From 93509279039fde4cabc054870d24e7467f34c3d4 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Thu, 27 Jul 2023 22:27:52 -0700
Subject: [PATCH 01/12] Delete support for compilers without
 std::collections::Bound

---
 serde/build.rs         | 3 ---
 serde/src/de/impls.rs  | 2 +-
 serde/src/lib.rs       | 2 +-
 serde/src/ser/impls.rs | 2 +-
 4 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/serde/build.rs b/serde/build.rs
index 929d8e172..0f363c954 100644
--- a/serde/build.rs
+++ b/serde/build.rs
@@ -21,9 +21,6 @@ fn main() {
     // https://doc.rust-lang.org/core/ops/enum.Bound.html
     if minor < 26 {
         println!("cargo:rustc-cfg=no_ops_bound");
-        if minor < 17 {
-            println!("cargo:rustc-cfg=no_collections_bound");
-        }
     }
 
     // core::cmp::Reverse stabilized in Rust 1.19:
diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index 12fbdfdb3..44fa36691 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -2709,7 +2709,7 @@ mod range_to {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(not(no_ops_bound), all(feature = "std", not(no_collections_bound))))]
+#[cfg(any(not(no_ops_bound), feature = "std"))]
 impl<'de, T> Deserialize<'de> for Bound<T>
 where
     T: Deserialize<'de>,
diff --git a/serde/src/lib.rs b/serde/src/lib.rs
index 30c5e4d60..66fba92b8 100644
--- a/serde/src/lib.rs
+++ b/serde/src/lib.rs
@@ -249,7 +249,7 @@ mod lib {
     #[cfg(feature = "std")]
     pub use std::time::{SystemTime, UNIX_EPOCH};
 
-    #[cfg(all(feature = "std", not(no_collections_bound), no_ops_bound))]
+    #[cfg(all(feature = "std", no_ops_bound))]
     pub use std::collections::Bound;
 
     #[cfg(not(no_core_reverse))]
diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index 9cafb3264..5eb8f3deb 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -310,7 +310,7 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(not(no_ops_bound), all(feature = "std", not(no_collections_bound))))]
+#[cfg(any(not(no_ops_bound), feature = "std"))]
 impl<T> Serialize for Bound<T>
 where
     T: Serialize,

From 9a0e14922580de424e2de37974a004cb936a1f74 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Thu, 27 Jul 2023 22:35:08 -0700
Subject: [PATCH 02/12] Sort version checks in build.rs

---
 serde/build.rs | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/serde/build.rs b/serde/build.rs
index 0f363c954..112281583 100644
--- a/serde/build.rs
+++ b/serde/build.rs
@@ -16,13 +16,6 @@ fn main() {
     let target = env::var("TARGET").unwrap();
     let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
 
-    // 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
-    if minor < 26 {
-        println!("cargo:rustc-cfg=no_ops_bound");
-    }
-
     // core::cmp::Reverse stabilized in Rust 1.19:
     // https://doc.rust-lang.org/stable/core/cmp/struct.Reverse.html
     if minor < 19 {
@@ -50,6 +43,13 @@ fn main() {
         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
+    if minor < 26 {
+        println!("cargo:rustc-cfg=no_ops_bound");
+    }
+
     // 128-bit integers stabilized in Rust 1.26:
     // https://blog.rust-lang.org/2018/05/10/Rust-1.26.html
     //

From a100719bc6c9fd3c823f0914a928e0bef19fb3ae Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Thu, 27 Jul 2023 22:30:30 -0700
Subject: [PATCH 03/12] Delete support for compilers without core::cmp::Reverse

---
 serde/build.rs         | 6 ------
 serde/src/de/impls.rs  | 1 -
 serde/src/lib.rs       | 4 +---
 serde/src/ser/impls.rs | 1 -
 4 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/serde/build.rs b/serde/build.rs
index 112281583..66f3b6edb 100644
--- a/serde/build.rs
+++ b/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";
 
-    // core::cmp::Reverse stabilized in Rust 1.19:
-    // https://doc.rust-lang.org/stable/core/cmp/struct.Reverse.html
-    if minor < 19 {
-        println!("cargo:rustc-cfg=no_core_reverse");
-    }
-
     // CString::into_boxed_c_str and PathBuf::into_boxed_path stabilized in Rust 1.20:
     // https://doc.rust-lang.org/std/ffi/struct.CString.html#method.into_boxed_c_str
     // https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.into_boxed_path
diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index 44fa36691..5dba42b26 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -753,7 +753,6 @@ macro_rules! forwarded_impl {
 ))]
 forwarded_impl!((), Box<CStr>, CString::into_boxed_c_str);
 
