Merge pull request #864 from Venti-/fn-density

Add option for vertical function argument list

6 files changed, 129 insertions, 1 deletions

diff --git a/src/config.rs b/src/config.rs
index 448ab3b8d51..32eb9af4b11 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -71,6 +71,8 @@ configuration_option_enum! { Density:
     Tall,
     // Try to compress if the body is empty.
     CompressedIfEmpty,
+    // Place every item on a separate line.
+    Vertical,
 }
 
 configuration_option_enum! { TypeDensity:
@@ -85,6 +87,7 @@ impl Density {
         match self {
             Density::Compressed => ListTactic::Mixed,
             Density::Tall | Density::CompressedIfEmpty => ListTactic::HorizontalVertical,
+            Density::Vertical => ListTactic::Vertical,
         }
     }
 }
diff --git a/src/items.rs b/src/items.rs
index b879080d92f..04382489b28 100644
--- a/src/items.rs
+++ b/src/items.rs
@@ -1544,13 +1544,18 @@ fn rewrite_args(context: &RewriteContext,
         _ => multi_line_budget,
     };
 
+    let end_with_newline = match context.config.fn_args_layout {
+        StructLitStyle::Block => true,
+        _ => false,
+    };
+
     let fmt = ListFormatting {
         tactic: tactic,
         separator: ",",
         trailing_separator: SeparatorTactic::Never,
         indent: indent,
         width: budget,
-        ends_with_newline: false,
+        ends_with_newline: end_with_newline,
         config: context.config,
     };
 
diff --git a/tests/source/fn-custom-7.rs b/tests/source/fn-custom-7.rs
new file mode 100644
index 00000000000..6a56c440d33
--- /dev/null
+++ b/tests/source/fn-custom-7.rs
@@ -0,0 +1,19 @@
+// rustfmt-fn_args_layout: Block
+// rustfmt-fn_args_density: Vertical
+// rustfmt-fn_arg_indent: Tabbed
+// rustfmt-fn_brace_style: AlwaysNextLine
+
+// Case with only one variable.
+fn foo(a: u8) -> u8 {
+    bar()
+}
+
+// Case with 2 variables and some pre-comments.
+fn foo(a: u8 /* Comment 1 */, b: u8 /* Comment 2 */) -> u8 {
+    bar()
+}
+
+// Case with 2 variables and some post-comments.
+fn foo(/* Comment 1 */ a: u8, /* Comment 2 */ b: u8) -> u8 {
+    bar()
+}
diff --git a/tests/source/fn_args_density-vertical.rs b/tests/source/fn_args_density-vertical.rs
new file mode 100644
index 00000000000..7dd4dcbfc4d
--- /dev/null
+++ b/tests/source/fn_args_density-vertical.rs
@@ -0,0 +1,33 @@
+// rustfmt-fn_args_density: Vertical
+
+// Empty list shoul stay on one line.
+fn do_bar(
+
+) -> u8 {
+    bar()
+}
+
+// A single argument should stay on the same line.
+fn do_bar(
+        a: u8) -> u8 {
+    bar()
+}
+
+// Multiple arguments should each get their own line.
+fn do_bar(a: u8, mut b: u8, c: &u8, d: &mut u8, closure: &Fn(i32) -> i32) -> i32 {
+    // This feature should not affect closures.
+    let bar = |x: i32, y: i32| -> i32 { x + y };
+    bar(a, b)
+}
+
+// If the first argument doesn't fit on the same line with the function name,
+// the whole list should probably be pushed to the next line with hanging
+// indent. That's not what happens though, so check current behaviour instead.
+// In any case, it should maintain single argument per line.
+fn do_this_that_and_the_other_thing(
+        aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa: u8,
+        b: u8, c: u8, d: u8) {
+    this();
+    that();
+    the_other_thing();
+}
diff --git a/tests/target/fn-custom-7.rs b/tests/target/fn-custom-7.rs
new file mode 100644
index 00000000000..1c4cbde24b8
--- /dev/null
+++ b/tests/target/fn-custom-7.rs
@@ -0,0 +1,32 @@
+// rustfmt-fn_args_layout: Block
+// rustfmt-fn_args_density: Vertical
+// rustfmt-fn_arg_indent: Tabbed
+// rustfmt-fn_brace_style: AlwaysNextLine
+
+// Case with only one variable.
+fn foo(
+    a: u8
+) -> u8
+{
+    bar()
+}
+
+// Case with 2 variables and some pre-comments.
+fn foo(
+    a: u8, // Comment 1
+    b: u8 // Comment 2
+) -> u8
+{
+    bar()
+}
+
+// Case with 2 variables and some post-comments.
+fn foo(
+    // Comment 1
+    a: u8,
+    // Comment 2
+    b: u8
+) -> u8
+{
+    bar()
+}
diff --git a/tests/target/fn_args_density-vertical.rs b/tests/target/fn_args_density-vertical.rs
new file mode 100644
index 00000000000..250d32654e5
--- /dev/null
+++ b/tests/target/fn_args_density-vertical.rs
@@ -0,0 +1,36 @@
+// rustfmt-fn_args_density: Vertical
+
+// Empty list shoul stay on one line.
+fn do_bar() -> u8 {
+    bar()
+}
+
+// A single argument should stay on the same line.
+fn do_bar(a: u8) -> u8 {
+    bar()
+}
+
+// Multiple arguments should each get their own line.
+fn do_bar(a: u8,
+          mut b: u8,
+          c: &u8,
+          d: &mut u8,
+          closure: &Fn(i32) -> i32)
+          -> i32 {
+    // This feature should not affect closures.
+    let bar = |x: i32, y: i32| -> i32 { x + y };
+    bar(a, b)
+}
+
+// If the first argument doesn't fit on the same line with the function name,
+// the whole list should probably be pushed to the next line with hanging
+// indent. That's not what happens though, so check current behaviour instead.
+// In any case, it should maintain single argument per line.
+fn do_this_that_and_the_other_thing(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa: u8,
+                                    b: u8,
+                                    c: u8,
+                                    d: u8) {
+    this();
+    that();
+    the_other_thing();
+}