1 files changed, 137 insertions, 0 deletions
diff --git a/tests/ui/errors/traits/blame-trait-error-spans-on-exprs.rs b/tests/ui/errors/traits/blame-trait-error-spans-on-exprs.rs
new file mode 100644
index 000000000..6fea409ed
--- /dev/null
+++ b/tests/ui/errors/traits/blame-trait-error-spans-on-exprs.rs
@@ -0,0 +1,137 @@
+// This test examines the error spans reported when a generic `impl` fails.
+// For example, if a function wants an `Option<T>` where `T: Copy` but you pass `Some(vec![1, 2])`,
+// then we want to point at the `vec![1, 2]` and not the `Some( ... )` expression.
+
+trait T1 {}
+trait T2 {}
+trait T3 {}
+trait T4 {}
+
+impl T2 for i32 {}
+impl T3 for i32 {}
+
+struct Wrapper<W> {
+    value: W,
+}
+impl<B: T2> T1 for Wrapper<B> {}
+
+struct Burrito<F> {
+    spicy: bool,
+    filling: F,
+}
+impl<A: T3> T2 for Burrito<A> {}
+
+struct BurritoTuple<F>(F);
+impl<C: T3> T2 for BurritoTuple<C> {}
+
+enum BurritoKinds<G> {
+    SmallBurrito { spicy: bool, small_filling: G },
+    LargeBurrito { spicy: bool, large_filling: G },
+    MultiBurrito { first_filling: G, second_filling: G },
+}
+impl<D: T3> T2 for BurritoKinds<D> {}
+
+struct Taco<H>(bool, H);
+impl<E: T3> T2 for Taco<E> {}
+
+enum TacoKinds<H> {
+    OneTaco(bool, H),
+    TwoTacos(bool, H, H),
+}
+impl<F: T3> T2 for TacoKinds<F> {}
+
+struct GenericBurrito<Spiciness, Filling> {
+    spiciness: Spiciness,
+    filling: Filling,
+}
+impl<X, Y: T3> T2 for GenericBurrito<X, Y> {}
+struct NotSpicy;
+
+impl<A: T3, B: T3> T2 for (A, B) {}
+impl<A: T2, B: T2> T1 for (A, B) {}
+
+fn want<V: T1>(_x: V) {}
+
+// Some more-complex examples:
+type AliasBurrito<T> = GenericBurrito<T, T>;
+
+// The following example is fairly confusing. The idea is that we want to "misdirect" the location
+// of the error.
+
+struct Two<A, B> {
+    a: A,
+    b: B,
+}
+
+impl<X, Y: T1, Z> T1 for Two<Two<X, Y>, Z> {}
+
+struct DoubleWrapper<T> {
+    item: Wrapper<T>,
+}
+
+impl<T: T1> T1 for DoubleWrapper<T> {}
+
+impl<'a, T: T2> T1 for &'a T {}
+
+fn example<Q>(q: Q) {
+    // In each of the following examples, we expect the error span to point at the 'q' variable,
+    // since the missing constraint is `Q: T3`.
+
+    // Verifies for struct:
+    want(Wrapper { value: Burrito { spicy: false, filling: q } });
+    //~^ ERROR the trait bound `Q: T3` is not satisfied [E0277]
+
+    // Verifies for enum with named fields in variant:
+    want(Wrapper { value: BurritoKinds::SmallBurrito { spicy: true, small_filling: q } });
+    //~^ ERROR the trait bound `Q: T3` is not satisfied [E0277]
+
+    // Verifies for tuple struct:
+    want(Wrapper { value: Taco(false, q) });
+    //~^ ERROR the trait bound `Q: T3` is not satisfied [E0277]
+
+    // Verifies for tuple enum variant:
+    want(Wrapper { value: TacoKinds::OneTaco(false, q) });
+    //~^ ERROR the trait bound `Q: T3` is not satisfied [E0277]
+
+    // Verifies for generic type with multiple parameters:
+    want(Wrapper { value: GenericBurrito { spiciness: NotSpicy, filling: q } });
+    //~^ ERROR the trait bound `Q: T3` is not satisfied [E0277]
+
+    // Verifies for tuple:
+    want((3, q));
+    //~^ ERROR the trait bound `Q: T2` is not satisfied [E0277]
+
+    // Verifies for nested tuple:
+    want(Wrapper { value: (3, q) });
+    //~^ ERROR the trait bound `Q: T3` is not satisfied [E0277]
+
+    // Verifies for nested tuple:
+    want(((3, q), 5));
+    //~^ ERROR the trait bound `Q: T3` is not satisfied [E0277]
+
+    want(DoubleWrapper { item: Wrapper { value: q } });
+    //~^ ERROR the trait bound `Q: T1` is not satisfied [E0277]
+
+    want(DoubleWrapper { item: Wrapper { value: DoubleWrapper { item: Wrapper { value: q } } } });
+    //~^ ERROR the trait bound `Q: T1` is not satisfied [E0277]
+
+    // Verifies for type alias to struct:
+    want(Wrapper { value: AliasBurrito { spiciness: q, filling: q } });
+    //~^ ERROR the trait bound `Q: T3` is not satisfied [E0277]
+
+    want(Two { a: Two { a: (), b: q }, b: () });
+    //~^ ERROR the trait bound `Q: T1` is not satisfied [E0277]
+
+    // We *should* blame the 'q'.
+    // FIXME: Right now, the wrong field is blamed.
+    want(
+        Two { a: Two { a: (), b: Two { a: Two { a: (), b: q }, b: () } }, b: () },
+        //~^ ERROR the trait bound `Q: T1` is not satisfied [E0277]
+    );
+
+    // Verifies for reference:
+    want(&Burrito { spicy: false, filling: q });
+    //~^ ERROR the trait bound `Q: T3` is not satisfied [E0277]
+}
+
+fn main() {}