-#[cfg(not(no_core_reverse))]
 forwarded_impl!((T), Reverse<T>, Reverse);
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/serde/src/lib.rs b/serde/src/lib.rs
index 66fba92b8..a8e568832 100644
--- a/serde/src/lib.rs
+++ b/serde/src/lib.rs
@@ -177,6 +177,7 @@ mod lib {
 
     pub use self::core::cell::{Cell, RefCell};
     pub use self::core::clone::{self, Clone};
+    pub use self::core::cmp::Reverse;
     pub use self::core::convert::{self, From, Into};
     pub use self::core::default::{self, Default};
     pub use self::core::fmt::{self, Debug, Display};
@@ -252,9 +253,6 @@ mod lib {
     #[cfg(all(feature = "std", no_ops_bound))]
     pub use std::collections::Bound;
 
-    #[cfg(not(no_core_reverse))]
-    pub use self::core::cmp::Reverse;
-
     #[cfg(not(no_ops_bound))]
     pub use self::core::ops::Bound;
 
diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index 5eb8f3deb..541acf2d6 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -963,7 +963,6 @@ where
     }
 }
 
-#[cfg(not(no_core_reverse))]
 impl<T> Serialize for Reverse<T>
 where
     T: Serialize,

From c91737fef1e107c7041c568cfe8e4d4eb65ca6ff Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Thu, 27 Jul 2023 22:32:00 -0700
Subject: [PATCH 04/12] Delete support for compilers without
 CString::into_boxed_c_str

---
 .github/workflows/ci.yml | 2 +-
 README.md                | 6 +++---
 serde/Cargo.toml         | 2 +-
 serde/build.rs           | 4 +---
 serde/src/de/impls.rs    | 5 +----
 5 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3450b7705..a3dea2e2b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -77,7 +77,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [1.19.0, 1.20.0, 1.21.0, 1.25.0, 1.26.0, 1.34.0]
+        rust: [1.20.0, 1.21.0, 1.25.0, 1.26.0, 1.34.0]
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v3
diff --git a/README.md b/README.md
index a049250b6..387a218d0 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,12 @@
-# Serde &emsp; [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.19+]][Rust 1.19] [![serde_derive: rustc 1.56+]][Rust 1.56]
+# Serde &emsp; [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.20+]][Rust 1.20] [![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 1.19+]: https://img.shields.io/badge/serde-rustc_1.19+-lightgray.svg
+[serde: rustc 1.20+]: https://img.shields.io/badge/serde-rustc_1.20+-lightgray.svg
 [serde_derive: rustc 1.56+]: https://img.shields.io/badge/serde_derive-rustc_1.56+-lightgray.svg
-[Rust 1.19]: https://blog.rust-lang.org/2017/07/20/Rust-1.19.html
+[Rust 1.20]: https://blog.rust-lang.org/2017/08/31/Rust-1.20.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.**
diff --git a/serde/Cargo.toml b/serde/Cargo.toml
index b9959cf02..b752f4075 100644
--- a/serde/Cargo.toml
+++ b/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 = "1.19"
+rust-version = "1.20"
 
 [dependencies]
 serde_derive = { version = "=1.0.179", optional = true, path = "../serde_derive" }
diff --git a/serde/build.rs b/serde/build.rs
index 66f3b6edb..7a5ce83af 100644
--- a/serde/build.rs
+++ b/serde/build.rs
@@ -16,11 +16,9 @@ fn main() {
     let target = env::var("TARGET").unwrap();
     let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
 
-    // CString::into_boxed_c_str and PathBuf::into_boxed_path stabilized in Rust 1.20:
-    // https://doc.rust-lang.org/std/ffi/struct.CString.html#method.into_boxed_c_str
+    // PathBuf::into_boxed_path stabilized in Rust 1.20:
     // https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.into_boxed_path
     if minor < 20 {
-        println!("cargo:rustc-cfg=no_de_boxed_c_str");
         println!("cargo:rustc-cfg=no_de_boxed_path");
     }
 
diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index 5dba42b26..b362a216a 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -747,10 +747,7 @@ macro_rules! forwarded_impl {
     }
 }
 
-#[cfg(all(
-    any(feature = "std", all(not(no_core_cstr), feature = "alloc")),
-    not(no_de_boxed_c_str)
-))]
+#[cfg(any(feature = "std", all(not(no_core_cstr), feature = "alloc")))]
 forwarded_impl!((), Box<CStr>, CString::into_boxed_c_str);
 
 forwarded_impl!((T), Reverse<T>, Reverse);

