1 files changed, 43 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/unnecessary_fallible_conversions_unfixable.rs b/src/tools/clippy/tests/ui/unnecessary_fallible_conversions_unfixable.rs
new file mode 100644
index 000000000..68e617cc0
--- /dev/null
+++ b/src/tools/clippy/tests/ui/unnecessary_fallible_conversions_unfixable.rs
@@ -0,0 +1,43 @@
+//@aux-build:proc_macros.rs
+//@no-rustfix
+#![warn(clippy::unnecessary_fallible_conversions)]
+
+extern crate proc_macros;
+
+struct Foo;
+impl TryFrom<i32> for Foo {
+    type Error = ();
+    fn try_from(_: i32) -> Result<Self, Self::Error> {
+        Ok(Foo)
+    }
+}
+impl From<i64> for Foo {
+    fn from(_: i64) -> Self {
+        Foo
+    }
+}
+
+fn main() {
+    // `Foo` only implements `TryFrom<i32>` and not `From<i32>`, so don't lint
+    let _: Result<Foo, _> = 0i32.try_into();
+    let _: Result<Foo, _> = i32::try_into(0i32);
+    let _: Result<Foo, _> = Foo::try_from(0i32);
+
+    // ... it does impl From<i64> however
+    let _: Result<Foo, _> = 0i64.try_into();
+    //~^ ERROR: use of a fallible conversion when an infallible one could be used
+    let _: Result<Foo, _> = i64::try_into(0i64);
+    //~^ ERROR: use of a fallible conversion when an infallible one could be used
+    let _: Result<Foo, _> = Foo::try_from(0i64);
+    //~^ ERROR: use of a fallible conversion when an infallible one could be used
+
+    let _: Result<i64, _> = 0i32.try_into();
+    //~^ ERROR: use of a fallible conversion when an infallible one could be used
+    let _: Result<i64, _> = i32::try_into(0i32);
+    //~^ ERROR: use of a fallible conversion when an infallible one could be used
+    let _: Result<i64, _> = <_>::try_from(0i32);
+    //~^ ERROR: use of a fallible conversion when an infallible one could be used
+
+    // From a macro
+    let _: Result<i64, _> = proc_macros::external!(0i32).try_into();
+}