Avoid vanity alignment in long pattern match

Fixes https://github.com/fsprojects/fantomas/issues/1926 Co-authored-by: ijanus <[email protected]>
nblockchain · Apr 20, 2022 · e83be9b · e83be9b
1 parent 4f64028
commit e83be9b
Show file tree

Hide file tree

Showing 2 changed files with 69 additions and 10 deletions.
diff --git a/src/Fantomas.Tests/PatternMatchingTests.fs b/src/Fantomas.Tests/PatternMatchingTests.fs
@@ -38,9 +38,13 @@ module Foo =
                 return failwith "unreachable"
             else
                 match baz with
-                | Some (AverageBetweenResponses (minimumNumberOfResponses,
-                                                 averageFunc)) ->
-                    return failwith "unreachable"
+                | Some
+                    (
+                        AverageBetweenResponses
+                            (
+                                minimumNumberOfResponses, averageFunc
+                            )
+                    ) -> return failwith "unreachable"
                 | _ -> return failwith "unreachable"
         }
 """
@@ -1217,8 +1221,10 @@ type Thing =
     | Foo of msg: string
     override this.ToString() =
         match this with
-        | Foo (ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff) ->
-            ""
+        | Foo
+            (
+                ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
+            ) -> ""
 """
 
 [<Test>]
@@ -1248,8 +1254,10 @@ type Thing =
     | Foo of msg : string
     override this.ToString() : string =
         match this with
-        | Foo (ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff) ->
-            ""
+        | Foo
+            (
+                ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
+            ) -> ""
 """
 
 [<Test>]
@@ -2165,6 +2173,37 @@ match! a with // foo
 | B b -> ()
 """
 
+[<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 ()
+| _ -> ()
+"""
+
 [<Test>]
 let ``comment after match keyword, 1851`` () =
     formatSourceString

diff --git a/src/Fantomas/CodePrinter.fs b/src/Fantomas/CodePrinter.fs
@@ -5028,9 +5028,29 @@ and genPat astContext pat =
 
     | PatParen (_, PatUnitConst, _) -> !- "()"
     | PatParen (lpr, p, rpr) ->
-        genTriviaFor SynPat_Paren_OpeningParenthesis lpr sepOpenT
-        +> genPat astContext p
-        +> genTriviaFor SynPat_Paren_ClosingParenthesis rpr sepCloseT
+        let shortExpr =
+            genTriviaFor SynPat_Paren_OpeningParenthesis lpr sepOpenT
+            +> genPat astContext p
+            +> genTriviaFor SynPat_Paren_ClosingParenthesis rpr sepCloseT
+
+        let longExpr =
+            ifElse
+                astContext.IsInsideMatchClausePattern
+                (indent
+                 +> sepNln
+                 +> indent
+                 +> genTriviaFor SynPat_Paren_OpeningParenthesis lpr sepOpenT
+                 +> sepNln
+                 +> genPat astContext p
+                 +> unindent
+                 +> sepNln
+                 +> genTriviaFor SynPat_Paren_ClosingParenthesis rpr sepCloseT
+                 +> unindent)
+                (genTriviaFor SynPat_Paren_OpeningParenthesis lpr sepOpenT
+                 +> genPat astContext p
+                 +> genTriviaFor SynPat_Paren_ClosingParenthesis rpr sepCloseT)
+
+        expressionFitsOnRestOfLine shortExpr longExpr
     | PatTuple ps ->
         expressionFitsOnRestOfLine
             (col sepComma ps (genPat astContext))