From 89976c2712c5e60a6da0d6e094a0977f111bc6dd Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Thu, 27 Jul 2023 22:36:48 -0700
Subject: [PATCH 05/12] Delete support for compilers without
 PathBuf::into_boxed_path

---
 serde/build.rs        | 6 ------
 serde/src/de/impls.rs | 2 +-
 2 files changed, 1 insertion(+), 7 deletions(-)

diff --git a/serde/build.rs b/serde/build.rs
index 7a5ce83af..da960fd8b 100644
--- a/serde/build.rs
+++ b/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";
 
-    // PathBuf::into_boxed_path stabilized in Rust 1.20:
-    // https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.into_boxed_path
-    if minor < 20 {
-        println!("cargo:rustc-cfg=no_de_boxed_path");
-    }
-
     // From<Box<T>> for Rc<T> / Arc<T> stabilized in Rust 1.21:
     // https://doc.rust-lang.org/std/rc/struct.Rc.html#impl-From<Box<T>>
     // https://doc.rust-lang.org/std/sync/struct.Arc.html#impl-From<Box<T>>
diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index b362a216a..959295d1d 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -1710,7 +1710,7 @@ impl<'de> Deserialize<'de> for PathBuf {
     }
 }
 
-#[cfg(all(feature = "std", not(no_de_boxed_path)))]
+#[cfg(feature = "std")]
 forwarded_impl!((), Box<Path>, PathBuf::into_boxed_path);
 
 ////////////////////////////////////////////////////////////////////////////////

From 27c8b2d66a7d6e92f48abea257dc6d451ea533f9 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Thu, 27 Jul 2023 22:38:04 -0700
Subject: [PATCH 06/12] Delete support for compilers without dynamically sized
 Rc construction

---
 .github/workflows/ci.yml |  2 +-
 README.md                |  6 +++---
 serde/Cargo.toml         |  2 +-
 serde/build.rs           |  7 -------
 serde/src/de/impls.rs    | 42 +++-------------------------------------
 5 files changed, 8 insertions(+), 51 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a3dea2e2b..c5946877a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -77,7 +77,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [1.20.0, 1.21.0, 1.25.0, 1.26.0, 1.34.0]
+        rust: [1.21.0, 1.25.0, 1.26.0, 1.34.0]
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v3
diff --git a/README.md b/README.md
index 387a218d0..234481b65 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,12 @@
-# Serde &emsp; [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.20+]][Rust 1.20] [![serde_derive: rustc 1.56+]][Rust 1.56]
+# Serde &emsp; [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.21+]][Rust 1.21] [![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 1.20+]: https://img.shields.io/badge/serde-rustc_1.20+-lightgray.svg
+[serde: rustc 1.21+]: https://img.shields.io/badge/serde-rustc_1.21+-lightgray.svg
 [serde_derive: rustc 1.56+]: https://img.shields.io/badge/serde_derive-rustc_1.56+-lightgray.svg
-[Rust 1.20]: https://blog.rust-lang.org/2017/08/31/Rust-1.20.html
+[Rust 1.21]: https://blog.rust-lang.org/2017/10/12/Rust-1.21.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.**
diff --git a/serde/Cargo.toml b/serde/Cargo.toml
index b752f4075..2fd979204 100644
--- a/serde/Cargo.toml
+++ b/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 = "1.20"
+rust-version = "1.21"
 
 [dependencies]
 serde_derive = { version = "=1.0.179", optional = true, path = "../serde_derive" }
diff --git a/serde/build.rs b/serde/build.rs
index da960fd8b..9c7748008 100644
--- a/serde/build.rs
+++ b/serde/build.rs
@@ -16,13 +16,6 @@ fn main() {
     let target = env::var("TARGET").unwrap();
     let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
 
-    // From<Box<T>> for Rc<T> / Arc<T> stabilized in Rust 1.21:
-    // https://doc.rust-lang.org/std/rc/struct.Rc.html#impl-From<Box<T>>
-    // https://doc.rust-lang.org/std/sync/struct.Arc.html#impl-From<Box<T>>
-    if minor < 21 {
-        println!("cargo:rustc-cfg=no_de_rc_dst");
-    }
-
     // 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 {
diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index 959295d1d..cfac35185 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -1791,30 +1791,6 @@ forwarded_impl!((T), Box<[T]>, Vec::into_boxed_slice);
 #[cfg(any(feature = "std", feature = "alloc"))]
 forwarded_impl!((), Box<str>, String::into_boxed_str);
 
