change new line point in the case of no args

src/items.rs

@@ -24,7 +24,7 @@ use comment::{
     combine_strs_with_missing_comments, contains_comment, recover_comment_removed,
     recover_missing_comment_in_span, rewrite_missing_comment, FindUncommented,
 };
-use config::{BraceStyle, Config, Density, IndentStyle};
+use config::{BraceStyle, Config, Density, IndentStyle, Version};
 use expr::{
     format_expr, is_empty_block, is_simple_block_stmt, rewrite_assign_rhs, rewrite_assign_rhs_with,
     ExprType, RhsTactics,
@@ -2064,6 +2064,8 @@ fn rewrite_fn_base(
     } && !fd.inputs.is_empty();
 
     let mut args_last_line_contains_comment = false;
+    let mut no_args_and_over_max_width = false;
+
     if put_args_in_block {
         arg_indent = indent.block_indent(context.config);
         result.push_str(&arg_indent.to_string_with_newline(context.config));
@@ -2083,10 +2085,19 @@ fn rewrite_fn_base(
             .lines()
             .last()
             .map_or(false, |last_line| last_line.contains("//"));
-        if closing_paren_overflow_max_width || args_last_line_contains_comment {
-            result.push_str(&indent.to_string_with_newline(context.config));
+
+        if context.config.version() == Version::Two {
+            result.push(')');
+            if closing_paren_overflow_max_width || args_last_line_contains_comment {
+                result.push_str(&indent.to_string_with_newline(context.config));
+                no_args_and_over_max_width = true;
+            }
+        } else {
+            if closing_paren_overflow_max_width || args_last_line_contains_comment {
+                result.push_str(&indent.to_string_with_newline(context.config));
+            }
+            result.push(')');
         }
-        result.push(')');
     }
 
     // Return type.
@@ -2126,7 +2137,14 @@ fn rewrite_fn_base(
             result.push_str(&indent.to_string_with_newline(context.config));
             indent
         } else {
-            result.push(' ');
+            if context.config.version() == Version::Two {
+                if arg_str.len() != 0 || !no_args_and_over_max_width {
+                    result.push(' ');
+                }
+            } else {
+                result.push(' ');
+            }
+
             Indent::new(indent.block_indent, last_line_width(&result))
         };
 

tests/source/issue-3278/version_one.rs

@@ -0,0 +1,8 @@
+// rustfmt-version: One
+
+pub fn parse_conditional<'a, I: 'a>(
+) -> impl Parser<Input = I, Output = Expr, PartialState = ()> + 'a
+where
+    I: Stream<Item = char>,
+{
+}

tests/source/issue-3278/version_two.rs

@@ -0,0 +1,8 @@
+// rustfmt-version: Two
+
+pub fn parse_conditional<'a, I: 'a>()
+-> impl Parser<Input = I, Output = Expr, PartialState = ()> + 'a
+where
+    I: Stream<Item = char>,
+{
+}

tests/source/long-fn-1.rs → tests/source/long-fn-1/version_one.rs

@@ -1,3 +1,4 @@
+// rustfmt-version: One
 // Tests that a function which is almost short enough, but not quite, gets
 // formatted correctly.
 

tests/source/long-fn-1/version_two.rs

@@ -0,0 +1,21 @@
+// rustfmt-version: Two
+// Tests that a function which is almost short enough, but not quite, gets
+// formatted correctly.
+
+impl Foo {
+    fn some_input(&mut self, input: Input, input_path: Option<PathBuf>, ) -> (Input, Option<PathBuf>) {}
+
+    fn some_inpu(&mut self, input: Input, input_path: Option<PathBuf>) -> (Input, Option<PathBuf>) {}
+}
+
+// #1843
+#[allow(non_snake_case)]
+pub extern "C" fn Java_com_exonum_binding_storage_indices_ValueSetIndexProxy_nativeContainsByHash() -> bool {
+    false
+}
+
+// #3009
+impl Something {
+    fn my_function_name_is_way_to_long_but_used_as_a_case_study_or_an_example_its_fine(
+) -> Result<  (), String  > {}
+}

tests/target/issue-3278/version_one.rs

@@ -0,0 +1,8 @@
+// rustfmt-version: One
+
+pub fn parse_conditional<'a, I: 'a>(
+) -> impl Parser<Input = I, Output = Expr, PartialState = ()> + 'a
+where
+    I: Stream<Item = char>,
+{
+}

tests/target/issue-3278/version_two.rs

@@ -0,0 +1,8 @@
+// rustfmt-version: Two
+
+pub fn parse_conditional<'a, I: 'a>()
+-> impl Parser<Input = I, Output = Expr, PartialState = ()> + 'a
+where
+    I: Stream<Item = char>,
+{
+}

tests/target/long-fn-1.rs → tests/target/long-fn-1/version_one.rs

@@ -1,3 +1,4 @@
+// rustfmt-version: One
 // Tests that a function which is almost short enough, but not quite, gets
 // formatted correctly.
 

tests/target/long-fn-1/version_two.rs

@@ -0,0 +1,29 @@
+// rustfmt-version: Two
+// Tests that a function which is almost short enough, but not quite, gets
+// formatted correctly.
+
+impl Foo {
+    fn some_input(
+        &mut self,
+        input: Input,
+        input_path: Option<PathBuf>,
+    ) -> (Input, Option<PathBuf>) {
+    }
+
+    fn some_inpu(&mut self, input: Input, input_path: Option<PathBuf>) -> (Input, Option<PathBuf>) {
+    }
+}
+
+// #1843
+#[allow(non_snake_case)]
+pub extern "C" fn Java_com_exonum_binding_storage_indices_ValueSetIndexProxy_nativeContainsByHash()
+-> bool {
+    false
+}
+
+// #3009
+impl Something {
+    fn my_function_name_is_way_to_long_but_used_as_a_case_study_or_an_example_its_fine()
+    -> Result<(), String> {
+    }
+}