Auto merge of #64739 - guanqun:remove-as-str, r=estebank

Remove as_str if the type is already &str

Fix https://github.com/rust-lang/rust/issues/62642

r? @estebank

do you think the suggestion tip is good enough?

2 files changed, 48 insertions, 0 deletions

diff --git a/src/test/ui/suggestions/remove-as_str.rs b/src/test/ui/suggestions/remove-as_str.rs
new file mode 100644
index 00000000000..d10300b48ba
--- /dev/null
+++ b/src/test/ui/suggestions/remove-as_str.rs
@@ -0,0 +1,21 @@
+fn foo1(s: &str) {
+    s.as_str();
+    //~^ ERROR no method named `as_str` found for type `&str` in the current scope
+}
+
+fn foo2<'a>(s: &'a str) {
+    s.as_str();
+    //~^ ERROR no method named `as_str` found for type `&'a str` in the current scope
+}
+
+fn foo3(s: &mut str) {
+    s.as_str();
+    //~^ ERROR no method named `as_str` found for type `&mut str` in the current scope
+}
+
+fn foo4(s: &&str) {
+    s.as_str();
+    //~^ ERROR no method named `as_str` found for type `&&str` in the current scope
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/remove-as_str.stderr b/src/test/ui/suggestions/remove-as_str.stderr
new file mode 100644
index 00000000000..2e8b72ebd4f
--- /dev/null
+++ b/src/test/ui/suggestions/remove-as_str.stderr
@@ -0,0 +1,27 @@
+error[E0599]: no method named `as_str` found for type `&str` in the current scope
+  --> $DIR/remove-as_str.rs:2:7
+   |
+LL |     s.as_str();
+   |       ^^^^^^ try removing `as_str`
+
+error[E0599]: no method named `as_str` found for type `&'a str` in the current scope
+  --> $DIR/remove-as_str.rs:7:7
+   |
+LL |     s.as_str();
+   |       ^^^^^^ try removing `as_str`
+
+error[E0599]: no method named `as_str` found for type `&mut str` in the current scope
+  --> $DIR/remove-as_str.rs:12:7
+   |
+LL |     s.as_str();
+   |       ^^^^^^ try removing `as_str`
+
+error[E0599]: no method named `as_str` found for type `&&str` in the current scope
+  --> $DIR/remove-as_str.rs:17:7
+   |
+LL |     s.as_str();
+   |       ^^^^^^ try removing `as_str`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0599`.