Merge #4648

4648: Support raw_ref_op's raw reference operator r=matklad a=robojumper

Fixes #4642.

This syntax (and its semantics) are implemented in rustc behind the `raw_ref_op` feature.

It is not entirely clear whether this is the syntax that will become stable, but [it seems like](https://github.com/rust-lang/rust/pull/72279) rust-analyzer must still support this unstable syntax to support future stable rust.

Also fixes a random inference failure involving a direct coercion from `&[T, _]` to `*const [T]`.

Co-authored-by: robojumper <[email protected]>

3 files changed, 34 insertions, 4 deletions

diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index e08d62dd6..905c0cf5d 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -28,7 +28,7 @@ use crate::{
     },
     item_scope::BuiltinShadowMode,
     path::{GenericArgs, Path},
-    type_ref::{Mutability, TypeRef},
+    type_ref::{Mutability, Rawness, TypeRef},
     AdtId, ConstLoc, ContainerId, DefWithBodyId, EnumLoc, FunctionLoc, Intern, ModuleDefId,
     StaticLoc, StructLoc, TraitLoc, TypeAliasLoc, UnionLoc,
 };
@@ -378,8 +378,21 @@ impl ExprCollector<'_> {
             }
             ast::Expr::RefExpr(e) => {
                 let expr = self.collect_expr_opt(e.expr());
-                let mutability = Mutability::from_mutable(e.mut_token().is_some());
-                self.alloc_expr(Expr::Ref { expr, mutability }, syntax_ptr)
+                let raw_tok = e.raw_token().is_some();
+                let mutability = if raw_tok {
+                    if e.mut_token().is_some() {
+                        Mutability::Mut
+                    } else if e.const_token().is_some() {
+                        Mutability::Shared
+                    } else {
+                        unreachable!("parser only remaps to raw_token() if matching mutability token follows")
+                    }
+                } else {
+                    Mutability::from_mutable(e.mut_token().is_some())
+                };
+                let rawness = Rawness::from_raw(raw_tok);
+
+                self.alloc_expr(Expr::Ref { expr, rawness, mutability }, syntax_ptr)
             }
             ast::Expr::PrefixExpr(e) => {
                 let expr = self.collect_expr_opt(e.expr());
diff --git a/crates/ra_hir_def/src/expr.rs b/crates/ra_hir_def/src/expr.rs
index a0cdad529..f25c6f958 100644
--- a/crates/ra_hir_def/src/expr.rs
+++ b/crates/ra_hir_def/src/expr.rs
@@ -19,7 +19,7 @@ use ra_syntax::ast::RangeOp;
 use crate::{
     builtin_type::{BuiltinFloat, BuiltinInt},
     path::{GenericArgs, Path},
-    type_ref::{Mutability, TypeRef},
+    type_ref::{Mutability, Rawness, TypeRef},
 };
 
 pub type ExprId = Idx<Expr>;
@@ -110,6 +110,7 @@ pub enum Expr {
     },
     Ref {
         expr: ExprId,
+        rawness: Rawness,
         mutability: Mutability,
     },
     Box {
diff --git a/crates/ra_hir_def/src/type_ref.rs b/crates/ra_hir_def/src/type_ref.rs
index 5bdad9efd..86a77b704 100644
--- a/crates/ra_hir_def/src/type_ref.rs
+++ b/crates/ra_hir_def/src/type_ref.rs
@@ -35,6 +35,22 @@ impl Mutability {
     }
 }
 
+#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
+pub enum Rawness {
+    RawPtr,
+    Ref,
+}
+
+impl Rawness {
+    pub fn from_raw(is_raw: bool) -> Rawness {
+        if is_raw {
+            Rawness::RawPtr
+        } else {
+            Rawness::Ref
+        }
+    }
+}
+
 /// Compare ty::Ty
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
 pub enum TypeRef {