From 22fb3ecbbf287a78cb8e449e550b871ae6fef126 Mon Sep 17 00:00:00 2001
From: Joel Dice <joel.dice@gmail.com>
Date: Wed, 29 Jun 2022 08:38:36 -0600
Subject: [PATCH] add ComponentType/Lift/Lower derive macro for record types
 (#4337)

This is the first stage of implementing
https://github.com/bytecodealliance/wasmtime/issues/4308, i.e. derive macros for
`ComponentType`, `Lift`, and `Lower` for composite types in the component model.
This stage only covers records; I expect the other composite types will follow a
similar pattern.

It borrows heavily from the work Jamey Sharp did in
https://github.com/bytecodealliance/wasmtime/pull/4217.  Thanks for that, and
thanks to both Jamey and Alex Crichton for their excellent review feedback.
Thanks also to Brian for pairing up on the initial draft.

Signed-off-by: Joel Dice <joel.dice@fermyon.com>
---
 Cargo.lock                                    |  10 +
 crates/component-macro/Cargo.toml             |  22 +
 crates/component-macro/src/lib.rs             | 382 ++++++++++++++++++
 crates/wasmtime/Cargo.toml                    |   2 +
 crates/wasmtime/src/component/func.rs         |   7 +-
 crates/wasmtime/src/component/func/host.rs    |   4 +-
 crates/wasmtime/src/component/func/options.rs |   2 +-
 crates/wasmtime/src/component/func/typed.rs   |  59 ++-
 crates/wasmtime/src/component/mod.rs          |  17 +-
 crates/wasmtime/src/store.rs                  |   1 +
 scripts/publish.rs                            |   1 +
 tests/all/component_model.rs                  |  21 +-
 tests/all/component_model/func.rs             |  20 +-
 tests/all/component_model/macros.rs           | 158 ++++++++
 14 files changed, 660 insertions(+), 46 deletions(-)
 create mode 100644 crates/component-macro/Cargo.toml
 create mode 100644 crates/component-macro/src/lib.rs
 create mode 100644 tests/all/component_model/macros.rs

diff --git a/Cargo.lock b/Cargo.lock
index 4796d80f2a..f6d8f01c96 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3332,6 +3332,7 @@ dependencies = [
  "wasi-cap-std-sync",
  "wasmparser",
  "wasmtime-cache",
+ "wasmtime-component-macro",
  "wasmtime-cranelift",
  "wasmtime-environ",
  "wasmtime-fiber",
@@ -3457,6 +3458,15 @@ dependencies = [
  "wasmtime",
 ]
 
