fix: use ExprIsRead::Yes for rhs of ordinary assignments

the rhs of an ordinary assignment `x = *never_ptr` was inferred with
`ExprIsRead::No`, which prevented `NeverToAny` coercion for place
expressions of type `!`. this caused false type mismatches and missing
divergence detection. the destructuring assignment path and let binding
path both correctly use `ExprIsRead::Yes` for the rhs value, since the
value is always consumed (read). this makes the ordinary assignment path
consistent with both.

Author: Albab-Hasan

crates/hir-ty/src/infer/expr.rs

@@ -751,7 +751,7 @@ impl<'db> InferenceContext<'_, 'db> {
 
                 if let Some(lhs_ty) = lhs_ty {
                     self.write_pat_ty(target, lhs_ty);
-                    self.infer_expr_coerce(value, &Expectation::has_type(lhs_ty), ExprIsRead::No);
+                    self.infer_expr_coerce(value, &Expectation::has_type(lhs_ty), ExprIsRead::Yes);
                 } else {
                     let rhs_ty = self.infer_expr(value, &Expectation::none(), ExprIsRead::Yes);
                     let resolver_guard =

crates/hir-ty/src/tests/never_type.rs

@@ -786,6 +786,22 @@ fn coerce_ref_mut_binding() -> ! {
     )
 }
 
+#[test]
+fn assign_never_place_no_mismatch() {
+    check_no_mismatches(
+        r#"
+//- minicore: sized
+fn foo() {
+    unsafe {
+        let p: *mut ! = 0 as _;
+        let mut x: () = ();
+        x = *p;
+    }
+}
+"#,
+    );
+}
+
 #[test]
 fn never_place_isnt_diverging() {
     check_infer_with_mismatches(