Merge pull request #15012 from dotty-staging/tighten-quoted-and-spliced-types

Disallow old uses of quoted and spliced types

Author: nicolasstucki

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -1911,8 +1911,6 @@ object desugar {
         new UntypedTreeTraverser {
           def traverse(tree: untpd.Tree)(using Context): Unit = tree match {
             case Splice(expr) => collect(expr)
-            case TypSplice(expr) =>
-              report.error(TypeSpliceInValPattern(expr), tree.srcPos)
             case _ => traverseChildren(tree)
           }
         }.traverse(expr)

compiler/src/dotty/tools/dotc/ast/untpd.scala

@@ -110,7 +110,6 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
   case class Splice(expr: Tree)(implicit @constructorOnly src: SourceFile) extends TermTree {
     def isInBraces: Boolean = span.end != expr.span.end
   }
-  case class TypSplice(expr: Tree)(implicit @constructorOnly src: SourceFile) extends TypTree
   case class ForYield(enums: List[Tree], expr: Tree)(implicit @constructorOnly src: SourceFile) extends TermTree
   case class ForDo(enums: List[Tree], body: Tree)(implicit @constructorOnly src: SourceFile) extends TermTree
   case class GenFrom(pat: Tree, expr: Tree, checkMode: GenCheckMode)(implicit @constructorOnly src: SourceFile) extends Tree
@@ -613,10 +612,6 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
       case tree: Splice if expr eq tree.expr => tree
       case _ => finalize(tree, untpd.Splice(expr)(tree.source))
     }
-    def TypSplice(tree: Tree)(expr: Tree)(using Context): Tree = tree match {
-      case tree: TypSplice if expr eq tree.expr => tree
-      case _ => finalize(tree, untpd.TypSplice(expr)(tree.source))
-    }
     def ForYield(tree: Tree)(enums: List[Tree], expr: Tree)(using Context): TermTree = tree match {
       case tree: ForYield if (enums eq tree.enums) && (expr eq tree.expr) => tree
       case _ => finalize(tree, untpd.ForYield(enums, expr)(tree.source))
@@ -695,8 +690,6 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
         cpy.Quote(tree)(transform(t))
       case Splice(expr) =>
         cpy.Splice(tree)(transform(expr))
-      case TypSplice(expr) =>
-        cpy.TypSplice(tree)(transform(expr))
       case ForYield(enums, expr) =>
         cpy.ForYield(tree)(transform(enums), transform(expr))
       case ForDo(enums, body) =>
@@ -754,8 +747,6 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
         this(x, t)
       case Splice(expr) =>
         this(x, expr)
-      case TypSplice(expr) =>
-        this(x, expr)
       case ForYield(enums, expr) =>
         this(this(x, enums), expr)
       case ForDo(enums, body) =>

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

@@ -452,8 +452,6 @@ object Parsers {
         makeParameter(nme.ERROR, tree, mods)
       case Typed(id @ Ident(name), tpt) =>
         makeParameter(name.asTermName, tpt, mods, isBackquoted = isBackquoted(id)).withSpan(tree.span)
-      case Typed(Splice(Ident(name)), tpt) =>
-        makeParameter(("$" + name).toTermName, tpt, mods).withSpan(tree.span)
       case _ =>
         syntaxError(s"not a legal $expected", tree.span)
         makeParameter(nme.ERROR, tree, mods)
@@ -1572,13 +1570,15 @@ object Parsers {
     /** The block in a quote or splice */
     def stagedBlock() = inBraces(block(simplify = true))
 
