fix: comments between lhs and rhs

Author: calebcartwright

src/comment.rs

@@ -112,7 +112,7 @@ impl<'a> CommentStyle<'a> {
     }
 }
 
-fn comment_style(orig: &str, normalize_comments: bool) -> CommentStyle<'_> {
+pub(crate) fn comment_style(orig: &str, normalize_comments: bool) -> CommentStyle<'_> {
     if !normalize_comments {
         if orig.starts_with("/**") && !orig.starts_with("/**/") {
             CommentStyle::DoubleBullet

src/expr.rs

@@ -9,8 +9,8 @@ use syntax::{ast, ptr};
 use crate::chains::rewrite_chain;
 use crate::closures;
 use crate::comment::{
-    combine_strs_with_missing_comments, contains_comment, recover_comment_removed, rewrite_comment,
-    rewrite_missing_comment, CharClasses, FindUncommented,
+    combine_strs_with_missing_comments, comment_style, contains_comment, recover_comment_removed,
+    rewrite_comment, rewrite_missing_comment, CharClasses, FindUncommented,
 };
 use crate::config::lists::*;
 use crate::config::{Config, ControlBraceStyle, IndentStyle, Version};
@@ -808,7 +808,7 @@ impl<'a> ControlFlow<'a> {
         debug!("rewrite_pat_expr {:?} {:?} {:?}", shape, self.pat, expr);
 
         let cond_shape = shape.offset_left(offset)?;
-        if !self.pat.is_none() {
+        if let Some(pat) = self.pat {
             let matcher = if self.matcher.is_empty() {
                 self.matcher.to_owned()
             } else {
@@ -817,12 +817,41 @@ impl<'a> ControlFlow<'a> {
             let pat_shape = cond_shape
                 .offset_left(matcher.len())?
                 .sub_width(self.connector.len())?;
-            let pat_string = if let Some(pat) = self.pat {
-                pat.rewrite(context, pat_shape)?
+            let pat_string = pat.rewrite(context, pat_shape)?;
+            let comments_lo = context
+                .snippet_provider
+                .span_after(self.span, self.connector.trim());
+            let missing_comments = if let Some(comment) =
+                rewrite_missing_comment(mk_sp(comments_lo, expr.span.lo()), cond_shape, context)
+            {
+                if !self.connector.is_empty() && !comment.is_empty() {
+                    if comment_style(&comment, false).is_line_comment() || comment.contains("\n") {
+                        let newline = &pat_shape
+                            .indent
+                            .block_indent(context.config)
+                            .to_string_with_newline(context.config);
+                        // An extra space is added when the lhs and rhs are joined
+                        // so we need to remove one space from the end to ensure
+                        // the comment and rhs are aligned.
+                        let mut suffix = newline.as_ref().to_string();
+                        if !suffix.is_empty() {
+                            suffix.truncate(suffix.len() - 1);
+                        }
+                        format!("{}{}{}", newline, comment, suffix)
+                    } else {
+                        format!(" {}", comment)
+                    }
+                } else {
+                    comment
+                }
             } else {
                 "".to_owned()
             };
-            let result = format!("{}{}{}", matcher, pat_string, self.connector);
+
+            let result = format!(
+                "{}{}{}{}",
+                matcher, pat_string, self.connector, missing_comments
+            );
             return rewrite_assign_rhs(context, result, expr, cond_shape);
         }
 

tests/source/issue_3853.rs

@@ -33,3 +33,20 @@ fn issue_3853() {
 if let Some(ref /*mut*/ state) = foo {
 					}
 }
+
+fn double_slash_comment_between_lhs_and_rhs() {
+    if let Some(e) =
+				 // self.foo.bar(e, tx)
+				 packet.transaction.state.committed
+                {
+            // body
+                            println!(
+                                "a2304712836123");
+                                }
+}
+
+fn block_comment_between_lhs_and_rhs() {
+if let Some(ref     /*def*/  mut     /*abc*/       state)=          /*abc*/foo{
+				println!(
+        "asdfasdfasdf");	}
+}

tests/target/issue_3853.rs

@@ -29,3 +29,19 @@ fn no_prefix_block_before_ident() {
 fn issue_3853() {
     if let Some(ref /*mut*/ state) = foo {}
 }
+
+fn double_slash_comment_between_lhs_and_rhs() {
+    if let Some(e) =
+        // self.foo.bar(e, tx)
+        packet.transaction.state.committed
+    {
+        // body
+        println!("a2304712836123");
+    }
+}
+
+fn block_comment_between_lhs_and_rhs() {
+    if let Some(ref /*def*/ mut /*abc*/ state) = /*abc*/ foo {
+        println!("asdfasdfasdf");
+    }
+}