Add an explicit std feature so that features are purely additive.

lib/wasm/Cargo.toml

@@ -12,12 +12,13 @@ name = "cton_wasm"
 
 [dependencies]
 wasmparser = "0.14.1"
-cretonne = { path = "../cretonne", version = "0.1.0" }
-cretonne-frontend = { path = "../frontend", version = "0.1.0" }
+cretonne = { path = "../cretonne", version = "0.1.0", default_features = false }
+cretonne-frontend = { path = "../frontend", version = "0.1.0", default_features = false }
 
 [dependencies.hashmap_core]
 version = "0.1.1"
 optional = true
+
 [dependencies.error_core]
 version = "0.1.0"
 optional = true
@@ -26,6 +27,6 @@ optional = true
 tempdir = "0.3.5"
 
 [features]
-# Currently, the only feature is the `no_std` feature.
-# Enabling this disables use of `stdlib`.
-no_std = ["hashmap_core", "error_core", "cretonne/no_std", "cretonne-frontend/no_std"]
+default = ["std"]
+std = ["cretonne/std", "cretonne-frontend/std"]
+no_std = ["hashmap_core", "error_core", "cretonne/no_std", "cretonne-frontend/no_std"]

lib/wasm/src/lib.rs

@@ -9,12 +9,12 @@
 //!
 //! The main function of this module is [`translate_module`](fn.translate_module.html).
 
-#![cfg_attr(feature = "no_std", no_std)]
 #![deny(missing_docs)]
 
-#![cfg_attr(feature = "no_std", feature(alloc))]
+#![cfg_attr(not(feature = "std"), no_std)]
+#![cfg_attr(not(feature = "std"), feature(alloc))]
 
-#[cfg(feature = "no_std")]
+#[cfg(not(feature = "std"))]
 #[macro_use]
 extern crate alloc;
 
@@ -42,7 +42,7 @@ pub use environ::{FuncEnvironment, ModuleEnvironment, DummyEnvironment, GlobalVa
 pub use translation_utils::{FunctionIndex, GlobalIndex, TableIndex, MemoryIndex, SignatureIndex,
                             Global, GlobalInit, Table, Memory};
 
-#[cfg(feature = "no_std")]
+#[cfg(not(feature = "std"))]
 mod std {
     pub use alloc::vec;
     pub use alloc::string;