auto merge of #19378 : japaric/rust/no-as-slice, r=alexcrichton

Now that we have an overloaded comparison (`==`) operator, and that `Vec`/`String` deref to `[T]`/`str` on method calls, many `as_slice()`/`as_mut_slice()`/`to_string()` calls have become redundant. This patch removes them. These were the most common patterns:

- `assert_eq(test_output.as_slice(), "ground truth")` -> `assert_eq(test_output, "ground truth")`
- `assert_eq(test_output, "ground truth".to_string())` -> `assert_eq(test_output, "ground truth")`
- `vec.as_mut_slice().sort()` -> `vec.sort()`
- `vec.as_slice().slice(from, to)` -> `vec.slice(from_to)`

---

Note that e.g. `a_string.push_str(b_string.as_slice())` has been left untouched in this PR, since we first need to settle down whether we want to favor the `&*b_string` or the `b_string[]` notation.

This is rebased on top of #19167

cc @alexcrichton @aturon 

3 files changed, 21 insertions, 23 deletions

diff --git a/src/libsyntax/parse/lexer/comments.rs b/src/libsyntax/parse/lexer/comments.rs
index b62d2d744c9..aeec6ee13fd 100644
--- a/src/libsyntax/parse/lexer/comments.rs
+++ b/src/libsyntax/parse/lexer/comments.rs
@@ -66,21 +66,20 @@ pub fn strip_doc_comment_decoration(comment: &str) -> String {
         let mut j = lines.len();
         // first line of all-stars should be omitted
         if lines.len() > 0 &&
-                lines[0].as_slice().chars().all(|c| c == '*') {
+                lines[0].chars().all(|c| c == '*') {
             i += 1;
         }
-        while i < j && lines[i].as_slice().trim().is_empty() {
+        while i < j && lines[i].trim().is_empty() {
             i += 1;
         }
         // like the first, a last line of all stars should be omitted
         if j > i && lines[j - 1]
-                         .as_slice()
                          .chars()
                          .skip(1)
                          .all(|c| c == '*') {
             j -= 1;
         }
-        while j > i && lines[j - 1].as_slice().trim().is_empty() {
+        while j > i && lines[j - 1].trim().is_empty() {
             j -= 1;
         }
         return lines.slice(i, j).iter().map(|x| (*x).clone()).collect();
@@ -92,7 +91,7 @@ pub fn strip_doc_comment_decoration(comment: &str) -> String {
         let mut can_trim = true;
         let mut first = true;
         for line in lines.iter() {
-            for (j, c) in line.as_slice().chars().enumerate() {
+            for (j, c) in line.chars().enumerate() {
                 if j > i || !"* \t".contains_char(c) {
                     can_trim = false;
                     break;
@@ -117,7 +116,7 @@ pub fn strip_doc_comment_decoration(comment: &str) -> String {
 
         if can_trim {
             lines.iter().map(|line| {
-                line.as_slice().slice(i + 1, line.len()).to_string()
+                line.slice(i + 1, line.len()).to_string()
             }).collect()
         } else {
             lines
@@ -228,7 +227,7 @@ fn trim_whitespace_prefix_and_push_line(lines: &mut Vec<String> ,
     let s1 = match all_whitespace(s.as_slice(), col) {
         Some(col) => {
             if col < len {
-                s.as_slice().slice(col, len).to_string()
+                s.slice(col, len).to_string()
             } else {
                 "".to_string()
             }
@@ -265,7 +264,7 @@ fn read_block_comment(rdr: &mut StringReader,
         if is_block_doc_comment(curr_line.as_slice()) {
             return
         }
-        assert!(!curr_line.as_slice().contains_char('\n'));
+        assert!(!curr_line.contains_char('\n'));
         lines.push(curr_line);
     } else {
         let mut level: int = 1;
@@ -390,41 +389,41 @@ mod test {
     #[test] fn test_block_doc_comment_1() {
         let comment = "/**\n * Test \n **  Test\n *   Test\n*/";
         let stripped = strip_doc_comment_decoration(comment);
-        assert_eq!(stripped, " Test \n*  Test\n   Test".to_string());
+        assert_eq!(stripped, " Test \n*  Test\n   Test");
     }
 
