Expand the documentation for E0747

Author: varkor

src/librustc_error_codes/error_codes/E0747.md

@@ -9,3 +9,12 @@ struct S<'a, T>(&'a T);
 type X = S<(), 'static>; // error: the type argument is provided before the
                          // lifetime argument
 ```
+
+The argument order should be changed to match the parameter declaration
+order, as in the following.
+
+```
+struct S<'a, T>(&'a T);
+
+type X = S<'static, ()>; // ok
+```

src/test/ui/const-generics/const-param-after-const-literal-arg.rs

@@ -1,7 +1,7 @@
 // check-pass
 
+#![allow(incomplete_features)]
 #![feature(const_generics)]
-//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
 
 struct Foo<const A: usize, const B: usize>;
 

src/test/ui/const-generics/const-param-after-const-literal-arg.stderr

@@ -1,5 +1,5 @@
+#![allow(incomplete_features)]
 #![feature(const_generics)]
-//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
 
 fn bar<const X: (), 'a>(_: &'a ()) {
     //~^ ERROR lifetime parameters must be declared prior to const parameters