wasm-encoder: Return Indices from builder functions where applicable

crates/wasm-encoder/README.md

@@ -36,12 +36,11 @@ let mut module = Module::new();
 let mut types = TypeSection::new();
 let params = vec![ValType::I32, ValType::I32];
 let results = vec![ValType::I32];
-types.function(params, results);
+let type_index = types.function(params, results);
 module.section(&types);
 
 // Encode the function section.
 let mut functions = FunctionSection::new();
-let type_index = 0;
 functions.function(type_index);
 module.section(&functions);
 

crates/wasm-encoder/src/component/aliases.rs

@@ -106,10 +106,11 @@ impl ComponentAliasSection {
     }
 
     /// Define an alias to a component instance's export.
-    pub fn alias(&mut self, alias: Alias<'_>) -> &mut Self {
+    pub fn alias(&mut self, alias: Alias<'_>) -> u32 {
         alias.encode(&mut self.bytes);
+        let index = self.num_added;
         self.num_added += 1;
-        self
+        index
     }
 }
 

crates/wasm-encoder/src/component/canonicals.rs

@@ -83,7 +83,7 @@ impl CanonicalFunctionSection {
     }
 
     /// Define a function that will lift a core WebAssembly function to the canonical ABI.
-    pub fn lift<O>(&mut self, core_func_index: u32, type_index: u32, options: O) -> &mut Self
+    pub fn lift<O>(&mut self, core_func_index: u32, type_index: u32, options: O) -> u32
     where
         O: IntoIterator<Item = CanonicalOption>,
         O::IntoIter: ExactSizeIterator,
@@ -97,12 +97,14 @@ impl CanonicalFunctionSection {
             option.encode(&mut self.bytes);
         }
         type_index.encode(&mut self.bytes);
+
+        let index = self.num_added;
         self.num_added += 1;
-        self
+        index
     }
 
     /// Define a function that will lower a canonical ABI function to a core WebAssembly function.
-    pub fn lower<O>(&mut self, func_index: u32, options: O) -> &mut Self
+    pub fn lower<O>(&mut self, func_index: u32, options: O) -> u32
     where
         O: IntoIterator<Item = CanonicalOption>,
         O::IntoIter: ExactSizeIterator,
@@ -115,8 +117,10 @@ impl CanonicalFunctionSection {
         for option in options {
             option.encode(&mut self.bytes);
         }
+
+        let index = self.num_added;
         self.num_added += 1;
-        self
+        index
     }
 }
 

crates/wasm-encoder/src/component/exports.rs

@@ -92,13 +92,15 @@ impl ComponentExportSection {
         url: &str,
         kind: ComponentExportKind,
         index: u32,
-    ) -> &mut Self {
+    ) -> u32 {
         name.encode(&mut self.bytes);
         url.encode(&mut self.bytes);
         kind.encode(&mut self.bytes);
         index.encode(&mut self.bytes);
+
+        let index = self.num_added;
         self.num_added += 1;
-        self
+        index
     }
 }
 

crates/wasm-encoder/src/component/imports.rs

@@ -94,7 +94,8 @@ impl Encode for ComponentTypeRef {
 ///       ("b", PrimitiveValType::String)
 ///     ]
 ///   )
-///   .result(PrimitiveValType::String);
+///   .result(PrimitiveValType::String)
+///   .finish();
 ///
 /// // This imports a function named `f` with the type defined above
 /// let mut imports = ComponentImportSection::new();
@@ -129,12 +130,14 @@ impl ComponentImportSection {
     }
 
     /// Define an import in the component import section.
-    pub fn import(&mut self, name: &str, url: &str, ty: ComponentTypeRef) -> &mut Self {
+    pub fn import(&mut self, name: &str, url: &str, ty: ComponentTypeRef) -> u32 {
         name.encode(&mut self.bytes);
         url.encode(&mut self.bytes);
         ty.encode(&mut self.bytes);
+
+        let index = self.num_added;
         self.num_added += 1;
-        self
+        index
     }
 }
 

crates/wasm-encoder/src/component/instances.rs

@@ -59,7 +59,7 @@ impl InstanceSection {
     }
 
     /// Define an instance by instantiating a core module.
-    pub fn instantiate<'a, A>(&mut self, module_index: u32, args: A) -> &mut Self
+    pub fn instantiate<'a, A>(&mut self, module_index: u32, args: A) -> u32
     where
         A: IntoIterator<Item = (&'a str, ModuleArg)>,
         A::IntoIter: ExactSizeIterator,
@@ -72,12 +72,14 @@ impl InstanceSection {
             name.encode(&mut self.bytes);
             arg.encode(&mut self.bytes);
         }
+
+        let index = self.num_added;
         self.num_added += 1;
-        self
+        index
     }
 
     /// Define an instance by exporting core WebAssembly items.
-    pub fn export_items<'a, E>(&mut self, exports: E) -> &mut Self
+    pub fn export_items<'a, E>(&mut self, exports: E) -> u32
     where
         E: IntoIterator<Item = (&'a str, ExportKind, u32)>,
         E::IntoIter: ExactSizeIterator,
@@ -90,8 +92,10 @@ impl InstanceSection {
             kind.encode(&mut self.bytes);
             index.encode(&mut self.bytes);
         }
+
+        let index = self.num_added;
         self.num_added += 1;
-        self
+        index
     }
 }
 
@@ -146,7 +150,7 @@ impl ComponentInstanceSection {
     }
 
     /// Define an instance by instantiating a component.
-    pub fn instantiate<'a, A>(&mut self, component_index: u32, args: A) -> &mut Self
+    pub fn instantiate<'a, A>(&mut self, component_index: u32, args: A) -> u32
     where
         A: IntoIterator<Item = (&'a str, ComponentExportKind, u32)>,
         A::IntoIter: ExactSizeIterator,
@@ -160,12 +164,13 @@ impl ComponentInstanceSection {
             kind.encode(&mut self.bytes);
             index.encode(&mut self.bytes);
         }
+        let index = self.num_added;
         self.num_added += 1;
-        self
+        index
     }
 
     /// Define an instance by exporting items.
-    pub fn export_items<'a, E>(&mut self, exports: E) -> &mut Self
+    pub fn export_items<'a, E>(&mut self, exports: E) -> u32
     where
         E: IntoIterator<Item = (&'a str, ComponentExportKind, u32)>,
         E::IntoIter: ExactSizeIterator,
@@ -178,8 +183,10 @@ impl ComponentInstanceSection {
             kind.encode(&mut self.bytes);
             index.encode(&mut self.bytes);
         }
+
+        let index = self.num_added;
         self.num_added += 1;
-        self
+        index
     }
 }