     #[test] fn test_block_doc_comment_2() {
         let comment = "/**\n * Test\n *  Test\n*/";
         let stripped = strip_doc_comment_decoration(comment);
-        assert_eq!(stripped, " Test\n  Test".to_string());
+        assert_eq!(stripped, " Test\n  Test");
     }
 
     #[test] fn test_block_doc_comment_3() {
         let comment = "/**\n let a: *int;\n *a = 5;\n*/";
         let stripped = strip_doc_comment_decoration(comment);
-        assert_eq!(stripped, " let a: *int;\n *a = 5;".to_string());
+        assert_eq!(stripped, " let a: *int;\n *a = 5;");
     }
 
     #[test] fn test_block_doc_comment_4() {
         let comment = "/*******************\n test\n *********************/";
         let stripped = strip_doc_comment_decoration(comment);
-        assert_eq!(stripped, " test".to_string());
+        assert_eq!(stripped, " test");
     }
 
     #[test] fn test_line_doc_comment() {
         let stripped = strip_doc_comment_decoration("/// test");
-        assert_eq!(stripped, " test".to_string());
+        assert_eq!(stripped, " test");
         let stripped = strip_doc_comment_decoration("///! test");
-        assert_eq!(stripped, " test".to_string());
+        assert_eq!(stripped, " test");
         let stripped = strip_doc_comment_decoration("// test");
-        assert_eq!(stripped, " test".to_string());
+        assert_eq!(stripped, " test");
         let stripped = strip_doc_comment_decoration("// test");
-        assert_eq!(stripped, " test".to_string());
+        assert_eq!(stripped, " test");
         let stripped = strip_doc_comment_decoration("///test");
-        assert_eq!(stripped, "test".to_string());
+        assert_eq!(stripped, "test");
         let stripped = strip_doc_comment_decoration("///!test");
-        assert_eq!(stripped, "test".to_string());
+        assert_eq!(stripped, "test");
         let stripped = strip_doc_comment_decoration("//test");
-        assert_eq!(stripped, "test".to_string());
+        assert_eq!(stripped, "test");
     }
 }
diff --git a/src/libsyntax/parse/lexer/mod.rs b/src/libsyntax/parse/lexer/mod.rs
index b282db5ba2b..ab2c15d54c5 100644
--- a/src/libsyntax/parse/lexer/mod.rs
+++ b/src/libsyntax/parse/lexer/mod.rs
@@ -265,7 +265,7 @@ impl<'a> StringReader<'a> {
     /// Calls `f` with a string slice of the source text spanning from `start`
     /// up to but excluding `end`.
     fn with_str_from_to<T>(&self, start: BytePos, end: BytePos, f: |s: &str| -> T) -> T {
-        f(self.filemap.src.as_slice().slice(
+        f(self.filemap.src.slice(
                 self.byte_offset(start).to_uint(),
                 self.byte_offset(end).to_uint()))
     }
@@ -321,7 +321,6 @@ impl<'a> StringReader<'a> {
             let last_char = self.curr.unwrap();
             let next = self.filemap
                           .src
-                          .as_slice()
                           .char_range_at(current_byte_offset);
             let byte_offset_diff = next.next - current_byte_offset;
             self.pos = self.pos + Pos::from_uint(byte_offset_diff);
@@ -343,7 +342,7 @@ impl<'a> StringReader<'a> {
     pub fn nextch(&self) -> Option<char> {
         let offset = self.byte_offset(self.pos).to_uint();
         if offset < self.filemap.src.len() {
-            Some(self.filemap.src.as_slice().char_at(offset))
+            Some(self.filemap.src.char_at(offset))
         } else {
             None
         }
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index 8d0c2de048a..951fe11a470 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -954,7 +954,7 @@ mod test {
             }\
         ]\
     }\
-]".to_string()
+]"
         );
     }