Auto merge of rust-lang#156589 - cuviper:revert-dbg-tearing, r=the8472

Revert tearing changes to `dbg!`

Since the primary change to `dbg!` in rust-lang#149869, we've been chasing a few regressions:

* rust-lang#153850, fixed by rust-lang#154074
* rust-lang#154988, fixed by rust-lang#154994
* rust-lang#155902, proposed fix in rust-lang#155915

We already reverted this once, on beta only to prevent these regressions from shipping in 1.95.

In that most recent PR, we decided that it would be better to revert `dbg!` to its original state everywhere (`main` and 1.96-`beta`), and then we can consider it from scratch later. So here I've reverted the change and its fixes, but kept the regression tests, including the pending one.

cc @joboet @dianne @rust-lang/libs 
@rustbot label beta-nominated

Author: bors

clippy_lints/src/dbg_macro.rs

@@ -92,26 +92,33 @@ impl LateLintPass<'_> for DbgMacro {
                                 (macro_call.span, String::from("()"))
                             }
                         },
-                        ExprKind::Match(args, _, _) => {
-                            let suggestion = match args.kind {
-                                // dbg!(1) => 1
-                                ExprKind::Tup([val]) => {
-                                    snippet_with_applicability(cx, val.span.source_callsite(), "..", &mut applicability)
-                                        .to_string()
+                        // dbg!(1)
+                        ExprKind::Match(val, ..) => (
+                            macro_call.span,
+                            snippet_with_applicability(cx, val.span.source_callsite(), "..", &mut applicability)
+                                .to_string(),
+                        ),
+                        // dbg!(2, 3)
+                        ExprKind::Tup(
+                            [
+                                Expr {
+                                    kind: ExprKind::Match(first, ..),
+                                    ..
                                 },
-                                // dbg!(2, 3) => (2, 3)
-                                ExprKind::Tup([first, .., last]) => {
-                                    let snippet = snippet_with_applicability(
-                                        cx,
-                                        first.span.source_callsite().to(last.span.source_callsite()),
-                                        "..",
-                                        &mut applicability,
-                                    );
-                                    format!("({snippet})")
+                                ..,
+                                Expr {
+                                    kind: ExprKind::Match(last, ..),
+                                    ..
                                 },
-                                _ => unreachable!(),
-                            };
-                            (macro_call.span, suggestion)
+                            ],
+                        ) => {
+                            let snippet = snippet_with_applicability(
+                                cx,
+                                first.span.source_callsite().to(last.span.source_callsite()),
+                                "..",
+                                &mut applicability,
+                            );
+                            (macro_call.span, format!("({snippet})"))
                         },
                         _ => unreachable!(),
                     };

clippy_utils/src/sym.rs

@@ -202,6 +202,7 @@ generate! {
     cx,
     cycle,
     cyclomatic_complexity,
+    dbg_macro,
     de,
     debug_struct,
     deprecated_in_future,