feat!: bump supported Rust version to 1.81.0

Author: bavshin-f5

Cargo.toml

@@ -9,7 +9,7 @@ edition = "2021"
 license = "Apache-2.0"
 homepage = "https://github.com/nginx/ngx-rust"
 repository = "https://github.com/nginx/ngx-rust"
-rust-version = "1.79.0"
+rust-version = "1.81.0"
 
 [package]
 name = "ngx"
@@ -33,7 +33,6 @@ default = ["vendored","std"]
 # If no `std` flag, `alloc` crate is internally used instead. This flag is mainly for `no_std` build.
 alloc = []
 # Enables the components using `std` crate.
-# Currently the only difference to `alloc` flag is `std::error::Error` implementation.
 std = ["alloc"]
 # Build our own copy of the NGINX by default.
 # This could be disabled with `--no-default-features` to minimize the dependency

src/http/module.rs

@@ -1,3 +1,4 @@
+use core::error;
 use core::ffi::{c_char, c_void};
 use core::fmt;
 use core::ptr;
@@ -13,8 +14,7 @@ pub enum MergeConfigError {
     NoValue,
 }
 
-#[cfg(feature = "std")]
-impl std::error::Error for MergeConfigError {}
+impl error::Error for MergeConfigError {}
 
 impl fmt::Display for MergeConfigError {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {

src/http/request.rs

@@ -1,3 +1,4 @@
+use core::error;
 use core::ffi::c_void;
 use core::fmt;
 use core::ptr::NonNull;
@@ -711,8 +712,7 @@ impl fmt::Display for InvalidMethod {
     }
 }
 
-#[cfg(feature = "std")]
-impl std::error::Error for InvalidMethod {}
+impl error::Error for InvalidMethod {}
 
 #[derive(Clone, PartialEq, Eq, Hash)]
 enum MethodInner {

src/http/status.rs

@@ -1,4 +1,4 @@
-use core::fmt;
+use core::{error, fmt};
 
 use crate::core::Status;
 use crate::ffi::*;
@@ -28,8 +28,7 @@ impl fmt::Display for InvalidHTTPStatusCode {
     }
 }
 
-#[cfg(feature = "std")]
-impl std::error::Error for InvalidHTTPStatusCode {}
+impl error::Error for InvalidHTTPStatusCode {}
 
 impl From<HTTPStatus> for Status {
     fn from(val: HTTPStatus) -> Self {