regression test case

tests/FSharp.Compiler.ComponentTests/EmittedIL/Inlining/Inlining.fs

@@ -40,6 +40,18 @@ module Inlining =
         compilation
         |> verifyCompilation
 
+    [<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"Regression17607.fs"|])>]
+    let ``Mutually recursive inner let - regression 17607 - realsig off`` compilation =
+        compilation
+        |> withRealInternalSignatureOff
+        |> verifyCompilation
+
+    [<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"Regression17607.fs"|])>]
+    let ``Mutually recursive inner let - regression 17607 - real sig on`` compilation =
+        compilation
+        |> withRealInternalSignatureOn
+        |> verifyCompilation
+
     // SOURCE=StructUnion01.fs SCFLAGS="-a --optimize+" COMPILE_ONLY=1 POSTCMD="..\\CompareIL.cmd StructUnion01.dll"	# StructUnion01.fs
     [<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"StructUnion01.fs"|])>]
     let ``StructUnion01_fs`` compilation =

tests/FSharp.Compiler.ComponentTests/EmittedIL/Inlining/Regression17607.fs

@@ -0,0 +1,67 @@
+open System
+open System.Diagnostics
+
+// 16 byte struct
+[<Struct>]
+type Point2D(x: double, y: double) =
+    member _.X = x
+    member _.Y = y
+
+// Will create a tail il instruction and force a tail call. This is will become
+// a fast tail call on unix x64 as the caller and callee have equal stack size
+let fifth() =
+    let rec fifthMethodFirstCallee(iterationCount, firstArg: Point2D, secondArg: Point2D, thirdArg: Point2D, fourthArg: Point2D, fifthArg: Point2D) =
+        if firstArg.X <> 10.0 then -100
+        else if firstArg.Y <> 20.0 then -101
+        else if secondArg.X <> 30.0 then -102
+        else if secondArg.Y <> 40.0 then -103
+        else if thirdArg.X <> 10.0 then -104
+        else if thirdArg.Y <> 20.0 then -105
+        else if fourthArg.X <> 30.0 then -106
+        else if fourthArg.Y <> 40.0 then -107
+        else if fifthArg.X <> 10.0 then -108
+        else if fifthArg.Y <> 20.0 then -109
+        else if iterationCount = 0 then
+            100
+        else if iterationCount % 2 = 0 then
+            fifthMethodSecondCallee(iterationCount - 1, firstArg, secondArg, thirdArg, fourthArg, fifthArg)
+        else
+            fifthMethodFirstCallee(iterationCount - 1, firstArg, secondArg, thirdArg, fourthArg, fifthArg)
+
+    and fifthMethodSecondCallee(iterationCount, firstArg, secondArg, thirdArg, fourthArg, fifthArg) =
+        if firstArg.X <> 10.0 then -150
+        else if firstArg.Y <> 20.0 then -151
+        else if secondArg.X <> 30.0 then -152
+        else if secondArg.Y <> 40.0 then -153
+        else if thirdArg.X <> 10.0 then -154
+        else if thirdArg.Y <> 20.0 then -155
+        else if fourthArg.X <> 30.0 then -156
+        else if fourthArg.Y <> 40.0 then -157
+        else if fifthArg.X <> 10.0 then -158
+        else if fifthArg.Y <> 20.0 then -159
+        else if iterationCount = 0 then
+            101
+        else if iterationCount % 2 = 0 then
+            fifthMethodSecondCallee(iterationCount - 1, firstArg, secondArg, thirdArg, fourthArg, fifthArg)
+        else
+            fifthMethodFirstCallee(iterationCount - 1, firstArg, secondArg, thirdArg, fourthArg, fifthArg)
+
+    let point = Point2D(10.0, 20.0)
+    let secondPoint = Point2D(30.0, 40.0)
+
+    let retVal = fifthMethodFirstCallee(1000000, point, secondPoint, point, secondPoint, point)
+
+    if retVal <> 100 && retVal <> 101 then
+        printfn "Method -- Failed, expected result: 100 or 101, calculated: %d" retVal
+        -5
+    else
+        0
+
+[<EntryPoint>]
+let main argv =
+    let startTime = Stopwatch.StartNew()
+    for i in 0..100 do
+        ignore (fifth ())
+    let elapsedTime = startTime.Elapsed.TotalMilliseconds
+    printfn "%fms" elapsedTime
+    0