Rename fn_args_layout -> fn_params_layout

This option was renamed to better communicate that it affects the layout
of parameters in function signatures and not the layout of arguments in
function calls.

Because the `fn_args_layout` is a stable option the renamed option is
also stable, however users who set `fn_args_layout` will get a warning
message letting them know that the option has been renamed.

Author: ytmimi

Configurations.md

@@ -645,7 +645,7 @@ trailing whitespaces.
 
 ## `fn_args_layout`
 
-Control the layout of arguments in a function
+This option has been renamed to `fn_params_layout` to better communicate that it affects the layout of parameters in function signatures.
 
 - **Default value**: `"Tall"`
 - **Possible values**: `"Compressed"`, `"Tall"`, `"Vertical"`
@@ -753,6 +753,8 @@ trait Lorem {
 }
 ```
 
+See also [`fn_params_layout`](#fn_params_layout)
+
 ## `fn_call_width`
 
 Maximum width of the args of a function call before falling back to vertical formatting.
@@ -765,6 +767,117 @@ By default this option is set as a percentage of [`max_width`](#max_width) provi
 
 See also [`max_width`](#max_width) and [`use_small_heuristics`](#use_small_heuristics)
 
+## `fn_params_layout`
+
+Control the layout of parameters in function signatures.
+
+- **Default value**: `"Tall"`
+- **Possible values**: `"Compressed"`, `"Tall"`, `"Vertical"`
+- **Stable**: Yes
+
+#### `"Tall"` (default):
+
+```rust
+trait Lorem {
+    fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet);
+
+    fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet) {
+        // body
+    }
+
+    fn lorem(
+        ipsum: Ipsum,
+        dolor: Dolor,
+        sit: Sit,
+        amet: Amet,
+        consectetur: Consectetur,
+        adipiscing: Adipiscing,
+        elit: Elit,
+    );
+
+    fn lorem(
+        ipsum: Ipsum,
+        dolor: Dolor,
+        sit: Sit,
+        amet: Amet,
+        consectetur: Consectetur,
+        adipiscing: Adipiscing,
+        elit: Elit,
+    ) {
+        // body
+    }
+}
+```
+
+#### `"Compressed"`:
+
+```rust
+trait Lorem {
+    fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet);
+
+    fn lorem(ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet) {
+        // body
+    }
+
+    fn lorem(
+        ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet, consectetur: Consectetur,
+        adipiscing: Adipiscing, elit: Elit,
+    );
+
+    fn lorem(
+        ipsum: Ipsum, dolor: Dolor, sit: Sit, amet: Amet, consectetur: Consectetur,
+        adipiscing: Adipiscing, elit: Elit,
+    ) {
+        // body
+    }
+}
+```
+
+#### `"Vertical"`:
+
+```rust
+trait Lorem {
+    fn lorem(
+        ipsum: Ipsum,
+        dolor: Dolor,
+        sit: Sit,
+        amet: Amet,
+    );
+
+    fn lorem(
+        ipsum: Ipsum,
+        dolor: Dolor,
+        sit: Sit,
+        amet: Amet,
+    ) {
+        // body
+    }
+
+    fn lorem(
+        ipsum: Ipsum,
+        dolor: Dolor,
+        sit: Sit,
+        amet: Amet,
+        consectetur: Consectetur,
+        adipiscing: Adipiscing,
+        elit: Elit,
+    );
+
+    fn lorem(
+        ipsum: Ipsum,
+        dolor: Dolor,
+        sit: Sit,
+        amet: Amet,
+        consectetur: Consectetur,
+        adipiscing: Adipiscing,
+        elit: Elit,
+    ) {
+        // body
+    }
+}
+```
+
+
 ## `fn_single_line`
 
 Put single-expression functions on a single line

src/config/config_type.rs

@@ -102,6 +102,7 @@ macro_rules! create_config {
                     | "array_width"
                     | "chain_width" => self.0.set_heuristics(),
                     "merge_imports" => self.0.set_merge_imports(),
+                    "fn_args_layout" => self.0.set_fn_args_layout(),
