Don't bail out of formatting code blocks if lines are >100 chars

Today rustfmt bails when trying to handle a code block that, after
formatting, has lines >100 chars. The reasoning was that if there were
lines longer than 100 chars it wasn't clear if we failed to format or
that was the intended result, so to be cautious the handler would bail.

However, if formatting the snippet fails the code block formatter will
already have jumped out by the time this line-width check is done:

https://github.com/rust-lang/rustfmt/blob/ff57cc6293ce450380dbb6da6a1a3656dbae538d/src/formatting/util.rs#L81

So I am not sure that this check is needed, and removing it broke no
tests except one designed explicitly for it. NB w.r.t. that unit test,
formatting a code like

```
fn main() {
    let expected = "this_line_is_100_characters_long_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(x, y, z);";
}
```

would yield no change, so I believe it is also the expected result.

Closes #4325

src/formatting/utils.rs

@@ -792,12 +792,6 @@ pub(crate) fn format_code_block(code_snippet: &str, config: &Config) -> Option<F
         }
         let trimmed_line = if !is_indented {
             line
-        } else if line.len() > config.max_width() {
-            // If there are lines that are larger than max width, we cannot tell
-            // whether we have succeeded but have some comments or strings that
-            // are too long, or we have failed to format code block. We will be
-            // conservative and just return `None` in this case.
-            return None;
         } else if line.len() > indent_str.len() {
             // Make sure that the line has leading whitespaces.
             if line.starts_with(indent_str.as_ref()) {
@@ -885,13 +879,6 @@ mod test {
         assert!(test_format_inner(format_snippet, snippet, expected));
     }
 
-    #[test]
-    fn test_format_code_block_fail() {
-        #[rustfmt::skip]
-        let code_block = "this_line_is_100_characters_long_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(x, y, z);";
-        assert!(format_code_block(code_block, &Config::default()).is_none());
-    }
-
     #[test]
     fn test_format_code_block() {
         // simple code block
@@ -942,5 +929,11 @@ false,
     )
 };";
         assert!(test_format_inner(format_code_block, code_block, expected));
+
+        #[rustfmt::skip]
+        let code_block = "this_line_is_100_characters_long_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(x, y, z);";
+        #[rustfmt::skip]
+        let expected = "this_line_is_100_characters_long_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx(x, y, z);";
+        assert!(test_format_inner(format_code_block, code_block, expected));
     }
 }

tests/target/issue-4325.rs

@@ -0,0 +1,10 @@
+macro_rules! bad {
+    () => {
+        macro_rules! inner {
+            () => {
+                // This needs to have a width of over 100 characters to trigger the issue 12345678901
+                ("a", "B")
+            };
+        }
+    };
+}