Try fix static compilation of state machines

src/Compiler/Optimize/LowerStateMachines.fs

@@ -187,8 +187,17 @@ type LowerStateMachine(g: TcGlobals) =
         | Expr.Let (defn, bodyExpr, _, _) when isStateMachineBindingVar g defn.Var -> 
             if sm_verbose then printfn "binding %A --> %A..." defn.Var defn.Expr
             let envR = { env with ResumableCodeDefns = env.ResumableCodeDefns.Add defn.Var defn.Expr }
+            let envR, _ = BindResumableCodeDefinitions envR defn.Expr
             BindResumableCodeDefinitions envR bodyExpr
 
+        | Expr.Lambda (valParams = valParams; bodyExpr = bodyExpr; overallType = ty) when isReturnsResumableCodeTy g ty ->
+            if sm_verbose then printfn "binding fun %A --> %A..." valParams bodyExpr
+            BindResumableCodeDefinitions env bodyExpr
+
+        | Expr.DebugPoint (_, innerExpr) ->
+            let envR, _ = BindResumableCodeDefinitions env innerExpr
+            envR, expr
+
          // Eliminate 'if __useResumableCode ...'
          | IfUseResumableStateMachinesExpr g (thenExpr, _) ->
             if sm_verbose then printfn "eliminating 'if __useResumableCode...'"
@@ -313,11 +322,14 @@ type LowerStateMachine(g: TcGlobals) =
             | Some innerExpr2 -> Some (Expr.DebugPoint (dp, innerExpr2))
             | None -> None
 
+        | Expr.App _ ->
+            TryReduceExpr env expr args id
+
         | _ -> 
             None
 
     // Apply a single expansion of resumable code at the outermost position in an arbitrary expression
-    let rec TryReduceExpr (env: env) expr args remake = 
+    and TryReduceExpr (env: env) expr args remake = 
         if sm_verbose then printfn "expanding defns and reducing %A..." expr
         //if sm_verbose then printfn "checking %A for possible resumable code application..." expr
         match expr with

tests/FSharp.Compiler.ComponentTests/Language/StateMachineTests.fs

@@ -102,6 +102,97 @@ let compute () =
 // multiple invocations to trigger tiered compilation
 for i in 1 .. 100 do
     compute().Wait ()
+"""
+        |> withOptimize
+        |> compileExeAndRun
+        |> shouldSucceed
+
+    [<Fact>] // https://github.com/dotnet/fsharp/issues/12839#issuecomment-1292310944
+    let ``Tasks with a for loop over tuples are statically compilable``() =
+        FSharp """
+module TestProject1
+
+let ret i = task { return i }
+
+let one (f: seq<string * string * int>) = task {
+    let mutable sum = 0
+
+    let! x = ret 1
+    sum <- sum + x
+
+    for name, _whatever, i in f do
+        let! x = ret i
+        sum <- sum + x
+
+        System.Console.Write name
+
+        let! x = ret i
+        sum <- sum + x
+
+    let! x = ret 1
+    sum <- sum + x
+
+    return sum
+}
+
+let two (f: seq<string * string * int>) = task {
+    let mutable sum = 0
+
+    let! x = ret 1
+    sum <- sum + x
+
+    for name, _whatever, i in f do
+        let! x = ret i
+        sum <- sum + x
+
+        System.Console.Write name
+
+    let! x = ret 1
+    sum <- sum + x
+
+    return sum
+}
+
+let three (f: seq<string * string * int>) = task {
+    let mutable sum = 0
+
+    let! x = ret 1
+    sum <- sum + x
+
+    for name, _whatever, i in f do
+        let! x = ret i
+        sum <- sum + x
+
+        System.Console.Write name
+
+    return sum
+}
+
+let four (f: seq<string * int>) = task {
+    let mutable sum = 0
+
+    let! x = ret 5
+    sum <- sum + x
+
+    for name, _i in f do
+        System.Console.Write name
+
+    let! x = ret 1
+    sum <- sum + x
+
+    return sum
+}
+
+if (one [ ("", "", 1); ("", "", 2) ]).Result <> 8 then
+    failwith "unexpected result one"
+if (one []).Result <> 2 then
+    failwith "unexpected result one"
+if (two [ ("", "", 2) ]).Result <> 4 then
+    failwith "unexpected result two"
+if (three [ ("", "", 5) ]).Result <> 6 then
+    failwith "unexpected result three"
+if (four [ ("", 10) ]).Result <> 6 then
+    failwith "unexpected result four"
 """
         |> withOptimize
         |> compileExeAndRun