-    /** SimpleExpr  ::=  spliceId | ‘$’ ‘{’ Block ‘}’)  unless inside quoted pattern
-     *  SimpleType  ::=  spliceId | ‘$’ ‘{’ Block ‘}’)  unless inside quoted pattern
-     *
-     *  SimpleExpr  ::=  spliceId | ‘$’ ‘{’ Pattern ‘}’)  when inside quoted pattern
-     *  SimpleType  ::=  spliceId | ‘$’ ‘{’ Pattern ‘}’)  when inside quoted pattern
+    /** ExprSplice  ::=  ‘$’ spliceId          --     if inside quoted block
+     *                |  ‘$’ ‘{’ Block ‘}’     -- unless inside quoted pattern
+     *                |  ‘$’ ‘{’ Pattern ‘}’   --   when inside quoted pattern
+     *  TypeSplice  ::=  ‘$’ spliceId          --    if inside quoted type
+     *                |  ‘$’ ‘{’ Block ‘}’     -- unless inside quoted type pattern
+     *                |  ‘$’ ‘{’ Pattern ‘}’   --   when inside quoted type pattern
      */
     def splice(isType: Boolean): Tree =
+      val start = in.offset
       atSpan(in.offset) {
         val expr =
           if (in.name.length == 1) {
@@ -1591,13 +1591,22 @@ object Parsers {
             in.nextToken()
             id
           }
-        if (isType) TypSplice(expr) else Splice(expr)
+        if isType then
+          val msg = "Type splicing with `$` in quotes not supported anymore"
+          val inPattern = (staged & StageKind.QuotedPattern) != 0
+          val hint =
+            if inPattern then "Use lower cased variable name without the `$` instead"
+            else "To use a given Type[T] in a quote just write T directly"
+          syntaxError(s"$msg\n\nHint: $hint", Span(start, in.lastOffset))
+          Ident(nme.ERROR.toTypeName)
+        else
+          Splice(expr)
       }
 
     /**  SimpleType      ::=  SimpleLiteral
      *                     |  ‘?’ SubtypeBounds
      *                     |  SimpleType1
-     *                     |  SimpeType ‘(’ Singletons ‘)’  -- under language.experimental.dependent, checked in Typer
+     *                     |  SimpleType ‘(’ Singletons ‘)’  -- under language.experimental.dependent, checked in Typer
      *   Singletons      ::=  Singleton {‘,’ Singleton}
      */
     def simpleType(): Tree =
@@ -1635,7 +1644,7 @@ object Parsers {
      *                     |  Singleton `.' type
      *                     |  ‘(’ ArgTypes ‘)’
      *                     |  Refinement
-     *                     |  ‘$’ ‘{’ Block ‘}’
+     *                     |  TypeSplice                -- deprecated syntax (since 3.0.0)
      *                     |  SimpleType1 TypeArgs
      *                     |  SimpleType1 `#' id
      */
@@ -2237,7 +2246,7 @@ object Parsers {
     /** SimpleExpr    ::= ‘new’ ConstrApp {`with` ConstrApp} [TemplateBody]
      *                 |  ‘new’ TemplateBody
      *                 |  BlockExpr
-     *                 |  ‘$’ ‘{’ Block ‘}’
+     *                 |  ExprSplice
      *                 |  Quoted
      *                 |  quoteId
      *                 |  SimpleExpr1 [`_`]

compiler/src/dotty/tools/dotc/printing/RefinedPrinter.scala

@@ -691,8 +691,6 @@ class RefinedPrinter(_ctx: Context) extends PlainPrinter(_ctx) {
         keywordStr("'{") ~ toTextGlobal(dropBlock(tree)) ~ keywordStr("}")
       case Splice(tree) =>
         keywordStr("${") ~ toTextGlobal(dropBlock(tree)) ~ keywordStr("}")
-      case TypSplice(tree) =>
-        keywordStr("${") ~ toTextGlobal(dropBlock(tree)) ~ keywordStr("}")
       case Thicket(trees) =>
         "Thicket {" ~~ toTextGlobal(trees, "\n") ~~ "}"
       case MacroTree(call) =>

