SimplePattern errors should now be recovered as wildcard instead of unimplemented expr (#21438)

rochala · WojciechMazur · commit 28d13976feda · 2024-12-03T21:15:33.000+01:00
We should not emit more errors that came from our error recovery term trees. Previously, we've recovered those situations with unimplemented expression term added in #19103 and before that it was just a `null` [Cherry-picked f036195]
diff --git a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -3035,7 +3035,7 @@ object Parsers {
         else {
           val start = in.lastOffset
           syntaxErrorOrIncomplete(IllegalStartOfSimplePattern(), expectedOffset)
-          errorTermTree(start)
+          atSpan(Span(start, in.offset)) { Ident(nme.WILDCARD) }
         }
     }
 
diff --git a/tests/neg/i5004.scala b/tests/neg/i5004.scala
@@ -2,5 +2,5 @@ object i0 {
 1 match {
 def this(): Int  // error
   def this()
-} // error
+}
 }
diff --git a/tests/neg/parser-stability-1.scala b/tests/neg/parser-stability-1.scala
@@ -1,4 +1,3 @@
 object x0 {
 x1 match  // error
 def this // error
-// error

Original file line number	Diff line number	Diff line change
`@@ -3035,7 +3035,7 @@ object Parsers {`
`3035`	`3035`	`else {`
`3036`	`3036`	`val start = in.lastOffset`
`3037`	`3037`	`syntaxErrorOrIncomplete(IllegalStartOfSimplePattern(), expectedOffset)`
`3038`		`- errorTermTree(start)`
	`3038`	`+ atSpan(Span(start, in.offset)) { Ident(nme.WILDCARD) }`
`3039`	`3039`	`}`
`3040`	`3040`	`}`
`3041`	`3041`
Original file line number	Diff line number	Diff line change
`@@ -2,5 +2,5 @@ object i0 {`
`2`	`2`	`1 match {`
`3`	`3`	`def this(): Int // error`
`4`	`4`	`def this()`
`5`		`-} // error`
	`5`	`+}`
`6`	`6`	`}`