Rollup merge of rust-lang#5425 - xiongmao86:issue5367, r=flip1995

Ehance opt_as_ref_deref lint.

- [x] Added passing UI tests (including committed `.stderr` file)
- [x] `cargo test` passes locally
- [x] Run `cargo dev fmt`

Lint on opt.as_ref().map(|x| &**x). Fixes rust-lang#5367.

changelog: lint on opt.as_ref().map(|x| &**x)

clippy_lints/src/loops.rs

@@ -654,15 +654,15 @@ fn combine_branches(b1: NeverLoopResult, b2: NeverLoopResult) -> NeverLoopResult
 
 fn never_loop_block(block: &Block<'_>, main_loop_id: HirId) -> NeverLoopResult {
     let stmts = block.stmts.iter().map(stmt_to_expr);
-    let expr = once(block.expr.as_ref().map(|p| &**p));
+    let expr = once(block.expr.as_deref());
     let mut iter = stmts.chain(expr).filter_map(|e| e);
     never_loop_expr_seq(&mut iter, main_loop_id)
 }
 
 fn stmt_to_expr<'tcx>(stmt: &Stmt<'tcx>) -> Option<&'tcx Expr<'tcx>> {
     match stmt.kind {
         StmtKind::Semi(ref e, ..) | StmtKind::Expr(ref e, ..) => Some(e),
-        StmtKind::Local(ref local) => local.init.as_ref().map(|p| &**p),
+        StmtKind::Local(ref local) => local.init.as_deref(),
         _ => None,
     }
 }

clippy_lints/src/methods/mod.rs

@@ -3233,6 +3233,8 @@ fn lint_option_as_ref_deref<'a, 'tcx>(
     map_args: &[hir::Expr<'_>],
     is_mut: bool,
 ) {
+    let same_mutability = |m| (is_mut && m == &hir::Mutability::Mut) || (!is_mut && m == &hir::Mutability::Not);
+
     let option_ty = cx.tables.expr_ty(&as_ref_args[0]);
     if !match_type(cx, option_ty, &paths::OPTION) {
         return;
@@ -3255,39 +3257,56 @@ fn lint_option_as_ref_deref<'a, 'tcx>(
         hir::ExprKind::Closure(_, _, body_id, _, _) => {
             let closure_body = cx.tcx.hir().body(body_id);
             let closure_expr = remove_blocks(&closure_body.value);
-            if_chain! {
-                if let hir::ExprKind::MethodCall(_, _, args) = &closure_expr.kind;
-                if args.len() == 1;
-                if let hir::ExprKind::Path(qpath) = &args[0].kind;
-                if let hir::def::Res::Local(local_id) = cx.tables.qpath_res(qpath, args[0].hir_id);
-                if closure_body.params[0].pat.hir_id == local_id;
-                let adj = cx.tables.expr_adjustments(&args[0]).iter().map(|x| &x.kind).collect::<Box<[_]>>();
-                if let [ty::adjustment::Adjust::Deref(None), ty::adjustment::Adjust::Borrow(_)] = *adj;
-                then {
-                    let method_did = cx.tables.type_dependent_def_id(closure_expr.hir_id).unwrap();
-                    deref_aliases.iter().any(|path| match_def_path(cx, method_did, path))
-                } else {
-                    false
-                }
+
+            match &closure_expr.kind {
+                hir::ExprKind::MethodCall(_, _, args) => {
+                    if_chain! {
+                        if args.len() == 1;
+                        if let hir::ExprKind::Path(qpath) = &args[0].kind;
+                        if let hir::def::Res::Local(local_id) = cx.tables.qpath_res(qpath, args[0].hir_id);
+                        if closure_body.params[0].pat.hir_id == local_id;
+                        let adj = cx.tables.expr_adjustments(&args[0]).iter().map(|x| &x.kind).collect::<Box<[_]>>();
+                        if let [ty::adjustment::Adjust::Deref(None), ty::adjustment::Adjust::Borrow(_)] = *adj;
+                        then {
+                            let method_did = cx.tables.type_dependent_def_id(closure_expr.hir_id).unwrap();
+                            deref_aliases.iter().any(|path| match_def_path(cx, method_did, path))
+                        } else {
+                            false
+                        }
+                    }
+                },
+                hir::ExprKind::AddrOf(hir::BorrowKind::Ref, m, ref inner) if same_mutability(m) => {
+                    if_chain! {
+                        if let hir::ExprKind::Unary(hir::UnOp::UnDeref, ref inner1) = inner.kind;
+                        if let hir::ExprKind::Unary(hir::UnOp::UnDeref, ref inner2) = inner1.kind;
+                        if let hir::ExprKind::Path(ref qpath) = inner2.kind;
+                        if let hir::def::Res::Local(local_id) = cx.tables.qpath_res(qpath, inner2.hir_id);
+                        then {
+                            closure_body.params[0].pat.hir_id == local_id
+                        } else {
+                            false
+                        }
+                    }
+                },
+                _ => false,
             }
         },
-
         _ => false,
     };
 
