Allow unreachable_patterns in rust-analyzer.

Author: cjgillot

src/tools/rust-analyzer/crates/hir-ty/src/diagnostics/match_check/deconstruct_pat.rs

@@ -41,6 +41,9 @@
 //! or-patterns; instead we just try the alternatives one-by-one. For details on splitting
 //! wildcards, see [`SplitWildcard`]; for integer ranges, see [`SplitIntRange`].
 
+// This uses uninhabited types to encode statically unused variants.
+#![allow(unreachable_patterns)]
+
 use std::{
     cell::Cell,
     cmp::{max, min},

src/tools/rust-analyzer/crates/hir-ty/src/display.rs

@@ -1620,6 +1620,7 @@ impl HirDisplay for LifetimeData {
             }
             LifetimeData::Static => write!(f, "'static"),
             LifetimeData::Erased => Ok(()),
+            #[allow(unreachable_patterns)]
             LifetimeData::Phantom(_, _) => Ok(()),
         }
     }

src/tools/rust-analyzer/crates/hir-ty/src/infer/closure.rs

@@ -214,6 +214,7 @@ impl CapturedItem {
                     result = format!("{result}.{field}");
                     field_need_paren = false;
                 }
+                #[allow(unreachable_patterns)]
                 ProjectionElem::Index(_)
                 | ProjectionElem::ConstantIndex { .. }
                 | ProjectionElem::Subslice { .. }

src/tools/rust-analyzer/crates/hir-ty/src/mir/eval/shim.rs

@@ -9,6 +9,7 @@ macro_rules! from_bytes {
     ($ty:tt, $value:expr) => {
         ($ty::from_le_bytes(match ($value).try_into() {
             Ok(x) => x,
+            #[allow(unreachable_patterns)]
             Err(_) => return Err(MirEvalError::TypeError("mismatched size")),
         }))
     };

src/tools/rust-analyzer/crates/hir-ty/src/mir/lower.rs

@@ -1028,6 +1028,7 @@ impl<'ctx> MirLowerCtx<'ctx> {
                                 ProjectionElem::ConstantIndex { offset, from_end } => ProjectionElem::ConstantIndex { offset, from_end },
                                 ProjectionElem::Subslice { from, to } => ProjectionElem::Subslice { from, to },
                                 ProjectionElem::OpaqueCast(x) => ProjectionElem::OpaqueCast(x),
+                                #[allow(unreachable_patterns)]
                                 ProjectionElem::Index(x) => match x { },
                             }
                         }).collect(),