Add `level` arg to `into_diagnostic`.

And make all hand-written `IntoDiagnostic` impls generic, by using
`DiagnosticBuilder::new(dcx, level, ...)` instead of e.g.
`dcx.struct_err(...)`.

This means the `create_*` functions are the source of the error level.
This change will let us remove `struct_diagnostic`.

Note: `#[rustc_lint_diagnostics]` is added to `DiagnosticBuilder::new`,
it's necessary to pass diagnostics tests now that it's used in
`into_diagnostic` functions.

1 files changed, 8 insertions, 4 deletions

diff --git a/compiler/rustc_session/src/errors.rs b/compiler/rustc_session/src/errors.rs
index c3360815ac9..8ab31f6f382 100644
--- a/compiler/rustc_session/src/errors.rs
+++ b/compiler/rustc_session/src/errors.rs
@@ -3,7 +3,10 @@ use std::num::NonZeroU32;
 use crate::parse::ParseSess;
 use rustc_ast::token;
 use rustc_ast::util::literal::LitError;
-use rustc_errors::{error_code, DiagnosticMessage, ErrorGuaranteed, IntoDiagnostic, MultiSpan};
+use rustc_errors::{
+    error_code, DiagCtxt, DiagnosticBuilder, DiagnosticMessage, ErrorGuaranteed, IntoDiagnostic,
+    Level, MultiSpan,
+};
 use rustc_macros::Diagnostic;
 use rustc_span::{BytePos, Span, Symbol};
 use rustc_target::spec::{SplitDebuginfo, StackProtector, TargetTriple};
@@ -17,9 +20,10 @@ impl<'a> IntoDiagnostic<'a> for FeatureGateError {
     #[track_caller]
     fn into_diagnostic(
         self,
-        dcx: &'a rustc_errors::DiagCtxt,
-    ) -> rustc_errors::DiagnosticBuilder<'a, ErrorGuaranteed> {
-        let mut diag = dcx.struct_err(self.explain);
+        dcx: &'a DiagCtxt,
+        level: Level,
+    ) -> DiagnosticBuilder<'a, ErrorGuaranteed> {
+        let mut diag = DiagnosticBuilder::new(dcx, level, self.explain);
         diag.set_span(self.span);
         diag.code(error_code!(E0658));
         diag