From a18a40cbc141ad1437796a53b1d1a893c5cb5dff Mon Sep 17 00:00:00 2001
From: Seiichi Uchida <seuchida@gmail.com>
Date: Mon, 21 Aug 2017 23:19:01 +0900
Subject: [PATCH] Add indent to macro we could not format

---
 src/macros.rs          | 65 +++++++++++++++++++++++++++++++++++++++---
 tests/source/macros.rs |  9 ++++++
 tests/target/macros.rs | 12 ++++++++
 3 files changed, 82 insertions(+), 4 deletions(-)

diff --git a/src/macros.rs b/src/macros.rs
index ae2a16510b8..b1f740e6a87 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -19,6 +19,8 @@
 // List-like invocations with parentheses will be formatted as function calls,
 // and those with brackets will be formatted as array literals.
 
+use std::iter::repeat;
+
 use syntax::ast;
 use syntax::codemap::BytePos;
 use syntax::parse::new_parser_from_tts;
@@ -27,7 +29,7 @@
 use syntax::tokenstream::TokenStream;
 use syntax::util::ThinVec;
 
-use Shape;
+use {Indent, Shape};
 use codemap::SpanUtils;
 use comment::{contains_comment, FindUncommented};
 use expr::{rewrite_array, rewrite_call_inner};
@@ -116,14 +118,14 @@ pub fn rewrite_macro(
                 Ok(expr) => {
                     // Recovered errors.
                     if context.parse_session.span_diagnostic.has_errors() {
-                        return Some(context.snippet(mac.span));
+                        return indent_macro_snippet(&context.snippet(mac.span), shape.indent);
                     }
 
                     expr
                 }
                 Err(mut e) => {
                     e.cancel();
-                    return Some(context.snippet(mac.span));
+                    return indent_macro_snippet(&context.snippet(mac.span), shape.indent);
                 }
             };
 
@@ -242,7 +244,7 @@ pub fn rewrite_macro(
         }
         MacroStyle::Braces => {
             // Skip macro invocations with braces, for now.
-            None
+            indent_macro_snippet(&context.snippet(mac.span), shape.indent)
         }
     }
 }
@@ -280,3 +282,58 @@ fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
         MacroStyle::Braces
     }
 }
+
+/// Indent each line according to the specified `indent`.
+/// e.g.
+/// ```rust
+/// foo!{
+/// x,
+/// y,
+/// foo(
+///     a,
+///     b,
+///     c,
+/// ),
+/// }
+/// ```
+/// will become
+/// ```rust
+/// foo!{
+///     x,
+///     y,
+///     foo(
+///         a,
+///         b,
+///         c,
+//      ),
+/// }
+/// ```
+fn indent_macro_snippet(macro_str: &str, indent: Indent) -> Option<String> {
+    let min_prefix_space_width =
+        try_opt!(macro_str.lines().skip(1).map(get_prefix_space_width).min());
+
+    let mut lines = macro_str.lines();
+    let first_line = try_opt!(lines.next());
+
+    Some(
+        String::from(first_line) + "\n" +
+            &lines
+                .map(|line| {
+                    let new_indent_width = indent.width() +
+                        get_prefix_space_width(line)
+                            .checked_sub(min_prefix_space_width)
+                            .unwrap_or(0);
+                    repeat_white_space(new_indent_width) + line.trim()
+                })
+                .collect::<Vec<_>>()
+                .join("\n"),
+    )
+}
+
+fn get_prefix_space_width(s: &str) -> usize {
+    s.chars().position(|c| c != ' ').unwrap_or(0)
+}
+
+fn repeat_white_space(ws_count: usize) -> String {
+    repeat(" ").take(ws_count).collect::<String>()
+}
diff --git a/tests/source/macros.rs b/tests/source/macros.rs
index e3d7229a0e1..d8e6efe9199 100644
--- a/tests/source/macros.rs
+++ b/tests/source/macros.rs
@@ -112,6 +112,7 @@ macro_rules! foo {
 
     foo!(#[doc = "bar"] baz);
 }
+
 fn issue1739() {
     sql_function!(add_rss_item,
                   add_rss_item_t,
@@ -125,6 +126,14 @@ fn issue1739() {
         .par_map_inplace(|el| *el = 0.);
 }
 
+fn issue_1885() {
+    let threads = people.into_iter().map(|name| {
+        chan_select! {
+            rx.recv() => {}
+        }
+    }).collect::<Vec<_>>();
+}
+
 // Put the following tests with macro invocations whose arguments cannot be parsed as expressioins
 // at the end of the file for now.
 
diff --git a/tests/target/macros.rs b/tests/target/macros.rs
index f80f6843fe2..21c0b983ff9 100644
--- a/tests/target/macros.rs
+++ b/tests/target/macros.rs
@@ -146,6 +146,7 @@ macro_rules! foo {
         baz
     );
 }
+
 fn issue1739() {
     sql_function!(
         add_rss_item,
@@ -166,6 +167,17 @@ fn issue1739() {
     ]).par_map_inplace(|el| *el = 0.);
 }
 
+fn issue_1885() {
+    let threads = people
+        .into_iter()
+        .map(|name| {
+            chan_select! {
+                rx.recv() => {}
+            }
+        })
+        .collect::<Vec<_>>();
+}
+
 // Put the following tests with macro invocations whose arguments cannot be parsed as expressioins
 // at the end of the file for now.