feat: support formatting Cargo.toml

Cargo.toml

@@ -53,6 +53,7 @@ thiserror = "1.0.40"
 toml = "0.7.4"
 tracing = "0.1.37"
 tracing-subscriber = { version = "0.3.17", features = ["env-filter"] }
+toml_edit = "0.20.4"
 unicode-segmentation = "1.9"
 unicode-width = "0.1"
 unicode-properties = { version = "0.1", default-features = false, features = ["general-category"] }

Configurations.md

@@ -1040,6 +1040,44 @@ fn add_one(x: i32) -> i32 {
 }
 ```
 
+## `format_cargo_toml`
+
+Format `Cargo.toml` files according to the [Cargo.toml conventions](https://github.com/rust-dev-tools/fmt-rfcs/blob/master/guide/cargo.md).
+
+- **Default value**: `false`
+- **Possible values**: `true`, `false`
+- **Stable**: No (tracking issue: [#4091](https://github.com/rust-lang/rustfmt/issues/4091))
+
+#### `false` (default):
+
+```toml
+  [package]
+edition="2018"
+
+version="0.1.0"
+  name="e"
+[dependencies]
+a="0.1"
+
+
+c="0.3"
+b="0.2"
+```
+
+#### `true`:
+
+```toml
+[package]
+name = "e"
+version = "0.1.0"
+edition = "2018"
+
+[dependencies]
+a = "0.1"
+b = "0.2"
+c = "0.3"
+```
+
 ## `doc_comment_code_block_width`
 
 Max width for code snippets included in doc comments. Only used if [`format_code_in_doc_comments`](#format_code_in_doc_comments) is true.

src/cargo-fmt/main.rs

@@ -285,6 +285,15 @@ impl Target {
             edition: target.edition,
         }
     }
+
+    /// `Cargo.toml` file to format.
+    pub fn manifest_target(manifest_path: PathBuf) -> Self {
+        Target {
+            path: manifest_path,
+            kind: String::from("manifest"),
+            edition: Edition::E2021, // The value doesn't matter for formatting Cargo.toml.
+        }
+    }
 }
 
 impl PartialEq for Target {
@@ -366,6 +375,9 @@ fn get_targets_root_only(
 ) -> Result<(), io::Error> {
     let metadata = get_cargo_metadata(manifest_path)?;
     let workspace_root_path = PathBuf::from(&metadata.workspace_root).canonicalize()?;
+    targets.insert(Target::manifest_target(
+        workspace_root_path.join("Cargo.toml"),
+    ));
     let (in_workspace_root, current_dir_manifest) = if let Some(target_manifest) = manifest_path {
         (
             workspace_root_path == target_manifest,
@@ -380,7 +392,15 @@ fn get_targets_root_only(
     };
 
     let package_targets = match metadata.packages.len() {
-        1 => metadata.packages.into_iter().next().unwrap().targets,
+        1 => {
+            let p = metadata.packages.into_iter().next().unwrap();
+            targets.insert(Target::manifest_target(
+                PathBuf::from(&p.manifest_path)
+                    .canonicalize()
+                    .unwrap_or_default(),
+            ));
+            p.targets
+        }
         _ => metadata
             .packages
             .into_iter()
@@ -391,13 +411,18 @@ fn get_targets_root_only(
                         .unwrap_or_default()
                         == current_dir_manifest
             })
-            .flat_map(|p| p.targets)
+            .flat_map(|p| {
+                targets.insert(Target::manifest_target(
+                    PathBuf::from(&p.manifest_path)
+                        .canonicalize()
+                        .unwrap_or_default(),
+                ));
+                p.targets
+            })
             .collect(),
     };
 
-    for target in package_targets {
-        targets.insert(Target::from_target(&target));
-    }
+    add_targets(&package_targets, targets);
 
     Ok(())
 }
@@ -409,6 +434,11 @@ fn get_targets_recursive(
 ) -> Result<(), io::Error> {
     let metadata = get_cargo_metadata(manifest_path)?;
     for package in &metadata.packages {
+        targets.insert(Target::manifest_target(
+            PathBuf::from(&package.manifest_path)
+                .canonicalize()
+                .unwrap_or_default(),
+        ));
         add_targets(&package.targets, targets);
 
         // Look for local dependencies using information available since cargo v1.51
@@ -448,6 +478,11 @@ fn get_targets_with_hitlist(
 
     for package in metadata.packages {
         if workspace_hitlist.remove(&package.name) {
+            targets.insert(Target::manifest_target(
+                PathBuf::from(&package.manifest_path)
+                    .canonicalize()
+                    .unwrap_or_default(),
+            ));
             for target in package.targets {
                 targets.insert(Target::from_target(&target));
             }

src/cargo-fmt/test/targets.rs

@@ -57,7 +57,7 @@ mod all_targets {
                 manifest_suffix,
                 "divergent-crate-dir-names",
                 &exp_targets,
-                3,
+                3 + 3, // include 3 Cargo.toml files
             );
         }
 
@@ -112,7 +112,7 @@ mod all_targets {
                 manifest_suffix,
                 "workspaces/path-dep-above",
                 &exp_targets,
-                6,
+                6 + 6, // include 6 Cargo.toml files,
             );
         }
 

src/config/mod.rs

@@ -176,6 +176,7 @@ create_config! {
          or they are left with trailing whitespaces";
     ignore: IgnoreList, IgnoreList::default(), false,
         "Skip formatting the specified files and directories";
+    format_cargo_toml: bool, false, false, "Format Cargo.toml files";
 
     // Not user-facing
     verbose: Verbosity, Verbosity::Normal, false, "How much to information to emit to the user";
@@ -685,6 +686,7 @@ hide_parse_errors = false
 error_on_line_overflow = false
 error_on_unformatted = false
 ignore = []
+format_cargo_toml = false
 emit_mode = "Files"
 make_backup = false
 "#,