Ignore empty lines inside arguments of macro with brace

src/lib.rs

@@ -231,6 +231,16 @@ impl Indent {
         }
     }
 
+    pub fn from_width(config: &Config, width: usize) -> Indent {
+        if config.hard_tabs() {
+            let tab_num = width / config.tab_spaces();
+            let alignment = width % config.tab_spaces();
+            Indent::new(config.tab_spaces() * tab_num, alignment)
+        } else {
+            Indent::new(width, 0)
+        }
+    }
+
     pub fn empty() -> Indent {
         Indent::new(0, 0)
     }

src/macros.rs

@@ -19,8 +19,6 @@
 // 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;
@@ -118,14 +116,18 @@ pub fn rewrite_macro(
                 Ok(expr) => {
                     // Recovered errors.
                     if context.parse_session.span_diagnostic.has_errors() {
-                        return indent_macro_snippet(&context.snippet(mac.span), shape.indent);
+                        return indent_macro_snippet(
+                            context,
+                            &context.snippet(mac.span),
+                            shape.indent,
+                        );
                     }
 
                     expr
                 }
                 Err(mut e) => {
                     e.cancel();
-                    return indent_macro_snippet(&context.snippet(mac.span), shape.indent);
+                    return indent_macro_snippet(context, &context.snippet(mac.span), shape.indent);
                 }
             };
 
@@ -244,7 +246,7 @@ pub fn rewrite_macro(
         }
         MacroStyle::Braces => {
             // Skip macro invocations with braces, for now.
-            indent_macro_snippet(&context.snippet(mac.span), shape.indent)
+            indent_macro_snippet(context, &context.snippet(mac.span), shape.indent)
         }
     }
 }
@@ -308,32 +310,62 @@ fn macro_style(mac: &ast::Mac, context: &RewriteContext) -> MacroStyle {
 //      ),
 /// }
 /// ```
-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());
-
+fn indent_macro_snippet(
+    context: &RewriteContext,
+    macro_str: &str,
+    indent: Indent,
+) -> Option<String> {
     let mut lines = macro_str.lines();
-    let first_line = try_opt!(lines.next());
+    let first_line = try_opt!(lines.next().map(|s| s.trim_right()));
+    let mut trimmed_lines = Vec::with_capacity(16);
+
+    let min_prefix_space_width = try_opt!(
+        lines
+            .filter_map(|line| {
+                let prefix_space_width = if is_empty_line(line) {
+                    None
+                } else {
+                    Some(get_prefix_space_width(context, line))
+                };
+                trimmed_lines.push((line.trim(), prefix_space_width));
+                prefix_space_width
+            })
+            .min()
+    );
 
     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()
+            &trimmed_lines
+                .iter()
+                .map(|&(line, prefix_space_width)| match prefix_space_width {
+                    Some(original_indent_width) => {
+                        let new_indent_width = indent.width() +
+                            original_indent_width
+                                .checked_sub(min_prefix_space_width)
+                                .unwrap_or(0);
+                        let new_indent = Indent::from_width(context.config, new_indent_width);
+                        new_indent.to_string(context.config) + line.trim()
+                    }
+                    None => String::new(),
                 })
                 .collect::<Vec<_>>()
                 .join("\n"),
     )
 }
 
-fn get_prefix_space_width(s: &str) -> usize {
-    s.chars().position(|c| c != ' ').unwrap_or(0)
+fn get_prefix_space_width(context: &RewriteContext, s: &str) -> usize {
+    let mut width = 0;
+    let mut iter = s.chars();
+    while let Some(c) = iter.next() {
+        match c {
+            ' ' => width += 1,
+            '\t' => width += context.config.tab_spaces(),
+            _ => return width,
+        }
+    }
+    width
 }
 
-fn repeat_white_space(ws_count: usize) -> String {
-    repeat(" ").take(ws_count).collect::<String>()
+fn is_empty_line(s: &str) -> bool {
+    s.is_empty() || s.chars().all(char::is_whitespace)
 }

tests/source/macros.rs

@@ -134,6 +134,36 @@ fn issue_1885() {
     }).collect::<Vec<_>>();
 }
 
+fn issue_1917() {
+    mod x {
+        quickcheck! {
+            fn test(a: String, s: String, b: String) -> TestResult {
+                if a.find(&s).is_none() {
+
+                    TestResult::from_bool(true)
+                } else {
+                    TestResult::discard()
+                }
+            }
+        }
+    }
+}
+
+fn issue_1921() {
+    // Macro with tabs.
+    lazy_static! {
+	static ref ONE: u32 = 1;
+	static ref TWO: u32 = 2;
+	static ref THREE: u32 = 3;
+	static ref FOUR: u32 = {
+		let mut acc = 1;
+		acc += 1;
+		acc += 2;
+		acc
+	}
+}
+}
+
 // Put the following tests with macro invocations whose arguments cannot be parsed as expressioins
 // at the end of the file for now.
 

tests/target/macros.rs

@@ -178,6 +178,36 @@ fn issue_1885() {
         .collect::<Vec<_>>();
 }
 
+fn issue_1917() {
+    mod x {
+        quickcheck! {
+            fn test(a: String, s: String, b: String) -> TestResult {
+                if a.find(&s).is_none() {
+
+                    TestResult::from_bool(true)
+                } else {
+                    TestResult::discard()
+                }
+            }
+        }
+    }
+}
+
+fn issue_1921() {
+    // Macro with tabs.
+    lazy_static! {
+        static ref ONE: u32 = 1;
+        static ref TWO: u32 = 2;
+        static ref THREE: u32 = 3;
+        static ref FOUR: u32 = {
+            let mut acc = 1;
+            acc += 1;
+            acc += 2;
+            acc
+        }
+    }
+}
+
 // Put the following tests with macro invocations whose arguments cannot be parsed as expressioins
 // at the end of the file for now.