Merge pull request #1997 from topecongiro/issue-1995

Fix a budget bug in Arg::rewrite()

Author: nrc

src/items.rs

@@ -1598,11 +1598,12 @@ impl Rewrite for ast::Arg {
                 if context.config.space_after_type_annotation_colon() {
                     result.push_str(" ");
                 }
-                let max_width = try_opt!(shape.width.checked_sub(result.len()));
-                let ty_str = try_opt!(self.ty.rewrite(
-                    context,
-                    Shape::legacy(max_width, shape.indent + result.len()),
-                ));
+                let overhead = last_line_width(&result);
+                let max_width = try_opt!(shape.width.checked_sub(overhead));
+                let ty_str = try_opt!(
+                    self.ty
+                        .rewrite(context, Shape::legacy(max_width, shape.indent))
+                );
                 result.push_str(&ty_str);
             }
 

tests/source/impls.rs

@@ -139,3 +139,16 @@ pub trait Number: Copy + Eq +      Not<Output = Self> + Shl<u8, Output = Self> +
 pub trait SomeTrait : Clone + Eq + PartialEq + Ord + PartialOrd + Default + Hash + Debug + Display + Write + Read + FromStr {
     // comment
 }
+
+// #1995
+impl Foo {
+    fn f(
+		    S {
+			      aaaaaaaaaa: aaaaaaaaaa,
+			      bbbbbbbbbb: bbbbbbbbbb,
+			      cccccccccc: cccccccccc,
+		    }: S
+    ) -> u32{
+        1
+    }
+}

tests/target/impls.rs

@@ -202,3 +202,16 @@ pub trait SomeTrait
     + FromStr {
     // comment
 }
+
+// #1995
+impl Foo {
+    fn f(
+        S {
+            aaaaaaaaaa: aaaaaaaaaa,
+            bbbbbbbbbb: bbbbbbbbbb,
+            cccccccccc: cccccccccc,
+        }: S,
+    ) -> u32 {
+        1
+    }
+}