Respect the order of type name. Fixes fsprojects#1018.

nojaf · Aug 21, 2020 · 6188d1e · 6188d1e
1 parent 8665356
commit 6188d1e
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Showing 2 changed files with 11 additions and 1 deletion.
diff --git a/src/Fantomas.Tests/TypeDeclarationTests.fs b/src/Fantomas.Tests/TypeDeclarationTests.fs
@@ -1678,3 +1678,9 @@ type Box() =
     // If there's no get/set, the comment is preserved
     member x.hello = "world"
 """
+
+[<Test>]
+let ``union type with constraint`` () =
+    formatSourceString false """type 'a t when 'a :> IDisposable = T  of  'a option"""  config
+    |> should equal """type 'a t when 'a :> IDisposable = T of 'a option
+"""
diff --git a/src/Fantomas/CodePrinter.fs b/src/Fantomas/CodePrinter.fs
@@ -539,7 +539,11 @@ and genTypeAndParam astContext typeName tds tcs preferPostfix =
          +> colPre (!- " when ") wordAnd tcs (genTypeConstraint astContext) -- closeSep)
     if List.isEmpty tds then !- typeName
     elif preferPostfix then !- typeName +> types "<" ">"
-    elif List.atMostOne tds then types "" "" -- " " -- typeName
+    elif List.atMostOne tds then
+        genTyparDecl { astContext with IsFirstTypeParam = true } (List.head tds)
+        +> sepSpace
+        -- typeName
+        +> colPre (!- " when ") wordAnd tcs (genTypeConstraint astContext)
     else types "(" ")" -- " " -- typeName
 
 and genTypeParamPostfix astContext tds tcs = genTypeAndParam astContext "" tds tcs true