Test: debug-inline capture of a local function from a nested-closure …

…callsite Regression coverage for #20297. The reduced repro keeps the reported shape - a captured local function, a callsite inside a nested closure, and '>>' composition - and crashes with AccessViolationException on release/10.0.4xx, where <addEnum>__debug@N is emitted as a two-argument static method that does 'ldarg.0; ldfld tee' against the string parameter. It passes once #20089 is present. SRTP 30-38 all call the inline function directly from the enclosing method, so none of them cover a callsite inside a closure. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
T-Gro · Aug 24, 2026 · Aug 19, 2026 · Aug 20, 2026 · Aug 20, 2026 · Aug 19, 2026
commit 00f0fe652dfceb7d05adb57848625dd73116f28f
@@ -1252,6 +1252,27 @@ let main _ =
         |> compileAndRun
         |> verifySequencePoints
 
+    // https://github.com/dotnet/fsharp/issues/20297
+    [<Fact>]
+    let ``SRTP 39 - Captured local function, callsite in a nested closure`` () =
+        FSharp """
+let f () =
+    let tee g (x: int) = g x; x
+    let addName (key: string) (v: string) = tee (fun x -> printfn "%s=%s" key v)
+    let inline addEnum (key: string) value = tee (fun x -> printfn "%s=%d" key (x + int value))
+    let pipeline v = addName "a" "n" >> addEnum "b" v
+    pipeline 1uy 41
+
+[<EntryPoint>]
+let main _ =
+    if f () = 41 then 0 else 1
+"""
+        |> withDebug
+        |> withNoOptimize
+        |> asExe
+        |> compileAndRun
+        |> verifySequencePoints
+
     [<Fact>]
     let ``Member 01 - Non-generic`` () =
         FSharp """