                     &_ => (),
                 }
             }
@@ -161,6 +162,7 @@ macro_rules! create_config {
                 self.set_heuristics();
                 self.set_ignore(dir);
                 self.set_merge_imports();
+                self.set_fn_args_layout();
                 self
             }
 
@@ -243,14 +245,21 @@ macro_rules! create_config {
                     | "array_width"
                     | "chain_width" => self.set_heuristics(),
                     "merge_imports" => self.set_merge_imports(),
+                    "fn_args_layout" => self.set_fn_args_layout(),
                     &_ => (),
                 }
             }
 
             #[allow(unreachable_pub)]
             pub fn is_hidden_option(name: &str) -> bool {
-                const HIDE_OPTIONS: [&str; 5] =
-                    ["verbose", "verbose_diff", "file_lines", "width_heuristics", "merge_imports"];
+                const HIDE_OPTIONS: [&str; 6] = [
+                    "verbose",
+                    "verbose_diff",
+                    "file_lines",
+                    "width_heuristics",
+                    "merge_imports",
+                    "fn_args_layout"
+                ];
                 HIDE_OPTIONS.contains(&name)
             }
 
@@ -400,6 +409,17 @@ macro_rules! create_config {
                 }
             }
 
+            fn set_fn_args_layout(&mut self) {
+                if self.was_set().fn_args_layout() {
+                    eprintln!(
+                        "Warning: the `fn_args_layout` option was renamed to `fn_params_layout`."
+                    );
+                    if !self.was_set().fn_params_layout() {
+                        self.fn_params_layout.2 = self.fn_args_layout();
+                    }
+                }
+            }
+
             #[allow(unreachable_pub)]
             /// Returns `true` if the config key was explicitly set and is the default value.
             pub fn is_default(&self, key: &str) -> bool {

src/config/mod.rs

@@ -117,7 +117,9 @@ create_config! {
     force_multiline_blocks: bool, false, false,
         "Force multiline closure bodies and match arms to be wrapped in a block";
     fn_args_layout: Density, Density::Tall, true,
-        "Control the layout of arguments in a function";
+        "Renamed to `fn_params_layout`. Use `fn_params_layout` instead.";
+    fn_params_layout: Density, Density::Tall, true,
+        "Control the layout of parameters in function signatures.";
     brace_style: BraceStyle, BraceStyle::SameLineWhere, false, "Brace style for items";
     control_brace_style: ControlBraceStyle, ControlBraceStyle::AlwaysSameLine, false,
         "Brace style for control flow constructs";
@@ -425,6 +427,12 @@ mod test {
                 "Merge imports";
             merge_imports: bool, false, false, "(deprecated: use imports_granularity instead)";
 
+            // fn_args_layout renamed to fn_params_layout
+            fn_args_layout: Density, Density::Tall, true,
+                "Renamed to `fn_params_layout`. Use `fn_params_layout` instead.";
+            fn_params_layout: Density, Density::Tall, true,
+                "Control the layout of parameters in a function signatures.";
+
             // Width Heuristics
             use_small_heuristics: Heuristics, Heuristics::Default, true,
                 "Whether to use different formatting for items and \
@@ -565,6 +573,7 @@ match_arm_blocks = true
 match_arm_leading_pipes = "Never"
 force_multiline_blocks = false
 fn_args_layout = "Tall"
+fn_params_layout = "Tall"
 brace_style = "SameLineWhere"
 control_brace_style = "AlwaysSameLine"
 trailing_semicolon = true

