Fix manual_map: don't lint when partially moved values are used.

Fix `manual_map`: don't lint when `return`, `break`, and `continue` are used.
rust-lang · Feb 26, 2021 · 4616e9c · 4616e9c
1 parent d5223be
commit 4616e9c
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Showing 5 changed files with 168 additions and 22 deletions.
diff --git a/clippy_lints/src/manual_map.rs b/clippy_lints/src/manual_map.rs
@@ -2,13 +2,17 @@ use crate::{
     map_unit_fn::OPTION_MAP_UNIT_FN,
     matches::MATCH_AS_REF,
     utils::{
-        is_allowed, is_type_diagnostic_item, match_def_path, match_var, paths, peel_hir_expr_refs,
-        peel_mid_ty_refs_is_mutable, snippet_with_applicability, span_lint_and_sugg,
+        can_partially_move_ty, is_allowed, is_type_diagnostic_item, match_def_path, match_var, paths,
+        peel_hir_expr_refs, peel_mid_ty_refs_is_mutable, snippet_with_applicability, span_lint_and_sugg,
     },
 };
 use rustc_ast::util::parser::PREC_POSTFIX;
 use rustc_errors::Applicability;
-use rustc_hir::{Arm, BindingAnnotation, Block, Expr, ExprKind, Mutability, Pat, PatKind, QPath};
+use rustc_hir::{
+    def::Res,
+    intravisit::{walk_expr, ErasedMap, NestedVisitorMap, Visitor},
+    Arm, BindingAnnotation, Block, Expr, ExprKind, Mutability, Pat, PatKind, Path, QPath,
+};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -99,6 +103,10 @@ impl LateLintPass<'_> for ManualMap {
                 return;
             }
 
+            if !can_move_expr_to_closure(cx, some_expr) {
+                return;
+            }
+
             // Determine which binding mode to use.
             let explicit_ref = some_pat.contains_explicit_ref_binding();
             let binding_ref = explicit_ref.or_else(|| (ty_ref_count != pat_ref_count).then(|| ty_mutability));
@@ -171,6 +179,46 @@ impl LateLintPass<'_> for ManualMap {
     }
 }
 
+// Checks if the expression can be moved into a closure as is.
+fn can_move_expr_to_closure(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> bool {
+    struct V<'cx, 'tcx> {
+        cx: &'cx LateContext<'tcx>,
+        make_closure: bool,
+    }
+    impl Visitor<'tcx> for V<'_, 'tcx> {
+        type Map = ErasedMap<'tcx>;
+        fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
+            NestedVisitorMap::None
+        }
+
+        fn visit_expr(&mut self, e: &'tcx Expr<'_>) {
+            match e.kind {
+                ExprKind::Break(..) | ExprKind::Continue(_) | ExprKind::Ret(_) => {
+                    self.make_closure = false;
+                },
+                // Accessing a field of a local value can only be done if the type isn't
+                // partially moved.
+                ExprKind::Field(base_expr, _)
+                    if matches!(
+                        base_expr.kind,
+                        ExprKind::Path(QPath::Resolved(_, Path { res: Res::Local(_), .. }))
+                    ) && can_partially_move_ty(self.cx, self.cx.typeck_results().expr_ty(base_expr)) =>
+                {
+                    // TODO: check if the local has been partially moved. Assume it has for now.
+                    self.make_closure = false;
+                    return;
+                }
+                _ => (),
+            };
+            walk_expr(self, e);
+        }
+    }
+
+    let mut v = V { cx, make_closure: true };
+    v.visit_expr(expr);
+    v.make_closure
+}
+
 // Checks whether the expression could be passed as a function, or whether a closure is needed.
 // Returns the function to be passed to `map` if it exists.
 fn can_pass_as_func(cx: &LateContext<'tcx>, binding: Ident, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {

diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs
@@ -456,6 +456,18 @@ pub fn has_drop<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
     }
 }
 
+/// Checks whether a type can be partially moved.
+pub fn can_partially_move_ty(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
+    if has_drop(cx, ty) || is_copy(cx, ty) {
+        return false;
+    }
+    match ty.kind() {
+        ty::Param(_) => false,
+        ty::Adt(def, subs) => def.all_fields().any(|f| !is_copy(cx, f.ty(cx.tcx, subs))),
+        _ => true,
+    }
+}
+
 /// Returns the method names and argument list of nested method call expressions that make up
 /// `expr`. method/span lists are sorted with the most recent call first.
 pub fn method_calls<'tcx>(

diff --git a/tests/ui/manual_map_option.fixed b/tests/ui/manual_map_option.fixed
@@ -1,7 +1,13 @@
 // run-rustfix
 
