Fix #1846: add regression test

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

@@ -1564,7 +1564,6 @@ object Parsers {
      *                    |  `(' [Patterns] `)'
      *                    |  SimplePattern1 [TypeArgs] [ArgumentPatterns]
      *  SimplePattern1   ::= Path
-     *                    |  `{' Block `}'
      *                    |  SimplePattern1 `.' id
      *  PatVar           ::= id
      *                    |  `_'
@@ -1587,8 +1586,6 @@ object Parsers {
         } else wildIndent
       case LPAREN =>
         atPos(in.offset) { makeTupleOrParens(inParens(patternsOpt())) }
-      case LBRACE =>
-        dotSelectors(blockExpr())
       case XMLSTART =>
         xmlLiteralPattern()
       case _ =>

compiler/src/dotty/tools/dotc/typer/ReTyper.scala

@@ -35,7 +35,8 @@ class ReTyper extends Typer {
 
   override def typedSelect(tree: untpd.Select, pt: Type)(implicit ctx: Context): Tree = {
     assert(tree.hasType, tree)
-    val qual1 = typed(tree.qualifier, AnySelectionProto)
+    // a qualifier cannot be a pattern
+    val qual1 = typed(tree.qualifier, AnySelectionProto)(ctx.retractMode(Mode.Pattern))
     untpd.cpy.Select(tree)(qual1, tree.name).withType(tree.typeOpt)
   }
 

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -2453,7 +2453,7 @@ class Typer extends Namer
     */
   protected def checkEqualityEvidence(tree: tpd.Tree, pt: Type)(implicit ctx: Context) : Unit = {
     tree match {
-      case _: RefTree | _: Literal
+      case _: RefTree | _: Literal | _: Apply
         if !isVarPattern(tree) &&
           !(tree.tpe <:< pt) (ctx.addMode(Mode.GADTflexible)) =>
         val cmp =

docs/docs/internals/syntax.md

@@ -202,7 +202,7 @@ ParArgumentExprs  ::=  ‘(’ ExprsInParens ‘)’
                     |  ‘(’ [ExprsInParens] PostfixExpr ‘:’ ‘_’ ‘*’ ‘)’          exprs :+ Typed(expr, Ident(wildcardStar))
 ArgumentExprs     ::=  ParArgumentExprs
                     |  [nl] BlockExpr
-BlockExpr         ::=  ‘{’ BlockExprContents ‘}’                                
+BlockExpr         ::=  ‘{’ BlockExprContents ‘}’
 BlockExprContents ::=  CaseClauses | Block
 Block             ::=  {BlockStat semi} [BlockResult]                           Block(stats, expr?)
 BlockStat         ::=  Import
@@ -234,7 +234,6 @@ SimplePattern     ::=  PatVar
                     |  XmlPattern
                     |  SimplePattern1 [TypeArgs] [ArgumentPatterns]
 SimplePattern1    ::=  Path
-                    |  ‘{’ Block ‘}’
                     |  SimplePattern1 ‘.’ id
 PatVar            ::=  varid
                     |  ‘_’

tests/neg/i1846.scala

@@ -0,0 +1,21 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    val x = 42
+    val Y = "42"
+
+    x match { case { 42 }           => () } // error
+    x match { case { 42.toString }  => () } // error
+    x match { case { 42 }.toString  => () } // error
+    x match { case "42".toInt       => () } // error
+    x match { case { "42".toInt }   => () } // error
+    x match { case { "42" }.toInt   => () } // error
+    x match { case { "42".toInt }   => () } // error
+    x match { case Y                => () } // error
+    x match { case Y.toInt          => () } // ok
+    x match { case { Y.toInt }      => () } // error
+    x match { case { Y }.toInt      => () } // error
+    x match { case Y.toString       => () } // error
+    x match { case { Y }.toString   => () } // error
+    x match { case { Y.toString }   => () } // error
+  }
+}

tests/neg/i3812.scala

@@ -0,0 +1,14 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    val x = 42
+    val Y = "42"
+
+    x match { case { 42 }           => () } // error
+    x match { case { "42".toInt }   => () } // error
+    x match { case { "42" }.toInt   => () } // error
+    x match { case { "42".toInt }   => () } // error
+    x match { case { Y.toInt }      => () } // error
+    x match { case { Y }.toInt      => () } // error
+    x match { case Y.toInt          => () } // ok
+  }
+}

tests/run/i3812.scala

@@ -0,0 +1,8 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    val x = 42
+    val Y = "42"
+
+    x match { case Y.toInt          => () } // ok
+  }
+}