Update no_std support.

This `no_std` support isn't complete though, as some dependencies
don't support it.

lib/environ/Cargo.toml

@@ -17,11 +17,12 @@ cranelift-wasm = "0.26.0"
 cast = { version = "0.2.2", default-features = false }
 failure = { version = "0.1.3", default-features = false }
 failure_derive = { version = "0.1.3", default-features = false }
+hashmap_core = { version = "0.1.9", optional = true }
 
 [features]
 default = ["std"]
 std = ["cranelift-codegen/std", "cranelift-wasm/std"]
-core = ["cranelift-codegen/core", "cranelift-wasm/core"]
+core = ["hashmap_core", "cranelift-codegen/core", "cranelift-wasm/core"]
 
 [badges]
 maintenance = { status = "experimental" }

lib/environ/src/func_environ.rs

@@ -2,6 +2,7 @@ use crate::module::{MemoryPlan, MemoryStyle, Module, TableStyle};
 use crate::vmoffsets::VMOffsets;
 use crate::WASM_PAGE_SIZE;
 use cast;
+use core::clone::Clone;
 use cranelift_codegen::cursor::FuncCursor;
 use cranelift_codegen::ir;
 use cranelift_codegen::ir::condcodes::*;
@@ -16,7 +17,6 @@ use cranelift_wasm::{
     self, FuncIndex, GlobalIndex, GlobalVariable, MemoryIndex, SignatureIndex, TableIndex,
     WasmResult,
 };
-use std::clone::Clone;
 use std::vec::Vec;
 
 /// Compute an `ir::ExternalName` for a given wasm function index.

lib/environ/src/lib.rs

@@ -24,14 +24,23 @@
         clippy::use_self
     )
 )]
-#![cfg_attr(not(feature = "std"), no_std)]
+#![no_std]
 #![cfg_attr(not(feature = "std"), feature(alloc))]
 
-use cranelift_wasm;
 #[cfg(not(feature = "std"))]
 #[macro_use]
-extern crate alloc;
+extern crate alloc as std;
+#[cfg(feature = "std")]
+#[macro_use]
+extern crate std;
+
+#[cfg(not(feature = "std"))]
+use hashmap_core::HashMap;
+#[cfg(feature = "std")]
+use std::collections::HashMap;
+
 use cast;
+use cranelift_wasm;
 use failure;
 #[macro_use]
 extern crate failure_derive;
@@ -63,10 +72,3 @@ pub const WASM_PAGE_SIZE: u32 = 0x10000;
 
 /// The number of pages we can have before we run out of byte index space.
 pub const WASM_MAX_PAGES: u32 = 0x10000;
-
-#[cfg(not(feature = "std"))]
-mod std {
-    pub use alloc::{string, vec};
-    pub use core::*;
-    pub use core::{i32, str, u32};
-}

lib/environ/src/module.rs

@@ -1,5 +1,6 @@
 //! Data structures for representing decoded wasm modules.
 
+use super::HashMap;
 use crate::tunables::Tunables;
 use cranelift_codegen::ir;
 use cranelift_entity::{EntityRef, PrimaryMap};
@@ -7,7 +8,6 @@ use cranelift_wasm::{
     DefinedFuncIndex, DefinedGlobalIndex, DefinedMemoryIndex, DefinedTableIndex, FuncIndex, Global,
     GlobalIndex, Memory, MemoryIndex, SignatureIndex, Table, TableIndex,
 };
-use std::collections::HashMap;
 use std::string::String;
 use std::vec::Vec;
 

lib/environ/src/module_environ.rs

@@ -1,6 +1,7 @@
 use crate::func_environ::FuncEnvironment;
 use crate::module::{Export, MemoryPlan, Module, TableElements, TablePlan};
 use crate::tunables::Tunables;
+use core::clone::Clone;
 use cranelift_codegen::ir;
 use cranelift_codegen::ir::{AbiParam, ArgumentPurpose};
 use cranelift_codegen::isa::TargetFrontendConfig;
@@ -9,7 +10,6 @@ use cranelift_wasm::{
     self, translate_module, DefinedFuncIndex, FuncIndex, Global, GlobalIndex, Memory, MemoryIndex,
     SignatureIndex, Table, TableIndex, WasmResult,
 };
-use std::clone::Clone;
 use std::string::String;
 use std::vec::Vec;