Work around deprecation of str::trim_left_matches

serde_derive/src/dummy.rs

@@ -0,0 +1,32 @@
+use proc_macro2::{Ident, Span, TokenStream};
+
+use try;
+
+pub fn wrap_in_const(trait_: &str, ty: &Ident, code: TokenStream) -> TokenStream {
+    let try_replacement = try::replacement();
+
+    let dummy_const = Ident::new(
+        &format!("_IMPL_{}_FOR_{}", trait_, unraw(ty)),
+        Span::call_site(),
+    );
+
+    quote! {
+        #[allow(non_upper_case_globals, unused_attributes, unused_qualifications)]
+        const #dummy_const: () = {
+            #[allow(unknown_lints)]
+            #[cfg_attr(feature = "cargo-clippy", allow(useless_attribute))]
+            #[allow(rust_2018_idioms)]
+            extern crate serde as _serde;
+            #try_replacement
+            #code
+        };
+    }
+}
+
+#[allow(deprecated)]
+fn unraw(ident: &Ident) -> String {
+    // str::trim_start_matches was added in 1.30, trim_left_matches deprecated
+    // in 1.33. We currently support rustc back to 1.15 so we need to continue
+    // to use the deprecated one.
+    ident.to_string().trim_left_matches("r#").to_owned()
+}