Add test for mixing types from two incompatible crate versions

Author: estebank

tests/ui/crate-loading/auxiliary/dep-2-reexport.rs

@@ -0,0 +1,4 @@
+//@ edition:2021
+//@ aux-build:multiple-dep-versions-2.rs
+extern crate dependency;
+pub use dependency::do_something;

tests/ui/crate-loading/auxiliary/multiple-dep-versions-1.rs

@@ -0,0 +1,7 @@
+#![crate_name="dependency"]
+//@ edition:2021
+//@ compile-flags: -C metadata=1 -C extra-filename=-1
+pub struct Type;
+pub trait Trait {}
+impl Trait for Type {}
+pub fn do_something<X: Trait>(_: X) { }

tests/ui/crate-loading/auxiliary/multiple-dep-versions-2.rs

@@ -0,0 +1,7 @@
+#![crate_name="dependency"]
+//@ edition:2021
+//@ compile-flags: -C metadata=2 -C extra-filename=-2
+pub struct Type(pub i32);
+pub trait Trait {}
+impl Trait for Type {}
+pub fn do_something<X: Trait>(_: X) {}

tests/ui/crate-loading/multiple-dep-versions.rs

@@ -0,0 +1,14 @@
+//@ aux-build:dep-2-reexport.rs
+//@ aux-build:multiple-dep-versions-1.rs
+//@ edition:2021
+//@ compile-flags: --error-format=human --color=always --crate-type bin --extern dependency={{build-base}}/crate-loading/multiple-dep-versions/auxiliary/libdependency-1.so --extern dep_2_reexport={{build-base}}/crate-loading/multiple-dep-versions/auxiliary/libdep_2_reexport.so
+//@ ignore-windows
+
+extern crate dependency;
+extern crate dep_2_reexport;
+use dependency::Type;
+use dep_2_reexport::do_something;
+
+fn main() {
+    do_something(Type);
+}