Some clean-up work. (#391)

* Fix some typos and linter warnings.

This commit fixes some random comment typos and various linter warnings.

* wit-component: rename `decode_interface_component`.

This commit renames `decode_interface_component` to
`decode_component_interfaces` to better describe what the function does.

Previously it was meant to decode an "interface-only" component, but now it
returns all the interfaces (i.e. the "world") of the component.

* wit-component: implement multi-value return printing.

This commit implements printing of multi-value returns of interfaces decoded
from a component.

* Remove `module` field from `Interface`.

The `module` field was originally used by `cargo component` but is no longer
necessary and otherwise unused from `wit-bindgen` itself.

* Remove `symbol_namespace` from Rust generator.

This field is no longer used anywhere in the wit-bindgen repo.

* Add method to `Interface` for determining core export names.

This commit extracts the expected core export name out of `wit-component` and
into `Interface`, allowing generators to conform to the name expected by
`wit-component`.

Author: Peter Huene

build.rs

@@ -26,7 +26,9 @@ fn commit_info() {
     let mut next = || parts.next().unwrap();
     println!("cargo:rustc-env=CARGO_GIT_HASH={}", next());
     println!(
-        "cargo:rustc-env=CARGO_VERSION_INFO={}",
-        format!("{} ({} {})", env!("CARGO_PKG_VERSION"), next(), next())
+        "cargo:rustc-env=CARGO_VERSION_INFO={} ({} {})",
+        env!("CARGO_PKG_VERSION"),
+        next(),
+        next()
     );
 }

crates/bindgen-core/src/component.rs

@@ -31,7 +31,7 @@ pub fn generate(
     // will likely change as worlds are iterated on in the component model
     // standard. Regardless though this is the step where types are learned
     // and `Interface`s are constructed for further code generation below.
-    let interfaces = wit_component::decode_interface_component(binary)
+    let interfaces = wit_component::decode_component_interfaces(binary)
         .context("failed to extract interface information from component")?;
 
     // Components are complicated, there's no real way around that. To

crates/bindgen-core/src/lib.rs

@@ -139,8 +139,8 @@ pub trait Generator {
 
         for f in iface.functions.iter() {
             match dir {
-                Direction::Import => self.import(iface, &f),
-                Direction::Export => self.export(iface, &f),
+                Direction::Import => self.import(iface, f),
+                Direction::Export => self.export(iface, f),
             }
         }
 
@@ -266,7 +266,7 @@ impl Types {
             }
         }
         self.type_info.insert(ty, info);
-        return info;
+        info
     }
 
     pub fn type_info(&mut self, iface: &Interface, ty: &Type) -> TypeInfo {
@@ -415,7 +415,7 @@ impl Source {
         let lines = src.lines().collect::<Vec<_>>();
         for (i, line) in lines.iter().enumerate() {
             let trimmed = line.trim();
-            if trimmed.starts_with("}") && self.s.ends_with("  ") {
+            if trimmed.starts_with('}') && self.s.ends_with("  ") {
                 self.s.pop();
                 self.s.pop();
             }
@@ -434,7 +434,7 @@ impl Source {
                 // looking at the source code rather than getting a panic.
                 self.indent = self.indent.saturating_sub(1);
             }
-            if i != lines.len() - 1 || src.ends_with("\n") {
+            if i != lines.len() - 1 || src.ends_with('\n') {
                 self.newline();
             }
         }
@@ -449,7 +449,7 @@ impl Source {
     }
 
     fn newline(&mut self) {
-        self.s.push_str("\n");
+        self.s.push('\n');
         for _ in 0..self.indent {
             self.s.push_str("  ");
         }

crates/gen-guest-c/src/lib.rs

@@ -1098,6 +1098,10 @@ impl Generator for C {
 
         let sig = iface.wasm_signature(AbiVariant::GuestExport, func);
 
+        // Currently the C generator always emits default exports
+        // This needs to change once the generator works from a world
+        let export_name = iface.core_export_name(true, func);
+
         // Print the actual header for this function into the header file, and
         // it's what we'll be calling.
         let c_sig = self.print_sig(iface, func);
@@ -1106,8 +1110,7 @@ impl Generator for C {
         // canonical ABI.
         uwriteln!(
             self.src.c_adapters,
-            "\n__attribute__((export_name(\"{}\")))",
-            func.name
+            "__attribute__((export_name(\"{export_name}\")))"
         );
         let import_name = self.names.tmp(&format!(
             "__wasm_export_{}_{}",
@@ -1151,8 +1154,7 @@ impl Generator for C {
         if iface.guest_export_needs_post_return(func) {
             uwriteln!(
                 self.src.c_fns,
-                "\n__attribute__((weak, export_name(\"cabi_post_{}\")))",
-                func.name
+                "__attribute__((export_name(\"cabi_post_{export_name}\")))"
             );
             uwrite!(self.src.c_fns, "void {import_name}_post_return(");
 

crates/gen-guest-rust/src/lib.rs

@@ -32,11 +32,6 @@ pub struct Opts {
     #[cfg_attr(feature = "clap", arg(long))]
     pub unchecked: bool,
 
