Only allow _numeric_ literals in typed patterns

Author: dwijnand

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -2810,7 +2810,8 @@ object Parsers {
       else Nil
 
     /**  Pattern1     ::= PatVar Ascription
-     *                  | SimpleLiteral Ascription
+     *                  | [‘-’] integerLiteral Ascription
+     *                  | [‘-’] floatingPointLiteral Ascription
      *                  | Pattern2
      */
     def pattern1(location: Location = Location.InPattern): Tree =

docs/_docs/internals/syntax.md

@@ -319,7 +319,8 @@ TypeCaseClause    ::=  ‘case’ (InfixType | ‘_’) ‘=>’ Type [semi]
 
 Pattern           ::=  Pattern1 { ‘|’ Pattern1 }                                Alternative(pats)
 Pattern1          ::=  PatVar ‘:’ RefinedType                                   Bind(name, Typed(Ident(wildcard), tpe))
-                    |  SimpleLiteral ‘:’ RefinedType                            Typed(pat, tpe)
+                    | [‘-’] integerLiteral ‘:’ RefinedType                      Typed(pat, tpe)
+                    | [‘-’] floatingPointLiteral ‘:’ RefinedType                Typed(pat, tpe)
                     |  Pattern2
 Pattern2          ::=  [id ‘@’] InfixPattern [‘*’]                              Bind(name, pat)
 InfixPattern      ::=  SimplePattern { id [nl] SimplePattern }                  InfixOp(pat, op, pat)