Rollup merge of #25255 - caipre:diagnostic-messages, r=alexcrichton

Add a few diagnostic messages; part of  #24407.

src/librustc_typeck/diagnostics.rs

@@ -46,6 +46,23 @@ enum variant, one of the fields was not provided. Each field should be specified
 exactly once.
 "##,
 
+E0067: r##"
+The left-hand side of an assignment operator must be an lvalue expression. An
+lvalue expression represents a memory location and includes item paths (ie,
+namespaced variables), dereferences, indexing expressions, and field references.
+
+```
+use std::collections::LinkedList;
+
+// Good
+let mut list = LinkedList::new();
+
+
+// Bad: assignment to non-lvalue expression
+LinkedList::new() += 1;
+```
+"##,
+
 E0081: r##"
 Enum discriminants are used to differentiate enum variants stored in memory.
 This error indicates that the same value was used for two or more variants,
@@ -119,6 +136,20 @@ construct an instance of the following type using only safe code:
 ```
 enum Empty {}
 ```
+"##,
+
+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 `()`.
+"##,
+
+E0132: r##"
+It is not possible to declare type parameters on a function that has the `start`
+attribute. Such a function must have the following type signature:
+
+```
+fn(isize, *const *const u8) -> isize
+```
 "##
 
 }
@@ -149,7 +180,6 @@ register_diagnostics! {
     E0060,
     E0061,
     E0066,
-    E0067,
     E0068,
     E0069,
     E0070,
@@ -189,8 +219,6 @@ register_diagnostics! {
     E0128,
     E0129,
     E0130,
-    E0131,
-    E0132,
     E0141,
     E0159,
     E0163,