+[[package]]
+name = "wasmtime-component-macro"
+version = "0.39.0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "wasmtime-cranelift"
 version = "0.39.0"
diff --git a/crates/component-macro/Cargo.toml b/crates/component-macro/Cargo.toml
new file mode 100644
index 0000000000..4e924ec976
--- /dev/null
+++ b/crates/component-macro/Cargo.toml
@@ -0,0 +1,22 @@
+[package]
+name = "wasmtime-component-macro"
+version = "0.39.0"
+authors = ["The Wasmtime Project Developers"]
+description = "Macros for deriving component interface types from Rust types"
+license = "Apache-2.0 WITH LLVM-exception"
+repository = "https://github.com/bytecodealliance/wasmtime"
+documentation = "https://docs.rs/wasmtime-component-macro/"
+categories = ["wasm"]
+keywords = ["webassembly", "wasm"]
+edition = "2021"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = { version = "1.0", features = ["extra-traits"] }
+
+[badges]
+maintenance = { status = "actively-developed" }
diff --git a/crates/component-macro/src/lib.rs b/crates/component-macro/src/lib.rs
new file mode 100644
index 0000000000..d319e6df75
--- /dev/null
+++ b/crates/component-macro/src/lib.rs
@@ -0,0 +1,382 @@
+use proc_macro2::{Literal, TokenStream, TokenTree};
+use quote::{format_ident, quote};
+use std::collections::HashSet;
+use syn::{parse_macro_input, parse_quote, Data, DeriveInput, Error, Result};
+
+#[derive(Debug)]
+enum Style {
+    Record,
+    Variant,
+    Enum,
+    Union,
+}
+
+fn find_style(input: &DeriveInput) -> Result<Style> {
+    let mut style = None;
+
+    for attribute in &input.attrs {
+        if attribute.path.leading_colon.is_some() || attribute.path.segments.len() != 1 {
+            continue;
+        }
+
+        let ident = &attribute.path.segments[0].ident;
+
+        if "component" != &ident.to_string() {
+            continue;
+        }
+
+        let syntax_error = || {
+            Err(Error::new_spanned(
+                &attribute.tokens,
+                "expected `component(<style>)` syntax",
+            ))
+        };
+
+        let style_string = if let [TokenTree::Group(group)] =
+            &attribute.tokens.clone().into_iter().collect::<Vec<_>>()[..]
+        {
+            if let [TokenTree::Ident(style)] = &group.stream().into_iter().collect::<Vec<_>>()[..] {
+                style.to_string()
+            } else {
+                return syntax_error();
+            }
+        } else {
+            return syntax_error();
+        };
+
+        if style.is_some() {
+            return Err(Error::new(ident.span(), "duplicate `component` attribute"));
+        }
+
+        style = Some(match style_string.as_ref() {
+            "record" => Style::Record,
+            "variant" => Style::Variant,
+            "enum" => Style::Enum,
+            "union" => Style::Union,
+            "flags" => {
+                return Err(Error::new_spanned(
+                    &attribute.tokens,
+                    "`flags` not allowed here; \
+                     use `wasmtime::component::flags!` macro to define `flags` types",
+                ))
+            }
+            _ => {
+                return Err(Error::new_spanned(
+                    &attribute.tokens,
+                    "unrecognized component type keyword \
+                     (expected `record`, `variant`, `enum`, or `union`)",
+                ))
+            }
+        });
+    }
+
+    style.ok_or_else(|| Error::new_spanned(input, "missing `component` attribute"))
+}
+
+fn find_rename(field: &syn::Field) -> Result<Option<Literal>> {
+    let mut name = None;
+
+    for attribute in &field.attrs {
+        if attribute.path.leading_colon.is_some() || attribute.path.segments.len() != 1 {
+            continue;
+        }
+
+        let ident = &attribute.path.segments[0].ident;
+
+        if "component" != &ident.to_string() {
+            continue;
+        }
+
+        let syntax_error = || {
+            Err(Error::new_spanned(
+                &attribute.tokens,
+                "expected `component(name = <name literal>)` syntax",
+            ))
+        };
+
+        let name_literal = if let [TokenTree::Group(group)] =
+            &attribute.tokens.clone().into_iter().collect::<Vec<_>>()[..]
+        {
+            match &group.stream().into_iter().collect::<Vec<_>>()[..] {
+                [TokenTree::Ident(key), TokenTree::Punct(op), TokenTree::Literal(literal)]
+                    if "name" == &key.to_string() && '=' == op.as_char() =>
+                {
+                    literal.clone()
+                }
+                _ => return syntax_error(),
+            }
+        } else {
+            return syntax_error();
+        };
+
+        if name.is_some() {
+            return Err(Error::new(ident.span(), "duplicate field rename attribute"));
+        }
+
+        name = Some(name_literal);
+    }
+
+    Ok(name)
+}
+
+fn add_trait_bounds(generics: &syn::Generics) -> syn::Generics {
+    let mut generics = generics.clone();
+    for param in &mut generics.params {
+        if let syn::GenericParam::Type(ref mut type_param) = *param {
+            type_param
+                .bounds
