Merge pull request rust-lang#3109 from scampi/issue-3038

force a newline after the `if` condition if there is a different indentation level

Author: nrc

src/expr.rs

@@ -801,6 +801,20 @@ impl<'a> ControlFlow<'a> {
     }
 }
 
+/// Returns true if the last line of pat_str has leading whitespace and it is wider than the
+/// shape's indent.
+fn last_line_offsetted(start_column: usize, pat_str: &str) -> bool {
+    let mut leading_whitespaces = 0;
+    for c in pat_str.chars().rev() {
+        match c {
+            '\n' => break,
+            _ if c.is_whitespace() => leading_whitespaces += 1,
+            _ => leading_whitespaces = 0,
+        }
+    }
+    leading_whitespaces > start_column
+}
+
 impl<'a> ControlFlow<'a> {
     fn rewrite_pat_expr(
         &self,
@@ -885,7 +899,8 @@ impl<'a> ControlFlow<'a> {
             .saturating_sub(constr_shape.used_width() + offset + brace_overhead);
         let force_newline_brace = (pat_expr_string.contains('\n')
             || pat_expr_string.len() > one_line_budget)
-            && !last_line_extendable(&pat_expr_string);
+            && (!last_line_extendable(&pat_expr_string)
+                || last_line_offsetted(shape.used_width(), &pat_expr_string));
 
         // Try to format if-else on single line.
         if self.allow_single_line
@@ -1977,3 +1992,29 @@ pub fn is_method_call(expr: &ast::Expr) -> bool {
         _ => false,
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::last_line_offsetted;
+
+    #[test]
+    fn test_last_line_offsetted() {
+        let lines = "one\n    two";
+        assert_eq!(last_line_offsetted(2, lines), true);
+        assert_eq!(last_line_offsetted(4, lines), false);
+        assert_eq!(last_line_offsetted(6, lines), false);
+
+        let lines = "one    two";
+        assert_eq!(last_line_offsetted(2, lines), false);
+        assert_eq!(last_line_offsetted(0, lines), false);
+
+        let lines = "\ntwo";
+        assert_eq!(last_line_offsetted(2, lines), false);
+        assert_eq!(last_line_offsetted(0, lines), false);
+
+        let lines = "one\n    two      three";
+        assert_eq!(last_line_offsetted(2, lines), true);
+        let lines = "one\n two      three";
+        assert_eq!(last_line_offsetted(2, lines), false);
+    }
+}

tests/source/issue-3038.rs

@@ -0,0 +1,20 @@
+impl HTMLTableElement {
+    fn func() {
+        if number_of_row_elements == 0 {
+            if let Some(last_tbody) = node.rev_children()
+                    .filter_map(DomRoot::downcast::<Element>)
+                    .find(|n| n.is::<HTMLTableSectionElement>() && n.local_name() == &local_name!("tbody")) {
+                        last_tbody.upcast::<Node>().AppendChild(new_row.upcast::<Node>())
+                                                   .expect("InsertRow failed to append first row.");
+                    }
+        }
+
+        if number_of_row_elements == 0 {
+            if let Some(last_tbody) = node
+                    .find(|n| n.is::<HTMLTableSectionElement>() && n.local_name() == &local_name!("tbody")) {
+                        last_tbody.upcast::<Node>().AppendChild(new_row.upcast::<Node>())
+                                                   .expect("InsertRow failed to append first row.");
+                    }
+        }
+    }
+}

tests/target/issue-2985.rs

@@ -27,7 +27,8 @@ fn foo() {
                                                           .map(String::as_ref)
                                                           .unwrap_or("")
                                                           .is_empty()
-                                                    }) {
+                                                    })
+            {
                 do_something();
             }
         }

tests/target/issue-3038.rs

@@ -0,0 +1,29 @@
+impl HTMLTableElement {
+    fn func() {
+        if number_of_row_elements == 0 {
+            if let Some(last_tbody) = node
+                .rev_children()
+                .filter_map(DomRoot::downcast::<Element>)
+                .find(|n| {
+                    n.is::<HTMLTableSectionElement>() && n.local_name() == &local_name!("tbody")
+                })
+            {
+                last_tbody
+                    .upcast::<Node>()
+                    .AppendChild(new_row.upcast::<Node>())
+                    .expect("InsertRow failed to append first row.");
+            }
+        }
+
+        if number_of_row_elements == 0 {
+            if let Some(last_tbody) = node.find(|n| {
+                n.is::<HTMLTableSectionElement>() && n.local_name() == &local_name!("tbody")
+            }) {
+                last_tbody
+                    .upcast::<Node>()
+                    .AppendChild(new_row.upcast::<Node>())
+                    .expect("InsertRow failed to append first row.");
+            }
+        }
+    }
+}