Fix analysis of conjunctive patterns for exhaustiveness (#13020)

* try to fix analysis of conjunctive patterns

* add test cases
Co-authored-by: NVlad Zarytovskii <vzaritovsky@hotmail.com>

src/Compiler/Checking/PatternMatchCompilation.fs

@@ -143,7 +143,6 @@ let GetSubExprOfInput g (gtps, tyargs, tinst) (SubExpr(accessf, (ve2, v2))) =
 // The ints record which choices taken, e.g. tuple/record fields.
 type Path =
     | PathQuery of Path * Unique
-    | PathConj of Path * int
     | PathTuple of Path * TypeInst * int
     | PathRecd of Path * TyconRef * TypeInst * int
     | PathUnionConstr of Path * UnionCaseRef * TypeInst * int
@@ -154,7 +153,6 @@ type Path =
 let rec pathEq p1 p2 =
     match p1, p2 with
     | PathQuery(p1, n1), PathQuery(p2, n2) -> (n1 = n2) && pathEq p1 p2
-    | PathConj(p1, n1), PathConj(p2, n2) -> (n1 = n2) && pathEq p1 p2
     | PathTuple(p1, _, n1), PathTuple(p2, _, n2) -> (n1 = n2) && pathEq p1 p2
     | PathRecd(p1, _, _, n1), PathRecd(p2, _, _, n2) -> (n1 = n2) && pathEq p1 p2
     | PathUnionConstr(p1, _, _, n1), PathUnionConstr(p2, _, _, n2) -> (n1 = n2) && pathEq p1 p2
@@ -203,8 +201,6 @@ let RefuteDiscrimSet g m path discrims =
     let rec go path tm =
         match path with
         | PathQuery _ -> raise CannotRefute
-        | PathConj (p, _j) ->
-            go p tm
         | PathTuple (p, tys, j) ->
             let k, eCoversVals = mkOneKnown tm j tys
             go p (fun _ -> mkRefTupled g m k tys, eCoversVals)
@@ -391,8 +387,6 @@ type Frontier = Frontier of ClauseNumber * Actives * ValMap<Expr>
 type InvestigationPoint = Investigation of ClauseNumber * DecisionTreeTest * Path
 
 // Note: actives must be a SortedDictionary
-// REVIEW: improve these data structures, though surprisingly these functions don't tend to show up
-// on profiling runs
 let rec isMemOfActives p1 actives =
     match actives with
     | [] -> false
@@ -1624,7 +1618,7 @@ let CompilePatternBasic
             subPats |> List.collect (fun subPat -> BindProjectionPattern (Active(inpPath, inpExpr, subPat)) activeState)
 
         | TPat_conjs(subPats, _m) ->
-            let newActives = List.mapi (mkSubActive (fun path j -> PathConj(path, j)) (fun _j -> inpAccess)) subPats
+            let newActives = List.mapi (mkSubActive (fun path _j -> path) (fun _j -> inpAccess)) subPats
             BindProjectionPatterns newActives activeState
 
         | TPat_range (c1, c2, m) ->

tests/fsharp/tests.fs

@@ -2586,6 +2586,21 @@ module TypecheckTests =
         peverify cfg "pos40.exe"
         exec cfg ("." ++ "pos40.exe") ""
 
+    [<Test>]
+    let ``sigs pos1281`` () =
+        let cfg = testConfig "typecheck/sigs"
+        // This checks that warning 25 "incomplete matches" is not triggered
+        fsc cfg "%s --target:exe -o:pos1281.exe --warnaserror --nowarn:26" cfg.fsc_flags ["pos1281.fs"]
+        peverify cfg "pos1281.exe"
+        exec cfg ("." ++ "pos1281.exe") ""
+
+    [<Test>]
+    let ``sigs pos3294`` () =
+        let cfg = testConfig "typecheck/sigs"
+        fsc cfg "%s --target:exe -o:pos3294.exe --warnaserror" cfg.fsc_flags ["pos3294.fs"]
+        peverify cfg "pos3294.exe"
+        exec cfg ("." ++ "pos3294.exe") ""
+
     [<Test>]
     let ``sigs pos23`` () =
         let cfg = testConfig "typecheck/sigs"

tests/fsharp/typecheck/sigs/pos1281.fs

+module Pos1281
+
+type Cond = Foo | Bar | Baz
+let (|SetV|) x _ = x
+
+let c = Cond.Foo
+
+match c with
+| Baz -> 
+    printfn "Baz"
+| Foo & SetV "and" kwd
+| Bar & SetV "or" kwd ->
+    printfn "Keyword: %s" kwd
+| Baz -> failwith "wat"
+
+printfn "test completed"
+exit 0

tests/fsharp/typecheck/sigs/pos3294.fs

+module Pos40
+
+let f = function
+    | [] -> 0
+    | (_ :: _) & _ -> 0
+
+printfn "test completed"
+exit 0