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 

8 files changed, 43 insertions, 45 deletions

diff --git a/src/libsyntax/ast_map/mod.rs b/src/libsyntax/ast_map/mod.rs
index 2913666a315..ce2fe6e7220 100644
--- a/src/libsyntax/ast_map/mod.rs
+++ b/src/libsyntax/ast_map/mod.rs
@@ -260,7 +260,7 @@ impl<'ast> Map<'ast> {
     }
 
     fn find_entry(&self, id: NodeId) -> Option<MapEntry<'ast>> {
-        self.map.borrow().as_slice().get(id as uint).map(|e| *e)
+        self.map.borrow().get(id as uint).map(|e| *e)
     }
 
     pub fn krate(&self) -> &'ast Crate {
diff --git a/src/libsyntax/codemap.rs b/src/libsyntax/codemap.rs
index 27e8c265e5c..6bcf562204b 100644
--- a/src/libsyntax/codemap.rs
+++ b/src/libsyntax/codemap.rs
@@ -290,7 +290,7 @@ impl FileMap {
         lines.get(line_number).map(|&line| {
             let begin: BytePos = line - self.start_pos;
             let begin = begin.to_uint();
-            let slice = self.src.as_slice().slice_from(begin);
+            let slice = self.src.slice_from(begin);
             match slice.find('\n') {
                 Some(e) => slice.slice_to(e),
                 None => slice
@@ -308,8 +308,8 @@ impl FileMap {
     }
 
     pub fn is_real_file(&self) -> bool {
-        !(self.name.as_slice().starts_with("<") &&
-          self.name.as_slice().ends_with(">"))
+        !(self.name.starts_with("<") &&
+          self.name.ends_with(">"))
     }
 }
 
@@ -336,8 +336,8 @@ impl CodeMap {
         // Remove utf-8 BOM if any.
         // FIXME #12884: no efficient/safe way to remove from the start of a string
         // and reuse the allocation.
-        let mut src = if src.as_slice().starts_with("\ufeff") {
-            String::from_str(src.as_slice().slice_from(3))
+        let mut src = if src.starts_with("\ufeff") {
+            String::from_str(src.slice_from(3))
         } else {
             String::from_str(src.as_slice())
         };
@@ -346,7 +346,7 @@ impl CodeMap {
         // This is a workaround to prevent CodeMap.lookup_filemap_idx from accidentally
         // overflowing into the next filemap in case the last byte of span is also the last
         // byte of filemap, which leads to incorrect results from CodeMap.span_to_*.
-        if src.len() > 0 && !src.as_slice().ends_with("\n") {
+        if src.len() > 0 && !src.ends_with("\n") {
             src.push('\n');
         }
 
@@ -426,14 +426,14 @@ impl CodeMap {
         if begin.fm.start_pos != end.fm.start_pos {
             None
         } else {
-            Some(begin.fm.src.as_slice().slice(begin.pos.to_uint(),
-                                               end.pos.to_uint()).to_string())
+            Some(begin.fm.src.slice(begin.pos.to_uint(),
+                                    end.pos.to_uint()).to_string())
         }
     }
 
     pub fn get_filemap(&self, filename: &str) -> Rc<FileMap> {
         for fm in self.files.borrow().iter() {
-            if filename == fm.name.as_slice() {
+            if filename == fm.name {
                 return fm.clone();
             }
         }
@@ -614,11 +614,11 @@ mod test {
         let cm = init_code_map();
 
         let fmabp1 = cm.lookup_byte_offset(BytePos(22));
-        assert_eq!(fmabp1.fm.name, "blork.rs".to_string());
+        assert_eq!(fmabp1.fm.name, "blork.rs");
         assert_eq!(fmabp1.pos, BytePos(22));
 
         let fmabp2 = cm.lookup_byte_offset(BytePos(24));
-        assert_eq!(fmabp2.fm.name, "blork2.rs".to_string());
+        assert_eq!(fmabp2.fm.name, "blork2.rs");
         assert_eq!(fmabp2.pos, BytePos(0));
     }
 
@@ -640,12 +640,12 @@ mod test {
         let cm = init_code_map();
 
         let loc1 = cm.lookup_char_pos(BytePos(22));
-        assert_eq!(loc1.file.name, "blork.rs".to_string());
+        assert_eq!(loc1.file.name, "blork.rs");
         assert_eq!(loc1.line, 2);
         assert_eq!(loc1.col, CharPos(10));
 
         let loc2 = cm.lookup_char_pos(BytePos(24));
-        assert_eq!(loc2.file.name, "blork2.rs".to_string());
+        assert_eq!(loc2.file.name, "blork2.rs");
         assert_eq!(loc2.line, 1);
         assert_eq!(loc2.col, CharPos(0));
     }
@@ -701,7 +701,7 @@ mod test {
         let span = Span {lo: BytePos(12), hi: BytePos(23), expn_id: NO_EXPANSION};
         let file_lines = cm.span_to_lines(span);
 
-        assert_eq!(file_lines.file.name, "blork.rs".to_string());
+        assert_eq!(file_lines.file.name, "blork.rs");
         assert_eq!(file_lines.lines.len(), 1);
         assert_eq!(file_lines.lines[0], 1u);
     }
@@ -723,6 +723,6 @@ mod test {
         let span = Span {lo: BytePos(12), hi: BytePos(23), expn_id: NO_EXPANSION};
         let sstr =  cm.span_to_string(span);
 
-        assert_eq!(sstr, "blork.rs:2:1: 2:12".to_string());
+        assert_eq!(sstr, "blork.rs:2:1: 2:12");
     }
 }
diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 8d0d399fa31..0787518f04f 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -527,7 +527,7 @@ impl<'a> ExtCtxt<'a> {
         let mut call_site = None;
         loop {
             let expn_info = self.codemap().with_expn_info(expn_id, |ei| {
-                ei.map(|ei| (ei.call_site, ei.callee.name.as_slice() == "include"))
+                ei.map(|ei| (ei.call_site, ei.callee.name == "include"))
             });
             match expn_info {
                 None => break,
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 11c65d531f6..4af7b35079a 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -132,7 +132,7 @@ impl<'a> Context<'a> {
     }
 
     fn has_feature(&self, feature: &str) -> bool {
-        self.features.iter().any(|n| n.as_slice() == feature)
+        self.features.iter().any(|&n| n == feature)
     }
 }
 
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()
+]"
         );
     }
 
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index e9937dc9b60..6ce0ee79c62 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -2844,7 +2844,7 @@ impl<'a> State<'a> {
             comments::BlankLine => {
                 // We need to do at least one, possibly two hardbreaks.
                 let is_semi = match self.s.last_token() {
-                    pp::String(s, _) => ";" == s.as_slice(),
+                    pp::String(s, _) => ";" == s,
                     _ => false
                 };
                 if is_semi || self.is_begin() || self.is_end() {
@@ -2961,9 +2961,9 @@ mod test {
             variadic: false
         };
         let generics = ast_util::empty_generics();
-        assert_eq!(&fun_to_string(&decl, ast::NormalFn, abba_ident,
+        assert_eq!(fun_to_string(&decl, ast::NormalFn, abba_ident,
                                None, &generics),
-                   &"fn abba()".to_string());
+                   "fn abba()");
     }
 
     #[test]
@@ -2981,7 +2981,7 @@ mod test {
         });
 
         let varstr = variant_to_string(&var);
-        assert_eq!(&varstr,&"pub principal_skinner".to_string());
+        assert_eq!(varstr, "pub principal_skinner");
     }
 
     #[test]