Move back to only one WASI submodule (#1434)

* Move back to only one WASI submodule

This commit fixes the issue where we have two WASI submodules for build
reasons in this repository. The fix was to place the submodule in the
`wasi-common` crate, and then anyone using the `wig` crate has to be
sure to define a `WASI_ROOT` env var in a build script to be able to
parse witx files.

With all that in place `wasi-common` becomes the source of truth for the
witx files we're parsing, and crates like `wasmtime-wasi` use
build-scripts shenanigans to read the same witx files. This should
hopefully get us so we're compatible with publishing and still only have
one submodule!

* rustfmt

crates/wasi-common/wig/src/hostcalls.rs

@@ -3,21 +3,17 @@ use proc_macro2::TokenStream;
 use quote::{format_ident, quote};
 
 pub fn define(args: TokenStream) -> TokenStream {
-    let (path, phase) = utils::witx_path_from_args(args);
+    let path = utils::witx_path_from_args(args);
     let doc = match witx::load(&[&path]) {
         Ok(doc) => doc,
         Err(e) => {
-            panic!("error opening file {}: {}", path, e);
+            panic!("error opening file {}: {}", path.display(), e);
         }
     };
 
     let mut ret = TokenStream::new();
 
-    let old = match phase.as_str() {
-        "snapshot" => false,
-        "old/snapshot_0" => true,
-        s => panic!("unsupported phase: {}", s),
-    };
+    let old = true;
 
     for module in doc.modules() {
         for func in module.funcs() {

crates/wasi-common/wig/src/raw_types.rs

@@ -25,11 +25,11 @@ impl Mode {
 pub fn gen(args: TokenStream, mode: Mode) -> TokenStream {
     let mut output = TokenStream::new();
 
-    let (path, _phase) = utils::witx_path_from_args(args);
+    let path = utils::witx_path_from_args(args);
     let doc = match witx::load(&[&path]) {
         Ok(doc) => doc,
         Err(e) => {
-            panic!("error opening file {}: {}", path, e);
+            panic!("error opening file {}: {}", path.display(), e);
         }
     };
 

crates/wasi-common/wig/src/utils.rs

@@ -1,8 +1,9 @@
 use proc_macro2::{Ident, Literal, TokenStream, TokenTree};
+use std::path::PathBuf;
 
 /// Given the input tokens to a macro invocation, return the path to the
 /// witx file to process.
-pub(crate) fn witx_path_from_args(args: TokenStream) -> (String, String) {
+pub(crate) fn witx_path_from_args(args: TokenStream) -> PathBuf {
     let mut strings = Vec::new();
 
     for arg in args {
@@ -15,20 +16,11 @@ pub(crate) fn witx_path_from_args(args: TokenStream) -> (String, String) {
         }
     }
 
-    if strings.len() != 2 {
-        panic!("expected two string literals");
+    if strings.len() != 1 {
+        panic!("expected one string literals");
     }
-
-    let phase = &strings[0];
-    let id = &strings[1];
-    let path = witx_path(phase, id);
-
-    (path, phase.clone())
-}
-
-fn witx_path(phase: &str, id: &str) -> String {
-    let root = env!("CARGO_MANIFEST_DIR");
-    format!("{}/WASI/phases/{}/witx/{}.witx", root, phase, id)
+    let root = PathBuf::from(std::env::var("WASI_ROOT").unwrap());
+    return root.join(&strings[0]);
 }
 
 // Convert a `Literal` holding a string literal into the `String`.

crates/wasi-common/wig/src/wasi.rs

@@ -21,11 +21,11 @@ enum Abi {
 /// I'd recommend using `cargo +nightly expand` to explore the output of this
 /// macro some more.
 pub fn define_struct(args: TokenStream) -> TokenStream {
-    let (path, _phase) = utils::witx_path_from_args(args);
+    let path = utils::witx_path_from_args(args);
     let doc = match witx::load(&[&path]) {
         Ok(doc) => doc,
         Err(e) => {
-            panic!("error opening file {}: {}", path, e);
+            panic!("error opening file {}: {}", path.display(), e);
         }
     };
 
@@ -265,11 +265,11 @@ pub fn define_struct(args: TokenStream) -> TokenStream {
 }
 
 pub fn define_struct_for_wiggle(args: TokenStream) -> TokenStream {
-    let (path, _phase) = utils::witx_path_from_args(args);
+    let path = utils::witx_path_from_args(args);
     let doc = match witx::load(&[&path]) {
         Ok(doc) => doc,
         Err(e) => {
-            panic!("error opening file {}: {}", path, e);
+            panic!("error opening file {}: {}", path.display(), e);
         }
     };