Minimal `cc_bindings_from_rs` scaffolding.
PiperOrigin-RevId: 475538943
diff --git a/cc_bindings_from_rs/lib.rs b/cc_bindings_from_rs/lib.rs
new file mode 100644
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--- /dev/null
+++ b/cc_bindings_from_rs/lib.rs
@@ -0,0 +1,138 @@
+// Part of the Crubit project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+use rustc_hir::{Item, ItemKind, Node};
+use rustc_interface::Queries;
+use rustc_middle::middle::exported_symbols::ExportedSymbol;
+use rustc_middle::ty::TyCtxt;
+use rustc_span::def_id::LOCAL_CRATE;
+
+// TODO(lukasza): Replace `get_names_of_exported_fns` with something that can
+// generate C++ bindings.
+pub fn get_names_of_exported_fns(tcx: TyCtxt) -> impl Iterator<Item = String> + '_ {
+ tcx.exported_symbols(LOCAL_CRATE).iter().filter_map(move |(symbol, _)| match symbol {
+ ExportedSymbol::NonGeneric(def_id) => {
+ match tcx.hir().find_by_def_id(def_id.expect_local()).unwrap() {
+ Node::Item(Item { kind: ItemKind::Fn { .. }, .. }) => {
+ Some(tcx.def_path_str(*def_id))
+ }
+ _ => None,
+ }
+ }
+ ExportedSymbol::Generic(..) | ExportedSymbol::DropGlue(_) | ExportedSymbol::NoDefId(_) => {
+ None
+ }
+ })
+}
+
+/// Helper (used by `main` and `test::run_compiler`) for invokind functions
+/// operating on `TyCtxt`.
+pub fn enter_tcx<'tcx, F, T>(
+ queries: &'tcx Queries<'tcx>,
+ f: F,
+) -> rustc_interface::interface::Result<T>
+where
+ F: FnOnce(rustc_middle::ty::TyCtxt<'tcx>) -> T + Send,
+ T: Send,
+{
+ let query_context = queries.global_ctxt()?;
+ Ok(query_context.peek_mut().enter(f))
+}
+
+#[cfg(test)]
+mod tests {
+ use itertools::Itertools;
+
+ #[test]
+ fn test_get_names_of_exported_fns_public_vs_private() {
+ let test_src = r#"
+ pub fn public_function() {
+ private_function()
+ }
+
+ fn private_function() {}
+ "#;
+ let exported_functions = get_names_of_exported_fns(test_src);
+ assert_eq!(1, exported_functions.len());
+ assert_eq!("public_function", exported_functions[0]);
+ }
+
+ #[test]
+ #[should_panic]
+ fn test_panic_when_syntax_errors_in_test_inputs() {
+ get_names_of_exported_fns("syntax error here");
+ }
+
+ fn get_names_of_exported_fns(source: &str) -> Vec<String> {
+ run_compiler(source, |tcx| super::get_names_of_exported_fns(tcx).collect_vec())
+ }
+
+ /// Compiles Rust `source` then calls `f` on the `TyCtxt` representation
+ /// of the compiled `source`.
+ fn run_compiler<F, T>(source: impl Into<String>, f: F) -> T
+ where
+ F: for<'tcx> FnOnce(rustc_middle::ty::TyCtxt<'tcx>) -> T + Send,
+ T: Send,
+ {
+ use lazy_static::lazy_static;
+ use rustc_session::config::{CrateType, Input, Options, OutputType, OutputTypes};
+ use std::path::PathBuf;
+
+ // TODO(lukasza): This probably won't work in Bazel...
+ lazy_static! {
+ static ref RUSTC_SYSROOT: String = {
+ let output = std::process::Command::new("rustc")
+ .arg("--print=sysroot")
+ .current_dir(".")
+ .output()
+ .expect("For now we depend on `rustc` invocation to succeed... sorry...");
+ std::str::from_utf8(&output.stdout)
+ .expect("Only UTF-8 compatible rustc sysroot is supported... sorry...")
+ .trim()
+ .into()
+ };
+ }
+
+ const TEST_FILENAME: &str = "crubit_unittests.rs";
+
+ // Setting `output_types` that will trigger code gen - otherwise some parts of
+ // the analysis will be missing (e.g. `tcx.exported_symbols()`).
+ // The choice of `Bitcode` is somewhat arbitrary (e.g. `Assembly`,
+ // `Mir`, etc. would also trigger code gen).
+ let output_types = OutputTypes::new(&[(OutputType::Bitcode, None /* PathBuf */)]);
+
+ let opts = Options {
+ crate_types: vec![CrateType::Rlib], // Test inputs simulate library crates.
+ maybe_sysroot: Some(PathBuf::from(RUSTC_SYSROOT.clone())),
+ output_types,
+ ..Default::default()
+ };
+
+ let config = rustc_interface::interface::Config {
+ opts,
+ crate_cfg: Default::default(),
+ crate_check_cfg: Default::default(),
+ input: Input::Str {
+ name: rustc_span::FileName::Custom(TEST_FILENAME.to_string()),
+ input: source.into(),
+ },
+ input_path: None,
+ output_file: None,
+ output_dir: None,
+ file_loader: None,
+ diagnostic_output: rustc_session::DiagnosticOutput::Default,
+ lint_caps: Default::default(),
+ parse_sess_created: None,
+ register_lints: None,
+ override_queries: None,
+ make_codegen_backend: None,
+ registry: rustc_errors::registry::Registry::new(rustc_error_codes::DIAGNOSTICS),
+ };
+
+ rustc_interface::interface::run_compiler(config, |compiler| {
+ compiler.enter(|queries| super::enter_tcx(queries, f))
+ })
+ .expect("Test inputs shouldn't cause compilation errors.")
+ }
+}
