85 lines
2.6 KiB
Rust
85 lines
2.6 KiB
Rust
//! Used by `rustc` when loading a plugin.
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use crate::Registry;
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use libloading::Library;
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use rustc_ast::Crate;
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use rustc_errors::struct_span_err;
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use rustc_metadata::locator;
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use rustc_session::cstore::MetadataLoader;
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use rustc_session::Session;
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use rustc_span::symbol::{sym, Ident};
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use rustc_span::Span;
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use std::borrow::ToOwned;
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use std::env;
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use std::mem;
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use std::path::PathBuf;
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/// Pointer to a registrar function.
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type PluginRegistrarFn = fn(&mut Registry<'_>);
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fn call_malformed_plugin_attribute(sess: &Session, span: Span) {
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struct_span_err!(sess, span, E0498, "malformed `plugin` attribute")
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.span_label(span, "malformed attribute")
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.emit();
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}
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/// Read plugin metadata and dynamically load registrar functions.
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pub fn load_plugins(
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sess: &Session,
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metadata_loader: &dyn MetadataLoader,
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krate: &Crate,
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) -> Vec<PluginRegistrarFn> {
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let mut plugins = Vec::new();
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for attr in &krate.attrs {
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if !attr.has_name(sym::plugin) {
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continue;
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}
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for plugin in attr.meta_item_list().unwrap_or_default() {
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match plugin.ident() {
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Some(ident) if plugin.is_word() => {
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load_plugin(&mut plugins, sess, metadata_loader, ident)
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}
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_ => call_malformed_plugin_attribute(sess, plugin.span()),
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}
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}
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}
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plugins
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}
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fn load_plugin(
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plugins: &mut Vec<PluginRegistrarFn>,
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sess: &Session,
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metadata_loader: &dyn MetadataLoader,
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ident: Ident,
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) {
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let lib = locator::find_plugin_registrar(sess, metadata_loader, ident.span, ident.name);
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let fun = dylink_registrar(lib).unwrap_or_else(|err| {
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// This is fatal: there are almost certainly macros we need inside this crate, so
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// continuing would spew "macro undefined" errors.
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sess.span_fatal(ident.span, &err.to_string());
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});
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plugins.push(fun);
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}
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/// Dynamically link a registrar function into the compiler process.
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fn dylink_registrar(lib_path: PathBuf) -> Result<PluginRegistrarFn, libloading::Error> {
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// Make sure the path contains a / or the linker will search for it.
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let lib_path = env::current_dir().unwrap().join(&lib_path);
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let lib = unsafe { Library::new(&lib_path) }?;
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let registrar_sym = unsafe { lib.get::<PluginRegistrarFn>(b"__rustc_plugin_registrar") }?;
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// Intentionally leak the dynamic library. We can't ever unload it
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// since the library can make things that will live arbitrarily long
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// (e.g., an Rc cycle or a thread).
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let registrar_sym = unsafe { registrar_sym.into_raw() };
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mem::forget(lib);
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Ok(*registrar_sym)
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}
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