Preserve comments inside attributes

src/expr.rs

@@ -157,9 +157,8 @@ fn format_expr(
         ast::ExprKind::Loop(..) |
         ast::ExprKind::While(..) |
         ast::ExprKind::WhileLet(..) => {
-            to_control_flow(expr, expr_type).and_then(|control_flow| {
-                control_flow.rewrite(context, shape)
-            })
+            to_control_flow(expr, expr_type)
+                .and_then(|control_flow| control_flow.rewrite(context, shape))
         }
         ast::ExprKind::Block(ref block) => block.rewrite(context, shape),
         ast::ExprKind::Match(ref cond, ref arms) => {

src/visitor.rs

@@ -19,7 +19,7 @@ use strings::string_buffer::StringBuffer;
 use {Indent, Shape};
 use utils::{self, mk_sp};
 use codemap::{LineRangeUtils, SpanUtils};
-use comment::FindUncommented;
+use comment::{contains_comment, FindUncommented};
 use config::Config;
 use rewrite::{Rewrite, RewriteContext};
 use comment::rewrite_comment;
@@ -761,7 +761,7 @@ impl Rewrite for ast::MetaItem {
             ast::MetaItemKind::NameValue(ref literal) => {
                 let name = self.name.as_str();
                 let value = context.snippet(literal.span);
-                if &*name == "doc" && value.starts_with("///") {
+                if &*name == "doc" && contains_comment(&value) {
                     let doc_shape = Shape {
                         width: cmp::min(shape.width, context.config.comment_width())
                             .checked_sub(shape.indent.width())
@@ -786,7 +786,12 @@ impl Rewrite for ast::Attribute {
             if rw.starts_with("///") {
                 rw
             } else {
-                format!("#[{}]", rw)
+                let original = context.snippet(self.span);
+                if contains_comment(&original) {
+                    original
+                } else {
+                    format!("#[{}]", rw)
+                }
             }
         })
     }

tests/target/issue-1703.rs

@@ -0,0 +1,9 @@
+// rustfmt should not remove doc comments or comments inside attributes.
+
+/**
+This function has a block doc comment.
+ */
+fn test_function() {}
+
+#[foo /* do not remove this! */]
+fn foo() {}