Help with defdef

Author: som-snytt

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

@@ -4191,6 +4191,10 @@ object Parsers {
             tpt = scalaUnit
             if (in.token == LBRACE) expr()
             else EmptyTree
+          else if in.token == IDENTIFIER && paramss.isEmpty && name.endsWith(":") then
+            val help = i"; identifier ends in colon, did you mean `${name.toSimpleName.dropRight(1)}`: in backticks?"
+            syntaxErrorOrIncomplete(ExpectedTokenButFound(EQUALS, in.token, suffix = help))
+            EmptyTree
           else
             if (!isExprIntro) syntaxError(MissingReturnType(), in.lastOffset)
             accept(EQUALS)

tests/neg/i18020b.check

@@ -9,7 +9,7 @@
 -- [E040] Syntax Error: tests/neg/i18020b.scala:4:10 -------------------------------------------------------------------
 4 |  def g_: Int = 27 // error
   |          ^^^
-  |          '=' expected, but identifier found
+  |          '=' expected, but identifier found; identifier ends in colon, did you mean `g_`: in backticks?
 -- [E040] Syntax Error: tests/neg/i18020b.scala:6:12 -------------------------------------------------------------------
 6 |    val x_: Int = 1 // error
   |            ^^^