stash

clippy_lints/src/matches/manual_utils.rs

@@ -1,17 +1,18 @@
+use std::ops::ControlFlow;
 use crate::map_unit_fn::OPTION_MAP_UNIT_FN;
 use crate::matches::MATCH_AS_REF;
 use clippy_utils::source::{snippet_with_applicability, snippet_with_context};
 use clippy_utils::sugg::Sugg;
 use clippy_utils::ty::{is_copy, is_type_diagnostic_item, peel_mid_ty_refs_is_mutable, type_is_unsafe_function};
+use clippy_utils::visitors::for_each_expr;
 use clippy_utils::{
-    can_move_expr_to_closure, is_else_clause, is_lint_allowed, is_res_lang_ctor, path_res, path_to_local_id,
-    peel_blocks, peel_hir_expr_refs, peel_hir_expr_while, CaptureKind,
+    can_move_expr_to_closure, is_else_clause, is_lint_allowed, is_res_lang_ctor, path_res, path_to_local, path_to_local_id, peel_blocks, peel_hir_expr_refs, peel_hir_expr_while, CaptureKind
 };
 use rustc_ast::util::parser::PREC_POSTFIX;
 use rustc_errors::Applicability;
 use rustc_hir::def::Res;
 use rustc_hir::LangItem::{OptionNone, OptionSome};
-use rustc_hir::{BindingMode, Expr, ExprKind, HirId, Mutability, Pat, PatKind, Path, QPath};
+use rustc_hir::{BindingMode, Expr, ExprKind, HirId, LetStmt, Mutability, Node, Pat, PatKind, Path, QPath, TyKind};
 use rustc_lint::LateContext;
 use rustc_span::{sym, SyntaxContext};
 
@@ -73,7 +74,7 @@ where
     }
 
     // `map` won't perform any adjustments.
-    if !cx.typeck_results().expr_adjustments(some_expr.expr).is_empty() {
+    if expr_ty_is_explicitly_labeled(cx, expr) && some_expr.expr_contains_ty_adjustments(cx) {
         return None;
     }
 
@@ -238,6 +239,16 @@ impl<'tcx> SomeExpr<'tcx> {
         let sugg = Sugg::hir_with_context(cx, self.expr, ctxt, "..", app);
         if self.needs_negated { !sugg } else { sugg }
     }
+
+    fn expr_contains_ty_adjustments(&self, cx: &LateContext<'tcx>) -> bool {
+        for_each_expr(self.expr, |ex| {
+            if !cx.typeck_results().expr_adjustments(ex).is_empty() {
+                ControlFlow::Break(true)
+            } else {
+                ControlFlow::Continue(())
+            }
+        }).unwrap_or_default()
+    }
 }
 
 // Try to parse into a recognized `Option` pattern.
@@ -274,3 +285,29 @@ pub(super) fn try_parse_pattern<'tcx>(
 fn is_none_expr(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     is_res_lang_ctor(cx, path_res(cx, peel_blocks(expr)), OptionNone)
 }
+
+/// Return `true` if a given expr's type is labeled explicitly.
+/// 
+/// Such as the init binding of:
+/// 
+/// ```rust
+/// let x: &[u8;5] = b"hello";
+/// //               ^^^^^^^^
+/// ```
+/// 
+/// Or the return of a function:
+/// 
+/// ```rust
+/// fn foo() -> u8 {
+///     0
+/// //  ^
+/// }
+/// ```
+fn expr_ty_is_explicitly_labeled(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
+    let parent = cx.tcx.parent_hir_node(expr.hir_id);
+    if let Node::LetStmt(LetStmt { ty: None, .. }) = parent {
+        false
+    } else {
+        true
+    }
+}

tests/ui/manual_map_option_2.fixed

@@ -54,3 +54,40 @@ fn main() {
     let _ = Some(0).map(|x| unsafe { f(x) });
     let _ = Some(0).map(|x| unsafe { f(x) });
 }
+
+mod issue_12659 {
+    trait DummyTrait {}
+
+    fn foo<T: DummyTrait, F: Fn() -> Result<T, ()>>(f: F) {
+        // Don't lint
+        let _: Option<Result<Box<dyn DummyTrait>, ()>> = match Some(0) {
+            Some(_) => Some(match f() {
+                Ok(res) => Ok(Box::new(res)),
+                _ => Err(()),
+            }),
+            None => None,
+        };
+
+        let _: Option<Box<&[u8]>> = match Some(()) {
+            Some(_) => Some(Box::new(b"1234")),
+            None => None,
+        };
+
+        let x = String::new();
+        let _: Option<Box<&str>> = match Some(()) {
+            Some(_) => Some(Box::new(&x)),
+            None => None,
+        };
+
+        let _: Option<&str> = match Some(()) {
+            Some(_) => Some(&x),
+            None => None,
+        };
+
+        //~v ERROR: manual implementation of `Option::map`
+        let _ = Some(0).map(|_| match f() {
+                Ok(res) => Ok(Box::new(res)),
+                _ => Err(()),
+            });
+    }
+}

tests/ui/manual_map_option_2.rs

@@ -69,3 +69,43 @@ fn main() {
         None => None,
     };
 }
+
+mod issue_12659 {
+    trait DummyTrait {}
+
+    fn foo<T: DummyTrait, F: Fn() -> Result<T, ()>>(f: F) {
+        // Don't lint
+        let _: Option<Result<Box<dyn DummyTrait>, ()>> = match Some(0) {
+            Some(_) => Some(match f() {
+                Ok(res) => Ok(Box::new(res)),
+                _ => Err(()),
+            }),
+            None => None,
+        };
+
+        let _: Option<Box<&[u8]>> = match Some(()) {
+            Some(_) => Some(Box::new(b"1234")),
+            None => None,
+        };
+
+        let x = String::new();
+        let _: Option<Box<&str>> = match Some(()) {
+            Some(_) => Some(Box::new(&x)),
+            None => None,
+        };
+
+        let _: Option<&str> = match Some(()) {
+            Some(_) => Some(&x),
+            None => None,
+        };
+
+        //~v ERROR: manual implementation of `Option::map`
+        let _ = match Some(0) {
+            Some(_) => Some(match f() {
+                Ok(res) => Ok(Box::new(res)),
+                _ => Err(()),
+            }),
+            None => None,
+        };
+    }
+}

tests/ui/manual_map_option_2.stderr

@@ -61,5 +61,26 @@ LL | |         None => None,
 LL | |     };
    | |_____^ help: try: `Some(0).map(|x| unsafe { f(x) })`
 
-error: aborting due to 5 previous errors
+error: manual implementation of `Option::map`
+  --> tests/ui/manual_map_option_2.rs:103:17
+   |
+LL |           let _ = match Some(0) {
+   |  _________________^
+LL | |             Some(_) => Some(match f() {
+LL | |                 Ok(res) => Ok(Box::new(res)),
+LL | |                 _ => Err(()),
+LL | |             }),
+LL | |             None => None,
+LL | |         };
+   | |_________^
+   |
+help: try
+   |
+LL ~         let _ = Some(0).map(|_| match f() {
+LL +                 Ok(res) => Ok(Box::new(res)),
+LL +                 _ => Err(()),
+LL ~             });
+   |
+
+error: aborting due to 6 previous errors