Vendor dependencies

Let's see how I like this workflow.

vendor/pin-project-lite/tests/ui/pin_project/unsupported.rs

@@ -0,0 +1,27 @@
+use pin_project_lite::pin_project;
+
+pin_project! {
+    struct Struct1 {} //~ ERROR no rules expected the token `}`
+}
+
+pin_project! {
+    struct Struct2(); //~ ERROR no rules expected the token `(`
+}
+
+pin_project! {
+    struct Struct3; //~ ERROR no rules expected the token `;`
+}
+
+pin_project! {
+    enum Enum { //~ ERROR no rules expected the token `enum`
+        A(u8)
+    }
+}
+
+pin_project! {
+    union Union { //~ ERROR no rules expected the token `union`
+        x: u8,
+    }
+}
+
+fn main() {}