1 files changed, 49 insertions, 0 deletions
diff --git a/vendor/derive_more/src/from_str.rs b/vendor/derive_more/src/from_str.rs
new file mode 100644
index 000000000..5f26fdd18
--- /dev/null
+++ b/vendor/derive_more/src/from_str.rs
@@ -0,0 +1,49 @@
+use crate::utils::{SingleFieldData, State};
+use proc_macro2::TokenStream;
+use quote::quote;
+use syn::{parse::Result, DeriveInput};
+
+/// Provides the hook to expand `#[derive(FromStr)]` into an implementation of `FromStr`
+pub fn expand(input: &DeriveInput, trait_name: &'static str) -> Result<TokenStream> {
+    let state = State::new(
+        input,
+        trait_name,
+        quote!(::core::str),
+        trait_name.to_lowercase(),
+    )?;
+
+    // We cannot set defaults for fields, once we do we can remove this check
+    if state.fields.len() != 1 || state.enabled_fields().len() != 1 {
+        panic_one_field(trait_name);
+    }
+
+    let single_field_data = state.assert_single_enabled_field();
+    let SingleFieldData {
+        input_type,
+        field_type,
+        trait_path,
+        casted_trait,
+        impl_generics,
+        ty_generics,
+        where_clause,
+        ..
+    } = single_field_data.clone();
+
+    let initializers = [quote!(#casted_trait::from_str(src)?)];
+    let body = single_field_data.initializer(&initializers);
+
+    Ok(quote! {
+        impl#impl_generics #trait_path for #input_type#ty_generics #where_clause
+        {
+            type Err = <#field_type as #trait_path>::Err;
+            #[inline]
+            fn from_str(src: &str) -> ::core::result::Result<Self, Self::Err> {
+                Ok(#body)
+            }
+        }
+    })
+}
+
+fn panic_one_field(trait_name: &str) -> ! {
+    panic!("Only structs with one field can derive({})", trait_name)
+}