     if is_deref {
         let current_method = if is_mut {
-            ".as_mut().map(DerefMut::deref_mut)"
+            format!(".as_mut().map({})", snippet(cx, map_args[1].span, ".."))
         } else {
-            ".as_ref().map(Deref::deref)"
+            format!(".as_ref().map({})", snippet(cx, map_args[1].span, ".."))
         };
         let method_hint = if is_mut { "as_deref_mut" } else { "as_deref" };
         let hint = format!("{}.{}()", snippet(cx, as_ref_args[0].span, ".."), method_hint);
         let suggestion = format!("try using {} instead", method_hint);
 
         let msg = format!(
-            "called `{0}` (or with one of deref aliases) on an Option value. \
-             This can be done more directly by calling `{1}` instead",
+            "called `{0}` on an Option value. This can be done more directly \
+            by calling `{1}` instead",
             current_method, hint
         );
         span_lint_and_sugg(

tests/ui/option_as_ref_deref.fixed

@@ -35,4 +35,7 @@ fn main() {
     let _ = Some(1_usize).as_ref().map(|x| vc[*x].as_str()); // should not be linted
 
     let _: Option<&str> = Some(&String::new()).as_ref().map(|x| x.as_str()); // should not be linted
+
+    let _ = opt.as_deref();
+    let _ = opt.as_deref_mut();
 }

tests/ui/option_as_ref_deref.rs

@@ -38,4 +38,7 @@ fn main() {
     let _ = Some(1_usize).as_ref().map(|x| vc[*x].as_str()); // should not be linted
 
     let _: Option<&str> = Some(&String::new()).as_ref().map(|x| x.as_str()); // should not be linted
+
+    let _ = opt.as_ref().map(|x| &**x);
+    let _ = opt.as_mut().map(|x| &mut **x);
 }

tests/ui/option_as_ref_deref.stderr

@@ -1,12 +1,12 @@
-error: called `.as_ref().map(Deref::deref)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `opt.clone().as_deref()` instead
+error: called `.as_ref().map(Deref::deref)` on an Option value. This can be done more directly by calling `opt.clone().as_deref()` instead
   --> $DIR/option_as_ref_deref.rs:13:13
    |
 LL |     let _ = opt.clone().as_ref().map(Deref::deref).map(str::len);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref instead: `opt.clone().as_deref()`
    |
    = note: `-D clippy::option-as-ref-deref` implied by `-D warnings`
 
-error: called `.as_ref().map(Deref::deref)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `opt.clone().as_deref()` instead
+error: called `.as_ref().map(Deref::deref)` on an Option value. This can be done more directly by calling `opt.clone().as_deref()` instead
   --> $DIR/option_as_ref_deref.rs:16:13
    |
 LL |       let _ = opt.clone()
@@ -16,77 +16,89 @@ LL | |             Deref::deref
 LL | |         )
    | |_________^ help: try using as_deref instead: `opt.clone().as_deref()`
 
-error: called `.as_mut().map(DerefMut::deref_mut)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `opt.as_deref_mut()` instead
+error: called `.as_mut().map(DerefMut::deref_mut)` on an Option value. This can be done more directly by calling `opt.as_deref_mut()` instead
   --> $DIR/option_as_ref_deref.rs:22:13
    |
 LL |     let _ = opt.as_mut().map(DerefMut::deref_mut);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref_mut instead: `opt.as_deref_mut()`
 
-error: called `.as_ref().map(Deref::deref)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `opt.as_deref()` instead
+error: called `.as_ref().map(String::as_str)` on an Option value. This can be done more directly by calling `opt.as_deref()` instead
   --> $DIR/option_as_ref_deref.rs:24:13
    |
 LL |     let _ = opt.as_ref().map(String::as_str);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref instead: `opt.as_deref()`
 
-error: called `.as_ref().map(Deref::deref)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `opt.as_deref()` instead
+error: called `.as_ref().map(|x| x.as_str())` on an Option value. This can be done more directly by calling `opt.as_deref()` instead
   --> $DIR/option_as_ref_deref.rs:25:13
    |
 LL |     let _ = opt.as_ref().map(|x| x.as_str());
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref instead: `opt.as_deref()`
 
-error: called `.as_mut().map(DerefMut::deref_mut)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `opt.as_deref_mut()` instead
+error: called `.as_mut().map(String::as_mut_str)` on an Option value. This can be done more directly by calling `opt.as_deref_mut()` instead
   --> $DIR/option_as_ref_deref.rs:26:13
    |
 LL |     let _ = opt.as_mut().map(String::as_mut_str);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref_mut instead: `opt.as_deref_mut()`
 
