Rollup merge of #145747 - joshtriplett:builtin-diag-dyn, r=jdonszelmann

Refactor lint buffering to avoid requiring a giant enum

Lint buffering currently relies on a giant enum `BuiltinLintDiag` containing all the lints that might potentially get buffered. In addition to being an unwieldy enum in a central crate, this also makes `rustc_lint_defs` a build bottleneck: it depends on various types from various crates (with a steady pressure to add more), and many crates depend on it.

Having all of these variants in a separate crate also prevents detecting when a variant becomes unused, which we can do with a dedicated type defined and used in the same crate.

Refactor this to use a dyn trait, to allow using `LintDiagnostic` types directly.

Because the existing `BuiltinLintDiag` requires some additional types in order to decorate some variants, which are only available later in `rustc_lint`, use an enum `DecorateDiagCompat` to handle both the `dyn LintDiagnostic` case and the `BuiltinLintDiag` case.

---

With the infrastructure in place, use it to migrate three of the enum variants to use `LintDiagnostic` directly, as a proof of concept and to demonstrate that the net result is a reduction in code size and a removal of a boilerplate-heavy layer of indirection.

Also remove an unused `BuiltinLintDiag` variant.

1 files changed, 9 insertions, 9 deletions

diff --git a/compiler/rustc_parse/src/lexer/mod.rs b/compiler/rustc_parse/src/lexer/mod.rs
index 7c7e7e50b27..9792240a548 100644
--- a/compiler/rustc_parse/src/lexer/mod.rs
+++ b/compiler/rustc_parse/src/lexer/mod.rs
@@ -543,21 +543,21 @@ impl<'psess, 'src> Lexer<'psess, 'src> {
             })
             .collect();
 
+        let label = label.to_string();
         let count = spans.len();
-        let labels = point_at_inner_spans.then_some(spans.clone());
+        let labels = point_at_inner_spans
+            .then_some(errors::HiddenUnicodeCodepointsDiagLabels { spans: spans.clone() });
+        let sub = if point_at_inner_spans && !spans.is_empty() {
+            errors::HiddenUnicodeCodepointsDiagSub::Escape { spans }
+        } else {
+            errors::HiddenUnicodeCodepointsDiagSub::NoEscape { spans }
+        };
 
         self.psess.buffer_lint(
             TEXT_DIRECTION_CODEPOINT_IN_LITERAL,
             span,
             ast::CRATE_NODE_ID,
-            BuiltinLintDiag::HiddenUnicodeCodepoints {
-                label: label.to_string(),
-                count,
-                span_label: span,
-                labels,
-                escape: point_at_inner_spans && !spans.is_empty(),
-                spans,
-            },
+            errors::HiddenUnicodeCodepointsDiag { label, count, span_label: span, labels, sub },
         );
     }