Make more code work with no_std. (#407)

* Make more code work with no_std.

no_std support is still incomplete, but this patch takes care of the
bulk of the straightforward parts.

wasmtime-interface-types/Cargo.toml

@@ -11,10 +11,10 @@ readme = "README.md"
 edition = "2018"
 
 [dependencies]
-cranelift-codegen = "0.44.0"
-failure = "0.1"
+cranelift-codegen = { version = "0.44.0", default-features = false }
+failure = { version = "0.1", default-features = false }
 walrus = "0.12.0"
-wasmparser = "0.39.1"
+wasmparser = { version = "0.39.1", default-features = false }
 wasm-webidl-bindings = "0.5.0"
-wasmtime-jit = { path = '../wasmtime-jit' }
-wasmtime-runtime = { path = '../wasmtime-runtime' }
+wasmtime-jit = { path = '../wasmtime-jit', default-features = false }
+wasmtime-runtime = { path = '../wasmtime-runtime', default-features = false }

wasmtime-interface-types/src/lib.rs

@@ -7,11 +7,17 @@
 
 #![deny(missing_docs)]
 
+#[macro_use]
+extern crate alloc;
+
+use alloc::boxed::Box;
+use alloc::string::ToString;
+use alloc::vec::Vec;
+use core::convert::TryFrom;
+use core::slice;
+use core::str;
 use cranelift_codegen::ir;
 use failure::{bail, format_err, Error};
-use std::convert::TryFrom;
-use std::slice;
-use std::str;
 use wasm_webidl_bindings::ast;
 use wasmtime_jit::{ActionOutcome, Context, RuntimeValue};
 use wasmtime_runtime::{Export, InstanceHandle};

wasmtime-interface-types/src/value.rs

@@ -1,5 +1,6 @@
-use std::convert::TryFrom;
-use std::fmt;
+use alloc::string::{String, ToString};
+use core::convert::TryFrom;
+use core::fmt;
 
 /// The set of all possible WebAssembly Interface Types
 #[derive(Debug, Clone)]