Add migration rewrite for deprecated assignment syntax

Author: WojciechMazur

compiler/src/dotty/tools/dotc/config/MigrationVersion.scala

@@ -26,7 +26,7 @@ enum MigrationVersion(val warnFrom: SourceVersion, val errorFrom: SourceVersion)
   case WithOperator extends MigrationVersion(`3.4`, future)
   case FunctionUnderscore extends MigrationVersion(`3.4`, future)
   case NonNamedArgumentInJavaAnnotation extends MigrationVersion(`3.6`, `3.6`)
-  case AmbiguousNamedTupleInfixApply extends MigrationVersion(`3.6`, never)
+  case AmbiguousNamedTupleSyntax extends MigrationVersion(`3.6`, future)
   case ImportWildcard extends MigrationVersion(future, future)
   case ImportRename extends MigrationVersion(future, future)
   case ParameterEnclosedByParenthesis extends MigrationVersion(future, future)

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

@@ -1149,8 +1149,8 @@ object Parsers {
       if isType then infixOp
       else infixOp.right match
         case Tuple(args) if args.exists(_.isInstanceOf[NamedArg]) && !isNamedTupleOperator =>
-          report.errorOrMigrationWarning(AmbiguousNamedTupleInfixApply(), infixOp.right.srcPos, MigrationVersion.AmbiguousNamedTupleInfixApply)
-          if MigrationVersion.AmbiguousNamedTupleInfixApply.needsPatch then
+          report.errorOrMigrationWarning(DeprecatedInfixNamedArgumentSyntax(), infixOp.right.srcPos, MigrationVersion.AmbiguousNamedTupleSyntax)
+          if MigrationVersion.AmbiguousNamedTupleSyntax.needsPatch then
             val asApply = cpy.Apply(infixOp)(Select(opInfo.operand, opInfo.operator.name), args)
             patch(source, infixOp.span, asApply.show(using ctx.withoutColors))
             asApply // allow to use pre-3.6 syntax in migration mode

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

@@ -216,8 +216,8 @@ enum ErrorMessageID(val isActive: Boolean = true) extends java.lang.Enum[ErrorMe
   case FinalLocalDefID // errorNumber: 200
   case NonNamedArgumentInJavaAnnotationID // errorNumber: 201
   case QuotedTypeMissingID // errorNumber: 202
-  case AmbiguousNamedTupleAssignmentID // errorNumber: 203
-  case AmbiguousNamedTupleInfixApplyID // errorNumber: 204
+  case DeprecatedAssignmentSyntaxID // errorNumber: 203
+  case DeprecatedInfixNamedArgumentSyntaxID // errorNumber: 204
 
   def errorNumber = ordinal - 1
 

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

@@ -3344,21 +3344,19 @@ final class QuotedTypeMissing(tpe: Type)(using Context) extends StagingMessage(Q
 
 end QuotedTypeMissing
 
-final class AmbiguousNamedTupleAssignment(key: Name, value: untpd.Tree)(using Context) extends SyntaxMsg(AmbiguousNamedTupleAssignmentID):
+final class DeprecatedAssignmentSyntax(key: Name, value: untpd.Tree)(using Context) extends SyntaxMsg(DeprecatedAssignmentSyntaxID):
   override protected def msg(using Context): String =
-    i"""Ambiguous syntax: this is interpreted as a named tuple with one element,
+    i"""Deprecated syntax: in the future it would be interpreted as a named tuple with one element,
       |not as an assignment.
       |
       |To assign a value, use curly braces: `{${key} = ${value}}`."""
-  
+
   override protected def explain(using Context): String = ""
 
-class AmbiguousNamedTupleInfixApply()(using Context) extends SyntaxMsg(AmbiguousNamedTupleInfixApplyID):
+class DeprecatedInfixNamedArgumentSyntax()(using Context) extends SyntaxMsg(DeprecatedInfixNamedArgumentSyntaxID):
   def msg(using Context) =
-    "Ambigious syntax: this infix call argument list is interpreted as single named tuple argument, not as an named arguments list."
-    + Message.rewriteNotice("This", version = SourceVersion.`3.6-migration`)
+    i"""Deprecated syntax: infix named arguments lists are deprecated; in the future it would be interpreted as a single name tuple argument.
+       |To avoid this warning, either remove the argument names or use dotted selection."""
+        + Message.rewriteNotice("This", version = SourceVersion.`3.6-migration`)
 
-  def explain(using Context) =
-    i"""Starting with Scala 3.6 infix named arguments are interpretted as Named Tuple.
-        |
-        |To avoid this warning, either remove the argument names or use dotted selection."""
+  def explain(using Context) = ""

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

@@ -3404,7 +3404,7 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
   /** Translate tuples of all arities */
   def typedTuple(tree: untpd.Tuple, pt: Type)(using Context): Tree =
     val tree1 = desugar.tuple(tree, pt)
-    checkAmbiguousNamedTupleAssignment(tree)
+    checkDeprecatedAssignmentSyntax(tree)
     if tree1 ne tree then typed(tree1, pt)
     else
       val arity = tree.trees.length
@@ -3433,15 +3433,15 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
  /** Checks if `tree` is a named tuple with one element that could be
   *  interpreted as an assignment, such as `(x = 1)`. If so, issues a warning.
   */
-  def checkAmbiguousNamedTupleAssignment(tree: untpd.Tuple)(using Context): Unit =
+  def checkDeprecatedAssignmentSyntax(tree: untpd.Tuple)(using Context): Unit =
     tree.trees match
       case List(NamedArg(name, value)) =>
         val tmpCtx = ctx.fresh.setNewTyperState()
         typedAssign(untpd.Assign(untpd.Ident(name), value), WildcardType)(using tmpCtx)
         if !tmpCtx.reporter.hasErrors then
           // If there are no errors typing the above, then the named tuple is
           // ambiguous and we issue a warning.
-          report.migrationWarning(AmbiguousNamedTupleAssignment(name, value), tree.srcPos)
+          report.migrationWarning(DeprecatedAssignmentSyntax(name, value), tree.srcPos)
       case _ => ()
 
