Support serde_derive on no_std

serde/src/export.rs

@@ -0,0 +1,33 @@
+#[cfg(all(feature = "collections", not(feature = "std")))]
+use collections::String;
+
+#[cfg(feature = "std")]
+use std::borrow::Cow;
+#[cfg(all(feature = "collections", not(feature = "std")))]
+use collections::borrow::Cow;
+
+pub use core::default::Default;
+pub use core::fmt;
+pub use core::marker::PhantomData;
+pub use core::result::Result;
+
+#[cfg(any(feature = "collections", feature = "std"))]
+pub fn from_utf8_lossy(bytes: &[u8]) -> Cow<str> {
+    String::from_utf8_lossy(bytes)
+}
+
+// The generated code calls this like:
+//
+//     let value = &_serde::export::from_utf8_lossy(bytes);
+//     Err(_serde::de::Error::unknown_variant(value, VARIANTS))
+//
+// so it is okay for the return type to be different from the std case as long
+// as the above works.
+#[cfg(not(any(feature = "collections", feature = "std")))]
+pub fn from_utf8_lossy(bytes: &[u8]) -> &str {
+    use core::str;
+    // Three unicode replacement characters if it fails. They look like a
+    // white-on-black question mark. The user will recognize it as invalid
+    // UTF-8.
+    str::from_utf8(bytes).unwrap_or("\u{fffd}\u{fffd}\u{fffd}")
+}