Delete support for compilers without core::time

.github/workflows/ci.yml

@@ -77,7 +77,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [1.21.0, 1.25.0, 1.26.0, 1.34.0]
+        rust: [1.25.0, 1.26.0, 1.34.0]
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v3

README.md

@@ -1,12 +1,12 @@
-# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.21+]][Rust 1.21] [![serde_derive: rustc 1.56+]][Rust 1.56]
+# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.25+]][Rust 1.25] [![serde_derive: rustc 1.56+]][Rust 1.56]
 
 [Build Status]: https://img.shields.io/github/actions/workflow/status/serde-rs/serde/ci.yml?branch=master
 [actions]: https://github.com/serde-rs/serde/actions?query=branch%3Amaster
 [Latest Version]: https://img.shields.io/crates/v/serde.svg
 [crates.io]: https://crates.io/crates/serde
-[serde: rustc 1.21+]: https://img.shields.io/badge/serde-rustc_1.21+-lightgray.svg
+[serde: rustc 1.25+]: https://img.shields.io/badge/serde-rustc_1.25+-lightgray.svg
 [serde_derive: rustc 1.56+]: https://img.shields.io/badge/serde_derive-rustc_1.56+-lightgray.svg
-[Rust 1.21]: https://blog.rust-lang.org/2017/10/12/Rust-1.21.html
+[Rust 1.25]: https://blog.rust-lang.org/2018/03/29/Rust-1.25.html
 [Rust 1.56]: https://blog.rust-lang.org/2021/10/21/Rust-1.56.0.html
 
 **Serde is a framework for *ser*ializing and *de*serializing Rust data structures efficiently and generically.**

serde/Cargo.toml

@@ -11,7 +11,7 @@ keywords = ["serde", "serialization", "no_std"]
 license = "MIT OR Apache-2.0"
 readme = "crates-io.md"
 repository = "https://github.com/serde-rs/serde"
-rust-version = "1.21"
+rust-version = "1.25"
 
 [dependencies]
 serde_derive = { version = "=1.0.179", optional = true, path = "../serde_derive" }

serde/build.rs

@@ -16,12 +16,6 @@ fn main() {
     let target = env::var("TARGET").unwrap();
     let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
 
-    // Duration available in core since Rust 1.25:
-    // https://blog.rust-lang.org/2018/03/29/Rust-1.25.html#library-stabilizations
-    if minor < 25 {
-        println!("cargo:rustc-cfg=no_core_duration");
-    }
-
     // std::collections::Bound was stabilized in Rust 1.17
     // but it was moved to core::ops later in Rust 1.26:
     // https://doc.rust-lang.org/core/ops/enum.Bound.html

serde/src/de/impls.rs

@@ -1,12 +1,10 @@
 use lib::*;
 
 use de::{
-    Deserialize, Deserializer, EnumAccess, Error, SeqAccess, Unexpected, VariantAccess, Visitor,
+    Deserialize, Deserializer, EnumAccess, Error, MapAccess, SeqAccess, Unexpected, VariantAccess,
+    Visitor,
 };
 
-#[cfg(any(feature = "std", feature = "alloc", not(no_core_duration)))]
-use de::MapAccess;
-
 use seed::InPlaceSeed;
 
 #[cfg(any(feature = "std", feature = "alloc"))]
@@ -1923,7 +1921,6 @@ forwarded_impl!((T), RwLock<T>, RwLock::new);
 //         secs: u64,
 //         nanos: u32,
 //     }
-#[cfg(any(feature = "std", not(no_core_duration)))]
 impl<'de> Deserialize<'de> for Duration {
     fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
     where

serde/src/lib.rs

@@ -186,6 +186,7 @@ mod lib {
     pub use self::core::ops::{Range, RangeFrom, RangeTo};
     pub use self::core::option::{self, Option};
     pub use self::core::result::{self, Result};
+    pub use self::core::time::Duration;
 
     #[cfg(all(feature = "alloc", not(feature = "std")))]
     pub use alloc::borrow::{Cow, ToOwned};
@@ -279,9 +280,6 @@ mod lib {
     pub use std::sync::atomic::{AtomicI64, AtomicU64};
     #[cfg(all(feature = "std", not(no_target_has_atomic), target_has_atomic = "ptr"))]
     pub use std::sync::atomic::{AtomicIsize, AtomicUsize};
-
-    #[cfg(any(feature = "std", not(no_core_duration)))]
-    pub use self::core::time::Duration;
 }
 
 // None of this crate's error handling needs the `From::from` error conversion

serde/src/ser/impls.rs

@@ -662,7 +662,6 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(feature = "std", not(no_core_duration)))]
 impl Serialize for Duration {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
     where