mv compiler to compiler/

compiler/rustc_plugin_impl/src/load.rs

@@ -0,0 +1,99 @@
+//! Used by `rustc` when loading a plugin.
+
+use crate::Registry;
+use rustc_ast::Crate;
+use rustc_errors::struct_span_err;
+use rustc_metadata::locator;
+use rustc_middle::middle::cstore::MetadataLoader;
+use rustc_session::Session;
+use rustc_span::symbol::{sym, Ident};
+use rustc_span::Span;
+
+use std::borrow::ToOwned;
+use std::env;
+use std::mem;
+use std::path::PathBuf;
+
+/// Pointer to a registrar function.
+type PluginRegistrarFn = fn(&mut Registry<'_>);
+
+fn call_malformed_plugin_attribute(sess: &Session, span: Span) {
+    struct_span_err!(sess, span, E0498, "malformed `plugin` attribute")
+        .span_label(span, "malformed attribute")
+        .emit();
+}
+
+/// Read plugin metadata and dynamically load registrar functions.
+pub fn load_plugins(
+    sess: &Session,
+    metadata_loader: &dyn MetadataLoader,
+    krate: &Crate,
+) -> Vec<PluginRegistrarFn> {
+    let mut plugins = Vec::new();
+
+    for attr in &krate.attrs {
+        if !sess.check_name(attr, sym::plugin) {
+            continue;
+        }
+
+        for plugin in attr.meta_item_list().unwrap_or_default() {
+            match plugin.ident() {
+                Some(ident) if plugin.is_word() => {
+                    load_plugin(&mut plugins, sess, metadata_loader, ident)
+                }
+                _ => call_malformed_plugin_attribute(sess, plugin.span()),
+            }
+        }
+    }
+
+    plugins
+}
+
+fn load_plugin(
+    plugins: &mut Vec<PluginRegistrarFn>,
+    sess: &Session,
+    metadata_loader: &dyn MetadataLoader,
+    ident: Ident,
+) {
+    let (lib, disambiguator) =
+        locator::find_plugin_registrar(sess, metadata_loader, ident.span, ident.name);
+    let symbol = sess.generate_plugin_registrar_symbol(disambiguator);
+    let fun = dylink_registrar(sess, ident.span, lib, symbol);
+    plugins.push(fun);
+}
+
+// Dynamically link a registrar function into the compiler process.
+fn dylink_registrar(
+    sess: &Session,
+    span: Span,
+    path: PathBuf,
+    symbol: String,
+) -> PluginRegistrarFn {
+    use rustc_metadata::dynamic_lib::DynamicLibrary;
+
+    // Make sure the path contains a / or the linker will search for it.
+    let path = env::current_dir().unwrap().join(&path);
+
+    let lib = match DynamicLibrary::open(&path) {
+        Ok(lib) => lib,
+        // this is fatal: there are almost certainly macros we need
+        // inside this crate, so continue would spew "macro undefined"
+        // errors
+        Err(err) => sess.span_fatal(span, &err),
+    };
+
+    unsafe {
+        let registrar = match lib.symbol(&symbol) {
+            Ok(registrar) => mem::transmute::<*mut u8, PluginRegistrarFn>(registrar),
+            // again fatal if we can't register macros
+            Err(err) => sess.span_fatal(span, &err),
+        };
+
+        // Intentionally leak the dynamic library. We can't ever unload it
+        // since the library can make things that will live arbitrarily long
+        // (e.g., an @-box cycle or a thread).
+        mem::forget(lib);
+
+        registrar
+    }
+}