@@ -0,0 +1,166 @@
+let f () =
+    let tee g (x: int) = g x; x
+    let addName (key: string) (v: string) = tee (fun x -> printfn "%s=%s" key v)
+    let inline addEnum (key: string) value = tee (fun x -> printfn "%s=%d" key (x + int value))
+    let pipeline v = addName "a" "n" >> addEnum "b" v
+    pipeline 1uy 41
+
+[<EntryPoint>]
+let main _ =
+    if f () = 41 then 0 else 1
+--------------------------------------------------------------------------------
+
+Test::f
+  <hidden>
+    IL_0000:  ldsfld tee@3::@_instance
+    IL_0005:  stloc.0
+    IL_0006:  ldloc.0
+    IL_0007:  newobj addName@4::.ctor
+    IL_000c:  stloc.1
+    IL_000d:  ldloc.0
+    IL_000e:  newobj addEnum@5::.ctor
+    IL_0013:  stloc.2
+    IL_0014:  ldloc.0
+    IL_0015:  ldloc.1
+    IL_0016:  newobj pipeline@6::.ctor
+    IL_001b:  stloc.3
+
+  (7,5-7,20)  pipeline 1uy 41
+    IL_001c:  ldloc.3
+    IL_001d:  ldc.i4.1
+    IL_001e:  ldc.i4.s 41
+    IL_0020:  tail.
+    IL_0022:  call InvokeFast
+    IL_0027:  ret
+
+Test::main
+  (11,5-11,22)  if f () = 41 then
+    IL_0000:  call Test::f
+    IL_0005:  ldc.i4.s 41
+    IL_0007:  bne.un.s IL_000b
+
+  (11,23-11,24)  0
+    IL_0009:  ldc.i4.0
+    IL_000a:  ret
+
+  (11,30-11,31)  1
+    IL_000b:  ldc.i4.1
+    IL_000c:  ret
+
+Test::<addEnum>__debug@6
+  (5,46-5,96)  tee (fun x -> printfn "%s=%d" key (x + int value))
+    IL_0000:  ldarg.0
+    IL_0001:  ldarg.1
+    IL_0002:  ldarg.2
+    IL_0003:  newobj pipeline@5-1::.ctor
+    IL_0008:  tail.
+    IL_000a:  callvirt Invoke
+    IL_000f:  ret
+
+tee@3::Invoke
+  (3,26-3,29)  g x
+    IL_0000:  ldarg.1
+    IL_0001:  ldarg.2
+    IL_0002:  callvirt Invoke
+    IL_0007:  pop
+
+  (3,31-3,32)  x
+    IL_0008:  ldarg.2
+    IL_0009:  ret
+
+addName@4::Invoke
+  (4,45-4,81)  tee (fun x -> printfn "%s=%s" key v)
+    IL_0000:  ldarg.0
+    IL_0001:  ldfld addName@4::tee
+    IL_0006:  ldarg.1
+    IL_0007:  ldarg.2
+    IL_0008:  newobj addName@4-1::.ctor
+    IL_000d:  tail.
+    IL_000f:  callvirt Invoke
+    IL_0014:  ret
+
+addName@4-1::Invoke
+  (4,59-4,80)  printfn "%s=%s" key v
+    IL_0000:  ldstr "%s=%s"
+    IL_0005:  newobj .ctor
+    IL_000a:  call ExtraTopLevelOperators::PrintFormatLine
+    IL_000f:  stloc.0
+    IL_0010:  ldloc.0
+    IL_0011:  newobj addName@4-2::.ctor
+    IL_0016:  ldarg.0
+    IL_0017:  ldfld addName@4-1::key
+    IL_001c:  ldarg.0
+    IL_001d:  ldfld addName@4-1::v
+    IL_0022:  tail.
+    IL_0024:  call InvokeFast
+    IL_0029:  ret
+
+addEnum@5-1::Invoke
+  (5,46-5,96)  tee (fun x -> printfn "%s=%d" key (x + int value))
+    IL_0000:  ldarg.0
+    IL_0001:  ldfld tee
+    IL_0006:  ldarg.1
+    IL_0007:  ldarg.2
+    IL_0008:  newobj .ctor
+    IL_000d:  tail.
+    IL_000f:  callvirt Invoke
+    IL_0014:  ret
+
+addEnum@5-2::Invoke
+  (5,60-5,95)  printfn "%s=%d" key (x + int value)
+    IL_0000:  ldstr "%s=%d"
+    IL_0005:  newobj .ctor
+    IL_000a:  call ExtraTopLevelOperators::PrintFormatLine
+    IL_000f:  stloc.0
+    IL_0010:  ldloc.0
+    IL_0011:  newobj addEnum@5-3::.ctor
+    IL_0016:  ldarg.0
+    IL_0017:  ldfld key
+    IL_001c:  ldarg.1
+    IL_001d:  ldarg.0
+    IL_001e:  ldfld value
+    IL_0023:  stloc.1
+    IL_0024:  ldloc.1
+    IL_0025:  call LanguagePrimitives::ExplicitDynamic
+    IL_002a:  add
+    IL_002b:  tail.
+    IL_002d:  call InvokeFast
+    IL_0032:  ret
+
+pipeline@5-1::Invoke
+  (5,60-5,95)  printfn "%s=%d" key (x + int value)
+    IL_0000:  ldstr "%s=%d"
+    IL_0005:  newobj .ctor
+    IL_000a:  call ExtraTopLevelOperators::PrintFormatLine
+    IL_000f:  stloc.0
+    IL_0010:  ldloc.0
+    IL_0011:  newobj pipeline@5-2::.ctor
+    IL_0016:  ldarg.0
+    IL_0017:  ldfld pipeline@5-1::key
+    IL_001c:  ldarg.1
+    IL_001d:  ldarg.0
+    IL_001e:  ldfld pipeline@5-1::value
+    IL_0023:  conv.i4
+    IL_0024:  add
+    IL_0025:  tail.
+    IL_0027:  call InvokeFast
+    IL_002c:  ret
+
+pipeline@6::Invoke
+  (6,22-6,54)  addName "a" "n" >> addEnum "b" v
+    IL_0000:  ldarg.0
+    IL_0001:  ldfld pipeline@6::addName
+    IL_0006:  ldstr "a"
+    IL_000b:  ldstr "n"
+    IL_0010:  call InvokeFast
+    IL_0015:  stloc.0
+    IL_0016:  ldarg.0
+    IL_0017:  ldfld pipeline@6::tee
+    IL_001c:  ldstr "b"
+    IL_0021:  ldarg.1
+    IL_0022:  call Test::<addEnum>__debug@6
+    IL_0027:  stloc.1
+    IL_0028:  ldloc.0
+    IL_0029:  ldloc.1
+    IL_002a:  newobj pipeline@6-4::.ctor
+    IL_002f:  ret