all(
-    feature = "now",
-    not(all(
-        target_arch = "wasm32",
-        feature = "wasmbind",
-        not(any(target_os = "emscripten", target_os = "wasi"))
-    ))
-))]
-use std::time::{SystemTime, UNIX_EPOCH};
 
 #[cfg(any(feature = "rkyv", feature = "rkyv-16", feature = "rkyv-32", feature = "rkyv-64"))]
 use rkyv::{Archive, Deserialize, Serialize};
 
 use super::{FixedOffset, MappedLocalTime, Offset, TimeZone};
 use crate::naive::{NaiveDate, NaiveDateTime};
-#[cfg(feature = "now")]
-#[allow(deprecated)]
-use crate::{Date, DateTime};
 
 /// The UTC time zone. This is the most efficient time zone when you don't need the local time.
 /// It is also used as an offset (which is also a dummy type).
@@ -54,13 +42,19 @@ pub struct Utc;
 #[cfg(feature = "now")]
 impl Utc {
     /// Returns a `Date` which corresponds to the current date.
+    #[cfg(any(
+        not(target_arch = "wasm32"),
+        feature = "wasmbind",
+        target_os = "emscripten",
+        target_os = "wasi",
+    ))]
     #[deprecated(
         since = "0.4.23",
         note = "use `Utc::now()` instead, potentially with `.date_naive()`"
     )]
     #[allow(deprecated)]
     #[must_use]
-    pub fn today() -> Date<Utc> {
+    pub fn today() -> crate::Date<Utc> {
         Utc::now().date()
     }
 
@@ -86,16 +80,13 @@ impl Utc {
     /// let offset = FixedOffset::east_opt(5 * 60 * 60).unwrap();
     /// let now_with_offset = Utc::now().with_timezone(&offset);
     /// ```
-    #[cfg(not(all(
-        target_arch = "wasm32",
-        feature = "wasmbind",
-        not(any(target_os = "emscripten", target_os = "wasi"))
-    )))]
+    #[cfg(any(not(target_arch = "wasm32"), target_os = "emscripten", target_os = "wasi"))]
     #[must_use]
-    pub fn now() -> DateTime<Utc> {
-        let now =
-            SystemTime::now().duration_since(UNIX_EPOCH).expect("system time before Unix epoch");
-        DateTime::from_timestamp(now.as_secs() as i64, now.subsec_nanos()).unwrap()
+    pub fn now() -> crate::DateTime<Utc> {
+        let now = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .expect("system time before Unix epoch");
+        crate::DateTime::from_timestamp(now.as_secs() as i64, now.subsec_nanos()).unwrap()
     }
 
     /// Returns a `DateTime` which corresponds to the current date and time.
@@ -105,9 +96,9 @@ impl Utc {
         not(any(target_os = "emscripten", target_os = "wasi"))
     ))]
     #[must_use]
-    pub fn now() -> DateTime<Utc> {
+    pub fn now() -> crate::DateTime<Utc> {
         let now = js_sys::Date::new_0();
-        DateTime::<Utc>::from(now)
+        crate::DateTime::<Utc>::from(now)
     }
 }