+                .push(parse_quote!(wasmtime::component::ComponentType));
+        }
+    }
+    generics
+}
+
+trait Expander {
+    fn expand_record(&self, input: &DeriveInput, fields: &syn::FieldsNamed) -> Result<TokenStream>;
+
+    // TODO: expand_variant, expand_enum, etc.
+}
+
+fn expand(expander: &dyn Expander, input: DeriveInput) -> Result<TokenStream> {
+    match find_style(&input)? {
+        Style::Record => expand_record(expander, input),
+
+        style => Err(Error::new_spanned(input, format!("todo: expand {style:?}"))),
+    }
+}
+
+fn expand_record(expander: &dyn Expander, input: DeriveInput) -> Result<TokenStream> {
+    let name = &input.ident;
+
+    let body = if let Data::Struct(body) = &input.data {
+        body
+    } else {
+        return Err(Error::new(
+            name.span(),
+            "`record` component types can only be derived for `struct`s",
+        ));
+    };
+
+    match &body.fields {
+        syn::Fields::Named(fields) => expander.expand_record(&input, fields),
+
+        syn::Fields::Unnamed(_) | syn::Fields::Unit => Err(Error::new(
+            name.span(),
+            "`record` component types can only be derived for `struct`s with named fields",
+        )),
+    }
+}
+
+#[proc_macro_derive(Lift, attributes(component))]
+pub fn lift(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    expand(&LiftExpander, parse_macro_input!(input as DeriveInput))
+        .unwrap_or_else(Error::into_compile_error)
+        .into()
+}
+
+struct LiftExpander;
+
+impl Expander for LiftExpander {
+    fn expand_record(&self, input: &DeriveInput, fields: &syn::FieldsNamed) -> Result<TokenStream> {
+        let internal = quote!(wasmtime::component::__internal);
+
+        let mut lifts = TokenStream::new();
+        let mut loads = TokenStream::new();
+
+        for syn::Field { ty, ident, .. } in &fields.named {
+            lifts.extend(quote!(#ident: <#ty as wasmtime::component::Lift>::lift(
+                    store, options, &src.#ident
+                )?,));
+
+            loads.extend(quote!(#ident: <#ty as wasmtime::component::Lift>::load(
+                    memory,
+                    &bytes
+                        [#internal::next_field::<#ty>(&mut offset)..]
+                        [..<#ty as wasmtime::component::ComponentType>::size()]
+                )?,));
+        }
+
+        let name = &input.ident;
+        let generics = add_trait_bounds(&input.generics);
+        let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
+
+        let expanded = quote! {
+            unsafe impl #impl_generics wasmtime::component::Lift for #name #ty_generics #where_clause {
+                #[inline]
+                fn lift(
+                    store: &#internal::StoreOpaque,
+                    options: &#internal::Options,
+                    src: &Self::Lower,
+                ) -> #internal::anyhow::Result<Self> {
+                    Ok(Self {
+                        #lifts
+                    })
+                }
+
+                #[inline]
+                fn load(memory: &#internal::Memory, bytes: &[u8]) -> #internal::anyhow::Result<Self> {
+                    debug_assert!(
+                        (bytes.as_ptr() as usize)
+                            % (<Self as wasmtime::component::ComponentType>::align() as usize)
+                            == 0
+                    );
+                    let mut offset = 0;
+                    Ok(Self {
+                        #loads
+                    })
+                }
+            }
+        };
+
+        Ok(expanded)
+    }
+}
+
+#[proc_macro_derive(Lower, attributes(component))]
+pub fn lower(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    expand(&LowerExpander, parse_macro_input!(input as DeriveInput))
+        .unwrap_or_else(Error::into_compile_error)
+        .into()
+}
+
+struct LowerExpander;
+
+impl Expander for LowerExpander {
+    fn expand_record(&self, input: &DeriveInput, fields: &syn::FieldsNamed) -> Result<TokenStream> {
+        let internal = quote!(wasmtime::component::__internal);
+
+        let mut lowers = TokenStream::new();
+        let mut stores = TokenStream::new();
+
+        for syn::Field { ty, ident, .. } in &fields.named {
+            lowers.extend(quote!(wasmtime::component::Lower::lower(
+                    &self.#ident, store, options, #internal::map_maybe_uninit!(dst.#ident)
+                )?;));
+
+            stores.extend(quote!(wasmtime::component::Lower::store(
+                    &self.#ident, memory, #internal::next_field::<#ty>(&mut offset)
+                )?;));
+        }
+
+        let name = &input.ident;
+        let generics = add_trait_bounds(&input.generics);
+        let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
+
+        let expanded = quote! {
+            unsafe impl #impl_generics wasmtime::component::Lower for #name #ty_generics #where_clause {
+                #[inline]
+                fn lower<T>(
+                    &self,
+                    store: &mut wasmtime::StoreContextMut<T>,
+                    options: &#internal::Options,
+                    dst: &mut std::mem::MaybeUninit<Self::Lower>,