-    /// A prefix to prepend to all exported symbols. Note that this is only
-    /// intended for testing because it breaks the general form of the ABI.
-    #[cfg_attr(feature = "clap", arg(skip))]
-    pub symbol_namespace: String,
-
     /// If true, code generation should avoid any features that depend on `std`.
     #[cfg_attr(feature = "clap", arg(long))]
     pub no_std: bool,
@@ -106,12 +101,12 @@ impl WorldGenerator for RustWasm {
 
     fn export(&mut self, name: &str, iface: &Interface, _files: &mut Files) {
         self.interface(iface, TypeMode::Owned, false)
-            .generate_exports(name);
+            .generate_exports(name, false);
     }
 
     fn export_default(&mut self, name: &str, iface: &Interface, _files: &mut Files) {
         self.interface(iface, TypeMode::Owned, false)
-            .generate_exports(name);
+            .generate_exports(name, true);
     }
 
     fn finish(&mut self, name: &str, interfaces: &ComponentInterfaces, files: &mut Files) {
@@ -214,7 +209,7 @@ struct InterfaceGenerator<'a> {
 }
 
 impl InterfaceGenerator<'_> {
-    fn generate_exports(mut self, name: &str) {
+    fn generate_exports(mut self, name: &str, default_export: bool) {
         self.types();
 
         let camel = name.to_upper_camel_case();
@@ -228,7 +223,7 @@ impl InterfaceGenerator<'_> {
         uwriteln!(self.src, "}}");
 
         for func in self.iface.functions.iter() {
-            self.generate_guest_export(name, func);
+            self.generate_guest_export(name, func, default_export);
         }
 
         self.append_submodule(name);
@@ -301,18 +296,12 @@ impl InterfaceGenerator<'_> {
         }
     }
 
-    fn generate_guest_export(&mut self, module_name: &str, func: &Function) {
+    fn generate_guest_export(&mut self, module_name: &str, func: &Function, default_export: bool) {
         let module_name = module_name.to_snake_case();
         let trait_bound = module_name.to_upper_camel_case();
         let iface_snake = self.iface.name.to_snake_case();
         let name_snake = func.name.to_snake_case();
-        let name = match &self.iface.module {
-            Some(module) => {
-                format!("{module}#{}", func.name)
-            }
-            None => format!("{}{}", self.gen.opts.symbol_namespace, func.name),
-        };
-
+        let export_name = self.iface.core_export_name(default_export, func);
         let mut macro_src = Source::default();
 
         // Generate, simultaneously, the actual lifting/lowering function within
@@ -333,7 +322,7 @@ impl InterfaceGenerator<'_> {
         uwrite!(
             macro_src,
             "
-                #[export_name = \"{name}\"]
+                #[export_name = \"{export_name}\"]
                 unsafe extern \"C\" fn export_{iface_snake}_{name_snake}(\
             ",
         );
@@ -397,11 +386,9 @@ impl InterfaceGenerator<'_> {
             uwrite!(
                 macro_src,
                 "
-                    #[export_name = \"{}cabi_post_{}\"]
+                    #[export_name = \"cabi_post_{export_name}\"]
                     pub unsafe extern \"C\" fn post_return_{iface_snake}_{name_snake}(\
-                ",
-                self.gen.opts.symbol_namespace,
-                func.name,
+                "
             );
             let mut params = Vec::new();
             for (i, result) in sig.results.iter().enumerate() {
@@ -620,18 +607,16 @@ impl<'a, 'b> FunctionBindgen<'a, 'b> {
         params: &[WasmType],
         results: &[WasmType],
     ) -> String {
-        let module = iface.module.as_deref().unwrap_or(&iface.name);
-
         // Define the actual function we're calling inline
         self.push_str("#[link(wasm_import_module = \"");
-        self.push_str(module);
+        self.push_str(&iface.name);
         self.push_str("\")]\n");
         self.push_str("extern \"C\" {\n");
         self.push_str("#[cfg_attr(target_arch = \"wasm32\", link_name = \"");
         self.push_str(name);
         self.push_str("\")]\n");
         self.push_str("#[cfg_attr(not(target_arch = \"wasm32\"), link_name = \"");
-        self.push_str(module);
+        self.push_str(&iface.name);
         self.push_str("_");
         self.push_str(name);
         self.push_str("\")]\n");

crates/gen-guest-teavm-java/src/lib.rs

@@ -645,6 +645,10 @@ impl Generator for TeaVmJava {
     fn export(&mut self, iface: &Interface, func: &Function) {
         let sig = iface.wasm_signature(AbiVariant::GuestExport, func);
 
