From 3de2704b0f9ec6dc0e67c6b0c9a8f61cc6d83f1c Mon Sep 17 00:00:00 2001
From: Florian Verdonck <florian.verdonck@outlook.com>
Date: Wed, 15 Nov 2023 13:50:44 +0100
Subject: [PATCH] Add support for intersectionConstraints in SynTyparDecl.
 (#2986)

---
 CHANGELOG.md                                  |  5 ++++
 .../TypeDeclarationTests.fs                   | 30 +++++++++++++++++++
 src/Fantomas.Core/ASTTransformer.fs           | 15 ++++++++--
 src/Fantomas.Core/CodePrinter.fs              |  3 ++
 src/Fantomas.Core/SyntaxOak.fs                | 21 +++++++++++--
 5 files changed, 70 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6e7aef780d..948ba60cdd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Changelog
 
+## 6.3.0-alpha-003 - 2023-11-15
+
+### Fixed
+* Reformatting code with flexible type syntax remove hash symbol. [#2984](https://github.com/fsprojects/fantomas/issues/2984)
+
 ## 6.3.0-alpha-002 - 2023-11-07
 
 ### Changed
diff --git a/src/Fantomas.Core.Tests/TypeDeclarationTests.fs b/src/Fantomas.Core.Tests/TypeDeclarationTests.fs
index ecaae41409..90faea4c41 100644
--- a/src/Fantomas.Core.Tests/TypeDeclarationTests.fs
+++ b/src/Fantomas.Core.Tests/TypeDeclarationTests.fs
@@ -3631,3 +3631,33 @@ type MyArray3() =
         with get (x: int, y: int, z: int) = ()
         and set (x: int, y: int, z: int) v = ()
 """
+
+[<Test>]
+let ``intersection constraint, 2984`` () =
+    formatSourceString
+        false
+        """
+let typographyLabel<'msg, 'marker & #IFabLabel>() = ()
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let typographyLabel<'msg, 'marker & #IFabLabel> () = ()
+"""
+
+[<Test>]
+let ``multiple intersection constraint, 2984`` () =
+    formatSourceString
+        false
+        """
+let typographyLabel<'msg, 'marker & #IFabLabel & #IFoo & #Bar>() = ()
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let typographyLabel<'msg, 'marker & #IFabLabel & #IFoo & #Bar> () = ()
+"""
diff --git a/src/Fantomas.Core/ASTTransformer.fs b/src/Fantomas.Core/ASTTransformer.fs
index 7082cb47b4..c2cef3c8dc 100644
--- a/src/Fantomas.Core/ASTTransformer.fs
+++ b/src/Fantomas.Core/ASTTransformer.fs
@@ -1997,13 +1997,24 @@ let mkModuleDecl (creationAide: CreationAide) (decl: SynModuleDecl) =
         |> ModuleDecl.NestedModule
     | decl -> failwithf $"Failed to create ModuleDecl for %A{decl}"
 
-let mkSynTyparDecl (creationAide: CreationAide) (SynTyparDecl(attributes = attrs; typar = typar)) =
+let mkSynTyparDecl
+    (creationAide: CreationAide)
+    (SynTyparDecl(attributes = attrs; typar = typar; intersectionConstraints = intersectionConstraints; trivia = trivia))
+    =
     let m =
         match List.tryHead attrs with
         | None -> typar.Range
         | Some a -> unionRanges a.Range typar.Range
 
-    TyparDeclNode(mkAttributes creationAide attrs, mkSynTypar typar, m)
+    let intersectionConstraintNodes =
+        if intersectionConstraints.Length <> trivia.AmpersandRanges.Length then
+            failwith "Unexpected mismatch in SynTyparDecl between intersectionConstraints and AmpersandRanges"
+        else
+            (trivia.AmpersandRanges, intersectionConstraints)
+            ||> List.zip
+            |> List.collect (fun (amp, t) -> [ Choice2Of2(stn "&" amp); Choice1Of2(mkType creationAide t) ])
+
+    TyparDeclNode(mkAttributes creationAide attrs, mkSynTypar typar, intersectionConstraintNodes, m)
 
 let mkSynTyparDecls (creationAide: CreationAide) (tds: SynTyparDecls) : TyparDecls =
     match tds with
diff --git a/src/Fantomas.Core/CodePrinter.fs b/src/Fantomas.Core/CodePrinter.fs
index c97820350b..2f824c37fe 100644
--- a/src/Fantomas.Core/CodePrinter.fs
+++ b/src/Fantomas.Core/CodePrinter.fs
@@ -2538,6 +2538,9 @@ let genTyparDecl (isFirstTypeParam: bool) (td: TyparDeclNode) =
     genOnelinerAttributes td.Attributes
     +> onlyIf (isFirstTypeParam && String.startsWithOrdinal "^" td.TypeParameter.Text) sepSpace
     +> genSingleTextNode td.TypeParameter
+    +> colPre sepSpace sepSpace td.IntersectionConstraints (function
+        | Choice1Of2 t -> genType t
+        | Choice2Of2 amp -> genSingleTextNode amp)
     |> genNode td
 
 let genTyparDecls (td: TyparDecls) =
diff --git a/src/Fantomas.Core/SyntaxOak.fs b/src/Fantomas.Core/SyntaxOak.fs
index 6a962202ad..c9e4c066ab 100644
--- a/src/Fantomas.Core/SyntaxOak.fs
+++ b/src/Fantomas.Core/SyntaxOak.fs
@@ -2680,11 +2680,28 @@ type Constant =
         | Unit n -> n
         | Measure n -> n
 
-type TyparDeclNode(attributes: MultipleAttributeListNode option, typar: SingleTextNode, range) =
+type TyparDeclNode
+    (
+        attributes: MultipleAttributeListNode option,
+        typar: SingleTextNode,
+        intersectionConstraints: Choice<Type, SingleTextNode> list,
+        range
+    ) =
     inherit NodeBase(range)
-    override val Children: Node array = [| yield! noa attributes; yield typar |]
+
+    override val Children: Node array =
+        [| yield! noa attributes
+           yield typar
+           yield!
+               List.map
+                   (function
+                   | Choice1Of2 t -> Type.Node t
+                   | Choice2Of2 amp -> amp :> Node)
+                   intersectionConstraints |]
+
     member val Attributes = attributes
     member val TypeParameter = typar
+    member val IntersectionConstraints = intersectionConstraints
 
 type TyparDeclsPostfixListNode
     (