Fix unqualified result types causing compilation failures with derive…

… implementations

clap_derive/src/derives/args.rs

@@ -602,7 +602,7 @@ fn gen_parsers(
         Ty::OptionVec => quote_spanned! { ty.span()=>
             if #arg_matches.is_present(#name) {
                 Some(#arg_matches.#values_of(#name)
-                    .map(|v| v.map::<Result<#convert_type, clap::Error>, _>(#parse).collect::<Result<Vec<_>, clap::Error>>())
+                    .map(|v| v.map::<::std::result::Result<#convert_type, clap::Error>, _>(#parse).collect::<::std::result::Result<Vec<_>, clap::Error>>())
                     .transpose()?
                     .unwrap_or_else(Vec::new))
             } else {
@@ -613,7 +613,7 @@ fn gen_parsers(
         Ty::Vec => {
             quote_spanned! { ty.span()=>
                 #arg_matches.#values_of(#name)
-                    .map(|v| v.map::<Result<#convert_type, clap::Error>, _>(#parse).collect::<Result<Vec<_>, clap::Error>>())
+                    .map(|v| v.map::<::std::result::Result<#convert_type, clap::Error>, _>(#parse).collect::<::std::result::Result<Vec<_>, clap::Error>>())
                     .transpose()?
                     .unwrap_or_else(Vec::new)
             }

tests/derive/main.rs

@@ -25,6 +25,7 @@ mod privacy;
 mod raw_bool_literal;
 mod raw_idents;
 mod rename_all_env;
+mod result_type_alias_regression;
 mod skip;
 mod structopt;
 mod subcommands;

tests/derive/result_type_alias_regression.rs

@@ -0,0 +1,15 @@
+/// Regression test to ensure that Result type aliases do not cause compilation failures.
+use clap::Parser;
+
+#[allow(dead_code)]
+type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
+
+#[derive(Debug, Parser)]
+pub struct Opts {
+    strings: Vec<String>,
+}
+
+#[test]
+fn result_type_alias_regression() {
+    Opts::parse();
+}