handle hard tabs when formatting trailing comments (rust-lang#3836)

Author: scampi

src/missed_spans.rs

@@ -7,7 +7,7 @@ use crate::config::Version;
 use crate::coverage::transform_missing_snippet;
 use crate::shape::{Indent, Shape};
 use crate::source_map::LineRangeUtils;
-use crate::utils::{count_lf_crlf, count_newlines, last_line_indent, last_line_width, mk_sp};
+use crate::utils::{count_lf_crlf, count_newlines, last_line_width, mk_sp};
 use crate::visitor::FmtVisitor;
 
 struct SnippetStatus {
@@ -254,7 +254,7 @@ impl<'a> FmtVisitor<'a> {
             // the same level and avoid mixing it with possible other comment.
             on_same_line = true;
             self.push_str(" ");
-            Indent::from_width(self.config, last_line_indent(&self.buffer))
+            self.block_indent
         } else {
             self.push_str(" ");
             Indent::from_width(self.config, last_line_width(&self.buffer))

src/utils.rs

@@ -205,13 +205,6 @@ pub(crate) fn last_line_width(s: &str) -> usize {
     unicode_str_width(s.rsplitn(2, '\n').next().unwrap_or(""))
 }
 
-/// The indent width of the last line in s.
-#[inline]
-pub(crate) fn last_line_indent(s: &str) -> usize {
-    let last_line = s.rsplitn(2, '\n').next().unwrap_or("");
-    last_line.chars().take_while(|c| c.is_whitespace()).count()
-}
-
 /// The total used width of the last line.
 #[inline]
 pub(crate) fn last_line_used_width(s: &str, offset: usize) -> usize {

tests/source/trailing_comments/hard_tabs.rs

@@ -0,0 +1,21 @@
+// rustfmt-version: Two
+// rustfmt-wrap_comments: true
+// rustfmt-hard_tabs: true
+
+impl Foo {
+    fn foo() {
+        bar(); // comment 1
+        // comment 2
+        // comment 3
+        baz();
+    }
+}
+
+fn lorem_ipsum() {
+    let f = bar(); // Donec consequat mi. Quisque vitae dolor. Integer lobortis. Maecenas id nulla. Lorem.
+    // Id turpis. Nam posuere lectus vitae nibh. Etiam tortor orci, sagittis malesuada, rhoncus quis, hendrerit eget, libero. Quisque commodo nulla at nunc. Mauris consequat, enim vitae venenatis sollicitudin, dolor orci bibendum enim, a sagittis nulla nunc quis elit. Phasellus augue. Nunc suscipit, magna tincidunt lacinia faucibus, lacus tellus ornare purus, a pulvinar lacus orci eget nibh.  Maecenas sed nibh non lacus tempor faucibus. In hac habitasse platea dictumst. Vivamus a orci at nulla tristique condimentum. Donec arcu quam, dictum accumsan, convallis accumsan, cursus sit amet, ipsum.  In pharetra sagittis nunc.
+    let b = baz();
+
+    let normalized = self.ctfont.all_traits().normalized_weight(); // [-1.0, 1.0]
+    // TODO(emilio): It may make sense to make this range [.01, 10.0], to align with css-fonts-4's range of [1, 1000].
+}

tests/source/trailing_comments.rs renamed to tests/source/trailing_comments/soft_tabs.rs

@@ -0,0 +1,30 @@
+// rustfmt-version: Two
+// rustfmt-wrap_comments: true
+// rustfmt-hard_tabs: true
+
+impl Foo {
+	fn foo() {
+		bar(); // comment 1
+		// comment 2
+		// comment 3
+		baz();
+	}
+}
+
+fn lorem_ipsum() {
+	let f = bar(); // Donec consequat mi. Quisque vitae dolor. Integer lobortis. Maecenas id nulla. Lorem.
+	// Id turpis. Nam posuere lectus vitae nibh. Etiam tortor orci, sagittis
+	// malesuada, rhoncus quis, hendrerit eget, libero. Quisque commodo nulla at
+	// nunc. Mauris consequat, enim vitae venenatis sollicitudin, dolor orci
+	// bibendum enim, a sagittis nulla nunc quis elit. Phasellus augue. Nunc
+	// suscipit, magna tincidunt lacinia faucibus, lacus tellus ornare purus, a
+	// pulvinar lacus orci eget nibh.  Maecenas sed nibh non lacus tempor faucibus.
+	// In hac habitasse platea dictumst. Vivamus a orci at nulla tristique
+	// condimentum. Donec arcu quam, dictum accumsan, convallis accumsan, cursus sit
+	// amet, ipsum.  In pharetra sagittis nunc.
+	let b = baz();
+
+	let normalized = self.ctfont.all_traits().normalized_weight(); // [-1.0, 1.0]
+	// TODO(emilio): It may make sense to make this range [.01, 10.0], to align
+	// with css-fonts-4's range of [1, 1000].
+}