Disallow lines that span more than 160 columns.

The Rust style guide suggests 100, but we have too many violations in the
tree already. This check can be tightened over time.

components/devtools/protocol.rs

@@ -2,7 +2,9 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-/// Low-level wire protocol implementation. Currently only supports [JSON packets](https://wiki.mozilla.org/Remote_Debugging_Protocol_Stream_Transport#JSON_Packets).
+//! Low-level wire protocol implementation. Currently only supports
+//! [JSON packets]
+//! (https://wiki.mozilla.org/Remote_Debugging_Protocol_Stream_Transport#JSON_Packets).
 
 use serialize::{json, Encodable};
 use serialize::json::Json;

components/layout/fragment.rs

@@ -1256,11 +1256,24 @@ impl Fragment {
     pub fn find_split_info_by_new_line(&self)
             -> Option<(SplitInfo, Option<SplitInfo>, Arc<Box<TextRun>> /* TODO(bjz): remove */)> {
         match self.specific {
-            SpecificFragmentInfo::Canvas(_) | SpecificFragmentInfo::Generic | SpecificFragmentInfo::Iframe(_) | SpecificFragmentInfo::Image(_) | SpecificFragmentInfo::Table | SpecificFragmentInfo::TableCell |
+            SpecificFragmentInfo::Canvas(_) |
-            SpecificFragmentInfo::TableRow | SpecificFragmentInfo::TableWrapper => None,
+            SpecificFragmentInfo::Generic |
-            SpecificFragmentInfo::TableColumn(_) => panic!("Table column fragments do not need to split"),
+            SpecificFragmentInfo::Iframe(_) |
-            SpecificFragmentInfo::UnscannedText(_) => panic!("Unscanned text fragments should have been scanned by now!"),
+            SpecificFragmentInfo::Image(_) |
-            SpecificFragmentInfo::InlineBlock(_) | SpecificFragmentInfo::InlineAbsoluteHypothetical(_) => {
+            SpecificFragmentInfo::Table |
+            SpecificFragmentInfo::TableCell |
+            SpecificFragmentInfo::TableRow |
+            SpecificFragmentInfo::TableWrapper => {
+                None
+            }
+            SpecificFragmentInfo::TableColumn(_) => {
+                panic!("Table column fragments do not need to split")
+            }
+            SpecificFragmentInfo::UnscannedText(_) => {
+                panic!("Unscanned text fragments should have been scanned by now!")
+            }
+            SpecificFragmentInfo::InlineBlock(_) |
+            SpecificFragmentInfo::InlineAbsoluteHypothetical(_) => {
                 panic!("Inline blocks or inline absolute hypothetical fragments do not get split")
             }
             SpecificFragmentInfo::ScannedText(ref text_fragment_info) => {

components/script/dom/element.rs

@@ -111,7 +111,9 @@ impl Element {
         create_element(name, prefix, document, creator)
     }
 
-    pub fn new_inherited(type_id: ElementTypeId, local_name: DOMString, namespace: Namespace, prefix: Option<DOMString>, document: JSRef<Document>) -> Element {
+    pub fn new_inherited(type_id: ElementTypeId, local_name: DOMString,
+                         namespace: Namespace, prefix: Option<DOMString>,
+                         document: JSRef<Document>) -> Element {
         Element {
             node: Node::new_inherited(NodeTypeId::Element(type_id), document),
             local_name: Atom::from_slice(local_name.as_slice()),

components/util/smallvec.rs

@@ -531,7 +531,10 @@ pub mod tests {
         let mut v = SmallVec16::new();
         v.push("hello".into_string());
         v.push("there".into_string());
-        assert_eq!(v.as_slice(), vec!["hello".into_string(), "there".into_string()].as_slice());
+        assert_eq!(v.as_slice(), vec![
+            "hello".into_string(),
+            "there".into_string(),
+        ].as_slice());
     }
 
     #[test]
@@ -541,7 +544,12 @@ pub mod tests {
         v.push("there".into_string());
         v.push("burma".into_string());
         v.push("shave".into_string());
-        assert_eq!(v.as_slice(), vec!["hello".into_string(), "there".into_string(), "burma".into_string(), "shave".into_string()].as_slice());
+        assert_eq!(v.as_slice(), vec![
+            "hello".into_string(),
+            "there".into_string(),
+            "burma".into_string(),
+            "shave".into_string(),
+        ].as_slice());
     }
 
     #[test]
@@ -556,7 +564,14 @@ pub mod tests {
         v.push("burma".into_string());
         v.push("shave".into_string());
         assert_eq!(v.as_slice(), vec![
-            "hello".into_string(), "there".into_string(), "burma".into_string(), "shave".into_string(), "hello".into_string(), "there".into_string(), "burma".into_string(), "shave".into_string(),
+            "hello".into_string(),
+            "there".into_string(),
+            "burma".into_string(),
+            "shave".into_string(),
+            "hello".into_string(),
+            "there".into_string(),
+            "burma".into_string(),
+            "shave".into_string(),
         ].as_slice());
     }
 }

python/tidy.py

@@ -56,6 +56,13 @@ def check_license(contents):
         yield (1, "incorrect license")
 
 
+def check_length(contents):
+    lines = contents.splitlines(True)
+    for idx, line in enumerate(lines):
+        if len(line) >= 160:
+            yield (idx + 1, "(much) overlong line")
+
+
 def check_whitespace(contents):
     lines = contents.splitlines(True)
     for idx, line in enumerate(lines):
@@ -88,7 +95,7 @@ def scan():
     all_files = collect_file_names(directories_to_check)
     files_to_check = filter(should_check, all_files)
 
-    checking_functions = [check_license, check_whitespace]
+    checking_functions = [check_license, check_length, check_whitespace]
     errors = collect_errors_for_files(files_to_check, checking_functions)
     errors = list(errors)