+        // Currently the Java generator always emits default exports
+        // This needs to change once the generator works from a world
+        let export_name = iface.core_export_name(true, func);
+
         let mut bindgen = FunctionBindgen::new(
             self,
             &func.name,
@@ -661,7 +665,6 @@ impl Generator for TeaVmJava {
         assert!(!bindgen.needs_cleanup_list);
 
         let src = bindgen.src;
-        let name = &func.name;
 
         let result_type = match &sig.results[..] {
             [] => "void",
@@ -685,16 +688,14 @@ impl Generator for TeaVmJava {
         uwrite!(
             self.src,
             r#"
-            @Export(name = "{name}")
+            @Export(name = "{export_name}")
             private static {result_type} wasmExport{camel_name}({params}) {{
                 {src}
             }}
             "#
         );
 
         if iface.guest_export_needs_post_return(func) {
-            let name = &func.name;
-
             let params = sig
                 .results
                 .iter()
@@ -719,7 +720,7 @@ impl Generator for TeaVmJava {
             uwrite!(
                 self.src,
                 r#"
-                @Export(name = "cabi_post_{name}")
+                @Export(name = "cabi_post_{export_name}")
                 private static void wasmExport{camel_name}PostReturn({params}) {{
                     {src}
                 }}

crates/wit-component/src/cli.rs

@@ -1,10 +1,8 @@
 //! The WebAssembly component tool command line interface.
 
-#![deny(missing_docs)]
-
 use crate::extract::{extract_module_interfaces, ModuleInterfaces};
 use crate::{
-    decode_interface_component, ComponentEncoder, ComponentInterfaces, InterfacePrinter,
+    decode_component_interfaces, ComponentEncoder, ComponentInterfaces, InterfacePrinter,
     StringEncoding,
 };
 use anyhow::{anyhow, bail, Context, Result};
@@ -71,7 +69,7 @@ fn parse_adapter(s: &str) -> Result<(String, Vec<u8>, Interface)> {
                         default,
                     },
             } = extract_module_interfaces(&wasm)?;
-            if exports.len() > 0 || default.is_some() {
+            if !exports.is_empty() || default.is_some() {
                 bail!("adapter modules cannot have an exported interface");
             }
             let import = match imports.len() {
@@ -233,7 +231,7 @@ impl WasmToWitApp {
         let bytes = wat::parse_file(&self.component)
             .with_context(|| format!("failed to parse component `{}`", self.component.display()))?;
 
-        let interfaces = decode_interface_component(&bytes).with_context(|| {
+        let interfaces = decode_component_interfaces(&bytes).with_context(|| {
             format!("failed to decode component `{}`", self.component.display())
         })?;
         let which = match &self.import {

crates/wit-component/src/decoding.rs

@@ -91,11 +91,11 @@ struct InterfaceDecoder<'a> {
 #[derive(Default)]
 pub struct ComponentInterfaces {
     /// The "default export" which is the interface directly exported from the
-    /// component at the first level.
+    /// component at the top level.
     pub default: Option<Interface>,
-    /// Imported interfaces, keyed by name, to the component.
+    /// Imported interfaces, keyed by name, of the component.
     pub imports: IndexMap<String, Interface>,
-    /// Exported interfaces, keyed by name, to the component.
+    /// Exported interfaces, keyed by name, of the component.
     pub exports: IndexMap<String, Interface>,
 }
 
@@ -112,7 +112,7 @@ pub struct ComponentInterfaces {
 ///
 /// This can fail if the input component is invalid or otherwise isn't of the
 /// expected shape. At this time not all component shapes are supported here.
-pub fn decode_interface_component(bytes: &[u8]) -> Result<ComponentInterfaces> {
+pub fn decode_component_interfaces(bytes: &[u8]) -> Result<ComponentInterfaces> {
     let info = ComponentInfo::new(bytes)?;
     let mut imports = IndexMap::new();
     let mut exports = IndexMap::new();
@@ -224,7 +224,7 @@ impl<'a> InterfaceDecoder<'a> {
         }
 
         // Iterate over all exports an interpret them as defined items within
-        // the interface, either functiosn or types at this time.
+        // the interface, either functions or types at this time.
         for (name, ty) in map {
             match ty {
                 types::ComponentEntityType::Func(ty) => {