 #![warn(clippy::manual_map)]
-#![allow(clippy::no_effect, clippy::map_identity, clippy::unit_arg, clippy::match_ref_pats)]
+#![allow(
+    clippy::no_effect,
+    clippy::map_identity,
+    clippy::unit_arg,
+    clippy::match_ref_pats,
+    dead_code
+)]
 
 fn main() {
     Some(0).map(|_| 2);
@@ -67,4 +73,41 @@ fn main() {
         Some(Some((x, 1))) => Some(x),
         _ => None,
     };
+
+    // #6795
+    fn f1() -> Result<(), ()> {
+        let _ = match Some(Ok(())) {
+            Some(x) => Some(x?),
+            None => None,
+        };
+        Ok(())
+    }
+
+    for &x in Some(Some(true)).iter() {
+        let _ = match x {
+            Some(x) => Some(if x { continue } else { x }),
+            None => None,
+        };
+    }
+
+    // #6797
+    let x1 = (Some(String::new()), 0);
+    let x2 = x1.0;
+    match x2 {
+        Some(x) => Some((x, x1.1)),
+        None => None,
+    };
+
+    struct S1 {
+        x: Option<String>,
+        y: u32,
+    }
+    impl S1 {
+        fn f(self) -> Option<(String, u32)> {
+            match self.x {
+                Some(x) => Some((x, self.y)),
+                None => None,
+            }
+        }
+    }
 }
diff --git a/tests/ui/manual_map_option.rs b/tests/ui/manual_map_option.rs
@@ -1,7 +1,13 @@
 // run-rustfix
 
 #![warn(clippy::manual_map)]
-#![allow(clippy::no_effect, clippy::map_identity, clippy::unit_arg, clippy::match_ref_pats)]
+#![allow(
+    clippy::no_effect,
+    clippy::map_identity,
+    clippy::unit_arg,
+    clippy::match_ref_pats,
+    dead_code
+)]
 
