Merge pull request #238 from fsprojects/issue-237

Don't suggest eta reduction if lambda arg is part of a tuple
fsprojects · Aug 20, 2017 · 469dc78 · 469dc78
2 parents 72fd535 + eef1b29
commit 469dc78
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Showing 2 changed files with 12 additions and 1 deletion.
diff --git a/src/FSharpLint.Core/Rules/FunctionReimplementation.fs b/src/FSharpLint.Core/Rules/FunctionReimplementation.fs
@@ -27,7 +27,7 @@ module FunctionReimplementation =
             simplePatternsLength simplePatterns
 
     let rec private getLambdaParamIdent = function
-        | SynSimplePats.SimplePats(pattern::_, _) -> 
+        | SynSimplePats.SimplePats([pattern], _) -> 
             let rec getIdent = function
                 | SynSimplePat.Id(ident, _, _, _, _, _) -> ident
                 | SynSimplePat.Typed(simplePattern, _, _)

diff --git a/tests/FSharpLint.Core.Tests/Rules/TestFunctionReimplementationRules.fs b/tests/FSharpLint.Core.Tests/Rules/TestFunctionReimplementationRules.fs
@@ -43,6 +43,17 @@ let f = fun a b -> a * b
 
         this.ErrorMsg.Contains "`( * )`" |> Assert.IsTrue
 
+    /// Regression test for https://github.com/fsprojects/FSharpLint/issues/237
+    [<Test>]
+    member this.``When there's a tuple pattern in the lambda eta contraction should not be recommended.``() = 
+        this.Parse """
+module Program
+
+let f = List.map (fun (x,_) -> id x) []
+"""
+
+        this.AssertNoWarnings()
+
     [<Test>]
     member this.``Quickfix for lambda reimplementing operator is to replace the lambda with the operator.``() = 
         let source = """