Positive case of `len()` -> `is_empty()`

`s/(?<!\{ self)(?<=\.)len\(\) == 0/is_empty()/g`

4 files changed, 5 insertions, 5 deletions

diff --git a/src/libsyntax/ext/deriving/generic/mod.rs b/src/libsyntax/ext/deriving/generic/mod.rs
index ac96375095e..dcfc6b675e3 100644
--- a/src/libsyntax/ext/deriving/generic/mod.rs
+++ b/src/libsyntax/ext/deriving/generic/mod.rs
@@ -1248,7 +1248,7 @@ impl<'a> MethodDef<'a> {
 
             match_arms.push(catch_all_match_arm);
 
-        } else if variants.len() == 0 {
+        } else if variants.is_empty() {
             // As an additional wrinkle, For a zero-variant enum A,
             // currently the compiler
             // will accept `fn (a: &Self) { match   *a   { } }`
diff --git a/src/libsyntax/ext/env.rs b/src/libsyntax/ext/env.rs
index f72303985e7..2ca74644b3b 100644
--- a/src/libsyntax/ext/env.rs
+++ b/src/libsyntax/ext/env.rs
@@ -65,7 +65,7 @@ pub fn expand_option_env<'cx>(cx: &'cx mut ExtCtxt, sp: Span, tts: &[ast::TokenT
 pub fn expand_env<'cx>(cx: &'cx mut ExtCtxt, sp: Span, tts: &[ast::TokenTree])
                        -> Box<base::MacResult+'cx> {
     let mut exprs = match get_exprs_from_tts(cx, sp, tts) {
-        Some(ref exprs) if exprs.len() == 0 => {
+        Some(ref exprs) if exprs.is_empty() => {
             cx.span_err(sp, "env! takes 1 or 2 arguments");
             return DummyResult::expr(sp);
         }
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index b65798b8a49..74ec219af15 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -841,7 +841,7 @@ fn expand_non_macro_stmt(Spanned {node, span: stmt_span}: Stmt, fld: &mut MacroE
 fn expand_arm(arm: ast::Arm, fld: &mut MacroExpander) -> ast::Arm {
     // expand pats... they might contain macro uses:
     let expanded_pats = arm.pats.move_map(|pat| fld.fold_pat(pat));
-    if expanded_pats.len() == 0 {
+    if expanded_pats.is_empty() {
         panic!("encountered match arm with 0 patterns");
     }
     // all of the pats must have the same set of bindings, so use the
@@ -1887,7 +1887,7 @@ mod test {
             let binding_name = mtwt::resolve(bindings[binding_idx]);
             let binding_marks = mtwt::marksof(bindings[binding_idx].ctxt, invalid_name);
             // shouldmatch can't name varrefs that don't exist:
-            assert!((shouldmatch.len() == 0) ||
+            assert!((shouldmatch.is_empty()) ||
                     (varrefs.len() > *shouldmatch.iter().max().unwrap()));
             for (idx,varref) in varrefs.iter().enumerate() {
                 let print_hygiene_debug_info = || {
diff --git a/src/libsyntax/ext/tt/macro_parser.rs b/src/libsyntax/ext/tt/macro_parser.rs
index 4e0b74401a2..dcbf3c2c892 100644
--- a/src/libsyntax/ext/tt/macro_parser.rs
+++ b/src/libsyntax/ext/tt/macro_parser.rs
@@ -472,7 +472,7 @@ pub fn parse(sess: &ParseSess,
                     "local ambiguity: multiple parsing options: \
                      built-in NTs {} or {} other options.",
                     nts, next_eis.len()).to_string());
-            } else if bb_eis.len() == 0 && next_eis.len() == 0 {
+            } else if bb_eis.is_empty() && next_eis.is_empty() {
                 return Failure(sp, format!("no rules expected the token `{}`",
                             pprust::token_to_string(&tok)).to_string());
             } else if next_eis.len() > 0 {