+                ) -> #internal::anyhow::Result<()> {
+                    #lowers
+                    Ok(())
+                }
+
+                #[inline]
+                fn store<T>(
+                    &self,
+                    memory: &mut #internal::MemoryMut<'_, T>,
+                    mut offset: usize
+                ) -> #internal::anyhow::Result<()> {
+                    #stores
+                    Ok(())
+                }
+            }
+        };
+
+        Ok(expanded)
+    }
+}
+
+#[proc_macro_derive(ComponentType, attributes(component))]
+pub fn component_type(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    expand(
+        &ComponentTypeExpander,
+        parse_macro_input!(input as DeriveInput),
+    )
+    .unwrap_or_else(Error::into_compile_error)
+    .into()
+}
+
+struct ComponentTypeExpander;
+
+impl Expander for ComponentTypeExpander {
+    fn expand_record(&self, input: &DeriveInput, fields: &syn::FieldsNamed) -> Result<TokenStream> {
+        let internal = quote!(wasmtime::component::__internal);
+
+        let mut field_names_and_checks = TokenStream::new();
+        let mut lower_field_declarations = TokenStream::new();
+        let mut sizes = TokenStream::new();
+        let mut unique_types = HashSet::new();
+
+        for field @ syn::Field { ty, ident, .. } in &fields.named {
+            lower_field_declarations
+                .extend(quote!(#ident: <#ty as wasmtime::component::ComponentType>::Lower,));
+
+            let literal = find_rename(field)?
+                .unwrap_or_else(|| Literal::string(&ident.as_ref().unwrap().to_string()));
+
+            field_names_and_checks.extend(
+                quote!((#literal, <#ty as wasmtime::component::ComponentType>::typecheck),),
+            );
+
+            sizes.extend(quote!(#internal::next_field::<#ty>(&mut size);));
+
+            unique_types.insert(ty);
+        }
+
+        let alignments = unique_types
+            .into_iter()
+            .map(|ty| {
+                quote!(align = align.max(
+                        <#ty as wasmtime::component::ComponentType>::align()
+                    );)
+            })
+            .collect::<TokenStream>();
+
+        let name = &input.ident;
+        let generics = add_trait_bounds(&input.generics);
+        let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
+        let lower = format_ident!("_Lower{}", name);
+
+        let expanded = quote! {
+            #[doc(hidden)]
+            #[derive(Clone, Copy)]
+            #[repr(C)]
+            pub struct #lower {
+                #lower_field_declarations
+            }
+
+            unsafe impl #impl_generics wasmtime::component::ComponentType for #name #ty_generics #where_clause {
+                type Lower = #lower;
+
+                #[inline]
+                fn typecheck(
+                    ty: &#internal::InterfaceType,
+                    types: &#internal::ComponentTypes,
+                ) -> #internal::anyhow::Result<()> {
+                    #internal::typecheck_record(ty, types, &[#field_names_and_checks])
+                }
+
+                #[inline]
+                fn size() -> usize {
+                    let mut size = 0;
+                    #sizes
+                    size
+                }
+
+                #[inline]
+                fn align() -> u32 {
+                    let mut align = 1;
+                    #alignments
+                    align
+                }
+            }
+        };
+
+        Ok(quote!(const _: () = { #expanded };))
+    }
+}
diff --git a/crates/wasmtime/Cargo.toml b/crates/wasmtime/Cargo.toml
index 24a09a7747..21329348fd 100644
--- a/crates/wasmtime/Cargo.toml
+++ b/crates/wasmtime/Cargo.toml
@@ -19,6 +19,7 @@ wasmtime-jit = { path = "../jit", version = "=0.39.0" }
 wasmtime-cache = { path = "../cache", version = "=0.39.0", optional = true }
 wasmtime-fiber = { path = "../fiber", version = "=0.39.0", optional = true }
 wasmtime-cranelift = { path = "../cranelift", version = "=0.39.0", optional = true }
+wasmtime-component-macro = { path = "../component-macro", version = "=0.39.0", optional = true }
 target-lexicon = { version = "0.12.0", default-features = false }
 wasmparser = "0.86.0"
 anyhow = "1.0.19"
@@ -115,4 +116,5 @@ component-model = [
   "wasmtime-environ/component-model",
   "wasmtime-cranelift?/component-model",
   "wasmtime-runtime/component-model",
+  "dep:wasmtime-component-macro",
 ]
diff --git a/crates/wasmtime/src/component/func.rs b/crates/wasmtime/src/component/func.rs
index af45aaadea..cfcfd6890c 100644
--- a/crates/wasmtime/src/component/func.rs
+++ b/crates/wasmtime/src/component/func.rs
@@ -34,9 +34,11 @@ const MAX_STACK_RESULTS: usize = 1;
 /// let initial: &mut MaybeUninit<[u32; 2]> = ...;
 /// let element: &mut MaybeUninit<u32> = map_maybe_uninit!(initial[1]);
 /// ```
+#[doc(hidden)]
+#[macro_export]
 macro_rules! map_maybe_uninit {
     ($maybe_uninit:ident $($field:tt)*) => (#[allow(unused_unsafe)] unsafe {
-        use crate::component::func::MaybeUninitExt;
+        use $crate::component::__internal::MaybeUninitExt;
 
