Fix no_std build with "alloc" feature in Rust 1.29 and newer

.travis.yml

@@ -18,7 +18,11 @@ matrix:
         # See: https://github.com/BurntSushi/byteorder/pull/150
         - cargo update && cargo update -p byteorder --precise 1.2.7
         - cargo build --no-default-features --features core_io
-        - cargo build --no-default-features --features core_io,alloc,core_io/collections
+        - cargo build --no-default-features --features core_io,alloc
+    - rust: nightly-2019-07-01
+      script:
+        - cargo build --no-default-features --features core_io
+        - cargo build --no-default-features --features core_io,alloc
 
   allow_failures:
     - rust: nightly

src/dir.rs

@@ -1,5 +1,5 @@
 #[cfg(all(not(feature = "std"), feature = "alloc"))]
-use alloc::Vec;
+use alloc::vec::Vec;
 use core::{char, cmp, num, str};
 #[cfg(feature = "alloc")]
 use core::{iter, slice};

src/dir_entry.rs

@@ -1,5 +1,5 @@
 #[cfg(all(not(feature = "std"), feature = "alloc"))]
-use alloc::{String, Vec};
+use alloc::{string::String, vec::Vec};
 use core::char;
 use core::iter::FromIterator;
 use core::{fmt, str};

src/fs.rs

@@ -1,5 +1,5 @@
 #[cfg(all(not(feature = "std"), feature = "alloc"))]
-use alloc::String;
+use alloc::string::String;
 use core::cell::{Cell, RefCell};
 use core::char;
 use core::cmp;