compiler/src/dotty/tools/dotc/reporting/ErrorMessageID.scala

@@ -19,8 +19,8 @@ enum ErrorMessageID(val isActive: Boolean = true) extends java.lang.Enum[ErrorMe
   case TypeMismatchID // errorNumber: 7
   case NotAMemberID // errorNumber: 8
   case EarlyDefinitionsNotSupportedID // errorNumber: 9
-  case TopLevelImplicitClassID extends ErrorMessageID(isActive = false) // errorNumber: 10 
-  case ImplicitCaseClassID // errorNumber: 11 
+  case TopLevelImplicitClassID extends ErrorMessageID(isActive = false) // errorNumber: 10
+  case ImplicitCaseClassID // errorNumber: 11
   case ImplicitClassPrimaryConstructorArityID // errorNumber: 12
   case ObjectMayNotHaveSelfTypeID // errorNumber: 13
   case TupleTooLongID extends ErrorMessageID(isActive = false) // errorNumber: 14
@@ -97,7 +97,7 @@ enum ErrorMessageID(val isActive: Boolean = true) extends java.lang.Enum[ErrorMe
   case FunctionTypeNeedsNonEmptyParameterListID // errorNumber: 85
   case WrongNumberOfParametersID // errorNumber: 86
   case DuplicatePrivateProtectedQualifierID // errorNumber: 87
-  case ExpectedStartOfTopLevelDefinitionID // errorNumber: 88 
+  case ExpectedStartOfTopLevelDefinitionID // errorNumber: 88
   case MissingReturnTypeWithReturnStatementID // errorNumber: 89
   case NoReturnFromInlineableID // errorNumber: 90
   case ReturnOutsideMethodDefinitionID // errorNumber: 91
@@ -164,7 +164,7 @@ enum ErrorMessageID(val isActive: Boolean = true) extends java.lang.Enum[ErrorMe
   case ExtensionCanOnlyHaveDefsID // errorNumber: 152
   case UnexpectedPatternForSummonFromID // errorNumber: 153
   case AnonymousInstanceCannotBeEmptyID // errorNumber: 154
-  case TypeSpliceInValPatternID // errorNumber: 155
+  case TypeSpliceInValPatternID extends ErrorMessageID(isActive = false) // errorNumber: 155
   case ModifierNotAllowedForDefinitionID // errorNumber: 156
   case CannotExtendJavaEnumID // errorNumber: 157
   case InvalidReferenceInImplicitNotFoundAnnotationID // errorNumber: 158

compiler/src/dotty/tools/dotc/reporting/messages.scala

@@ -2447,15 +2447,6 @@ import transform.SymUtils._
            |""".stripMargin
   }
 
-  class TypeSpliceInValPattern(expr:  untpd.Tree)(using Context)
-    extends SyntaxMsg(TypeSpliceInValPatternID) {
-    def msg = "Type splices cannot be used in val patterns. Consider using `match` instead."
-    def explain =
-      em"""|Type splice: `$$${expr.show}` cannot be used in a `val` pattern. Consider rewriting the `val` pattern
-           |as a `match` with a corresponding `case` to replace the `val`.
-           |""".stripMargin
-  }
-
   class ModifierNotAllowedForDefinition(flag: Flag)(using Context)
     extends SyntaxMsg(ModifierNotAllowedForDefinitionID) {
     def msg = em"Modifier ${hl(flag.flagsString)} is not allowed for this definition"