-error: called `.as_mut().map(DerefMut::deref_mut)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `opt.as_deref_mut()` instead
+error: called `.as_mut().map(|x| x.as_mut_str())` on an Option value. This can be done more directly by calling `opt.as_deref_mut()` instead
   --> $DIR/option_as_ref_deref.rs:27:13
    |
 LL |     let _ = opt.as_mut().map(|x| x.as_mut_str());
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref_mut instead: `opt.as_deref_mut()`
 
-error: called `.as_ref().map(Deref::deref)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `Some(CString::new(vec![]).unwrap()).as_deref()` instead
+error: called `.as_ref().map(CString::as_c_str)` on an Option value. This can be done more directly by calling `Some(CString::new(vec![]).unwrap()).as_deref()` instead
   --> $DIR/option_as_ref_deref.rs:28:13
    |
 LL |     let _ = Some(CString::new(vec![]).unwrap()).as_ref().map(CString::as_c_str);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref instead: `Some(CString::new(vec![]).unwrap()).as_deref()`
 
-error: called `.as_ref().map(Deref::deref)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `Some(OsString::new()).as_deref()` instead
+error: called `.as_ref().map(OsString::as_os_str)` on an Option value. This can be done more directly by calling `Some(OsString::new()).as_deref()` instead
   --> $DIR/option_as_ref_deref.rs:29:13
    |
 LL |     let _ = Some(OsString::new()).as_ref().map(OsString::as_os_str);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref instead: `Some(OsString::new()).as_deref()`
 
-error: called `.as_ref().map(Deref::deref)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `Some(PathBuf::new()).as_deref()` instead
+error: called `.as_ref().map(PathBuf::as_path)` on an Option value. This can be done more directly by calling `Some(PathBuf::new()).as_deref()` instead
   --> $DIR/option_as_ref_deref.rs:30:13
    |
 LL |     let _ = Some(PathBuf::new()).as_ref().map(PathBuf::as_path);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref instead: `Some(PathBuf::new()).as_deref()`
 
-error: called `.as_ref().map(Deref::deref)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `Some(Vec::<()>::new()).as_deref()` instead
+error: called `.as_ref().map(Vec::as_slice)` on an Option value. This can be done more directly by calling `Some(Vec::<()>::new()).as_deref()` instead
   --> $DIR/option_as_ref_deref.rs:31:13
    |
 LL |     let _ = Some(Vec::<()>::new()).as_ref().map(Vec::as_slice);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref instead: `Some(Vec::<()>::new()).as_deref()`
 
-error: called `.as_mut().map(DerefMut::deref_mut)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `Some(Vec::<()>::new()).as_deref_mut()` instead
+error: called `.as_mut().map(Vec::as_mut_slice)` on an Option value. This can be done more directly by calling `Some(Vec::<()>::new()).as_deref_mut()` instead
   --> $DIR/option_as_ref_deref.rs:32:13
    |
 LL |     let _ = Some(Vec::<()>::new()).as_mut().map(Vec::as_mut_slice);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref_mut instead: `Some(Vec::<()>::new()).as_deref_mut()`
 
-error: called `.as_ref().map(Deref::deref)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `opt.as_deref()` instead
+error: called `.as_ref().map(|x| x.deref())` on an Option value. This can be done more directly by calling `opt.as_deref()` instead
   --> $DIR/option_as_ref_deref.rs:34:13
    |
 LL |     let _ = opt.as_ref().map(|x| x.deref());
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref instead: `opt.as_deref()`
 
-error: called `.as_mut().map(DerefMut::deref_mut)` (or with one of deref aliases) on an Option value. This can be done more directly by calling `opt.clone().as_deref_mut()` instead
+error: called `.as_mut().map(|x| x.deref_mut())` on an Option value. This can be done more directly by calling `opt.clone().as_deref_mut()` instead
   --> $DIR/option_as_ref_deref.rs:35:13
    |
 LL |     let _ = opt.clone().as_mut().map(|x| x.deref_mut()).map(|x| x.len());
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref_mut instead: `opt.clone().as_deref_mut()`
 
-error: aborting due to 14 previous errors
+error: called `.as_ref().map(|x| &**x)` on an Option value. This can be done more directly by calling `opt.as_deref()` instead
+  --> $DIR/option_as_ref_deref.rs:42:13
+   |
+LL |     let _ = opt.as_ref().map(|x| &**x);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref instead: `opt.as_deref()`
+
+error: called `.as_mut().map(|x| &mut **x)` on an Option value. This can be done more directly by calling `opt.as_deref_mut()` instead
+  --> $DIR/option_as_ref_deref.rs:43:13
+   |
+LL |     let _ = opt.as_mut().map(|x| &mut **x);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using as_deref_mut instead: `opt.as_deref_mut()`
+
+error: aborting due to 16 previous errors