Auto merge of #4848 - lzutao:result-map_or, r=flip1995

make use of Result::map_or

Fixes #1590

changelog: none

Author: bors

clippy_lints/src/escape.rs

@@ -152,7 +152,7 @@ impl<'a, 'tcx> EscapeDelegate<'a, 'tcx> {
     fn is_large_box(&self, ty: Ty<'tcx>) -> bool {
         // Large types need to be boxed to avoid stack overflows.
         if ty.is_box() {
-            self.cx.layout_of(ty.boxed_ty()).ok().map_or(0, |l| l.size.bytes()) > self.too_large_for_stack
+            self.cx.layout_of(ty.boxed_ty()).map_or(0, |l| l.size.bytes()) > self.too_large_for_stack
         } else {
             false
         }

clippy_lints/src/lib.rs

@@ -12,6 +12,7 @@
 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
 #![feature(crate_visibility_modifier)]
 #![feature(concat_idents)]
+#![feature(result_map_or)]
 
 // FIXME: switch to something more ergonomic here, once available.
 // (Currently there is no way to opt into sysroot crates without `extern crate`.)

clippy_lints/src/methods/mod.rs

@@ -291,7 +291,7 @@ declare_clippy_lint! {
     /// **What it does:** Checks for usage of `result.map(_).unwrap_or_else(_)`.
     ///
     /// **Why is this bad?** Readability, this can be written more concisely as
-    /// `result.ok().map_or_else(_, _)`.
+    /// `result.map_or_else(_, _)`.
     ///
     /// **Known problems:** None.
     ///
@@ -303,7 +303,7 @@ declare_clippy_lint! {
     /// ```
     pub RESULT_MAP_UNWRAP_OR_ELSE,
     pedantic,
-    "using `Result.map(f).unwrap_or_else(g)`, which is more succinctly expressed as `.ok().map_or_else(g, f)`"
+    "using `Result.map(f).unwrap_or_else(g)`, which is more succinctly expressed as `.map_or_else(g, f)`"
 }
 
 declare_clippy_lint! {
@@ -2217,7 +2217,7 @@ fn lint_map_unwrap_or_else<'a, 'tcx>(
              `map_or_else(g, f)` instead"
         } else {
             "called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling \
-             `ok().map_or_else(g, f)` instead"
+             `.map_or_else(g, f)` instead"
         };
         // get snippets for args to map() and unwrap_or_else()
         let map_snippet = snippet(cx, map_args[1].span, "..");
@@ -2238,10 +2238,8 @@ fn lint_map_unwrap_or_else<'a, 'tcx>(
                 msg,
                 expr.span,
                 &format!(
-                    "replace `map({0}).unwrap_or_else({1})` with `{2}map_or_else({1}, {0})`",
-                    map_snippet,
-                    unwrap_snippet,
-                    if is_result { "ok()." } else { "" }
+                    "replace `map({0}).unwrap_or_else({1})` with `map_or_else({1}, {0})`",
+                    map_snippet, unwrap_snippet,
                 ),
             );
         } else if same_span && multiline {

src/driver.rs

@@ -1,4 +1,5 @@
 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
+#![feature(result_map_or)]
 #![feature(rustc_private)]
 
 // FIXME: switch to something more ergonomic here, once available.
@@ -319,7 +320,7 @@ pub fn main() {
             // this check ensures that dependencies are built but not linted and the final
             // crate is
             // linted but not built
-            let clippy_enabled = env::var("CLIPPY_TESTS").ok().map_or(false, |val| val == "true")
+            let clippy_enabled = env::var("CLIPPY_TESTS").map_or(false, |val| val == "true")
                 || arg_value(&orig_args, "--emit", |val| val.split(',').any(|e| e == "metadata")).is_some();
 
             if clippy_enabled {

src/lintlist/mod.rs

@@ -1697,7 +1697,7 @@ pub const ALL_LINTS: [Lint; 337] = [
     Lint {
         name: "result_map_unwrap_or_else",
         group: "pedantic",
-        desc: "using `Result.map(f).unwrap_or_else(g)`, which is more succinctly expressed as `.ok().map_or_else(g, f)`",
+        desc: "using `Result.map(f).unwrap_or_else(g)`, which is more succinctly expressed as `.map_or_else(g, f)`",
         deprecation: None,
         module: "methods",
     },

tests/ui/result_map_unwrap_or_else.stderr

@@ -1,27 +1,27 @@
-error: called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling `ok().map_or_else(g, f)` instead
+error: called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling `.map_or_else(g, f)` instead
   --> $DIR/result_map_unwrap_or_else.rs:15:13
    |
 LL |     let _ = res.map(|x| x + 1).unwrap_or_else(|e| 0); // should lint even though this call is on a separate line
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D clippy::result-map-unwrap-or-else` implied by `-D warnings`
-   = note: replace `map(|x| x + 1).unwrap_or_else(|e| 0)` with `ok().map_or_else(|e| 0, |x| x + 1)`
+   = note: replace `map(|x| x + 1).unwrap_or_else(|e| 0)` with `map_or_else(|e| 0, |x| x + 1)`
 
-error: called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling `ok().map_or_else(g, f)` instead
+error: called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling `.map_or_else(g, f)` instead
   --> $DIR/result_map_unwrap_or_else.rs:17:13
    |
 LL |     let _ = res.map(|x| x + 1).unwrap_or_else(|e| 0);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: replace `map(|x| x + 1).unwrap_or_else(|e| 0)` with `ok().map_or_else(|e| 0, |x| x + 1)`
+   = note: replace `map(|x| x + 1).unwrap_or_else(|e| 0)` with `map_or_else(|e| 0, |x| x + 1)`
 
-error: called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling `ok().map_or_else(g, f)` instead
+error: called `map(f).unwrap_or_else(g)` on a Result value. This can be done more directly by calling `.map_or_else(g, f)` instead
   --> $DIR/result_map_unwrap_or_else.rs:18:13
    |
 LL |     let _ = res.map(|x| x + 1).unwrap_or_else(|e| 0);
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: replace `map(|x| x + 1).unwrap_or_else(|e| 0)` with `ok().map_or_else(|e| 0, |x| x + 1)`
+   = note: replace `map(|x| x + 1).unwrap_or_else(|e| 0)` with `map_or_else(|e| 0, |x| x + 1)`
 
 error: aborting due to 3 previous errors