preserve dependency features order

src/cargo/util/toml_mut/dependency.rs

@@ -4,12 +4,14 @@ use std::fmt::{Display, Formatter};
 use std::path::{Path, PathBuf};
 
 use indexmap::IndexSet;
+use itertools::Itertools;
 use toml_edit::KeyMut;
 
 use super::manifest::str_or_1_len_table;
 use crate::core::GitReference;
 use crate::core::SourceId;
 use crate::core::Summary;
+use crate::util::toml_mut::is_sorted;
 use crate::CargoResult;
 use crate::GlobalContext;
 
@@ -588,8 +590,13 @@ impl Dependency {
                             .collect::<Option<IndexSet<_>>>()
                     })
                     .unwrap_or_default();
+                let is_already_sorted = is_sorted(features.iter());
                 features.extend(new_features.iter().map(|s| s.as_str()));
-                let features = features.into_iter().collect::<toml_edit::Value>();
+                let features = if is_already_sorted {
+                    features.into_iter().sorted().collect::<toml_edit::Value>()
+                } else {
+                    features.into_iter().collect::<toml_edit::Value>()
+                };
                 table.set_dotted(false);
                 overwrite_value(table, "features", features);
             } else {

tests/testsuite/cargo_add/overwrite_inline_features/out/Cargo.toml

@@ -8,5 +8,5 @@ edition = "2015"
 [dependencies]
 unrelateed-crate = "99999.0.0"
 # Before your-face
-your-face = { version = "99999.0.0", features = ["eyes", "nose", "mouth", "ears"] }  # After your-face
+your-face = { version = "99999.0.0", features = ["ears", "eyes", "mouth", "nose"] }  # After your-face
 # End

tests/testsuite/cargo_add/preserve_features_sorted/out/Cargo.toml

@@ -6,4 +6,4 @@ version = "0.0.0"
 edition = "2015"
 
 [dependencies]
-my-package = { version = "99999.0.0", features = ["a", "b", "c", "e", "d"] }
+my-package = { version = "99999.0.0", features = ["a", "b", "c", "d", "e"] }