From 472de2565c8f6f8dff7884d5898b53a7c85b333a Mon Sep 17 00:00:00 2001
From: Wojciech Mazur <wmazur@virtuslab.com>
Date: Mon, 18 Nov 2024 10:34:32 +0100
Subject: [PATCH] Handle old given syntax where identifier and type are
 seperated by new line (#21957)

Fixes #21768

Fixes usages of `with {...}` and `= new {}` declarations presented in
tests.
[Cherry-picked 7644ecd6a4933a1750c527a16007f5890c45d0e7]
---
 compiler/src/dotty/tools/dotc/parsing/Parsers.scala | 12 ++++++++++++
 tests/pos/i21768.scala                              | 12 ++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 tests/pos/i21768.scala

diff --git a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
index 98dd5ff0f3f4..807755af7ab0 100644
--- a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
+++ b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -1001,6 +1001,18 @@ object Parsers {
              //      def f = ...
           lookahead.nextToken()
           !lookahead.isAfterLineEnd
+        } || {
+            // Support for for pre-3.6 syntax where type is put on the next line
+            // Examples:
+            //     given namedGiven:
+            //       X[T] with {}
+            //     given otherGiven:
+            //       X[T] = new X[T]{}
+          lookahead.isIdent && {
+            lookahead.nextToken()
+            skipParams()
+            lookahead.token == WITH || lookahead.token == EQUALS
+          }
         }
       }
 
diff --git a/tests/pos/i21768.scala b/tests/pos/i21768.scala
new file mode 100644
index 000000000000..85066d0cb8a6
--- /dev/null
+++ b/tests/pos/i21768.scala
@@ -0,0 +1,12 @@
+
+trait Foo[T]:
+  def foo(v: T): Unit
+
+given myFooOfInt:
+  Foo[Int] with
+  def foo(v: Int): Unit = ???
+
+given myFooOfLong:
+  Foo[Long] = new Foo[Long] {
+    def foo(v: Long): Unit = ???
+  }