1 files changed, 55 insertions, 0 deletions
diff --git a/third_party/rust/tracing/src/stdlib.rs b/third_party/rust/tracing/src/stdlib.rs
new file mode 100644
index 0000000000..12b54084d4
--- /dev/null
+++ b/third_party/rust/tracing/src/stdlib.rs
@@ -0,0 +1,55 @@
+//! Re-exports either the Rust `std` library or `core` and `alloc` when `std` is
+//! disabled.
+//!
+//! `crate::stdlib::...` should be used rather than `std::` when adding code that
+//! will be available with the standard library disabled.
+//!
+//! Note that this module is called `stdlib` rather than `std`, as Rust 1.34.0
+//! does not permit redefining the name `stdlib` (although this works on the
+//! latest stable Rust).
+#[cfg(feature = "std")]
+pub(crate) use std::*;
+
+#[cfg(not(feature = "std"))]
+pub(crate) use self::no_std::*;
+
+#[cfg(not(feature = "std"))]
+mod no_std {
+    // We pre-emptively export everything from libcore/liballoc, (even modules
+    // we aren't using currently) to make adding new code easier. Therefore,
+    // some of these imports will be unused.
+    #![allow(unused_imports)]
+
+    pub(crate) use core::{
+        any, array, ascii, cell, char, clone, cmp, convert, default, f32, f64, ffi, future, hash,
+        hint, i128, i16, i8, isize, iter, marker, mem, num, ops, option, pin, ptr, result, task,
+        time, u128, u16, u32, u8, usize,
+    };
+
+    pub(crate) use alloc::{boxed, collections, rc, string, vec};
+
+    pub(crate) mod borrow {
+        pub(crate) use alloc::borrow::*;
+        pub(crate) use core::borrow::*;
+    }
+
+    pub(crate) mod fmt {
+        pub(crate) use alloc::fmt::*;
+        pub(crate) use core::fmt::*;
+    }
+
+    pub(crate) mod slice {
+        pub(crate) use alloc::slice::*;
+        pub(crate) use core::slice::*;
+    }
+
+    pub(crate) mod str {
+        pub(crate) use alloc::str::*;
+        pub(crate) use core::str::*;
+    }
+
+    pub(crate) mod sync {
+        pub(crate) use alloc::sync::*;
+        pub(crate) use core::sync::*;
+    }
+}