Index: clang/lib/Format/TokenAnnotator.cpp
===================================================================
--- clang/lib/Format/TokenAnnotator.cpp
+++ clang/lib/Format/TokenAnnotator.cpp
@@ -3716,6 +3716,10 @@
       return false;
     if (Right.is(TT_CSharpGenericTypeConstraint))
       return true;
+    if (Right.Next && Right.Next->is(TT_FatArrow) &&
+        (Right.is(tok::numeric_constant) ||
+         (Right.is(tok::identifier) && Right.TokenText == "_")))
+      return true;
 
     // Break after C# [...] and before public/protected/private/internal.
     if (Left.is(TT_AttributeSquare) && Left.is(tok::r_square) &&
Index: clang/unittests/Format/FormatTestCSharp.cpp
===================================================================
--- clang/unittests/Format/FormatTestCSharp.cpp
+++ clang/unittests/Format/FormatTestCSharp.cpp
@@ -1369,5 +1369,15 @@
                Style);
 }
 
+TEST_F(FormatTestCSharp, SwitchExpression) {
+  FormatStyle Style = getMicrosoftStyle(FormatStyle::LK_CSharp);
+  verifyFormat("int x = a switch {\n"
+               "    1 => (0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0),\n"
+               "    2 => 1,\n"
+               "    _ => 2\n"
+               "};\n",
+               Style);
+}
+
 } // namespace format
 } // end namespace clang