1 //! Used by `rustc` when loading a plugin.
5 use rustc_errors::struct_span_err;
6 use rustc_metadata::locator;
7 use rustc_session::cstore::MetadataLoader;
8 use rustc_session::Session;
9 use rustc_span::symbol::{sym, Ident};
12 use std::borrow::ToOwned;
15 use std::path::PathBuf;
17 /// Pointer to a registrar function.
18 type PluginRegistrarFn = fn(&mut Registry<'_>);
20 fn call_malformed_plugin_attribute(sess: &Session, span: Span) {
21 struct_span_err!(sess, span, E0498, "malformed `plugin` attribute")
22 .span_label(span, "malformed attribute")
26 /// Read plugin metadata and dynamically load registrar functions.
29 metadata_loader: &dyn MetadataLoader,
31 ) -> Vec<PluginRegistrarFn> {
32 let mut plugins = Vec::new();
34 for attr in &krate.attrs {
35 if !attr.has_name(sym::plugin) {
39 for plugin in attr.meta_item_list().unwrap_or_default() {
40 match plugin.ident() {
41 Some(ident) if plugin.is_word() => {
42 load_plugin(&mut plugins, sess, metadata_loader, ident)
44 _ => call_malformed_plugin_attribute(sess, plugin.span()),
53 plugins: &mut Vec<PluginRegistrarFn>,
55 metadata_loader: &dyn MetadataLoader,
58 let lib = locator::find_plugin_registrar(sess, metadata_loader, ident.span, ident.name);
59 let fun = dylink_registrar(sess, ident.span, lib);
63 // Dynamically link a registrar function into the compiler process.
64 fn dylink_registrar(sess: &Session, span: Span, path: PathBuf) -> PluginRegistrarFn {
65 use rustc_metadata::dynamic_lib::DynamicLibrary;
67 // Make sure the path contains a / or the linker will search for it.
68 let path = env::current_dir().unwrap().join(&path);
70 let lib = match DynamicLibrary::open(&path) {
72 // this is fatal: there are almost certainly macros we need
73 // inside this crate, so continue would spew "macro undefined"
75 Err(err) => sess.span_fatal(span, &err),
79 let registrar = match lib.symbol("__rustc_plugin_registrar") {
80 Ok(registrar) => mem::transmute::<*mut u8, PluginRegistrarFn>(registrar),
81 // again fatal if we can't register macros
82 Err(err) => sess.span_fatal(span, &err),
85 // Intentionally leak the dynamic library. We can't ever unload it
86 // since the library can make things that will live arbitrarily long
87 // (e.g., an Rc cycle or a thread).