         let m: &mut std::mem::MaybeUninit<_> = $maybe_uninit;
         // Note the usage of `addr_of_mut!` here which is an attempt to "stay
@@ -47,7 +49,8 @@ macro_rules! map_maybe_uninit {
     })
 }
 
-trait MaybeUninitExt<T> {
+#[doc(hidden)]
+pub trait MaybeUninitExt<T> {
     /// Maps `MaybeUninit<T>` to `MaybeUninit<U>` using the closure provided.
     ///
     /// Note that this is `unsafe` as there is no guarantee that `U` comes from
diff --git a/crates/wasmtime/src/component/func/host.rs b/crates/wasmtime/src/component/func/host.rs
index 3f20d4167d..85254e69f3 100644
--- a/crates/wasmtime/src/component/func/host.rs
+++ b/crates/wasmtime/src/component/func/host.rs
@@ -1,5 +1,5 @@
-use crate::component::func::{MAX_STACK_PARAMS, MAX_STACK_RESULTS};
-use crate::component::{ComponentParams, ComponentType, Lift, Lower, Memory, MemoryMut, Options};
+use crate::component::func::{Memory, MemoryMut, Options, MAX_STACK_PARAMS, MAX_STACK_RESULTS};
+use crate::component::{ComponentParams, ComponentType, Lift, Lower};
 use crate::{AsContextMut, StoreContextMut, ValRaw};
 use anyhow::{bail, Context, Result};
 use std::any::Any;
diff --git a/crates/wasmtime/src/component/func/options.rs b/crates/wasmtime/src/component/func/options.rs
index faa26cda40..fbc202fd82 100644
--- a/crates/wasmtime/src/component/func/options.rs
+++ b/crates/wasmtime/src/component/func/options.rs
@@ -196,7 +196,7 @@ impl<'a, T> MemoryMut<'a, T> {
     /// bounds-checks.
     pub fn get<const N: usize>(&mut self, offset: usize) -> &mut [u8; N] {
         // FIXME: this bounds check shouldn't actually be necessary, all
-        // callers of `ComponentValue::store` have already performed a bounds
+        // callers of `ComponentType::store` have already performed a bounds
         // check so we're guaranteed that `offset..offset+N` is in-bounds. That
         // being said we at least should do bounds checks in debug mode and
         // it's not clear to me how to easily structure this so that it's
diff --git a/crates/wasmtime/src/component/func/typed.rs b/crates/wasmtime/src/component/func/typed.rs
index a167b19583..00ec0b9066 100644
--- a/crates/wasmtime/src/component/func/typed.rs
+++ b/crates/wasmtime/src/component/func/typed.rs
@@ -3,7 +3,7 @@ use crate::component::func::{
 };
 use crate::store::StoreOpaque;
 use crate::{AsContext, AsContextMut, StoreContext, StoreContextMut, ValRaw};
-use anyhow::{bail, Result};
+use anyhow::{bail, Context, Result};
 use std::borrow::Cow;
 use std::marker;
 use std::mem::{self, MaybeUninit};
@@ -348,8 +348,8 @@ where
             // are all valid since they're coming from our store, and the
             // `params_and_results` should have the correct layout for the core
             // wasm function we're calling. Note that this latter point relies
-            // on the correctness of this module and `ComponentValue`
-            // implementations, hence `ComponentValue` being an `unsafe` trait.
+            // on the correctness of this module and `ComponentType`
+            // implementations, hence `ComponentType` being an `unsafe` trait.
             crate::Func::call_unchecked_raw(
                 store,
                 export.anyfunc,
@@ -615,14 +615,8 @@ pub unsafe trait ComponentType {
     #[doc(hidden)]
     fn align() -> u32;
 
