Switch back to get_string as it reports more errors

src/bin/cargo/main.rs

@@ -1,7 +1,7 @@
 #![warn(rust_2018_idioms)] // while we're getting used to 2018
 #![allow(clippy::all)]
 
-use cargo::util::config::{ConfigError, ConfigErrorKind, Value};
+use cargo::util::config::{ConfigError, ConfigErrorKind};
 use cargo::util::toml::StringOrVec;
 use cargo::util::CliError;
 use cargo::util::{self, closest_msg, command_prelude, CargoResult, CliResult, Config};
@@ -63,22 +63,26 @@ fn builtin_aliases_execs(cmd: &str) -> Option<&(&str, &str, &str)> {
 /// 4. If still no command is found, return `None`.
 fn aliased_command(config: &Config, command: &str) -> CargoResult<Option<Vec<String>>> {
     let alias_name = format!("alias.{command}");
-    let user_alias = match config.get::<Value<String>>(&alias_name) {
-        Ok(record) => Some(
+    let user_alias = match config.get_string(&alias_name) {
+        Ok(Some(record)) => Some(
             record
                 .val
                 .split_whitespace()
                 .map(|s| s.to_string())
                 .collect(),
         ),
-        Err(e) => match e.downcast_ref::<ConfigError>().map(|e| e.kind()) {
-            // Just report we cannot find anything.
-            Some(ConfigErrorKind::MissingKey) => None,
-            // Alias might be set as an toml array, fallback and try it.
-            Some(ConfigErrorKind::UnexpectedValue) => config.get::<Option<_>>(&alias_name)?,
-            // A unrecoverable error, e.g. TOML parsing error. Relay it to the user.
-            Some(ConfigErrorKind::Custom) | None => return Err(e),
-        },
+        // Just report we cannot find anything.
+        Ok(None) => None,
+        // Alias might be set as an toml array, fallback and try it.
+        Err(e)
+            if e.downcast_ref::<ConfigError>()
+                .map(|e| matches!(e.kind(), ConfigErrorKind::UnexpectedValue))
+                .unwrap_or_default() =>
+        {
+            config.get::<Option<_>>(&alias_name)?
+        }
+        // A unrecoverable error, e.g. TOML parsing error. Relay it to the user.
+        Err(e) => return Err(e),
     };
 
     let result = user_alias.or_else(|| {