Avoid vanity alignment in long pattern match

Fixes https://github.com/fsprojects/fantomas/issues/1926
nblockchain · Nov 11, 2021 · c0e56ec · c0e56ec
1 parent bc5733e
commit c0e56ec
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Showing 2 changed files with 50 additions and 4 deletions.
diff --git a/src/Fantomas.Tests/PatternMatchingTests.fs b/src/Fantomas.Tests/PatternMatchingTests.fs
@@ -2056,3 +2056,34 @@ match!
 | None -> false
 | Some balance -> someRetrievedBalance = balance
 """
+
+[<Test>]
+let ``vanity alignment used when using long case in match block, 1926`` () =
+    formatSourceString
+        false
+        """
+match foo with
+| SomeVeryLongMatchCase(1234567890, 1234567890, 1234567890, 1234567890, 1234567890, 1234567890, 1234567890, 1234567890, 1234567890, 1234567890) ->
+    bar()
+| _ -> () """
+        config
+    |> prepend newline
+    |> should
+        equal
+        """
+match foo with
+| SomeVeryLongMatchCase
+    (
+        1234567890,
+        1234567890,
+        1234567890,
+        1234567890,
+        1234567890,
+        1234567890,
+        1234567890,
+        1234567890,
+        1234567890,
+        1234567890
+    ) -> bar ()
+| _ -> ()
+"""
diff --git a/src/Fantomas/CodePrinter.fs b/src/Fantomas/CodePrinter.fs
@@ -4971,10 +4971,25 @@ and genPat astContext pat =
                     | _ -> true
                 | _ -> true
 
-        ifElse isParenNecessary sepOpenT sepSpace
-        +> genPat astContext p
-        +> enterNodeTokenByName pat.Range RPAREN
-        +> ifElse isParenNecessary sepCloseT sepNone
+        let shortExpr =
+            ifElse isParenNecessary sepOpenT sepSpace
+            +> genPat astContext p
+            +> enterNodeTokenByName pat.Range RPAREN
+            +> ifElse isParenNecessary sepCloseT sepNone
+
+        let longExpr =
+            ifElse
+                astContext.IsInsideMatchClausePattern
+                (ifElse isParenNecessary ((indent +> sepNln +> sepOpenT +> indent +> sepNln)) sepNone)
+                (ifElse isParenNecessary sepOpenT sepSpace)
+            +> genPat astContext p
+            +> enterNodeTokenByName pat.Range RPAREN
+            +> (ifElse
+                    astContext.IsInsideMatchClausePattern
+                    (ifElse isParenNecessary (unindent +> sepNln +> sepCloseT +> unindent) sepNone)
+                    (ifElse isParenNecessary sepCloseT sepNone))
+
+        expressionFitsOnRestOfLine shortExpr longExpr
     | PatTuple ps ->
         expressionFitsOnRestOfLine
             (col sepComma ps (genPat astContext))