-#[cfg(all(no_de_rc_dst, feature = "rc", any(feature = "std", feature = "alloc")))]
-forwarded_impl! {
-    /// This impl requires the [`"rc"`] Cargo feature of Serde.
-    ///
-    /// Deserializing a data structure containing `Arc` will not attempt to
-    /// deduplicate `Arc` references to the same data. Every deserialized `Arc`
-    /// will end up with a strong count of 1.
-    ///
-    /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
-    (T), Arc<T>, Arc::new
-}
-
-#[cfg(all(no_de_rc_dst, feature = "rc", any(feature = "std", feature = "alloc")))]
-forwarded_impl! {
-    /// This impl requires the [`"rc"`] Cargo feature of Serde.
-    ///
-    /// Deserializing a data structure containing `Rc` will not attempt to
-    /// deduplicate `Rc` references to the same data. Every deserialized `Rc`
-    /// will end up with a strong count of 1.
-    ///
-    /// [`"rc"`]: https://serde.rs/feature-flags.html#-features-rc
-    (T), Rc<T>, Rc::new
-}
-
 #[cfg(any(feature = "std", feature = "alloc"))]
 impl<'de, 'a, T: ?Sized> Deserialize<'de> for Cow<'a, T>
 where
@@ -1870,11 +1846,7 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(all(
-    not(no_de_rc_dst),
-    feature = "rc",
-    any(feature = "std", feature = "alloc")
-))]
+#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 macro_rules! box_forwarded_impl {
     (
         $(#[doc = $doc:tt])*
@@ -1895,11 +1867,7 @@ macro_rules! box_forwarded_impl {
     };
 }
 
-#[cfg(all(
-    not(no_de_rc_dst),
-    feature = "rc",
-    any(feature = "std", feature = "alloc")
-))]
+#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 box_forwarded_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///
@@ -1911,11 +1879,7 @@ box_forwarded_impl! {
     Rc
 }
 
-#[cfg(all(
-    not(no_de_rc_dst),
-    feature = "rc",
-    any(feature = "std", feature = "alloc")
-))]
+#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
 box_forwarded_impl! {
     /// This impl requires the [`"rc"`] Cargo feature of Serde.
     ///

From 4f59cd217a13311916cbcdee99cea7e34a509d75 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 30 Jul 2023 20:51:55 -0700
Subject: [PATCH 07/12] Delete support for compilers without core::time

---
 .github/workflows/ci.yml | 2 +-
 README.md                | 6 +++---
 serde/Cargo.toml         | 2 +-
 serde/build.rs           | 6 ------
 serde/src/de/impls.rs    | 7 ++-----
 serde/src/lib.rs         | 4 +---
 serde/src/ser/impls.rs   | 1 -
 7 files changed, 8 insertions(+), 20 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c5946877a..0275ea878 100644
--- a/.github/workflows/ci.yml
+++ b/.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
diff --git a/README.md b/README.md
index 234481b65..74e0ee988 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,12 @@
-# Serde &emsp; [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.21+]][Rust 1.21] [![serde_derive: rustc 1.56+]][Rust 1.56]
+# Serde &emsp; [![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.**
diff --git a/serde/Cargo.toml b/serde/Cargo.toml
index 2fd979204..53e4d414d 100644
--- a/serde/Cargo.toml
+++ b/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" }
diff --git a/serde/build.rs b/serde/build.rs
index 9c7748008..fd03d042b 100644
--- a/serde/build.rs
+++ b/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
diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index cfac35185..0102a7ab9 100644
--- a/serde/src/de/impls.rs
+++ b/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
diff --git a/serde/src/lib.rs b/serde/src/lib.rs
index a8e568832..0ef1b6c59 100644
--- a/serde/src/lib.rs
+++ b/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
diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index 541acf2d6..9469e7145 100644
--- a/serde/src/ser/impls.rs
+++ b/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

From 1b14cadf20fb85d5689fe8046a5356e2f7979055 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 30 Jul 2023 20:55:29 -0700
Subject: [PATCH 08/12] Delete support for compilers without core::ops::Bound