 fn main() {
     match Some(0) {
@@ -119,4 +125,41 @@ fn main() {
         Some(Some((x, 1))) => Some(x),
         _ => None,
     };
+
+    // #6795
+    fn f1() -> Result<(), ()> {
+        let _ = match Some(Ok(())) {
+            Some(x) => Some(x?),
+            None => None,
+        };
+        Ok(())
+    }
+
+    for &x in Some(Some(true)).iter() {
+        let _ = match x {
+            Some(x) => Some(if x { continue } else { x }),
+            None => None,
+        };
+    }
+
+    // #6797
+    let x1 = (Some(String::new()), 0);
+    let x2 = x1.0;
+    match x2 {
+        Some(x) => Some((x, x1.1)),
+        None => None,
+    };
+
+    struct S1 {
+        x: Option<String>,
+        y: u32,
+    }
+    impl S1 {
+        fn f(self) -> Option<(String, u32)> {
+            match self.x {
+                Some(x) => Some((x, self.y)),
+                None => None,
+            }
+        }
+    }
 }
diff --git a/tests/ui/manual_map_option.stderr b/tests/ui/manual_map_option.stderr
@@ -1,5 +1,5 @@
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:7:5
+  --> $DIR/manual_map_option.rs:13:5
    |
 LL | /     match Some(0) {
 LL | |         Some(_) => Some(2),
@@ -10,7 +10,7 @@ LL | |     };
    = note: `-D clippy::manual-map` implied by `-D warnings`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:12:5
+  --> $DIR/manual_map_option.rs:18:5
    |
 LL | /     match Some(0) {
 LL | |         Some(x) => Some(x + 1),
@@ -19,7 +19,7 @@ LL | |     };
    | |_____^ help: try this: `Some(0).map(|x| x + 1)`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:17:5
+  --> $DIR/manual_map_option.rs:23:5
    |
 LL | /     match Some("") {
 LL | |         Some(x) => Some(x.is_empty()),
@@ -28,7 +28,7 @@ LL | |     };
    | |_____^ help: try this: `Some("").map(|x| x.is_empty())`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:22:5
+  --> $DIR/manual_map_option.rs:28:5
    |
 LL | /     if let Some(x) = Some(0) {
 LL | |         Some(!x)
@@ -38,7 +38,7 @@ LL | |     };
    | |_____^ help: try this: `Some(0).map(|x| !x)`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:29:5
+  --> $DIR/manual_map_option.rs:35:5
    |
 LL | /     match Some(0) {
 LL | |         Some(x) => { Some(std::convert::identity(x)) }
@@ -47,7 +47,7 @@ LL | |     };
    | |_____^ help: try this: `Some(0).map(std::convert::identity)`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:34:5
+  --> $DIR/manual_map_option.rs:40:5
    |
 LL | /     match Some(&String::new()) {
 LL | |         Some(x) => Some(str::len(x)),
@@ -56,7 +56,7 @@ LL | |     };
    | |_____^ help: try this: `Some(&String::new()).map(|x| str::len(x))`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:44:5
+  --> $DIR/manual_map_option.rs:50:5
    |
 LL | /     match &Some([0, 1]) {
 LL | |         Some(x) => Some(x[0]),
@@ -65,7 +65,7 @@ LL | |     };
    | |_____^ help: try this: `Some([0, 1]).as_ref().map(|x| x[0])`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:49:5
+  --> $DIR/manual_map_option.rs:55:5
    |
 LL | /     match &Some(0) {
 LL | |         &Some(x) => Some(x * 2),
@@ -74,7 +74,7 @@ LL | |     };
    | |_____^ help: try this: `Some(0).map(|x| x * 2)`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:54:5
+  --> $DIR/manual_map_option.rs:60:5
    |
 LL | /     match Some(String::new()) {
 LL | |         Some(ref x) => Some(x.is_empty()),
@@ -83,7 +83,7 @@ LL | |     };
    | |_____^ help: try this: `Some(String::new()).as_ref().map(|x| x.is_empty())`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:59:5
+  --> $DIR/manual_map_option.rs:65:5
    |
 LL | /     match &&Some(String::new()) {
 LL | |         Some(x) => Some(x.len()),
@@ -92,7 +92,7 @@ LL | |     };
    | |_____^ help: try this: `Some(String::new()).as_ref().map(|x| x.len())`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:64:5
+  --> $DIR/manual_map_option.rs:70:5
    |
 LL | /     match &&Some(0) {
 LL | |         &&Some(x) => Some(x + x),
@@ -101,7 +101,7 @@ LL | |     };
    | |_____^ help: try this: `Some(0).map(|x| x + x)`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:77:9
+  --> $DIR/manual_map_option.rs:83:9
    |
 LL | /         match &mut Some(String::new()) {
 LL | |             Some(x) => Some(x.push_str("")),
@@ -110,7 +110,7 @@ LL | |         };
    | |_________^ help: try this: `Some(String::new()).as_mut().map(|x| x.push_str(""))`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:83:5
+  --> $DIR/manual_map_option.rs:89:5
    |
 LL | /     match &mut Some(String::new()) {
 LL | |         Some(ref x) => Some(x.len()),
@@ -119,7 +119,7 @@ LL | |     };
    | |_____^ help: try this: `Some(String::new()).as_ref().map(|x| x.len())`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:88:5
+  --> $DIR/manual_map_option.rs:94:5
    |
 LL | /     match &mut &Some(String::new()) {
 LL | |         Some(x) => Some(x.is_empty()),
@@ -128,7 +128,7 @@ LL | |     };
    | |_____^ help: try this: `Some(String::new()).as_ref().map(|x| x.is_empty())`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:93:5
+  --> $DIR/manual_map_option.rs:99:5
    |
 LL | /     match Some((0, 1, 2)) {
 LL | |         Some((x, y, z)) => Some(x + y + z),
@@ -137,7 +137,7 @@ LL | |     };
    | |_____^ help: try this: `Some((0, 1, 2)).map(|(x, y, z)| x + y + z)`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:98:5
+  --> $DIR/manual_map_option.rs:104:5
    |
 LL | /     match Some([1, 2, 3]) {
 LL | |         Some([first, ..]) => Some(first),
@@ -146,7 +146,7 @@ LL | |     };
    | |_____^ help: try this: `Some([1, 2, 3]).map(|[first, ..]| first)`
 
 error: manual implementation of `Option::map`
-  --> $DIR/manual_map_option.rs:103:5
+  --> $DIR/manual_map_option.rs:109:5
    |
 LL | /     match &Some((String::new(), "test")) {
 LL | |         Some((x, y)) => Some((y, x)),