From 7aa01b80a234f0a1d4cf06c71aa04159fc8bf724 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Wed, 8 Nov 2023 10:57:00 +0100
Subject: [PATCH] Desugar `lazy val` pattern bindings into `lazy val`s

Fixes #18878

Reverts change in 54f6399b6625cb8f841c1e5965841d46a3e9230c

Example:
```
lazy val (a, b) = ...
```
desugars into
```
private lazy val t$1 = ...
lazy val a = t$1._1 // before: def a = t$1._1
lazy val b = t$1._2 // before: def b = t$1._2
```
Where `a` and `b` should be stable identifiers.
---
 compiler/src/dotty/tools/dotc/ast/Desugar.scala | 13 ++++---------
 tests/pos/i18878.scala                          |  6 ++++++
 2 files changed, 10 insertions(+), 9 deletions(-)
 create mode 100644 tests/pos/i18878.scala

diff --git a/compiler/src/dotty/tools/dotc/ast/Desugar.scala b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
index 0607b3729654..7feb727df403 100644
--- a/compiler/src/dotty/tools/dotc/ast/Desugar.scala
+++ b/compiler/src/dotty/tools/dotc/ast/Desugar.scala
@@ -1311,16 +1311,11 @@ object desugar {
           val restDefs =
             for (((named, tpt), n) <- vars.zipWithIndex if named.name != nme.WILDCARD)
             yield
-              if mods.is(Lazy) then
-                DefDef(named.name.asTermName, Nil, tpt, selector(n))
-                  .withMods(mods &~ Lazy)
+              valDef(
+                ValDef(named.name.asTermName, tpt, selector(n))
+                  .withMods(mods)
                   .withSpan(named.span)
-              else
-                valDef(
-                  ValDef(named.name.asTermName, tpt, selector(n))
-                    .withMods(mods)
-                    .withSpan(named.span)
-                )
+              )
           flatTree(firstDef :: restDefs)
       }
   }
diff --git a/tests/pos/i18878.scala b/tests/pos/i18878.scala
new file mode 100644
index 000000000000..9f16983c8241
--- /dev/null
+++ b/tests/pos/i18878.scala
@@ -0,0 +1,6 @@
+object Foo:
+  lazy val (a, (b, c), d) = (1, (2, 3), 4)
+  def a2: a.type = a
+  def b2: b.type = b
+  def c2: c.type = c
+  def d2: d.type = d