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

@@ -38,8 +38,6 @@ trait QuotesAndSplices {
     tree.quoted match {
       case untpd.Splice(innerExpr) if tree.isTerm && !ctx.mode.is(Mode.Pattern) =>
         report.warning("Canceled splice directly inside a quote. '{ ${ XYZ } } is equivalent to XYZ.", tree.srcPos)
-      case untpd.TypSplice(innerType) if tree.isType =>
-        report.warning("Canceled splice directly inside a quote. '[ ${ XYZ } ] is equivalent to XYZ.", tree.srcPos)
       case _ =>
     }
     val qctx = inferImplicitArg(defn.QuotesClass.typeRef, tree.span)
@@ -52,11 +50,12 @@ trait QuotesAndSplices {
     if ctx.mode.is(Mode.Pattern) then
       typedQuotePattern(tree, pt, qctx).withSpan(tree.span)
     else if tree.quoted.isType then
-      val msg = em"Consider using canonical type constructor scala.quoted.Type.of[${tree.quoted}] instead"
-      if sourceVersion.isAtLeast(`future-migration`) then report.error(msg, tree.srcPos)
-      else report.warning(msg, tree.srcPos)
-      val typeOfTree = untpd.TypeApply(untpd.ref(defn.QuotedTypeModule_of.termRef), tree.quoted :: Nil).withSpan(tree.span)
-      makeInlineable(typedTypeApply(typeOfTree, pt)(using quoteContext).select(nme.apply).appliedTo(qctx).withSpan(tree.span))
+      val msg = em"""Quoted types `'[..]` can only be used in patterns.
+                    |
+                    |Hint: To get a scala.quoted.Type[T] use scala.quoted.Type.of[T] instead.
+                    |""".stripMargin
+      report.error(msg, tree.srcPos)
+      EmptyTree
     else
       val exprQuoteTree = untpd.Apply(untpd.ref(defn.QuotedRuntime_exprQuote.termRef), tree.quoted)
       makeInlineable(typedApply(exprQuoteTree, pt)(using pushQuotes(qctx)).select(nme.apply).appliedTo(qctx).withSpan(tree.span))
@@ -135,7 +134,7 @@ trait QuotesAndSplices {
         case arg: untpd.Ident =>
           typedExpr(arg)
         case arg =>
-          report.error("Open patttern exprected an identifier", arg.srcPos)
+          report.error("Open pattern expected an identifier", arg.srcPos)
           EmptyTree
       }
       if args.isEmpty then
@@ -145,30 +144,6 @@ trait QuotesAndSplices {
       ref(defn.QuotedRuntimePatterns_patternHigherOrderHole).appliedToType(pt).appliedTo(typedPat, SeqLiteral(typedArgs, TypeTree(defn.AnyType)))
   }
 
-  /** Translate ${ t: Type[T] }` into type `t.splice` while tracking the quotation level in the context */
-  def typedTypSplice(tree: untpd.TypSplice, pt: Type)(using Context): Tree = {
-    record("typedTypSplice")
-    checkSpliceOutsideQuote(tree)
-    tree.expr match {
-      case untpd.Quote(innerType) if innerType.isType =>
-        report.warning("Canceled quote directly inside a splice. ${ '[ XYZ ] } is equivalent to XYZ.", tree.srcPos)
-      case _ =>
-    }
-
-    if ctx.mode.is(Mode.QuotedPattern) && level == 1 then
-      report.error(
-            """`$` for quote pattern variable is not supported anymore.
-               |Use lower cased variable name without the `$` instead.""".stripMargin,
-            tree.srcPos)
-      ref(defn.NothingType)
-    else
-      val tree1 = typedSelect(untpd.Select(tree.expr, tpnme.Underlying), pt)(using spliceContext).withSpan(tree.span)
-      val msg = em"Consider using canonical type reference ${tree1.tpe} instead"
-      if sourceVersion.isAtLeast(`future-migration`) then report.error(msg, tree.srcPos)
-      else report.warning(msg, tree.srcPos)
-      tree1
-  }
-
   /** Type a pattern variable name `t` in quote pattern as `${given t$giveni: Type[t @ _]}`.
    *  The resulting pattern is the split in `splitQuotePattern`.
    */

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

@@ -2898,7 +2898,6 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
           case untpd.EmptyTree => tpd.EmptyTree
           case tree: untpd.Quote => typedQuote(tree, pt)
           case tree: untpd.Splice => typedSplice(tree, pt)
-          case tree: untpd.TypSplice => typedTypSplice(tree, pt)
           case tree: untpd.MacroTree => report.error("Unexpected macro", tree.srcPos); tpd.nullLiteral  // ill-formed code may reach here
           case tree: untpd.Hole => typedHole(tree, pt)
           case _ => typedUnadapted(desugar(tree), pt, locked)