src/items.rs

@@ -2602,7 +2602,7 @@ fn rewrite_params(
         &param_items,
         context
             .config
-            .fn_args_layout()
+            .fn_params_layout()
             .to_list_tactic(param_items.len()),
         Separator::Comma,
         one_line_budget,

tests/config/small_tabs.toml

@@ -3,7 +3,7 @@ comment_width = 80
 tab_spaces = 2
 newline_style = "Unix"
 brace_style = "SameLineWhere"
-fn_args_layout = "Tall"
+fn_params_layout = "Tall"
 trailing_comma = "Vertical"
 indent_style = "Block"
 reorder_imports = false

tests/source/configs/fn_args_layout/compressed.rs renamed to tests/source/configs/fn_params_layout/compressed.rs

@@ -1,4 +1,4 @@
-// rustfmt-fn_args_layout: Compressed
+// rustfmt-fn_params_layout: Compressed
 // Function arguments density
 
 trait Lorem {

tests/source/configs/fn_args_layout/tall.rs renamed to tests/source/configs/fn_params_layout/tall.rs

@@ -1,4 +1,4 @@
-// rustfmt-fn_args_layout: Tall
+// rustfmt-fn_params_layout: Tall
 // Function arguments density
 
 trait Lorem {

tests/source/configs/fn_args_layout/vertical.rs renamed to tests/source/configs/fn_params_layout/vertical.rs

@@ -1,4 +1,4 @@
-// rustfmt-fn_args_layout: Vertical
+// rustfmt-fn_params_layout: Vertical
 // Function arguments density
 
 trait Lorem {

tests/source/fn-custom-7.rs

@@ -1,5 +1,5 @@
 // rustfmt-normalize_comments: true
-// rustfmt-fn_args_layout: Vertical
+// rustfmt-fn_params_layout: Vertical
 // rustfmt-brace_style: AlwaysNextLine
 
 // Case with only one variable.

tests/source/fn-custom.rs

@@ -1,4 +1,4 @@
-// rustfmt-fn_args_layout: Compressed
+// rustfmt-fn_params_layout: Compressed
 // Test some of the ways function signatures can be customised.
 
 // Test compressed layout of args.

tests/source/fn_args_layout-vertical.rs

@@ -1,4 +1,4 @@
-// rustfmt-fn_args_layout: Vertical
+// rustfmt-fn_params_layout: Vertical
 
 // Empty list should stay on one line.
 fn do_bar(

tests/target/configs/fn_args_layout/compressed.rs renamed to tests/target/configs/fn_params_layout/compressed.rs

@@ -1,4 +1,4 @@
-// rustfmt-fn_args_layout: Compressed
+// rustfmt-fn_params_layout: Compressed
 // Function arguments density
 
 trait Lorem {

tests/target/configs/fn_args_layout/tall.rs renamed to tests/target/configs/fn_params_layout/tall.rs

@@ -1,4 +1,4 @@
-// rustfmt-fn_args_layout: Tall
+// rustfmt-fn_params_layout: Tall
 // Function arguments density
 
 trait Lorem {

tests/target/configs/fn_args_layout/vertical.rs renamed to tests/target/configs/fn_params_layout/vertical.rs

@@ -1,4 +1,4 @@
-// rustfmt-fn_args_layout: Vertical
+// rustfmt-fn_params_layout: Vertical
 // Function arguments density
 
 trait Lorem {

tests/target/fn-custom-7.rs

@@ -1,5 +1,5 @@
 // rustfmt-normalize_comments: true
-// rustfmt-fn_args_layout: Vertical
+// rustfmt-fn_params_layout: Vertical
 // rustfmt-brace_style: AlwaysNextLine
 
 // Case with only one variable.

tests/target/fn-custom.rs

@@ -1,4 +1,4 @@
-// rustfmt-fn_args_layout: Compressed
+// rustfmt-fn_params_layout: Compressed
 // Test some of the ways function signatures can be customised.
 
 // Test compressed layout of args.

tests/target/fn_args_layout-vertical.rs

@@ -1,4 +1,4 @@
-// rustfmt-fn_args_layout: Vertical
+// rustfmt-fn_params_layout: Vertical
 
 // Empty list should stay on one line.
 fn do_bar() -> u8 {

tests/target/issue-4791/issue_4928.rs

@@ -1,7 +1,7 @@
 // rustfmt-brace_style: SameLineWhere
 // rustfmt-comment_width: 100
 // rustfmt-edition: 2018
-// rustfmt-fn_args_layout: Compressed
+// rustfmt-fn_params_layout: Compressed
 // rustfmt-hard_tabs: false
 // rustfmt-match_block_trailing_comma: true
 // rustfmt-max_width: 100