core: Switch to unconditional no_std

Author: jplatte

tracing-core/src/callsite.rs

@@ -516,6 +516,7 @@ mod private {
 #[cfg(feature = "std")]
 mod dispatchers {
     use crate::{dispatcher, lazy::Lazy};
+    use alloc::vec::Vec;
     use std::sync::{
         atomic::{AtomicBool, Ordering},
         RwLock, RwLockReadGuard, RwLockWriteGuard,

tracing-core/src/dispatcher.rs

@@ -122,7 +122,7 @@
 //! [`get_default`] function, which executes a closure with a reference to the
 //! currently default `Dispatch`. This is used primarily by `tracing`
 //! instrumentation.
-//!
+
 use core::ptr::addr_of;
 
 use crate::{
@@ -182,7 +182,7 @@ enum Kind<T> {
 }
 
 #[cfg(feature = "std")]
-thread_local! {
+std::thread_local! {
     static CURRENT_STATE: State = const {
         State {
             default: RefCell::new(None),

tracing-core/src/field.rs

@@ -1120,6 +1120,9 @@ mod private {
 
 #[cfg(test)]
 mod test {
+    use alloc::boxed::Box;
+    use std::format;
+
     use super::*;
     use crate::metadata::{Kind, Level, Metadata};
     use crate::stdlib::{borrow::ToOwned, string::String};

tracing-core/src/lib.rs

@@ -116,11 +116,12 @@
 //! [`Dispatch`]: dispatcher::Dispatch
 //! [`tokio-rs/tracing`]: https://github.com/tokio-rs/tracing
 //! [`tracing`]: https://crates.io/crates/tracing
+
+#![no_std]
 #![doc(
     html_logo_url = "https://raw.githubusercontent.com/tokio-rs/tracing/main/assets/logo-type.png",
     issue_tracker_base_url = "https://github.com/tokio-rs/tracing/issues/"
 )]
-#![cfg_attr(not(feature = "std"), no_std)]
 #![cfg_attr(docsrs, feature(doc_cfg), deny(rustdoc::broken_intra_doc_links))]
 #![warn(
     missing_debug_implementations,
@@ -144,9 +145,12 @@
     unused_parens,
     while_true
 )]
-#[cfg(not(feature = "std"))]
+
 extern crate alloc;
 
+#[cfg(feature = "std")]
+extern crate std;
+
 #[doc(hidden)]
 pub mod __macro_support {
     // Re-export the `core` functions that are used in macros. This allows