Add no_std attribute and extern crate core for wasm32v1-none

serde/src/lib.rs

@@ -97,7 +97,9 @@
 // Serde types in rustdoc of other crates get linked to here.
 #![doc(html_root_url = "https://docs.rs/serde/1.0.228")]
 // Support using Serde without the standard library!
-#![cfg_attr(not(feature = "std"), no_std)]
+// Also force no_std on target_os = "none" (wasm32v1-none) even if std feature is enabled
+// This handles Cargo feature unification where std gets enabled for no_std targets
+#![cfg_attr(any(not(feature = "std"), target_os = "none"), no_std)]
 // Show which crate feature enables conditionally compiled APIs in documentation.
 #![cfg_attr(docsrs, feature(doc_cfg, rustdoc_internals))]
 #![cfg_attr(docsrs, allow(internal_features))]
@@ -168,6 +170,10 @@
 #[cfg(feature = "alloc")]
 extern crate alloc;
 
+// Explicitly import core crate for no_std targets (especially wasm32v1-none)
+#[cfg(any(not(feature = "std"), target_os = "none"))]
+extern crate core;
+
 // Rustdoc has a lot of shortcomings related to cross-crate re-exports that make
 // the rendered documentation of serde_core traits in serde more challenging to
 // understand than the equivalent documentation of the same items in serde_core.