Fix infix of match

`match` should have the same precedence as alphanumeric operators. This means that `a match { ... } + 1` should give a syntax error.

Author: odersky

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

@@ -983,9 +983,15 @@ object Parsers {
  }
  else
  val t = reduceStack(base, top, minPrec, leftAssoc = true, in.name, isType)
- if !isType && in.token == MATCH then recur(matchClause(t))
+ if !isType && in.token == MATCH then recurAtMinPrec(matchClause(t))
  else t
 
+ def recurAtMinPrec(top: Tree): Tree =
+ if isIdent && isOperator && precedence(in.name) == minInfixPrec
+ || in.token == MATCH
+ then recur(top)
+ else top
+
  recur(first)
  }
 
@@ -2758,8 +2764,8 @@ object Parsers {
  /** OLD: GivenTypes ::= AnnotType {‘,’ AnnotType}
  * NEW: GivenTypes ::= Type {‘,’ Type}
  */
- def givenTypes(newStyle: Boolean, nparams: Int, ofClass: Boolean): List[ValDef] =
- val tps = commaSeparated(() => if newStyle then typ() else annotType())
+ def givenTypes(nparams: Int, ofClass: Boolean): List[ValDef] =
+ val tps = commaSeparated(typ)
  var counter = nparams
  def nextIdx = { counter += 1; counter }
  val paramFlags = if ofClass then Private | Local | ParamAccessor else Param
@@ -2862,7 +2868,7 @@ object Parsers {
  || startParamTokens.contains(in.token)
  || isIdent && (in.name == nme.inline || in.lookaheadIn(BitSet(COLON)))
  if isParams then commaSeparated(() => param())
- else givenTypes(true, nparams, ofClass)
+ else givenTypes(nparams, ofClass)
  checkVarArgsRules(clause)
  clause
  }

tests/neg/match-infix.scala

@@ -0,0 +1,3 @@
+def f = 1 + 1 match {
+ case 2 => 3
+} + 1 // error // error