-    /// Performs a type-check to see whether this comopnent value type matches
+    /// Performs a type-check to see whether this component value type matches
     /// the interface type `ty` provided.
-    ///
-    /// The `op` provided is the operations which could be performed with this
-    /// type if the typecheck passes, either lifting or lowering. Some Rust
-    /// types are only valid for one operation and we can't prevent the wrong
-    /// one from being used at compile time so we rely on the runtime check
-    /// here.
     #[doc(hidden)]
     fn typecheck(ty: &InterfaceType, types: &ComponentTypes) -> Result<()>;
 }
@@ -754,7 +748,7 @@ forward_impls! {
     (T: Lower) Vec<T> => [T],
 }
 
-// Macro to help generate `ComponentValue` implementations for primitive types
+// Macro to help generate `ComponentType` implementations for primitive types
 // such as integers, char, bool, etc.
 macro_rules! integers {
     ($($primitive:ident = $ty:ident in $field:ident/$get:ident,)*) => ($(
@@ -1006,7 +1000,7 @@ unsafe impl Lift for char {
     }
 }
 
-// Note that this is similar to `ComponentValue for WasmStr` except it can only
+// Note that this is similar to `ComponentType for WasmStr` except it can only
 // be used for lowering, not lifting.
 unsafe impl ComponentType for str {
     type Lower = [ValRaw; 2];
@@ -1171,7 +1165,7 @@ impl WasmStr {
     }
 }
 
-// Note that this is similar to `ComponentValue for str` except it can only be
+// Note that this is similar to `ComponentType for str` except it can only be
 // used for lifting, not lowering.
 unsafe impl ComponentType for WasmStr {
     type Lower = <str as ComponentType>::Lower;
@@ -1431,7 +1425,7 @@ raw_wasm_list_accessors! {
     u8 u16 u32 u64
 }
 
-// Note that this is similar to `ComponentValue for str` except it can only be
+// Note that this is similar to `ComponentType for str` except it can only be
 // used for lifting, not lowering.
 unsafe impl<T: ComponentType> ComponentType for WasmList<T> {
     type Lower = <[T] as ComponentType>::Lower;
@@ -1491,7 +1485,6 @@ pub fn next_field<T: ComponentType>(offset: &mut usize) -> usize {
 }
 
 /// Verify that the given wasm type is a tuple with the expected fields in the right order.
-#[inline]
 fn typecheck_tuple(
     ty: &InterfaceType,
     types: &ComponentTypes,
@@ -1526,6 +1519,40 @@ fn typecheck_tuple(
     }
 }
 
+/// Verify that the given wasm type is a record with the expected fields in the right order and with the right
+/// names.
+pub fn typecheck_record(
+    ty: &InterfaceType,
+    types: &ComponentTypes,
+    expected: &[(&str, fn(&InterfaceType, &ComponentTypes) -> Result<()>)],
+) -> Result<()> {
+    match ty {
+        InterfaceType::Record(index) => {
+            let fields = &types[*index].fields;
+
+            if fields.len() != expected.len() {
+                bail!(
+                    "expected record of {} fields, found {} fields",
+                    expected.len(),
+                    fields.len()
+                );
+            }
+
+            for (field, &(name, check)) in fields.iter().zip(expected) {
+                check(&field.ty, types)
+                    .with_context(|| format!("type mismatch for field {}", name))?;
+
+                if field.name != name {
+                    bail!("expected record field named {}, found {}", name, field.name);
+                }
+            }
+
+            Ok(())
+        }
+        other => bail!("expected `record` found `{}`", desc(other)),
+    }
+}
+
 unsafe impl<T> ComponentType for Option<T>
 where
     T: ComponentType,
@@ -1565,7 +1592,7 @@ where
                 map_maybe_uninit!(dst.A1).write(ValRaw::i32(0));
                 // Note that this is unsafe as we're writing an arbitrary
                 // bit-pattern to an arbitrary type, but part of the unsafe
-                // contract of the `ComponentValue` trait is that we can assign
+                // contract of the `ComponentType` trait is that we can assign
                 // any bit-pattern. By writing all zeros here we're ensuring
                 // that the core wasm arguments this translates to will all be
                 // zeros (as the canonical ABI requires).
diff --git a/crates/wasmtime/src/component/mod.rs b/crates/wasmtime/src/component/mod.rs
index c83f72e59a..712c1d3424 100644
--- a/crates/wasmtime/src/component/mod.rs
+++ b/crates/wasmtime/src/component/mod.rs
@@ -16,14 +16,21 @@ pub use self::func::{
 };
 pub use self::instance::{Instance, InstancePre};
 pub use self::linker::{Linker, LinkerInstance};
+pub use wasmtime_component_macro::{ComponentType, Lift, Lower};
 
 // These items are expected to be used by an eventual
-// `#[derive(ComponentValue)]`, they are not part of Wasmtime's API stability
+// `#[derive(ComponentType)]`, they are not part of Wasmtime's API stability
 // guarantees
 #[doc(hidden)]
-pub use {
-    self::func::{Memory, MemoryMut, Options},
-    wasmtime_environ,
-};
+pub mod __internal {
+    pub use super::func::{
+        next_field, typecheck_record, MaybeUninitExt, Memory, MemoryMut, Options,
+    };
+    pub use crate::map_maybe_uninit;
+    pub use crate::store::StoreOpaque;
+    pub use anyhow;
+    pub use wasmtime_environ;
+    pub use wasmtime_environ::component::{ComponentTypes, InterfaceType};
+}
 
 pub(crate) use self::store::ComponentStoreData;
diff --git a/crates/wasmtime/src/store.rs b/crates/wasmtime/src/store.rs
index a125a49440..28aecdf9d2 100644
--- a/crates/wasmtime/src/store.rs
+++ b/crates/wasmtime/src/store.rs
@@ -1112,6 +1112,7 @@ impl<T> StoreInner<T> {
     }
 }
 