---
 .github/workflows/ci.yml | 2 +-
 README.md                | 6 +++---
 serde/Cargo.toml         | 2 +-
 serde/build.rs           | 7 -------
 serde/src/de/impls.rs    | 1 -
 serde/src/lib.rs         | 8 +-------
 serde/src/ser/impls.rs   | 1 -
 7 files changed, 6 insertions(+), 21 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0275ea878..6b67dbe30 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -77,7 +77,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        rust: [1.25.0, 1.26.0, 1.34.0]
+        rust: [1.26.0, 1.34.0]
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v3
diff --git a/README.md b/README.md
index 74e0ee988..0ad018e3e 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,12 @@
-# Serde &emsp; [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.25+]][Rust 1.25] [![serde_derive: rustc 1.56+]][Rust 1.56]
+# Serde &emsp; [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.26+]][Rust 1.26] [![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 1.25+]: https://img.shields.io/badge/serde-rustc_1.25+-lightgray.svg
+[serde: rustc 1.26+]: https://img.shields.io/badge/serde-rustc_1.26+-lightgray.svg
 [serde_derive: rustc 1.56+]: https://img.shields.io/badge/serde_derive-rustc_1.56+-lightgray.svg
-[Rust 1.25]: https://blog.rust-lang.org/2018/03/29/Rust-1.25.html
+[Rust 1.26]: https://blog.rust-lang.org/2018/05/10/Rust-1.26.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.**
diff --git a/serde/Cargo.toml b/serde/Cargo.toml
index 53e4d414d..65d59b497 100644
--- a/serde/Cargo.toml
+++ b/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 = "1.25"
+rust-version = "1.26"
 
 [dependencies]
 serde_derive = { version = "=1.0.179", optional = true, path = "../serde_derive" }
diff --git a/serde/build.rs b/serde/build.rs
index fd03d042b..1eab424f8 100644
--- a/serde/build.rs
+++ b/serde/build.rs
@@ -16,13 +16,6 @@ fn main() {
     let target = env::var("TARGET").unwrap();
     let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
 
-    // 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
-    if minor < 26 {
-        println!("cargo:rustc-cfg=no_ops_bound");
-    }
-
     // 128-bit integers stabilized in Rust 1.26:
     // https://blog.rust-lang.org/2018/05/10/Rust-1.26.html
     //
diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index 0102a7ab9..acb251f7e 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -2666,7 +2666,6 @@ mod range_to {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(not(no_ops_bound), feature = "std"))]
 impl<'de, T> Deserialize<'de> for Bound<T>
 where
     T: Deserialize<'de>,
diff --git a/serde/src/lib.rs b/serde/src/lib.rs
index 0ef1b6c59..ec4e1ba12 100644
--- a/serde/src/lib.rs
+++ b/serde/src/lib.rs
@@ -183,7 +183,7 @@ mod lib {
     pub use self::core::fmt::{self, Debug, Display};
     pub use self::core::marker::{self, PhantomData};
     pub use self::core::num::Wrapping;
-    pub use self::core::ops::{Range, RangeFrom, RangeTo};
+    pub use self::core::ops::{Bound, Range, RangeFrom, RangeTo};
     pub use self::core::option::{self, Option};
     pub use self::core::result::{self, Result};
     pub use self::core::time::Duration;
@@ -251,12 +251,6 @@ mod lib {
     #[cfg(feature = "std")]
     pub use std::time::{SystemTime, UNIX_EPOCH};
 
-    #[cfg(all(feature = "std", no_ops_bound))]
-    pub use std::collections::Bound;
-
-    #[cfg(not(no_ops_bound))]
-    pub use self::core::ops::Bound;
-
     #[cfg(not(no_range_inclusive))]
     pub use self::core::ops::RangeInclusive;
 
diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index 9469e7145..c2f9e78b8 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -310,7 +310,6 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(any(not(no_ops_bound), feature = "std"))]
 impl<T> Serialize for Bound<T>
 where
     T: Serialize,

From e77900fb94211b4372dd7bd2ac979ff660a7ff53 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 30 Jul 2023 20:58:16 -0700
Subject: [PATCH 09/12] Update integer128 case in build script

---
 serde/build.rs | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/serde/build.rs b/serde/build.rs
index 1eab424f8..48e52893f 100644
--- a/serde/build.rs
+++ b/serde/build.rs
@@ -16,16 +16,6 @@ fn main() {
     let target = env::var("TARGET").unwrap();
     let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
 
