Rollup merge of rust-lang#26742 - GuillaumeGomez:patch-2, r=arielb1

Part of rust-lang#24407.
r? @Manishearth

Author: steveklabnik

src/librustc_typeck/diagnostics.rs

@@ -1368,6 +1368,62 @@ struct Foo {
 ```
 "##,
 
+E0128: r##"
+Type parameter defaults can only use parameters that occur before them.
+Erroneous code example:
+
+```
+pub struct Foo<T=U, U=()> {
+    field1: T,
+    filed2: U,
+}
+// error: type parameters with a default cannot use forward declared
+// identifiers
+```
+
+Since type parameters are evaluated in-order, you may be able to fix this issue
+by doing:
+
+```
+pub struct Foo<U=(), T=U> {
+    field1: T,
+    filed2: U,
+}
+```
+
+Please also verify that this wasn't because of a name-clash and rename the type
+parameter if so.
+"##,
+
+E0130: r##"
+You declared a pattern as an argument in a foreign function declaration.
+Erroneous code example:
+
+```
+extern {
+    fn foo((a, b): (u32, u32)); // error: patterns aren't allowed in foreign
+                                //        function declarations
+}
+```
+
+Please replace the pattern argument with a regular one. Example:
+
+```
+struct SomeStruct {
+    a: u32,
+    b: u32,
+}
+
+extern {
+    fn foo(s: SomeStruct); // ok!
+}
+// or
+extern {
+    fn foo(a: (u32, u32)); // ok!
+}
+```
+"##,
+
 E0131: r##"
 It is not possible to define `main` with type parameters, or even with function
 parameters. When `main` is present, it must take no arguments and return `()`.
@@ -1382,6 +1438,30 @@ fn(isize, *const *const u8) -> isize
 ```
 "##,
 
+E0159: r##"
+You tried to use a trait as a struct constructor. Erroneous code example:
+
+```
+trait TraitNotAStruct {}
+
+TraitNotAStruct{ value: 0 }; // error: use of trait `TraitNotAStruct` as a
+                             //        struct constructor
+```
+
+Please verify you used the correct type name or please implement the trait
+on a struct and use this struct constructor. Example:
+
+```
+trait TraitNotAStruct {}
+
+struct Foo {
+    value: i32
+}
+
+Foo{ value: 0 }; // ok!
+```
+"##,
+
 E0166: r##"
 This error means that the compiler found a return expression in a function
 marked as diverging. A function diverges if it has `!` in the place of the
@@ -1978,11 +2058,8 @@ register_diagnostics! {
     E0122,
     E0123,
     E0127,
-    E0128,
     E0129,
-    E0130,
     E0141,
-    E0159,
     E0163,
     E0164,
     E0167,