Rollup merge of #100768 - Facel3ss1:plugin-impl-translation, r=davidtwco

Migrate `rustc_plugin_impl` to `SessionDiagnostic`

Migration of the `rustc_plugin_impl` crate.
~Draft PR because it is blocked on #100694 for `#[fatal(...)]` support~ (this has been merged, and I've changed over to `#[diag(...)]` now too), but I would also like to know if what I did with `LoadPluginError` is okay, because all it does is display the error message from `libloading` ([See conversation on zulip](https://rust-lang.zulipchat.com/#narrow/stream/147480-t-compiler.2Fwg-diagnostics/topic/.23100717.20diagnostic.20translation/near/294327843)). This crate is apparently for a deprecated feature which is used by servo, so I don't know how much this matters anyway.

1 files changed, 20 insertions, 0 deletions

diff --git a/compiler/rustc_plugin_impl/src/errors.rs b/compiler/rustc_plugin_impl/src/errors.rs
new file mode 100644
index 00000000000..2bdb6e4feca
--- /dev/null
+++ b/compiler/rustc_plugin_impl/src/errors.rs
@@ -0,0 +1,20 @@
+//! Errors emitted by plugin_impl
+
+use rustc_macros::SessionDiagnostic;
+use rustc_span::Span;
+
+#[derive(SessionDiagnostic)]
+#[diag(plugin_impl::load_plugin_error)]
+pub struct LoadPluginError {
+    #[primary_span]
+    pub span: Span,
+    pub msg: String,
+}
+
+#[derive(SessionDiagnostic)]
+#[diag(plugin_impl::malformed_plugin_attribute, code = "E0498")]
+pub struct MalformedPluginAttribute {
+    #[primary_span]
+    #[label]
+    pub span: Span,
+}