-    // 128-bit integers stabilized in Rust 1.26:
-    // https://blog.rust-lang.org/2018/05/10/Rust-1.26.html
-    //
-    // Disabled on Emscripten targets before Rust 1.40 since
-    // Emscripten did not support 128-bit integers until Rust 1.40
-    // (https://github.com/rust-lang/rust/pull/65251)
-    if minor < 26 || emscripten && minor < 40 {
-        println!("cargo:rustc-cfg=no_integer128");
-    }
-
     // Inclusive ranges methods stabilized in Rust 1.27:
     // https://github.com/rust-lang/rust/pull/50758
     // Also Iterator::try_for_each:
@@ -52,6 +42,13 @@ fn main() {
         println!("cargo:rustc-cfg=no_relaxed_trait_bounds");
     }
 
+    // Disabled on Emscripten targets before Rust 1.40 since
+    // Emscripten did not support 128-bit integers until Rust 1.40
+    // (https://github.com/rust-lang/rust/pull/65251)
+    if emscripten && minor < 40 {
+        println!("cargo:rustc-cfg=no_integer128");
+    }
+
     // Current minimum supported version of serde_derive crate is Rust 1.56.
     if minor < 56 {
         println!("cargo:rustc-cfg=no_serde_derive");

From 4dcf7917067d53d7b9b6a3846bfca90e8eec9fec Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 30 Jul 2023 20:59:38 -0700
Subject: [PATCH 10/12] Delete support for compilers without inclusive range
 accessors

---
 .github/workflows/ci.yml | 10 ++--------
 README.md                |  6 +++---
 serde/Cargo.toml         |  2 +-
 serde/build.rs           |  5 +----
 serde/src/de/impls.rs    |  1 -
 serde/src/lib.rs         |  5 +----
 serde/src/ser/impls.rs   |  1 -
 7 files changed, 8 insertions(+), 22 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6b67dbe30..cc9a693ff 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -72,18 +72,12 @@ jobs:
         if: matrix.os != 'windows'
 
   build:
-    name: Rust ${{matrix.rust}}
+    name: Rust 1.34.0
     runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        rust: [1.26.0, 1.34.0]
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v3
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: ${{matrix.rust}}
+      - uses: dtolnay/rust-toolchain@1.34.0
       - run: cd serde && cargo build --features rc
       - run: cd serde && cargo build --no-default-features
       - run: cd serde && cargo build
diff --git a/README.md b/README.md
index 0ad018e3e..6109fdf70 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,12 @@
-# Serde &emsp; [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.26+]][Rust 1.26] [![serde_derive: rustc 1.56+]][Rust 1.56]
+# Serde &emsp; [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.27+]][Rust 1.27] [![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 1.26+]: https://img.shields.io/badge/serde-rustc_1.26+-lightgray.svg
+[serde: rustc 1.27+]: https://img.shields.io/badge/serde-rustc_1.27+-lightgray.svg
 [serde_derive: rustc 1.56+]: https://img.shields.io/badge/serde_derive-rustc_1.56+-lightgray.svg
-[Rust 1.26]: https://blog.rust-lang.org/2018/05/10/Rust-1.26.html
+[Rust 1.27]: https://blog.rust-lang.org/2018/06/21/Rust-1.27.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.**
diff --git a/serde/Cargo.toml b/serde/Cargo.toml
index 65d59b497..6d7a849e7 100644
--- a/serde/Cargo.toml
+++ b/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 = "1.26"
+rust-version = "1.27"
 
 [dependencies]
 serde_derive = { version = "=1.0.179", optional = true, path = "../serde_derive" }
diff --git a/serde/build.rs b/serde/build.rs
index 48e52893f..ecbb96a6f 100644
--- a/serde/build.rs
+++ b/serde/build.rs
@@ -16,12 +16,9 @@ fn main() {
     let target = env::var("TARGET").unwrap();
     let emscripten = target == "asmjs-unknown-emscripten" || target == "wasm32-unknown-emscripten";
 
-    // Inclusive ranges methods stabilized in Rust 1.27:
-    // https://github.com/rust-lang/rust/pull/50758
-    // Also Iterator::try_for_each:
+    // Iterator::try_for_each stabilized in Rust 1.27:
     // https://blog.rust-lang.org/2018/06/21/Rust-1.27.html#library-stabilizations
     if minor < 27 {
-        println!("cargo:rustc-cfg=no_range_inclusive");
         println!("cargo:rustc-cfg=no_iterator_try_fold");
     }
 
diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index acb251f7e..124251def 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -2238,7 +2238,6 @@ where
     }
 }
 
