1 files changed, 24 insertions, 0 deletions
diff --git a/third_party/rust/serde_derive/src/try.rs b/third_party/rust/serde_derive/src/try.rs
new file mode 100644
index 0000000000..48cceebaaf
--- /dev/null
+++ b/third_party/rust/serde_derive/src/try.rs
@@ -0,0 +1,24 @@
+use proc_macro2::{Punct, Spacing, TokenStream};
+
+// None of our generated code requires the `From::from` error conversion
+// performed by the standard library's `try!` macro. With this simplified macro
+// we see a significant improvement in type checking and borrow checking time of
+// the generated code and a slight improvement in binary size.
+pub fn replacement() -> TokenStream {
+    // Cannot pass `$expr` to `quote!` prior to Rust 1.17.0 so interpolate it.
+    let dollar = Punct::new('$', Spacing::Alone);
+
+    quote! {
+        #[allow(unused_macros)]
+        macro_rules! try {
+            (#dollar __expr:expr) => {
+                match #dollar __expr {
+                    _serde::__private::Ok(__val) => __val,
+                    _serde::__private::Err(__err) => {
+                        return _serde::__private::Err(__err);
+                    }
+                }
+            }
+        }
+    }
+}