Add CompilerCommand::link_override (#412)

[capnpc] add `crate_provides()` to specify that an imported schema is provided by another crate

Author: dzfranklin

Cargo.toml

@@ -19,6 +19,7 @@ members = [
     "async-byte-channel",
     "benchmark",
     "capnpc/test",
+    "capnpc/test/external-crate",
     "capnpc/test-edition-2015",
     "capnpc/test-edition-2018",
     "capnpc/test-edition-2021",

capnpc/src/codegen.rs

@@ -38,6 +38,7 @@ pub struct CodeGenerationCommand {
     default_parent_module: Vec<String>,
     raw_code_generator_request_path: Option<PathBuf>,
     capnp_root: String,
+    crates_provide_map: HashMap<u64, String>,
 }
 
 impl Default for CodeGenerationCommand {
@@ -47,6 +48,7 @@ impl Default for CodeGenerationCommand {
             default_parent_module: Vec::new(),
             raw_code_generator_request_path: None,
             capnp_root: "::capnp".into(),
+            crates_provide_map: HashMap::new(),
         }
     }
 }
@@ -93,6 +95,19 @@ impl CodeGenerationCommand {
         self
     }
 
+    /// Sets the crate provides map.
+    ///
+    /// # Arguments
+    ///
+    /// - `map` - A map from capnp file id to the crate name that provides the
+    ///     corresponding generated code.
+    ///
+    /// See [`crate::CompilerCommand::crate_provides`] for more details.
+    pub fn crates_provide_map(&mut self, map: HashMap<u64, String>) -> &mut Self {
+        self.crates_provide_map = map;
+        self
+    }
+
     /// Generates Rust code according to a `schema_capnp::code_generator_request` read from `inp`.
     pub fn run<T>(&mut self, inp: T) -> ::capnp::Result<()>
     where
@@ -210,6 +225,8 @@ impl<'a> GeneratorContext<'a> {
             capnp_root: code_generation_command.capnp_root.clone(),
         };
 
+        let crates_provide = &code_generation_command.crates_provide_map;
+
         for node in ctx.request.get_nodes()? {
             ctx.node_map.insert(node.get_id(), node);
             ctx.node_parents.insert(node.get_id(), node.get_scope_id());
@@ -240,8 +257,15 @@ impl<'a> GeneratorContext<'a> {
                     "{}_capnp",
                     path_to_stem_string(importpath)?.replace('-', "_")
                 );
+                let parent_module_scope = if let Some(krate) = crates_provide.get(&import.get_id())
+                {
+                    vec![format!("::{krate}")]
+                } else {
+                    default_parent_module_scope.clone()
+                };
+
                 ctx.populate_scope_map(
-                    default_parent_module_scope.clone(),
+                    parent_module_scope,
                     root_name,
                     NameKind::Verbatim,
                     import.get_id(),
@@ -284,7 +308,9 @@ impl<'a> GeneratorContext<'a> {
             if annotation.get_id() == NAME_ANNOTATION_ID {
                 current_node_name = name_annotation_value(annotation)?.to_string();
             } else if annotation.get_id() == PARENT_MODULE_ANNOTATION_ID {
-                ancestor_scope_names = vec!["crate".to_string()];
+                let head = ancestor_scope_names[0].clone();
+                ancestor_scope_names.clear();
+                ancestor_scope_names.push(head);
                 ancestor_scope_names.append(&mut get_parent_module(annotation)?);
             }
         }

capnpc/src/lib.rs

@@ -71,7 +71,10 @@ pub mod codegen;
 pub mod codegen_types;
 mod pointer_constants;
 
-use std::path::{Path, PathBuf};
+use std::{
+    collections::HashMap,
+    path::{Path, PathBuf},
+};
 
 // Copied from capnp/src/lib.rs, where this conversion lives behind the "std" feature flag,
 // which we don't want to depend on here.
@@ -119,6 +122,7 @@ pub struct CompilerCommand {
     output_path: Option<PathBuf>,
     default_parent_module: Vec<String>,
     raw_code_generator_request_path: Option<PathBuf>,
+    crate_provides_map: HashMap<u64, String>,
 }
 
 impl CompilerCommand {
@@ -156,6 +160,75 @@ impl CompilerCommand {
         self
     }
 
