Merge pull request rust-lang#3458 from topecongiro/issue-3457

Avoid panic on macro inside deeply nested block

Author: scampi

src/shape.rs

@@ -228,6 +228,10 @@ impl Shape {
         }
     }
 
+    pub fn saturating_sub_width(&self, width: usize) -> Shape {
+        self.sub_width(width).unwrap_or(Shape { width: 0, ..*self })
+    }
+
     pub fn sub_width(&self, width: usize) -> Option<Shape> {
         Some(Shape {
             width: self.width.checked_sub(width)?,

src/visitor.rs

@@ -536,7 +536,7 @@ impl<'b, 'a: 'b> FmtVisitor<'a> {
         skip_out_of_file_lines_range_visitor!(self, mac.span);
 
         // 1 = ;
-        let shape = self.shape().sub_width(1).unwrap();
+        let shape = self.shape().saturating_sub_width(1);
         let rewrite = self.with_context(|ctx| rewrite_macro(mac, ident, ctx, shape, pos));
         self.push_rewrite(mac.span, rewrite);
     }

tests/source/expr.rs

@@ -479,3 +479,56 @@ fn issue3226() {
         }
     }
 }
+
+// #3457
+fn issue3457() {
+    {
+        {
+            {
+                {
+                    {
+                        {
+                            {
+                                {
+                                    {
+                                        {
+                                            {
+                                                {
+                                                    {
+                                                        {
+                                                            {
+                                                                {
+                                                                    {
+                                                                        {
+                                                                            {
+                                                                                {
+                                                                                    {
+                                                                                        {
+                                                                                            {
+                                                                                                {
+                                                                                                    println!("Test");
+                                                                                                }
+                                                                                            }
+                                                                                        }
+                                                                                    }
+                                                                                }
+                                                                            }
+                                                                        }
+                                                                    }
+                                                                }
+                                                            }
+                                                        }
+                                                    }
+                                                }
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}

tests/target/expr.rs

@@ -562,3 +562,56 @@ fn issue3226() {
         }
     }
 }
+
+// #3457
+fn issue3457() {
+    {
+        {
+            {
+                {
+                    {
+                        {
+                            {
+                                {
+                                    {
+                                        {
+                                            {
+                                                {
+                                                    {
+                                                        {
+                                                            {
+                                                                {
+                                                                    {
+                                                                        {
+                                                                            {
+                                                                                {
+                                                                                    {
+                                                                                        {
+                                                                                            {
+                                                                                                {
+                                                                                                    println!("Test");
+                                                                                                }
+                                                                                            }
+                                                                                        }
+                                                                                    }
+                                                                                }
+                                                                            }
+                                                                        }
+                                                                    }
+                                                                }
+                                                            }
+                                                        }
+                                                    }
+                                                }
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}