- add missing construction of return info node for deconstructed tupl…

…es to fix 2942

- add test cases
- add CHANGELOG entry

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## [Unreleased]
+
+### Fixed
+* Fix loss of tuple type annotation without parens. [#2942](https://github.com/fsprojects/fantomas/issues/2942)
+
 ## 6.3.7 - 2024-06-01
 
 ### Fixed

src/Fantomas.Core.Tests/TupleTests.fs

@@ -515,3 +515,39 @@ a |> fun b -> if b then 0 else 1
         """
 a |> (fun b -> if b then 0 else 1), 2
 """
+
+[<Test>]
+let ``removes type annotation without parens, 2942`` () =
+    formatSourceString
+        """
+let clReducedValues, clFirstActualKeys, clSecondActualKeys: ClArray<'a> * ClArray<int> * ClArray<int> =
+    reduce processor DeviceOnly resultLength clOffsets clFirstKeys clSecondKeys clValues
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let clReducedValues, clFirstActualKeys, clSecondActualKeys: ClArray<'a> * ClArray<int> * ClArray<int> =
+    reduce processor DeviceOnly resultLength clOffsets clFirstKeys clSecondKeys clValues
+"""
+
+[<Test>]
+let ``removes type annotation without parens multiline, 2942`` () =
+    formatSourceString
+        """
+let clReducedValues, // some comment 1
+    clFirstActualKeys, // some comment 2
+    clSecondActualKeys: ClArray<'a> * ClArray<int> * ClArray<int> =
+        reduce processor DeviceOnly resultLength clOffsets clFirstKeys clSecondKeys clValues
+"""
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+let (clReducedValues, // some comment 1
+     clFirstActualKeys, // some comment 2
+     clSecondActualKeys): ClArray<'a> * ClArray<int> * ClArray<int> =
+    reduce processor DeviceOnly resultLength clOffsets clFirstKeys clSecondKeys clValues
+"""

src/Fantomas.Core/CodePrinter.fs

@@ -2986,6 +2986,12 @@ let genBinding (b: BindingNode) (ctx: Context) : Context =
 
             let genDestructedTuples =
                 expressionFitsOnRestOfLine (genPat pat) (sepOpenT +> genPat pat +> sepCloseT)
+                +> optSingle
+                    (fun (rt: BindingReturnInfoNode) ->
+                        genSingleTextNode rt.Colon
+                        +> sepSpace
+                        +> atCurrentColumnIndent (genType rt.Type))
+                    b.ReturnType
 
             genXml b.XmlDoc
             +> genAttrAndPref