   /** Retrieve symbol attached to given tree */

tests/neg/infix-named-args.check

@@ -14,28 +14,24 @@
 -- [E204] Syntax Warning: tests/neg/infix-named-args.scala:4:15 --------------------------------------------------------
 4 |  def f = 42 + (x = 1) // error // werror
   |               ^^^^^^^
-  |Ambigious syntax: this infix call argument list is interpreted as single named tuple argument, not as an named arguments list.
+  |Deprecated syntax: infix named arguments lists are deprecated; in the future it would be interpreted as a single name tuple argument.
+  |To avoid this warning, either remove the argument names or use dotted selection.
   |This can be rewritten automatically under -rewrite -source 3.6-migration.
-  |
-  | longer explanation available when compiling with `-explain`
 -- [E204] Syntax Warning: tests/neg/infix-named-args.scala:7:26 --------------------------------------------------------
 7 |  def g = new C() `multi` (x = 42, y = 27) // werror
   |                          ^^^^^^^^^^^^^^^^
-  |Ambigious syntax: this infix call argument list is interpreted as single named tuple argument, not as an named arguments list.
+  |Deprecated syntax: infix named arguments lists are deprecated; in the future it would be interpreted as a single name tuple argument.
+  |To avoid this warning, either remove the argument names or use dotted selection.
   |This can be rewritten automatically under -rewrite -source 3.6-migration.
-  |
-  | longer explanation available when compiling with `-explain`
 -- [E204] Syntax Warning: tests/neg/infix-named-args.scala:8:21 --------------------------------------------------------
 8 |  def h = new C() ** (x = 42, y = 27) // werror
   |                     ^^^^^^^^^^^^^^^^
-  |Ambigious syntax: this infix call argument list is interpreted as single named tuple argument, not as an named arguments list.
+  |Deprecated syntax: infix named arguments lists are deprecated; in the future it would be interpreted as a single name tuple argument.
+  |To avoid this warning, either remove the argument names or use dotted selection.
   |This can be rewritten automatically under -rewrite -source 3.6-migration.
-  |
-  | longer explanation available when compiling with `-explain`
 -- [E204] Syntax Warning: tests/neg/infix-named-args.scala:15:18 -------------------------------------------------------
 15 |  def f = this ** (x = 2) // werror
    |                  ^^^^^^^
-   |Ambigious syntax: this infix call argument list is interpreted as single named tuple argument, not as an named arguments list.
+   |Deprecated syntax: infix named arguments lists are deprecated; in the future it would be interpreted as a single name tuple argument.
+   |To avoid this warning, either remove the argument names or use dotted selection.
    |This can be rewritten automatically under -rewrite -source 3.6-migration.
-   |
-   | longer explanation available when compiling with `-explain`

tests/warn/21681.check

@@ -1,7 +1,7 @@
 -- [E203] Syntax Migration Warning: tests/warn/21681.scala:5:2 ---------------------------------------------------------
 5 |  (age = 29) // warn
   |  ^^^^^^^^^^
-  |  Ambiguous syntax: this is interpreted as a named tuple with one element,
+  |  Deprecated syntax: in the future it would be interpreted as a named tuple with one element,
   |  not as an assignment.
   |
   |  To assign a value, use curly braces: `{age = 29}`.

tests/warn/21681b.check

@@ -1,7 +1,7 @@
 -- [E203] Syntax Migration Warning: tests/warn/21681b.scala:5:2 --------------------------------------------------------
 5 |  (age = 29) // warn
   |  ^^^^^^^^^^
-  |  Ambiguous syntax: this is interpreted as a named tuple with one element,
+  |  Deprecated syntax: in the future it would be interpreted as a named tuple with one element,
   |  not as an assignment.
   |
   |  To assign a value, use curly braces: `{age = 29}`.

tests/warn/21681c.check

@@ -1,7 +1,7 @@
 -- [E203] Syntax Migration Warning: tests/warn/21681c.scala:7:2 --------------------------------------------------------
 7 |  (age = 29) // warn
   |  ^^^^^^^^^^
-  |  Ambiguous syntax: this is interpreted as a named tuple with one element,
+  |  Deprecated syntax: in the future it would be interpreted as a named tuple with one element,
   |  not as an assignment.
   |
   |  To assign a value, use curly braces: `{age = 29}`.

tests/warn/21770.check

@@ -1,7 +1,7 @@
 -- [E203] Syntax Migration Warning: tests/warn/21770.scala:7:9 ---------------------------------------------------------
 7 |  f(i => (cache = Some(i))) // warn
   |         ^^^^^^^^^^^^^^^^^
-  |         Ambiguous syntax: this is interpreted as a named tuple with one element,
+  |         Deprecated syntax: in the future it would be interpreted as a named tuple with one element,
   |         not as an assignment.
   |
   |         To assign a value, use curly braces: `{cache = Some(i)}`.