+    /// Specify that `crate_name` provides generated code for `files`.
+    ///
+    /// This means that when your schema refers to types defined in `files` we
+    /// will generate Rust code that uses identifiers in `crate_name`.
+    ///
+    /// # Arguments
+    ///
+    /// - `crate_name`: The Rust identifier of the crate
+    /// - `files`: the Capnp file ids the crate provides generated code for
+    ///
+    /// # When to use
+    ///
+    /// You only need this when your generated code needs to refer to types in
+    /// the external crate. If you just want to use an annotation and the
+    /// argument to that annotation is a builtin type (e.g. `$Json.name`) this
+    /// isn't necessary.
+    ///
+    /// # Example
+    ///
+    /// If you write a schema like so
+    ///
+    /// ```capnp
+    /// // my_schema.capnp
+    ///
+    /// using Json = import "/capnp/compat/json.capnp";
+    ///
+    /// struct Foo {
+    ///     value @0 :Json.Value;
+    /// }
+    /// ```
+    ///
+    /// you'd look at [json.capnp][json.capnp] to see its capnp id.
+    ///
+    /// ```capnp
+    /// // json.capnp
+    ///
+    /// # Copyright (c) 2015 Sandstorm Development Group, Inc. and contributors ...
+    /// @0x8ef99297a43a5e34;
+    /// ```
+    ///
+    /// If you want the `foo::Builder::get_value` method generated for your
+    /// schema to return a `capnp_json::json_capnp::value::Reader` you'd add a
+    /// dependency on `capnp_json` to your `Cargo.toml` and specify it provides
+    /// `json.capnp` in your `build.rs`.
+    ///
+    /// ```rust,no_run
+    /// // build.rs
+    ///
+    /// capnpc::CompilerCommand::new()
+    ///     .crate_provides("json_capnp", [0x8ef99297a43a5e34])
+    ///     .file("my_schema.capnp")
+    ///     .run()
+    ///     .unwrap();
+    /// ```
+    ///
+    /// [json.capnp]:
+    ///     https://github.com/capnproto/capnproto/blob/master/c%2B%2B/src/capnp/compat/json.capnp
+    pub fn crate_provides(
+        &mut self,
+        crate_name: impl Into<String>,
+        files: impl IntoIterator<Item = u64>,
+    ) -> &mut Self {
+        let crate_name = crate_name.into();
+        for file in files.into_iter() {
+            self.crate_provides_map.insert(file, crate_name.clone());
+        }
+        self
+    }
+
     /// Adds the --no-standard-import flag, indicating that the default import paths of
     /// /usr/include and /usr/local/include should not bet included.
     pub fn no_standard_import(&mut self) -> &mut Self {
@@ -307,7 +380,8 @@ impl CompilerCommand {
         let mut code_generation_command = crate::codegen::CodeGenerationCommand::new();
         code_generation_command
             .output_directory(output_path)
-            .default_parent_module(self.default_parent_module.clone());
+            .default_parent_module(self.default_parent_module.clone())
+            .crates_provide_map(self.crate_provides_map.clone());
         if let Some(raw_code_generator_request_path) = &self.raw_code_generator_request_path {
             code_generation_command
                 .raw_code_generator_request_path(raw_code_generator_request_path.clone());

capnpc/test-edition-2015/Cargo.toml

@@ -16,3 +16,4 @@ capnpc = { path = "../" }
 [dependencies]
 capnp = { path = "../../capnp" }
 capnpc = { path = "../" }
+external-crate = { path = "../test/external-crate" }

capnpc/test-edition-2015/build.rs

@@ -1,5 +1,6 @@
 fn main() {
     capnpc::CompilerCommand::new()
+        .crate_provides("external_crate", [0xe6f94f52f7be8fe2])
         .file("../test/test.capnp")
         .src_prefix("../test/")
         .run()

capnpc/test-edition-2015/test.rs

@@ -1,5 +1,6 @@
 extern crate capnp;
 extern crate core;
+extern crate external_crate;
 
 pub mod test_capnp {
     include!(concat!(env!("OUT_DIR"), "/test_capnp.rs"));

capnpc/test-edition-2018/Cargo.toml

@@ -16,3 +16,4 @@ capnpc = { path = "../" }
 [dependencies]
 capnp = { path = "../../capnp" }
 capnpc = { path = "../" }
+external-crate = { path = "../test/external-crate" }

capnpc/test-edition-2018/build.rs

@@ -1,5 +1,6 @@
 fn main() {
     capnpc::CompilerCommand::new()
+        .crate_provides("external_crate", [0xe6f94f52f7be8fe2])
         .file("../test/test.capnp")
         .src_prefix("../test/")
         .run()

capnpc/test-edition-2021/Cargo.toml

@@ -16,3 +16,4 @@ capnpc = { path = "../" }
 [dependencies]
 capnp = { path = "../../capnp" }
 capnpc = { path = "../" }
+external-crate = { path = "../test/external-crate" }

capnpc/test-edition-2021/build.rs

@@ -1,5 +1,6 @@
 fn main() {
     capnpc::CompilerCommand::new()
+        .crate_provides("external_crate", [0xe6f94f52f7be8fe2])
         .file("../test/test.capnp")
         .src_prefix("../test/")
         .run()