cli: ditch Deref, implement AsRef and Display for RevisionArg instead

Deref has a super power, which we no longer need.

cli/src/cli_util.rs

@@ -19,7 +19,6 @@ use std::env::{self, ArgsOs, VarError};
 use std::ffi::OsString;
 use std::fmt::Debug;
 use std::io::{self, Write as _};
-use std::ops::Deref;
 use std::path::{Path, PathBuf};
 use std::process::ExitCode;
 use std::rc::Rc;
@@ -754,7 +753,7 @@ impl WorkspaceCommandHelper {
         let expression = self.parse_revset(revision_arg)?;
         let should_hint_about_all_prefix = false;
         revset_util::evaluate_revset_to_single_commit(
-            revision_arg,
+            revision_arg.as_ref(),
             &expression,
             || self.commit_summary_template(),
             should_hint_about_all_prefix,
@@ -784,7 +783,7 @@ impl WorkspaceCommandHelper {
             } else {
                 let should_hint_about_all_prefix = true;
                 let commit = revset_util::evaluate_revset_to_single_commit(
-                    revision_arg,
+                    revision_arg.as_ref(),
                     &expression,
                     || self.commit_summary_template(),
                     should_hint_about_all_prefix,
@@ -808,7 +807,7 @@ impl WorkspaceCommandHelper {
         &self,
         revision_arg: &RevisionArg,
     ) -> Result<RevsetExpressionEvaluator<'_>, CommandError> {
-        let expression = revset::parse(revision_arg, &self.revset_parse_context())?;
+        let expression = revset::parse(revision_arg.as_ref(), &self.revset_parse_context())?;
         self.attach_revset_evaluator(expression)
     }
 
@@ -819,7 +818,7 @@ impl WorkspaceCommandHelper {
         revision_arg: &RevisionArg,
     ) -> Result<(RevsetExpressionEvaluator<'_>, Option<RevsetModifier>), CommandError> {
         let context = self.revset_parse_context();
-        let (expression, modifier) = revset::parse_with_modifier(revision_arg, &context)?;
+        let (expression, modifier) = revset::parse_with_modifier(revision_arg.as_ref(), &context)?;
         Ok((self.attach_revset_evaluator(expression)?, modifier))
     }
 
@@ -831,7 +830,7 @@ impl WorkspaceCommandHelper {
         let context = self.revset_parse_context();
         let expressions: Vec<_> = revision_args
             .iter()
-            .map(|s| revset::parse(s, &context))
+            .map(|arg| revset::parse(arg.as_ref(), &context))
             .try_collect()?;
         let expression = RevsetExpression::union_all(&expressions);
         self.attach_revset_evaluator(expression)
@@ -2112,14 +2111,18 @@ impl From<String> for RevisionArg {
     }
 }
 
-impl Deref for RevisionArg {
-    type Target = str;
-
-    fn deref(&self) -> &Self::Target {
+impl AsRef<str> for RevisionArg {
+    fn as_ref(&self) -> &str {
         &self.0
     }
 }
 
+impl fmt::Display for RevisionArg {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
 impl ValueParserFactory for RevisionArg {
     type Parser = MapValueParser<NonEmptyStringValueParser, fn(String) -> RevisionArg>;
 

cli/src/commands/git.rs

@@ -14,7 +14,6 @@
 
 use std::collections::HashSet;
 use std::io::Write;
-use std::ops::Deref;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use std::{fmt, fs, io};
@@ -1130,9 +1129,7 @@ fn update_change_branches(
         if view.get_local_branch(&branch_name).is_absent() {
             writeln!(
                 ui.status(),
-                "Creating branch {} for revision {}",
-                branch_name,
-                change_arg.deref()
+                "Creating branch {branch_name} for revision {change_arg}",
             )?;
         }
         tx.mut_repo()
@@ -1207,10 +1204,9 @@ fn find_branches_targeted_by_revisions<'a>(
         expression.intersect_with(&RevsetExpression::branches(StringPattern::everything()));
         let mut commit_ids = expression.evaluate_to_commit_ids()?.peekable();
         if commit_ids.peek().is_none() {
-            let rev_str: &str = rev_arg;
             writeln!(
                 ui.warning_default(),
-                "No branches point to the specified revisions: {rev_str}"
+                "No branches point to the specified revisions: {rev_arg}"
             )?;
         }
         revision_commit_ids.extend(commit_ids);