Add csharp feature

Cargo.toml

@@ -39,6 +39,7 @@ wit-bindgen-c = { path = 'crates/c', version = '0.13.0' }
 wit-bindgen-rust = { path = "crates/rust", version = "0.13.0" }
 wit-bindgen-teavm-java = { path = 'crates/teavm-java', version = '0.13.0' }
 wit-bindgen-go = { path = 'crates/go', version = '0.13.0' }
+wit-bindgen-csharp = { path = 'crates/csharp', version = '0.13.0' }
 wit-bindgen-markdown = { path = 'crates/markdown', version = '0.13.0' }
 wit-bindgen = { path = 'crates/guest-rust', version = '0.13.0', default-features = false }
 wit-bindgen-rust-macro-shared = { path = 'crates/rust-macro-shared', version = '0.3.0' }
@@ -55,6 +56,7 @@ wit-bindgen-c = { workspace = true, features = ['clap'], optional = true }
 wit-bindgen-markdown = { workspace = true, features = ['clap'], optional = true }
 wit-bindgen-teavm-java = { workspace = true, features = ['clap'], optional = true }
 wit-bindgen-go = { workspace = true, features = ['clap'], optional = true }
+wit-bindgen-csharp = { workspace = true, features = ['clap'], optional = true }
 wit-component = { workspace = true }
 wasm-encoder = { workspace = true }
 wasmtime-wasi = { workspace = true }
@@ -66,12 +68,14 @@ default = [
   'markdown',
   'teavm-java',
   'go',
+  'csharp',
 ]
 c = ['dep:wit-bindgen-c']
 rust = ['dep:wit-bindgen-rust']
 markdown = ['dep:wit-bindgen-markdown']
 teavm-java = ['dep:wit-bindgen-teavm-java']
 go = ['dep:wit-bindgen-go']
+csharp = ['dep:wit-bindgen-csharp']
 
 [dev-dependencies]
 heck = { workspace = true }

crates/csharp/Cargo.toml

@@ -0,0 +1,28 @@
+[package]
+name = "wit-bindgen-csharp"
+authors = ["Timmy Silesmo <[email protected]>"]
+version = "0.13.0"
+edition.workspace = true
+repository = 'https://github.com/bytecodealliance/wit-bindgen'
+license = "Apache-2.0 WITH LLVM-exception"
+homepage = 'https://github.com/bytecodealliance/wit-bindgen'
+description = """
+C# bindings generator for WIT and the component model, typically used
+through the `wit-bindgen-cli` crate.
+"""
+
+[lib]
+doctest = false
+test = false
+
+[dependencies]
+wasm-encoder = { workspace = true }
+wit-bindgen-core = { workspace = true }
+wit-component = { workspace = true }
+wasm-metadata = { workspace = true }
+heck = { workspace = true }
+clap = { workspace = true, optional = true }
+anyhow = { workspace = true }
+
+[dev-dependencies]
+test-helpers = { path = '../test-helpers' }

crates/csharp/README.txt

@@ -0,0 +1,3 @@
+// generate the c# and the component meta module
+
+cargo run c-sharp  --string-encoding utf8 --out-dir testing-csharp tests/codegen/floats.wit

crates/csharp/src/component_type_object.rs

@@ -0,0 +1,58 @@
+use anyhow::Result;
+use heck::ToSnakeCase;
+use wasm_encoder::{
+    CodeSection, CustomSection, Function, FunctionSection, LinkingSection, Module, SymbolTable,
+    TypeSection,
+};
+use wit_bindgen_core::wit_parser::{Resolve, WorldId};
+use wit_component::StringEncoding;
+
+pub fn linking_symbol(name: &str) -> String {
+    let snake = name.to_snake_case();
+    format!("__component_type_object_force_link_{snake}")
+}
+
+pub fn object(resolve: &Resolve, world: WorldId, encoding: StringEncoding) -> Result<Vec<u8>> {
+    let mut module = Module::new();
+
+    // Build a module with one function that's a "dummy function"
+    let mut types = TypeSection::new();
+    types.function([], []);
+    module.section(&types);
+    let mut funcs = FunctionSection::new();
+    funcs.function(0);
+    module.section(&funcs);
+    let mut code = CodeSection::new();
+    code.function(&Function::new([]));
+    module.section(&code);
+
+    let mut producers = wasm_metadata::Producers::empty();
+    producers.add(
+        "processed-by",
+        env!("CARGO_PKG_NAME"),
+        env!("CARGO_PKG_VERSION"),
+    );
+    let data = wit_component::metadata::encode(resolve, world, encoding, Some(&producers)).unwrap();
+
+    // The custom section name here must start with "component-type" but
+    // otherwise is attempted to be unique here to ensure that this doesn't get
+    // concatenated to other custom sections by LLD by accident since LLD will
+    // concatenate custom sections of the same name.
+    let world_name = &resolve.worlds[world].name;
+    let section_name = format!("component-type:{world_name}");
+
+    // Add our custom section
+    module.section(&CustomSection {
+        name: std::borrow::Cow::Borrowed(&section_name),
+        data: std::borrow::Cow::Borrowed(data.as_slice()),
+    });
+
+    // Append the linking section, so that lld knows the custom section's symbol name
+    let mut linking = LinkingSection::new();
+    let mut symbols = SymbolTable::new();
+    symbols.function(0, 0, Some(&linking_symbol(&world_name)));
+    linking.symbol_table(&symbols);
+    module.section(&linking);
+
+    Ok(module.finish())
+}