Disallow dollars in names in safe mode

compiler/src/dotty/tools/dotc/cc/SafeRefs.scala

@@ -7,13 +7,15 @@ import Symbols.*
 import Annotations.*
 import util.Spans.NoSpan
 import util.{Property, SrcPos}
-import Contexts.Context
+import Contexts.{Context, ctx}
 import Constants.Constant
 import Decorators.*
 import ast.tpd.*
 import SymDenotations.*
 import Flags.*
 import Types.*
+import Names.Name
+import NameOps.isReplWrapperName
 import config.Printers.capt
 
 /** Check whether references from safe mode should be allowed */
@@ -172,6 +174,10 @@ object SafeRefs {
     rejectSafe("scala.runtime.LazyUnit")
   }
 
+  /** Allow name in safe mode even though it contains `$` characters */
+  def allowDollarIn(name: Name)(using Context): Boolean =
+    name.isReplWrapperName && ctx.mode.is(Mode.Interactive)
+
   private def fail(sym: Symbol, reason: String, pos: SrcPos)(using Context) =
     report.error(em"Cannot refer to ${sym.sanitizedDescription}${sym.showExtendedLocation} from safe code since $reason", pos)
     false

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

@@ -19,6 +19,7 @@ import config.Feature.{migrateTo3, sourceVersion}
 import config.SourceVersion.{`3.0`, `3.0-migration`}
 import config.MigrationVersion
 import reporting.*
+import cc.SafeRefs
 
 import java.util.Objects
 import dotty.tools.dotc.reporting.Message.rewriteNotice
@@ -146,8 +147,11 @@ object Scanners {
      *  If `target` is different from `this`, don't treat identifiers as end tokens.
      */
     def finishNamedToken(idtoken: Token, target: TokenData): Unit =
-      target.name = termName(litBuf.chars, 0, litBuf.length)
+      val name = termName(litBuf.chars, 0, litBuf.length)
+      target.name = name
       litBuf.clear()
+      if name.contains('$') && Feature.safeEnabled && !SafeRefs.allowDollarIn(name) then
+        report.error(em"Identifier may not contain '$$' in safe mode", sourcePos())
       target.token = idtoken
       if idtoken == IDENTIFIER then
         val converted = toToken(target.name.nn)

compiler/test/dotc/neg-best-effort-pickling.excludelist

@@ -21,5 +21,8 @@ i974.scala # cyclic reference
 i13864.scala # missing symbol in pickling
 type-params.scala # recursion limit exceeded
 
+unsafe-dollar-in-name.scala # missing owner in unpickler
+unsafe-dollar-in-name-2.scala # missing owner in unpickler
+
 # semantic db generation fails in the first compilation
 i15158.scala # cyclic reference - stack overflow

tests/neg/unsafe-dollar-in-name-2.check

@@ -0,0 +1,8 @@
+-- Error: tests/neg/unsafe-dollar-in-name-2.scala:3:7 ------------------------------------------------------------------
+3 |object Foo$ // error
+  |       ^
+  |       Identifier may not contain '$' in safe mode
+-- Error: tests/neg/unsafe-dollar-in-name-2.scala:5:6 ------------------------------------------------------------------
+5 |class `Bar$` // error
+  |      ^
+  |      Identifier may not contain '$' in safe mode

tests/neg/unsafe-dollar-in-name-2.scala

@@ -0,0 +1,5 @@
+//> using options -language:experimental.safe
+
+object Foo$ // error
+
+class `Bar$` // error

tests/neg/unsafe-dollar-in-name.check

@@ -0,0 +1,8 @@
+-- Error: tests/neg/unsafe-dollar-in-name.scala:3:7 --------------------------------------------------------------------
+3 |object Foo$ // error
+  |       ^
+  |       Identifier may not contain '$' in safe mode
+-- Error: tests/neg/unsafe-dollar-in-name.scala:5:6 --------------------------------------------------------------------
+5 |class `Bar$` // error
+  |      ^
+  |      Identifier may not contain '$' in safe mode

tests/neg/unsafe-dollar-in-name.scala

@@ -0,0 +1,5 @@
+import language.experimental.safe
+
+object Foo$ // error
+
+class `Bar$` // error

tests/neg/wildcard-imports.check

@@ -0,0 +1,8 @@
+-- [E049] Reference Error: tests/neg/wildcard-imports/Test.scala:7:12 --------------------------------------------------
+7 |  val bar = foo // error
+  |            ^^^
+  |            Reference to foo is ambiguous.
+  |            It is both imported by import test.A._
+  |            and imported subsequently by import test.B._
+  |
+  | longer explanation available when compiling with `-explain`

tests/neg/wildcard-imports/A.scala

@@ -0,0 +1,4 @@
+package test
+
+object A:
+  def foo: Int = 0

tests/neg/wildcard-imports/B.scala

@@ -0,0 +1,4 @@
+package test
+
+object B:
+  def foo: Int = 0

tests/neg/wildcard-imports/Test.scala

@@ -0,0 +1,8 @@
+package test
+
+import A.*
+import B.*
+
+object Test:
+  val bar = foo // error
+