add target to config

crates/wasi/src/lib.rs

@@ -7,6 +7,7 @@ pub use wasi_common::{WasiCtx, WasiCtxBuilder};
 // Defines a `struct Wasi` with member fields and appropriate APIs for dealing
 // with all the various WASI exports.
 wasmtime_wiggle::define_struct_for_wiggle!({
+    target: wasi_common::wasi,
     witx: ["../wasi-common/WASI/phases/snapshot/witx/wasi_snapshot_preview1.witx"],
     ctx: WasiCtx,
     instance: {

crates/wiggle/wasmtime/macro/src/config.rs

@@ -4,13 +4,14 @@ use {
         braced,
         parse::{Parse, ParseStream},
         punctuated::Punctuated,
-        Error, Ident, Result, Token,
+        Error, Ident, Path, Result, Token,
     },
     wiggle_generate::config::{CtxConf, WitxConf},
 };
 
 #[derive(Debug, Clone)]
 pub struct Config {
+    pub target: TargetConf,
     pub witx: WitxConf,
     pub ctx: CtxConf,
     pub instance: InstanceConf,
@@ -18,12 +19,14 @@ pub struct Config {
 
 #[derive(Debug, Clone)]
 pub enum ConfigField {
+    Target(TargetConf),
     Witx(WitxConf),
     Ctx(CtxConf),
     Instance(InstanceConf),
 }
 
 mod kw {
+    syn::custom_keyword!(target);
     syn::custom_keyword!(witx);
     syn::custom_keyword!(witx_literal);
     syn::custom_keyword!(ctx);
@@ -35,7 +38,11 @@ mod kw {
 impl Parse for ConfigField {
     fn parse(input: ParseStream) -> Result<Self> {
         let lookahead = input.lookahead1();
-        if lookahead.peek(kw::witx) {
+        if lookahead.peek(kw::target) {
+            input.parse::<kw::target>()?;
+            input.parse::<Token![:]>()?;
+            Ok(ConfigField::Target(input.parse()?))
+        } else if lookahead.peek(kw::witx) {
             input.parse::<kw::witx>()?;
             input.parse::<Token![:]>()?;
             Ok(ConfigField::Witx(WitxConf::Paths(input.parse()?)))
@@ -59,11 +66,18 @@ impl Parse for ConfigField {
 
 impl Config {
     pub fn build(fields: impl Iterator<Item = ConfigField>, err_loc: Span) -> Result<Self> {
+        let mut target = None;
         let mut witx = None;
         let mut ctx = None;
         let mut instance = None;
         for f in fields {
             match f {
+                ConfigField::Target(c) => {
+                    if target.is_some() {
+                        return Err(Error::new(err_loc, "duplicate `target` field"));
+                    }
+                    target = Some(c);
+                }
                 ConfigField::Witx(c) => {
                     if witx.is_some() {
                         return Err(Error::new(err_loc, "duplicate `witx` field"));
@@ -85,6 +99,9 @@ impl Config {
             }
         }
         Ok(Config {
+            target: target
+                .take()
+                .ok_or_else(|| Error::new(err_loc, "`target` field required"))?,
             witx: witx
                 .take()
                 .ok_or_else(|| Error::new(err_loc, "`witx` field required"))?,
@@ -117,6 +134,19 @@ impl Parse for Config {
     }
 }
 
+#[derive(Debug, Clone)]
+pub struct TargetConf {
+    pub path: Path,
+}
+
+impl Parse for TargetConf {
+    fn parse(input: ParseStream) -> Result<Self> {
+        Ok(TargetConf {
+            path: input.parse()?,
+        })
+    }
+}
+
 enum InstanceConfField {
     Name(Ident),
     Docs(String),

crates/wiggle/wasmtime/macro/src/lib.rs

@@ -6,7 +6,7 @@ use wiggle_generate::Names;
 
 mod config;
 
-use config::InstanceConf;
+use config::{InstanceConf, TargetConf};
 
 #[proc_macro]
 pub fn define_struct_for_wiggle(args: TokenStream) -> TokenStream {
@@ -17,7 +17,7 @@ pub fn define_struct_for_wiggle(args: TokenStream) -> TokenStream {
     let doc = config.load_document();
     let names = Names::new(&config.ctx.name, quote!(wasmtime_wiggle));
 
-    generate(&doc, &names, &config.instance).into()
+    generate(&doc, &names, &config.target, &config.instance).into()
 }
 
 enum Abi {
@@ -27,7 +27,12 @@ enum Abi {
     F64,
 }
 
-fn generate(doc: &witx::Document, names: &Names, instance_conf: &InstanceConf) -> TokenStream2 {
+fn generate(
+    doc: &witx::Document,
+    names: &Names,
+    target_conf: &TargetConf,
+    instance_conf: &InstanceConf,
+) -> TokenStream2 {
     let mut fields = Vec::new();
     let mut get_exports = Vec::new();
     let mut ctor_externs = Vec::new();
@@ -35,6 +40,7 @@ fn generate(doc: &witx::Document, names: &Names, instance_conf: &InstanceConf) -
     let mut linker_add = Vec::new();
 
     let runtime = names.runtime_mod();
+    let target_path = &target_conf.path;
 
     for module in doc.modules() {
         let module_name = module.name.as_str();
@@ -223,7 +229,7 @@ fn generate(doc: &witx::Document, names: &Names, instance_conf: &InstanceConf) -
                             // root of each function invocation is correct.
                             let bc = #runtime::BorrowChecker::new();
                             let mem = #runtime::WasmtimeGuestMemory::new( mem, bc );
-                            wasi_common::wasi::#module_id::#name_ident(
+                            #target_path::#module_id::#name_ident(
                                 &mut my_cx.borrow_mut(),
                                 &mem,
                                 #(#hostcall_args),*