-#[cfg(not(no_range_inclusive))]
 impl<'de, Idx> Deserialize<'de> for RangeInclusive<Idx>
 where
     Idx: Deserialize<'de>,
diff --git a/serde/src/lib.rs b/serde/src/lib.rs
index ec4e1ba12..ea0fa4726 100644
--- a/serde/src/lib.rs
+++ b/serde/src/lib.rs
@@ -183,7 +183,7 @@ mod lib {
     pub use self::core::fmt::{self, Debug, Display};
     pub use self::core::marker::{self, PhantomData};
     pub use self::core::num::Wrapping;
-    pub use self::core::ops::{Bound, Range, RangeFrom, RangeTo};
+    pub use self::core::ops::{Bound, Range, RangeFrom, RangeInclusive, RangeTo};
     pub use self::core::option::{self, Option};
     pub use self::core::result::{self, Result};
     pub use self::core::time::Duration;
@@ -251,9 +251,6 @@ mod lib {
     #[cfg(feature = "std")]
     pub use std::time::{SystemTime, UNIX_EPOCH};
 
-    #[cfg(not(no_range_inclusive))]
-    pub use self::core::ops::RangeInclusive;
-
     #[cfg(all(feature = "std", no_target_has_atomic, not(no_std_atomic)))]
     pub use std::sync::atomic::{
         AtomicBool, AtomicI16, AtomicI32, AtomicI8, AtomicIsize, AtomicU16, AtomicU32, AtomicU8,
diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index c2f9e78b8..f856b6c0a 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -274,7 +274,6 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
-#[cfg(not(no_range_inclusive))]
 impl<Idx> Serialize for RangeInclusive<Idx>
 where
     Idx: Serialize,

From 92e91b35578780a30fcec0feabc7dafc7e2a2dbc Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 30 Jul 2023 21:03:28 -0700
Subject: [PATCH 11/12] Delete support for compilers without
 Iterator::try_for_each

---
 serde/build.rs       |  6 ------
 serde/src/ser/mod.rs | 34 ++++------------------------------
 2 files changed, 4 insertions(+), 36 deletions(-)

diff --git a/serde/build.rs b/serde/build.rs
index ecbb96a6f..e76ac2368 100644
--- a/serde/build.rs
+++ b/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";
 
-    // Iterator::try_for_each stabilized in Rust 1.27:
-    // https://blog.rust-lang.org/2018/06/21/Rust-1.27.html#library-stabilizations
-    if minor < 27 {
-        println!("cargo:rustc-cfg=no_iterator_try_fold");
-    }
-
     // Non-zero integers stabilized in Rust 1.28:
     // https://blog.rust-lang.org/2018/08/02/Rust-1.28.html#library-stabilizations
     if minor < 28 {
diff --git a/serde/src/ser/mod.rs b/serde/src/ser/mod.rs
index 1aaa7570f..d1a70ddb0 100644
--- a/serde/src/ser/mod.rs
+++ b/serde/src/ser/mod.rs
@@ -1279,22 +1279,9 @@ pub trait Serializer: Sized {
         I: IntoIterator,
         <I as IntoIterator>::Item: Serialize,
     {
-        let iter = iter.into_iter();
+        let mut iter = iter.into_iter();
         let mut serializer = try!(self.serialize_seq(iterator_len_hint(&iter)));
-
-        #[cfg(not(no_iterator_try_fold))]
-        {
-            let mut iter = iter;
-            try!(iter.try_for_each(|item| serializer.serialize_element(&item)));
-        }
-
-        #[cfg(no_iterator_try_fold)]
-        {
-            for item in iter {
-                try!(serializer.serialize_element(&item));
-            }
-        }
-
+        try!(iter.try_for_each(|item| serializer.serialize_element(&item)));
         serializer.end()
     }
 
@@ -1330,22 +1317,9 @@ pub trait Serializer: Sized {
         V: Serialize,
         I: IntoIterator<Item = (K, V)>,
     {
-        let iter = iter.into_iter();
+        let mut iter = iter.into_iter();
         let mut serializer = try!(self.serialize_map(iterator_len_hint(&iter)));
-
-        #[cfg(not(no_iterator_try_fold))]
-        {
-            let mut iter = iter;
-            try!(iter.try_for_each(|(key, value)| serializer.serialize_entry(&key, &value)));
-        }
-
-        #[cfg(no_iterator_try_fold)]
-        {
-            for (key, value) in iter {
-                try!(serializer.serialize_entry(&key, &value));
-            }
-        }
-
+        try!(iter.try_for_each(|(key, value)| serializer.serialize_entry(&key, &value)));
         serializer.end()
     }
 

