Detect method not being present that is present in other tuple types

When a method is not present because of a trait bound not being met, and that trait bound is on a tuple, we check if making the tuple have no borrowed types makes the method to be found and highlight it if it does. This is a common problem for Bevy in particular and ORMs in general.

2 files changed, 97 insertions, 0 deletions

diff --git a/tests/ui/methods/missing-bound-on-tuple.rs b/tests/ui/methods/missing-bound-on-tuple.rs
new file mode 100644
index 00000000000..25deabf5926
--- /dev/null
+++ b/tests/ui/methods/missing-bound-on-tuple.rs
@@ -0,0 +1,39 @@
+trait WorksOnDefault {
+    fn do_something() {}
+}
+
+impl<T: Default> WorksOnDefault for T {}
+//~^ NOTE the following trait bounds were not satisfied
+//~| NOTE unsatisfied trait bound introduced here
+
+trait Foo {}
+
+trait WorksOnFoo {
+    fn do_be_do() {}
+}
+
+impl<T: Foo> WorksOnFoo for T {}
+//~^ NOTE the following trait bounds were not satisfied
+//~| NOTE unsatisfied trait bound introduced here
+
+impl<A: Foo, B: Foo, C: Foo> Foo for (A, B, C) {}
+//~^ NOTE `Foo` is implemented for `(i32, u32, String)`
+impl Foo for i32 {}
+impl Foo for &i32 {}
+impl Foo for u32 {}
+impl Foo for String {}
+
+fn main() {
+    let _success = <(i32, u32, String)>::do_something();
+    let _failure = <(i32, &u32, String)>::do_something(); //~ ERROR E0599
+    //~^ NOTE `Default` is implemented for `(i32, u32, String)`
+    //~| NOTE function or associated item cannot be called on
+    let _success = <(i32, u32, String)>::do_be_do();
+    let _failure = <(i32, &u32, String)>::do_be_do(); //~ ERROR E0599
+    //~^ NOTE function or associated item cannot be called on
+    let _success = <(i32, u32, String)>::default();
+    let _failure = <(i32, &u32, String)>::default(); //~ ERROR E0599
+    //~^ NOTE `Default` is implemented for `(i32, u32, String)`
+    //~| NOTE function or associated item cannot be called on
+    //~| NOTE the following trait bounds were not satisfied
+}
diff --git a/tests/ui/methods/missing-bound-on-tuple.stderr b/tests/ui/methods/missing-bound-on-tuple.stderr
new file mode 100644
index 00000000000..f3e0897e5e6
--- /dev/null
+++ b/tests/ui/methods/missing-bound-on-tuple.stderr
@@ -0,0 +1,58 @@
+error[E0599]: the function or associated item `do_something` exists for tuple `(i32, &u32, String)`, but its trait bounds were not satisfied
+  --> $DIR/missing-bound-on-tuple.rs:28:43
+   |
+LL |     let _failure = <(i32, &u32, String)>::do_something();
+   |                                           ^^^^^^^^^^^^ function or associated item cannot be called on `(i32, &u32, String)` due to unsatisfied trait bounds
+   |
+note: the following trait bounds were not satisfied:
+      `&(i32, &u32, String): Default`
+      `&mut (i32, &u32, String): Default`
+      `(i32, &u32, String): Default`
+  --> $DIR/missing-bound-on-tuple.rs:5:9
+   |
+LL | impl<T: Default> WorksOnDefault for T {}
+   |         ^^^^^^^  --------------     -
+   |         |
+   |         unsatisfied trait bound introduced here
+note: `Default` is implemented for `(i32, u32, String)` but not for `(i32, &u32, String)`
+  --> $SRC_DIR/core/src/tuple.rs:LL:COL
+   = note: this error originates in the macro `tuple_impls` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0599]: the function or associated item `do_be_do` exists for tuple `(i32, &u32, String)`, but its trait bounds were not satisfied
+  --> $DIR/missing-bound-on-tuple.rs:32:43
+   |
+LL |     let _failure = <(i32, &u32, String)>::do_be_do();
+   |                                           ^^^^^^^^ function or associated item cannot be called on `(i32, &u32, String)` due to unsatisfied trait bounds
+   |
+note: the following trait bounds were not satisfied:
+      `&(i32, &u32, String): Foo`
+      `&mut (i32, &u32, String): Foo`
+      `(i32, &u32, String): Foo`
+  --> $DIR/missing-bound-on-tuple.rs:15:9
+   |
+LL | impl<T: Foo> WorksOnFoo for T {}
+   |         ^^^  ----------     -
+   |         |
+   |         unsatisfied trait bound introduced here
+note: `Foo` is implemented for `(i32, u32, String)` but not for `(i32, &u32, String)`
+  --> $DIR/missing-bound-on-tuple.rs:19:1
+   |
+LL | impl<A: Foo, B: Foo, C: Foo> Foo for (A, B, C) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0599]: the function or associated item `default` exists for tuple `(i32, &u32, String)`, but its trait bounds were not satisfied
+  --> $DIR/missing-bound-on-tuple.rs:35:43
+   |
+LL |     let _failure = <(i32, &u32, String)>::default();
+   |                                           ^^^^^^^ function or associated item cannot be called on `(i32, &u32, String)` due to unsatisfied trait bounds
+   |
+   = note: the following trait bounds were not satisfied:
+           `&u32: Default`
+           which is required by `(i32, &u32, String): Default`
+note: `Default` is implemented for `(i32, u32, String)` but not for `(i32, &u32, String)`
+  --> $SRC_DIR/core/src/tuple.rs:LL:COL
+   = note: this error originates in the macro `tuple_impls` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0599`.