+#[doc(hidden)]
 impl StoreOpaque {
     pub fn id(&self) -> StoreId {
         self.store_data.id()
diff --git a/scripts/publish.rs b/scripts/publish.rs
index 30d402b360..292aba531c 100644
--- a/scripts/publish.rs
+++ b/scripts/publish.rs
@@ -40,6 +40,7 @@ const CRATES_TO_PUBLISH: &[&str] = &[
     "wiggle-generate",
     "wiggle-macro",
     // wasmtime
+    "wasmtime-component-macro",
     "wasmtime-jit-debug",
     "wasmtime-fiber",
     "wasmtime-environ",
diff --git a/tests/all/component_model.rs b/tests/all/component_model.rs
index 4049d9ddcd..9cb50554e9 100644
--- a/tests/all/component_model.rs
+++ b/tests/all/component_model.rs
@@ -1,12 +1,29 @@
 use anyhow::Result;
-use wasmtime::component::Component;
-use wasmtime::{Config, Engine};
+use wasmtime::component::{Component, ComponentParams, Lift, Lower, TypedFunc};
+use wasmtime::{AsContextMut, Config, Engine};
 
 mod func;
 mod import;
+mod macros;
 mod nested;
 mod post_return;
 
+trait TypedFuncExt<P, R> {
+    fn call_and_post_return(&self, store: impl AsContextMut, params: P) -> Result<R>;
+}
+
+impl<P, R> TypedFuncExt<P, R> for TypedFunc<P, R>
+where
+    P: ComponentParams + Lower,
+    R: Lift,
+{
+    fn call_and_post_return(&self, mut store: impl AsContextMut, params: P) -> Result<R> {
+        let result = self.call(&mut store, params)?;
+        self.post_return(&mut store)?;
+        Ok(result)
+    }
+}
+
 // A simple bump allocator which can be used with modules
 const REALLOC_AND_FREE: &str = r#"
     (global $last (mut i32) (i32.const 8))
diff --git a/tests/all/component_model/func.rs b/tests/all/component_model/func.rs
index 21d6fc2fc9..3b2aff3877 100644
--- a/tests/all/component_model/func.rs
+++ b/tests/all/component_model/func.rs
@@ -1,9 +1,9 @@
-use super::REALLOC_AND_FREE;
+use super::{TypedFuncExt, REALLOC_AND_FREE};
 use anyhow::Result;
 use std::rc::Rc;
 use std::sync::Arc;
 use wasmtime::component::*;
-use wasmtime::{AsContextMut, Store, StoreContextMut, Trap, TrapCode};
+use wasmtime::{Store, StoreContextMut, Trap, TrapCode};
 
 const CANON_32BIT_NAN: u32 = 0b01111111110000000000000000000000;
 const CANON_64BIT_NAN: u64 = 0b0111111111111000000000000000000000000000000000000000000000000000;
@@ -400,22 +400,6 @@ fn integers() -> Result<()> {
     Ok(())
 }
 
