Backport: Assignment indentation after one line comment (#4550)

* Fix #4502 issue - assignment indentation after one line comment

* Enhancement by using rewrite_assign_rhs_with_comments()

* Changes per comments received

Author: davidBar-On

src/items.rs

@@ -119,62 +119,51 @@ impl Rewrite for ast::Local {
                 mk_sp(self.pat.span.hi(), self.span.hi())
             };
 
-            if let Some(offset) = context.snippet(base_span).find_uncommented("=") {
-                let base_span_lo = base_span.lo();
+            let offset = context.snippet(base_span).find_uncommented("=")?;
+            let base_span_lo = base_span.lo();
 
-                let assign_lo = base_span_lo + BytePos(offset as u32);
-                let comment_start_pos = if let Some(ref ty) = self.ty {
-                    ty.span.hi()
-                } else {
-                    self.pat.span.hi()
-                };
-                let comment_before_assign =
-                    context.snippet(mk_sp(comment_start_pos, assign_lo)).trim();
+            let assign_lo = base_span_lo + BytePos(offset as u32);
+            let comment_start_pos = if let Some(ref ty) = self.ty {
+                ty.span.hi()
+            } else {
+                self.pat.span.hi()
+            };
+            let comment_before_assign = context.snippet(mk_sp(comment_start_pos, assign_lo)).trim();
 
-                let assign_hi = base_span_lo + BytePos((offset + 1) as u32);
-                let rhs_span_lo = init.span.lo();
-                let comment_end_pos = if init.attrs.is_empty() {
+            let assign_hi = base_span_lo + BytePos((offset + 1) as u32);
+            let rhs_span_lo = init.span.lo();
+            let comment_end_pos = if init.attrs.is_empty() {
+                rhs_span_lo
+            } else {
+                let attr_span_lo = init.attrs.first().unwrap().span.lo();
+                // for the case using block
+                // ex. let x = { #![my_attr]do_something(); }
+                if rhs_span_lo < attr_span_lo {
                     rhs_span_lo
                 } else {
-                    let attr_span_lo = init.attrs.first().unwrap().span.lo();
-                    // for the case using block
-                    // ex. let x = { #![my_attr]do_something(); }
-                    if rhs_span_lo < attr_span_lo {
-                        rhs_span_lo
-                    } else {
-                        attr_span_lo
-                    }
-                };
-                let comment_after_assign =
-                    context.snippet(mk_sp(assign_hi, comment_end_pos)).trim();
-
-                if !comment_before_assign.is_empty() {
-                    let new_indent_str = &pat_shape
-                        .block_indent(0)
-                        .to_string_with_newline(context.config);
-                    result = format!("{}{}{}", comment_before_assign, new_indent_str, result);
+                    attr_span_lo
                 }
+            };
 
-                if !comment_after_assign.is_empty() {
-                    let new_indent_str =
-                        &shape.block_indent(0).to_string_with_newline(context.config);
-                    result.push_str(new_indent_str);
-                    result.push_str(comment_after_assign);
-                    result.push_str(new_indent_str);
-                }
+            if !comment_before_assign.is_empty() {
+                let new_indent_str = &pat_shape
+                    .block_indent(0)
+                    .to_string_with_newline(context.config);
+                result = format!("{}{}{}", comment_before_assign, new_indent_str, result);
             }
 
             // 1 = trailing semicolon;
             let nested_shape = shape.sub_width(1)?;
-
-            result = rewrite_assign_rhs(
+            result = rewrite_assign_rhs_with_comments(
                 context,
                 result,
                 init,
-                &RhsAssignKind::Expr(&init.kind, init.span),
                 nested_shape,
+                &RhsAssignKind::Expr(&init.kind, init.span),
+                RhsTactics::Default,
+                mk_sp(assign_hi, comment_end_pos),
+                true,
             )?;
-            // todo else
         }
 
         result.push(';');

tests/source/issue-4502.rs

@@ -0,0 +1,5 @@
+fn main() {
+    let after = 
+            // after_comment 
+     1.0;
+  }

tests/target/issue-3851.rs

@@ -5,15 +5,15 @@ fn main() {
     };
 
     let after =
-    // after_comment
-    if true {
-        1.0
-    };
+        // after_comment
+        if true {
+            1.0
+        };
 
     // before_comment
     let both =
-    // after_comment
-    if true {
-        1.0
-    };
+        // after_comment
+        if true {
+            1.0
+        };
 }

tests/target/issue-4502.rs

@@ -0,0 +1,5 @@
+fn main() {
+    let after =
+        // after_comment
+        1.0;
+}