From c8a489ddffc992e62b2a09ae349d4940b8af66e8 Mon Sep 17 00:00:00 2001
From: aherlihy <herlihyap@gmail.com>
Date: Wed, 15 Oct 2025 12:31:59 +0200
Subject: [PATCH] Prohibit named tuple keys called 'apply'

---
 compiler/src/dotty/tools/dotc/ast/Desugar.scala |  4 ++++
 compiler/src/dotty/tools/dotc/typer/Typer.scala | 13 ++++++++-----
 tests/neg/i24021.check                          |  8 ++++++++
 tests/neg/i24021.scala                          |  4 ++++
 4 files changed, 24 insertions(+), 5 deletions(-)
 create mode 100644 tests/neg/i24021.check
 create mode 100644 tests/neg/i24021.scala

diff --git a/compiler/src/dotty/tools/dotc/ast/Desugar.scala b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
index ba7b9132e88a..e5d10483d28d 100644
--- a/compiler/src/dotty/tools/dotc/ast/Desugar.scala
+++ b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
@@ -1749,6 +1749,10 @@ object desugar {
         report.error(
             em"$name cannot be used as the name of a tuple element because it is a regular tuple selector",
             arg.srcPos)
+      if name == nme.apply then
+        report.error(
+            em"$name cannot be used as the name of a tuple element",
+            arg.srcPos)
 
     elems match
     case elem :: elems1 =>
diff --git a/compiler/src/dotty/tools/dotc/typer/Typer.scala b/compiler/src/dotty/tools/dotc/typer/Typer.scala
index e5841a3de768..12f185b34652 100644
--- a/compiler/src/dotty/tools/dotc/typer/Typer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Typer.scala
@@ -849,11 +849,14 @@ class Typer(@constructorOnly nestingLevel: Int = 0) extends Namer
       val namedTupleElems = qual.tpe.widenDealias.namedTupleElementTypes(true)
       val nameIdx = namedTupleElems.indexWhere(_._1 == selName)
       if nameIdx >= 0 && sourceVersion.enablesNamedTuples then
-        typed(
-          untpd.Apply(
-            untpd.Select(untpd.TypedSplice(qual), nme.apply),
-            untpd.Literal(Constant(nameIdx))),
-          pt)
+        if selName == nme.apply then
+          EmptyTree
+        else
+          typed(
+            untpd.Apply(
+              untpd.Select(untpd.TypedSplice(qual), nme.apply),
+              untpd.Literal(Constant(nameIdx))),
+            pt)
       else EmptyTree
 
     // Otherwise, map combinations of A *: B *: .... EmptyTuple with nesting levels <= 22
diff --git a/tests/neg/i24021.check b/tests/neg/i24021.check
new file mode 100644
index 000000000000..a34086e02265
--- /dev/null
+++ b/tests/neg/i24021.check
@@ -0,0 +1,8 @@
+-- Error: tests/neg/i24021.scala:2:3 -----------------------------------------------------------------------------------
+2 |  (apply = () => 1, k2 = 2).k2 // error
+  |   ^^^^^^^^^^^^^^^
+  |   apply cannot be used as the name of a tuple element
+-- Error: tests/neg/i24021.scala:3:3 -----------------------------------------------------------------------------------
+3 |  (apply = () => 1)() // error
+  |   ^^^^^^^^^^^^^^^
+  |   apply cannot be used as the name of a tuple element
diff --git a/tests/neg/i24021.scala b/tests/neg/i24021.scala
new file mode 100644
index 000000000000..08780adbe560
--- /dev/null
+++ b/tests/neg/i24021.scala
@@ -0,0 +1,4 @@
+@main def Test = {
+  (apply = () => 1, k2 = 2).k2 // error
+  (apply = () => 1)() // error
+}