Rollup merge of #101367 - compiler-errors:suggest-copied-or-cloned, r=lcnr

Suggest `{Option,Result}::{copied,clone}()` to satisfy type mismatch

Fixes #100699, but in the opposite direction (instead of suggesting to fix the signature, it fixes the body)

3 files changed, 129 insertions, 0 deletions

diff --git a/src/test/ui/suggestions/copied-and-cloned.fixed b/src/test/ui/suggestions/copied-and-cloned.fixed
new file mode 100644
index 00000000000..f801403feec
--- /dev/null
+++ b/src/test/ui/suggestions/copied-and-cloned.fixed
@@ -0,0 +1,23 @@
+// run-rustfix
+
+fn expect<T>(_: T) {}
+
+fn main() {
+    let x = Some(&());
+    expect::<Option<()>>(x.copied());
+    //~^ ERROR mismatched types
+    //~| HELP use `Option::copied` to copy the value inside the `Option`
+    let x = Ok(&());
+    expect::<Result<(), ()>>(x.copied());
+    //~^ ERROR mismatched types
+    //~| HELP use `Result::copied` to copy the value inside the `Result`
+    let s = String::new();
+    let x = Some(&s);
+    expect::<Option<String>>(x.cloned());
+    //~^ ERROR mismatched types
+    //~| HELP use `Option::cloned` to clone the value inside the `Option`
+    let x = Ok(&s);
+    expect::<Result<String, ()>>(x.cloned());
+    //~^ ERROR mismatched types
+    //~| HELP use `Result::cloned` to clone the value inside the `Result`
+}
diff --git a/src/test/ui/suggestions/copied-and-cloned.rs b/src/test/ui/suggestions/copied-and-cloned.rs
new file mode 100644
index 00000000000..640450b7655
--- /dev/null
+++ b/src/test/ui/suggestions/copied-and-cloned.rs
@@ -0,0 +1,23 @@
+// run-rustfix
+
+fn expect<T>(_: T) {}
+
+fn main() {
+    let x = Some(&());
+    expect::<Option<()>>(x);
+    //~^ ERROR mismatched types
+    //~| HELP use `Option::copied` to copy the value inside the `Option`
+    let x = Ok(&());
+    expect::<Result<(), ()>>(x);
+    //~^ ERROR mismatched types
+    //~| HELP use `Result::copied` to copy the value inside the `Result`
+    let s = String::new();
+    let x = Some(&s);
+    expect::<Option<String>>(x);
+    //~^ ERROR mismatched types
+    //~| HELP use `Option::cloned` to clone the value inside the `Option`
+    let x = Ok(&s);
+    expect::<Result<String, ()>>(x);
+    //~^ ERROR mismatched types
+    //~| HELP use `Result::cloned` to clone the value inside the `Result`
+}
diff --git a/src/test/ui/suggestions/copied-and-cloned.stderr b/src/test/ui/suggestions/copied-and-cloned.stderr
new file mode 100644
index 00000000000..a6336281b40
--- /dev/null
+++ b/src/test/ui/suggestions/copied-and-cloned.stderr
@@ -0,0 +1,83 @@
+error[E0308]: mismatched types
+  --> $DIR/copied-and-cloned.rs:7:26
+   |
+LL |     expect::<Option<()>>(x);
+   |     -------------------- ^ expected `()`, found `&()`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected enum `Option<()>`
+              found enum `Option<&()>`
+note: function defined here
+  --> $DIR/copied-and-cloned.rs:3:4
+   |
+LL | fn expect<T>(_: T) {}
+   |    ^^^^^^    ----
+help: use `Option::copied` to copy the value inside the `Option`
+   |
+LL |     expect::<Option<()>>(x.copied());
+   |                           +++++++++
+
+error[E0308]: mismatched types
+  --> $DIR/copied-and-cloned.rs:11:30
+   |
+LL |     expect::<Result<(), ()>>(x);
+   |     ------------------------ ^ expected `()`, found `&()`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected enum `Result<(), ()>`
+              found enum `Result<&(), _>`
+note: function defined here
+  --> $DIR/copied-and-cloned.rs:3:4
+   |
+LL | fn expect<T>(_: T) {}
+   |    ^^^^^^    ----
+help: use `Result::copied` to copy the value inside the `Result`
+   |
+LL |     expect::<Result<(), ()>>(x.copied());
+   |                               +++++++++
+
+error[E0308]: mismatched types
+  --> $DIR/copied-and-cloned.rs:16:30
+   |
+LL |     expect::<Option<String>>(x);
+   |     ------------------------ ^ expected struct `String`, found `&String`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected enum `Option<String>`
+              found enum `Option<&String>`
+note: function defined here
+  --> $DIR/copied-and-cloned.rs:3:4
+   |
+LL | fn expect<T>(_: T) {}
+   |    ^^^^^^    ----
+help: use `Option::cloned` to clone the value inside the `Option`
+   |
+LL |     expect::<Option<String>>(x.cloned());
+   |                               +++++++++
+
+error[E0308]: mismatched types
+  --> $DIR/copied-and-cloned.rs:20:34
+   |
+LL |     expect::<Result<String, ()>>(x);
+   |     ---------------------------- ^ expected struct `String`, found `&String`
+   |     |
+   |     arguments to this function are incorrect
+   |
+   = note: expected enum `Result<String, ()>`
+              found enum `Result<&String, _>`
+note: function defined here
+  --> $DIR/copied-and-cloned.rs:3:4
+   |
+LL | fn expect<T>(_: T) {}
+   |    ^^^^^^    ----
+help: use `Result::cloned` to clone the value inside the `Result`
+   |
+LL |     expect::<Result<String, ()>>(x.cloned());
+   |                                   +++++++++
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0308`.