-trait TypedFuncExt<P, R> {
-    fn call_and_post_return(&self, store: impl AsContextMut, params: P) -> Result<R>;
-}
-
-impl<P, R> TypedFuncExt<P, R> for TypedFunc<P, R>
-where
-    P: ComponentParams + Lower,
-    R: Lift,
-{
-    fn call_and_post_return(&self, mut store: impl AsContextMut, params: P) -> Result<R> {
-        let result = self.call(&mut store, params)?;
-        self.post_return(&mut store)?;
-        Ok(result)
-    }
-}
-
 #[test]
 fn type_layers() -> Result<()> {
     let component = r#"
diff --git a/tests/all/component_model/macros.rs b/tests/all/component_model/macros.rs
new file mode 100644
index 0000000000..7134c48f8f
--- /dev/null
+++ b/tests/all/component_model/macros.rs
@@ -0,0 +1,158 @@
+use super::TypedFuncExt;
+use anyhow::Result;
+use std::fmt::Write;
+use wasmtime::component::{Component, ComponentType, Lift, Linker, Lower};
+use wasmtime::Store;
+
+fn make_echo_component(type_definition: &str, type_size: u32) -> String {
+    if type_size <= 4 {
+        format!(
+            r#"
+            (component
+                (core module $m
+                    (func (export "echo") (param i32) (result i32)
+                        local.get 0
+                    )
+
+                    (memory (export "memory") 1)
+                )
+
+                (core instance $i (instantiate $m))
+
+                {}
+
+                (func (export "echo") (param $Foo) (result $Foo)
+                    (canon lift (core func $i "echo") (memory $i "memory"))
+                )
+            )"#,
+            type_definition
+        )
+    } else {
+        let mut params = String::new();
+        let mut store = String::new();
+
+        for index in 0..(type_size / 4) {
+            params.push_str(" i32");
+            write!(
+                &mut store,
+                "(i32.store offset={} (local.get $base) (local.get {}))",
+                index * 4,
+                index,
+            )
+            .unwrap();
+        }
+
+        format!(
+            r#"
+            (component
+                (core module $m
+                    (func (export "echo") (param{}) (result i32)
+                        (local $base i32)
+                        (local.set $base (i32.const 0))
+                        {}
+                        local.get $base
+                    )
+
+                    (memory (export "memory") 1)
+                )
+
+                (core instance $i (instantiate $m))
+
+                {}
+
+                (func (export "echo") (param $Foo) (result $Foo)
+                    (canon lift (core func $i "echo") (memory $i "memory"))
+                )
+            )"#,
+            params, store, type_definition
+        )
+    }
+}
+
+#[test]
+fn record_derive() -> Result<()> {
+    #[derive(ComponentType, Lift, Lower, PartialEq, Eq, Debug, Copy, Clone)]
+    #[component(record)]
+    struct Foo {
+        #[component(name = "foo-bar-baz")]
+        a: i32,
+        b: u32,
+    }
+
+    let engine = super::engine();
+    let mut store = Store::new(&engine, ());
+    let input = Foo { a: -42, b: 73 };
+
+    // Happy path: component type matches field count, names, and types
+
+    let component = Component::new(
+        &engine,
+        make_echo_component(
+            r#"(type $Foo (record (field "foo-bar-baz" s32) (field "b" u32)))"#,
+            8,
+        ),
+    )?;
+    let instance = Linker::new(&engine).instantiate(&mut store, &component)?;
+
+    let output = instance
+        .get_typed_func::<(Foo,), Foo, _>(&mut store, "echo")?
+        .call_and_post_return(&mut store, (input,))?;
+
+    assert_eq!(input, output);
+
+    // Sad path: field count mismatch (too few)
+
+    let component = Component::new(
+        &engine,
+        make_echo_component(r#"(type $Foo (record (field "foo-bar-baz" s32)))"#, 4),
+    )?;
+    let instance = Linker::new(&engine).instantiate(&mut store, &component)?;
+
+    assert!(instance
+        .get_typed_func::<(Foo,), Foo, _>(&mut store, "echo")
+        .is_err());
+
+    // Sad path: field count mismatch (too many)
+
+    let component = Component::new(
+        &engine,
+        make_echo_component(
+            r#"(type $Foo (record (field "foo-bar-baz" s32) (field "b" u32) (field "c" u32)))"#,
+            12,
+        ),
+    )?;
+    let instance = Linker::new(&engine).instantiate(&mut store, &component)?;
+
+    assert!(instance
+        .get_typed_func::<(Foo,), Foo, _>(&mut store, "echo")
+        .is_err());
+
+    // Sad path: field name mismatch
+
+    let component = Component::new(
+        &engine,
+        make_echo_component(r#"(type $Foo (record (field "a" s32) (field "b" u32)))"#, 8),
+    )?;
+    let instance = Linker::new(&engine).instantiate(&mut store, &component)?;
+
+    assert!(instance
+        .get_typed_func::<(Foo,), Foo, _>(&mut store, "echo")
+        .is_err());
+
+    // Sad path: field type mismatch
+
+    let component = Component::new(
+        &engine,
+        make_echo_component(
+            r#"(type $Foo (record (field "foo-bar-baz" s32) (field "b" s32)))"#,
+            8,
+        ),
+    )?;
+    let instance = Linker::new(&engine).instantiate(&mut store, &component)?;
+
+    assert!(instance
+        .get_typed_func::<(Foo,), Foo, _>(&mut store, "echo")
+        .is_err());
+
+    Ok(())
+}