Update upstream source from tag 'upstream/1.52.1+dfsg1'

[rustc.git] / src / tools / clippy / tests / ui / useless_conversion_try.rs

diff --git a/src/tools/clippy/tests/ui/useless_conversion_try.rs b/src/tools/clippy/tests/ui/useless_conversion_try.rs
new file mode 100644 (file)
index 0000000..3787ea9
--- /dev/null
+++ b/src/tools/clippy/tests/ui/useless_conversion_try.rs
@@ -0,0 +1,42 @@
+#![deny(clippy::useless_conversion)]
+
+use std::convert::{TryFrom, TryInto};
+
+fn test_generic<T: Copy>(val: T) -> T {
+    let _ = T::try_from(val).unwrap();
+    val.try_into().unwrap()
+}
+
+fn test_generic2<T: Copy + Into<i32> + Into<U>, U: From<T>>(val: T) {
+    // ok
+    let _: i32 = val.try_into().unwrap();
+    let _: U = val.try_into().unwrap();
+    let _ = U::try_from(val).unwrap();
+}
+
+fn main() {
+    test_generic(10i32);
+    test_generic2::<i32, i32>(10i32);
+
+    let _: String = "foo".try_into().unwrap();
+    let _: String = TryFrom::try_from("foo").unwrap();
+    let _ = String::try_from("foo").unwrap();
+    #[allow(clippy::useless_conversion)]
+    {
+        let _ = String::try_from("foo").unwrap();
+        let _: String = "foo".try_into().unwrap();
+    }
+    let _: String = "foo".to_string().try_into().unwrap();
+    let _: String = TryFrom::try_from("foo".to_string()).unwrap();
+    let _ = String::try_from("foo".to_string()).unwrap();
+    let _ = String::try_from(format!("A: {:04}", 123)).unwrap();
+    let _: String = format!("Hello {}", "world").try_into().unwrap();
+    let _: String = "".to_owned().try_into().unwrap();
+    let _: String = match String::from("_").try_into() {
+        Ok(a) => a,
+        Err(_) => "".into(),
+    };
+    // FIXME this is a false negative
+    #[allow(clippy::cmp_owned)]
+    if String::from("a") == TryInto::<String>::try_into(String::from("a")).unwrap() {}
+}