From a57a324d7254c282f6032f9a65044bb5da34c4e1 Mon Sep 17 00:00:00 2001
From: David Tolnay <dtolnay@gmail.com>
Date: Sun, 30 Jul 2023 21:05:06 -0700
Subject: [PATCH 12/12] Delete support for compilers without NonZero integer
 types

---
 .github/workflows/ci.yml | 10 ++--------
 README.md                |  6 +++---
 serde/Cargo.toml         |  2 +-
 serde/build.rs           |  6 ------
 serde/src/de/impls.rs    |  2 +-
 serde/src/ser/impls.rs   |  1 -
 6 files changed, 7 insertions(+), 20 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cc9a693ff..568b4d641 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -83,18 +83,12 @@ jobs:
       - run: cd serde && cargo build
 
   more:
-    name: Rust ${{matrix.rust}}
+    name: Rust 1.28.0
     runs-on: ubuntu-latest
-    strategy:
-      fail-fast: false
-      matrix:
-        rust: [1.27.0, 1.28.0]
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v3
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: ${{matrix.rust}}
+      - uses: dtolnay/rust-toolchain@1.28.0
         # Work around failing to parse manifest because editions are unstable.
       - run: sed -i /test_suite/d Cargo.toml
       - run: cd serde && cargo build --no-default-features
diff --git a/README.md b/README.md
index 6109fdf70..19f0d3c43 100644
--- a/README.md
+++ b/README.md
@@ -1,12 +1,12 @@
-# Serde &emsp; [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.27+]][Rust 1.27] [![serde_derive: rustc 1.56+]][Rust 1.56]
+# Serde &emsp; [![Build Status]][actions] [![Latest Version]][crates.io] [![serde: rustc 1.28+]][Rust 1.28] [![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 1.27+]: https://img.shields.io/badge/serde-rustc_1.27+-lightgray.svg
+[serde: rustc 1.28+]: https://img.shields.io/badge/serde-rustc_1.28+-lightgray.svg
 [serde_derive: rustc 1.56+]: https://img.shields.io/badge/serde_derive-rustc_1.56+-lightgray.svg
-[Rust 1.27]: https://blog.rust-lang.org/2018/06/21/Rust-1.27.html
+[Rust 1.28]: https://blog.rust-lang.org/2018/08/02/Rust-1.28.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.**
diff --git a/serde/Cargo.toml b/serde/Cargo.toml
index 6d7a849e7..eba6c5b74 100644
--- a/serde/Cargo.toml
+++ b/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 = "1.27"
+rust-version = "1.28"
 
 [dependencies]
 serde_derive = { version = "=1.0.179", optional = true, path = "../serde_derive" }
diff --git a/serde/build.rs b/serde/build.rs
index e76ac2368..fb1cfa6d1 100644
--- a/serde/build.rs
+++ b/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";
 
-    // Non-zero integers stabilized in Rust 1.28:
-    // https://blog.rust-lang.org/2018/08/02/Rust-1.28.html#library-stabilizations
-    if minor < 28 {
-        println!("cargo:rustc-cfg=no_num_nonzero");
-    }
-
     // TryFrom, Atomic types, non-zero signed integers, and SystemTime::checked_add
     // stabilized in Rust 1.34:
     // https://blog.rust-lang.org/2019/04/11/Rust-1.34.0.html#tryfrom-and-tryinto
diff --git a/serde/src/de/impls.rs b/serde/src/de/impls.rs
index 124251def..0dd039b3c 100644
--- a/serde/src/de/impls.rs
+++ b/serde/src/de/impls.rs
@@ -82,7 +82,7 @@ macro_rules! impl_deserialize_num {
     ($primitive:ident, $nonzero:ident $(cfg($($cfg:tt)*))*, $deserialize:ident $($method:ident!($($val:ident : $visit:ident)*);)*) => {
         impl_deserialize_num!($primitive, $deserialize $($method!($($val : $visit)*);)*);
 
-        #[cfg(all(not(no_num_nonzero), $($($cfg)*)*))]
+        $(#[cfg($($cfg)*)])*
         impl<'de> Deserialize<'de> for num::$nonzero {
             fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
             where
diff --git a/serde/src/ser/impls.rs b/serde/src/ser/impls.rs
index f856b6c0a..72933909f 100644
--- a/serde/src/ser/impls.rs
+++ b/serde/src/ser/impls.rs
@@ -536,7 +536,6 @@ where
 macro_rules! nonzero_integers {
     ($($T:ident,)+) => {
         $(
-            #[cfg(not(no_num_nonzero))]
             impl Serialize for num::$T {
                 fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
                 where