docs/_docs/internals/syntax.md

@@ -27,7 +27,7 @@ upper            ::=  ‘A’ | … | ‘Z’ | ‘\$’ | ‘_’  “… and U
 lower            ::=  ‘a’ | … | ‘z’ “… and Unicode category Ll”
 letter           ::=  upper | lower “… and Unicode categories Lo, Lt, Lm, Nl”
 digit            ::=  ‘0’ | … | ‘9’
-paren            ::=  ‘(’ | ‘)’ | ‘[’ | ‘]’ | ‘{’ | ‘}’ | ‘'(’ | ‘'[’ | ‘'{’
+paren            ::=  ‘(’ | ‘)’ | ‘[’ | ‘]’ | ‘{’ | ‘}’
 delim            ::=  ‘`’ | ‘'’ | ‘"’ | ‘.’ | ‘;’ | ‘,’
 opchar           ::=  ‘!’ | ‘#’ | ‘%’ | ‘&’ | ‘*’ | ‘+’ | ‘-’ | ‘/’ | ‘:’ |
                       ‘<’ | ‘=’ | ‘>’ | ‘?’ | ‘@’ | ‘\’ | ‘^’ | ‘|’ | ‘~’
@@ -45,6 +45,7 @@ id               ::=  plainid
                    |  ‘`’ { charNoBackQuoteOrNewline | UnicodeEscape | charEscapeSeq } ‘`’
 idrest           ::=  {letter | digit} [‘_’ op]
 quoteId          ::=  ‘'’ alphaid
+spliceId         ::=  ‘$’ alphaid ;
 
 integerLiteral   ::=  (decimalNumeral | hexNumeral) [‘L’ | ‘l’]
 decimalNumeral   ::=  ‘0’ | nonZeroDigit [{digit | ‘_’} digit]
@@ -183,8 +184,7 @@ SimpleType1       ::=  id
                     |  Singleton ‘.’ ‘type’                                     SingletonTypeTree(p)
                     |  ‘(’ Types ‘)’                                            Tuple(ts)
                     |  Refinement                                               RefinedTypeTree(EmptyTree, refinement)
-                    |  ‘$’ ‘{’ Block ‘}’                                        -- unless inside quoted pattern
-                    |  ‘$’ ‘{’ Pattern ‘}’                                      -- only inside quoted pattern
+                    |  TypeSplice                                               -- deprecated syntax
                     |  SimpleType1 TypeArgs                                     AppliedTypeTree(t, args)
                     |  SimpleType1 ‘#’ id                                       Select(t, name)
 Singleton         ::=  SimpleRef
@@ -243,8 +243,7 @@ SimpleExpr        ::=  SimpleRef
                     |  Literal
                     |  ‘_’
                     |  BlockExpr
-                    |  ‘$’ ‘{’ Block ‘}’                                        -- unless inside quoted pattern
-                    |  ‘$’ ‘{’ Pattern ‘}’                                      -- only inside quoted pattern
+                    |  ExprSplice
                     |  Quoted
                     |  quoteId                                                  -- only inside splices
                     |  ‘new’ ConstrApp {‘with’ ConstrApp} [TemplateBody]        New(constr | templ)
@@ -259,8 +258,14 @@ SimpleExpr        ::=  SimpleRef
                     |  SimpleExpr ‘_’                                           PostfixOp(expr, _) (to be dropped)
                     |  XmlExpr													                        -- to be dropped
 IndentedExpr      ::=  indent CaseClauses | Block outdent
-Quoted            ::=  ‘'’ ‘{’ Block ‘}’  
+Quoted            ::=  ‘'’ ‘{’ Block ‘}’
                     |  ‘'’ ‘[’ Type ‘]’
+ExprSplice        ::= spliceId                                                  -- if inside quoted block
+                    |  ‘$’ ‘{’ Block ‘}’                                        -- unless inside quoted pattern
+                    |  ‘$’ ‘{’ Pattern ‘}’                                      -- when inside quoted pattern
+TypeSplice        ::= spliceId                                                  -- if inside quoted type -- deprecated syntax
+                    |  ‘$’ ‘{’ Block ‘}’                                        -- unless inside quoted type pattern -- deprecated syntax
+                    |  ‘$’ ‘{’ Pattern ‘}’                                      -- when inside quoted type pattern -- deprecated syntax
 ExprsInParens     ::=  ExprInParens {‘,’ ExprInParens}
 ExprInParens      ::=  PostfixExpr ‘:’ Type                                     -- normal Expr allows only RefinedType here
                     |  Expr