Fix multiple line type expression with dotget idempotency (#3133)

* Fix multiple line type expression with dotget idempotency

* Minor refactor

---------

Co-authored-by: nojaf <florian.verdonck@outlook.com>

CHANGELOG.md

@@ -1,9 +1,14 @@
 # Changelog
 
+## 6.3.16 - 2024-10-29
+
+### Fixed
+* Idempotency problem when calling multi-line discriminated union with generic type parameter. [#3132](https://github.com/fsprojects/fantomas/issues/3132)
+
 ## 6.3.15 - 2024-09-14
 
 ### Fixed
-* Non needed parentheses are added around lambda call from tuple/members [#3082](https://github.com/fsprojects/fantomas/issues/3082)
+* Non needed parentheses are added around lambda call from tuple/members. [#3082](https://github.com/fsprojects/fantomas/issues/3082)
 
 ## 6.3.14 - 2024-09-14
 

src/Fantomas.Core.Tests/ChainTests.fs

@@ -414,3 +414,29 @@ v().w.x.y.z['a'].b
         """
 v().w.x.y.z['a'].b
 """
+
+[<Test>]
+let ``multiple line type expression with dotget, 3132`` () =
+    formatSourceString
+        """
+Animal<
+    Identifier
+ >
+    .Dog(
+        "Spot"
+    )
+"""
+        { config with
+            MaxDotGetExpressionWidth = 0
+            MaxLineLength = 10 }
+    |> prepend newline
+    |> should
+        equal
+        """
+Animal<
+    Identifier
+ >
+    .Dog(
+        "Spot"
+    )
+"""

src/Fantomas.Core/CodePrinter.fs

@@ -1014,8 +1014,9 @@ let genExpr (e: Expr) =
                         (coli sepNone leadingChain (fun idx -> genLink (idx = lastIndex)))
                         (match leadingChain with
                          | [] -> sepNone
-                         | head :: rest -> genLink false head +> indentSepNlnUnindent (genIndentedLinks false rest))
-                    +> indentSepNlnUnindent (genIndentedLinks false links)
+                         | [ head ] -> genLink false head
+                         | head :: rest -> genLink false head +> indentSepNlnUnindent (genIndentedLinks true rest))
+                    +> indentSepNlnUnindent (genIndentedLinks true links)
 
             | head :: links -> genFirstLinkAndIndentOther head links