Rollup merge of #149667 - Shinonn23:fix-ice-constblock-148138, r=dianne

Fix ICE by rejecting const blocks in patterns during AST lowering (closes #148138)

This PR fixes the ICE reported in rust-lang/rust#148138.

The root cause is that `const` blocks aren’t allowed in pattern position, but the AST lowering logic still attempted to create `PatExprKind::ConstBlock`, allowing invalid HIR to reach type checking and trigger a `span_bug!`.

Following the discussion in the issue, this patch removes the `ConstBlock` lowering path from `lower_expr_within_pat`. Any `ExprKind::ConstBlock` inside a pattern is now handled consistently with other invalid pattern expressions.

A new UI test is included to ensure the compiler reports a proper error and to prevent regressions.

Closes rust-lang/rust#148138.

clippy_lints/src/utils/author.rs

@@ -724,7 +724,6 @@ impl<'a, 'tcx> PrintVisitor<'a, 'tcx> {
                 kind!("Lit {{ ref {lit}, {negated} }}");
                 self.lit(lit);
             },
-            PatExprKind::ConstBlock(_) => kind!("ConstBlock(_)"),
             PatExprKind::Path(_) => self.maybe_path(pat),
         }
     }

clippy_utils/src/consts.rs

@@ -578,7 +578,6 @@ impl<'tcx> ConstEvalCtxt<'tcx> {
                     Some(val)
                 }
             },
-            PatExprKind::ConstBlock(ConstBlock { body, .. }) => self.expr(self.tcx.hir_body(*body).value),
             PatExprKind::Path(qpath) => self.qpath(qpath, pat_expr.hir_id),
         }
     }

clippy_utils/src/hir_utils.rs

@@ -705,9 +705,8 @@ impl HirEqInterExpr<'_, '_, '_> {
                     negated: right_neg,
                 },
             ) => left_neg == right_neg && left.node == right.node,
-            (PatExprKind::ConstBlock(left), PatExprKind::ConstBlock(right)) => self.eq_body(left.body, right.body),
             (PatExprKind::Path(left), PatExprKind::Path(right)) => self.eq_qpath(left, right),
-            (PatExprKind::Lit { .. } | PatExprKind::ConstBlock(..) | PatExprKind::Path(..), _) => false,
+            (PatExprKind::Lit { .. } | PatExprKind::Path(..), _) => false,
         }
     }
 
@@ -1312,7 +1311,6 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
                 lit.node.hash(&mut self.s);
                 negated.hash(&mut self.s);
             },
-            PatExprKind::ConstBlock(c) => self.hash_body(c.body),
             PatExprKind::Path(qpath) => self.hash_qpath(qpath),
         }
     }