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Migrate back to std:: stylistically (#554)

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* Migrate back to `std::` stylistically

This commit moves away from idioms such as `alloc::` and `core::` as
imports of standard data structures and types. Instead it migrates all
crates to uniformly use `std::` for importing standard data structures
and types. This also removes the `std` and `core` features from all
crates to and removes any conditional checking for `feature = "std"`

All of this support was previously added in #407 in an effort to make
wasmtime/cranelift "`no_std` compatible". Unfortunately though this
change comes at a cost:

* The usage of `alloc` and `core` isn't idiomatic. Especially trying to
  dual between types like `HashMap` from `std` as well as from
  `hashbrown` causes imports to be surprising in some cases.
* Unfortunately there was no CI check that crates were `no_std`, so none
  of them actually were. Many crates still imported from `std` or
  depended on crates that used `std`.

It's important to note, however, that **this does not mean that wasmtime
will not run in embedded environments**. The style of the code today and
idioms aren't ready in Rust to support this degree of multiplexing and
makes it somewhat difficult to keep up with the style of `wasmtime`.
Instead it's intended that embedded runtime support will be added as
necessary. Currently only `std` is necessary to build `wasmtime`, and
platforms that natively need to execute `wasmtime` will need to use a
Rust target that supports `std`. Note though that not all of `std` needs
to be supported, but instead much of it could be configured off to
return errors, and `wasmtime` would be configured to gracefully handle
errors.

The goal of this PR is to move `wasmtime` back to idiomatic usage of
features/`std`/imports/etc and help development in the short-term.
Long-term when platform concerns arise (if any) they can be addressed by
moving back to `no_std` crates (but fixing the issues mentioned above)
or ensuring that the target in Rust has `std` available.

* Start filling out platform support doc
This commit is contained in:
Alex Crichton
2019-11-19 00:04:06 -06:00
committed by Dan Gohman
parent c423a1c2f0
commit 39e57e3e9a
99 changed files with 271 additions and 444 deletions
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4
crates/interface-types/Cargo.toml
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@@ -17,8 +17,8 @@ walrus = "0.13"
wasmparser = { version = "0.39.2", default-features = false }
wasm-webidl-bindings = "0.6"
wasmtime = { path = '../api' }
wasmtime-jit = { path = '../jit', default-features = false }
wasmtime-runtime = { path = '../runtime', default-features = false }
wasmtime-jit = { path = '../jit' }
wasmtime-runtime = { path = '../runtime' }
wasmtime-wasi = { path = '../wasi' }
[badges]

9
crates/interface-types/src/lib.rs
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@@ -7,15 +7,10 @@
#![deny(missing_docs)]
extern crate alloc;
use alloc::boxed::Box;
use alloc::string::ToString;
use alloc::vec::Vec;
use anyhow::{bail, format_err, Result};
use core::convert::TryFrom;
use core::str;
use cranelift_codegen::ir;
use std::convert::TryFrom;
use std::str;
use wasm_webidl_bindings::ast;
use wasmtime_api as api;
use wasmtime_jit::RuntimeValue;

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