paramaterize the instance type name as well

crates/wasi/src/lib.rs

@@ -9,6 +9,7 @@ pub use wasi_common::{WasiCtx, WasiCtxBuilder};
 wasmtime_wiggle::define_struct_for_wiggle!({
     witx: ["../wasi-common/WASI/phases/snapshot/witx/wasi_snapshot_preview1.witx"],
     ctx: WasiCtx,
+    instance: Wasi,
 });
 
 pub fn is_wasi_module(name: &str) -> bool {

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

@@ -4,7 +4,7 @@ use {
         braced,
         parse::{Parse, ParseStream},
         punctuated::Punctuated,
-        Error, Result, Token,
+        Error, Ident, Result, Token,
     },
     wiggle_generate::config::{CtxConf, WitxConf},
 };
@@ -13,18 +13,21 @@ use {
 pub struct Config {
     pub witx: WitxConf,
     pub ctx: CtxConf,
+    pub instance_typename: InstanceTypenameConf,
 }
 
 #[derive(Debug, Clone)]
 pub enum ConfigField {
     Witx(WitxConf),
     Ctx(CtxConf),
+    InstanceTypename(InstanceTypenameConf),
 }
 
 mod kw {
     syn::custom_keyword!(witx);
     syn::custom_keyword!(witx_literal);
     syn::custom_keyword!(ctx);
+    syn::custom_keyword!(instance);
 }
 
 impl Parse for ConfigField {
@@ -42,6 +45,10 @@ impl Parse for ConfigField {
             input.parse::<kw::ctx>()?;
             input.parse::<Token![:]>()?;
             Ok(ConfigField::Ctx(input.parse()?))
+        } else if lookahead.peek(kw::instance) {
+            input.parse::<kw::instance>()?;
+            input.parse::<Token![:]>()?;
+            Ok(ConfigField::InstanceTypename(input.parse()?))
         } else {
             Err(lookahead.error())
         }
@@ -52,6 +59,7 @@ impl Config {
     pub fn build(fields: impl Iterator<Item = ConfigField>, err_loc: Span) -> Result<Self> {
         let mut witx = None;
         let mut ctx = None;
+        let mut instance_typename = None;
         for f in fields {
             match f {
                 ConfigField::Witx(c) => {
@@ -66,6 +74,12 @@ impl Config {
                     }
                     ctx = Some(c);
                 }
+                ConfigField::InstanceTypename(c) => {
+                    if instance_typename.is_some() {
+                        return Err(Error::new(err_loc, "duplicate `instance` field"));
+                    }
+                    instance_typename = Some(c);
+                }
             }
         }
         Ok(Config {
@@ -75,6 +89,9 @@ impl Config {
             ctx: ctx
                 .take()
                 .ok_or_else(|| Error::new(err_loc, "`ctx` field required"))?,
+            instance_typename: instance_typename
+                .take()
+                .ok_or_else(|| Error::new(err_loc, "`instance` field required"))?,
         })
     }
 
@@ -97,3 +114,16 @@ impl Parse for Config {
         Ok(Config::build(fields.into_iter(), input.span())?)
     }
 }
+
+#[derive(Debug, Clone)]
+pub struct InstanceTypenameConf {
+    pub name: Ident,
+}
+
+impl Parse for InstanceTypenameConf {
+    fn parse(input: ParseStream) -> Result<Self> {
+        Ok(InstanceTypenameConf {
+            name: input.parse()?,
+        })
+    }
+}

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

@@ -6,6 +6,8 @@ use wiggle_generate::Names;
 
 mod config;
 
+use config::InstanceTypenameConf;
+
 #[proc_macro]
 pub fn define_struct_for_wiggle(args: TokenStream) -> TokenStream {
     let mut config = parse_macro_input!(args as config::Config);
@@ -15,7 +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).into()
+    generate(&doc, &names, &config.instance_typename).into()
 }
 
 enum Abi {
@@ -25,7 +27,11 @@ enum Abi {
     F64,
 }
 
-fn generate(doc: &witx::Document, names: &Names) -> TokenStream2 {
+fn generate(
+    doc: &witx::Document,
+    names: &Names,
+    instance_typename: &InstanceTypenameConf,
+) -> TokenStream2 {
     let mut fields = Vec::new();
     let mut get_exports = Vec::new();
     let mut ctor_externs = Vec::new();
@@ -233,6 +239,7 @@ fn generate(doc: &witx::Document, names: &Names) -> TokenStream2 {
         }
     }
 
+    let inst_type = instance_typename.name.clone();
     let ctx_type = names.ctx_type();
 
     quote! {
@@ -241,23 +248,23 @@ fn generate(doc: &witx::Document, names: &Names) -> TokenStream2 {
         /// This represents a wasi module which can be used to instantiate other
         /// wasm modules. This structure exports all that various fields of the
         /// wasi instance as fields which can be used to implement your own
-        /// instantiation logic, if necessary. Additionally [`Wasi::get_export`]
+        /// instantiation logic, if necessary. Additionally [`#inst_type::get_export`]
         /// can be used to do name-based resolution.
-        pub struct Wasi {
+        pub struct #inst_type {
             #(#fields,)*
         }
 
-        impl Wasi {
+        impl #inst_type {
-            /// Creates a new [`Wasi`] instance.
+            /// Creates a new [`#inst_type`] instance.
             ///
             /// External values are allocated into the `store` provided and
             /// configuration of the wasi instance itself should be all
             /// contained in the `cx` parameter.
-            pub fn new(store: &wasmtime::Store, cx: #ctx_type) -> Wasi {
+            pub fn new(store: &wasmtime::Store, cx: #ctx_type) -> Self {
                 let cx = std::rc::Rc::new(std::cell::RefCell::new(cx));
                 #(#ctor_externs)*
 
-                Wasi {
+                Self {
                     #(#ctor_fields,)*
                 }
             }