Cleanup

src/fsharp/AugmentWithHashCompare.fs

@@ -376,10 +376,8 @@ let mkUnionCompare g tcref (tycon: Tycon) =
         let dtree = TDSwitch(thise, cases, dflt, m) 
         mbuilder.Close(dtree, m, g.int_ty)
 
-    let expr = 
-        match ucases with
-        | [_] -> expr
-        | _ ->
+    let expr =
+        if List.isSingleItem ucases then expr else
 
         let tagsEqTested = 
             mkCond DebugPointAtBinding.NoneAtSticky m g.int_ty  
@@ -440,10 +438,8 @@ let mkUnionCompareWithComparer g tcref (tycon: Tycon) (_thisv, thise) (_thatobjv
         let dtree = TDSwitch(thise, cases, dflt, m) 
         mbuilder.Close(dtree, m, g.int_ty)
 
-    let expr = 
-        match ucases with
-        | [_] -> expr
-        | _ ->
+    let expr =
+        if List.isSingleItem ucases then expr else
 
         let tagsEqTested = 
             mkCond DebugPointAtBinding.NoneAtSticky m g.int_ty  
@@ -503,10 +499,8 @@ let mkUnionEquality g tcref (tycon: Tycon) =
         let dtree = TDSwitch(thise, cases, dflt, m) 
         mbuilder.Close(dtree, m, g.bool_ty)
 
-    let expr = 
-        match ucases with
-        | [_] -> expr
-        | _ ->
+    let expr =
+        if List.isSingleItem ucases then expr else
 
         let tagsEqTested = 
           mkCond DebugPointAtBinding.NoneAtSticky m g.bool_ty  
@@ -568,10 +562,8 @@ let mkUnionEqualityWithComparer g tcref (tycon: Tycon) (_thisv, thise) thatobje
         let dtree = TDSwitch(thise, cases, dflt, m) 
         mbuilder.Close(dtree, m, g.bool_ty)
 
-    let expr = 
-        match ucases with
-        | [_] -> expr
-        | _ ->
+    let expr =
+        if List.isSingleItem ucases then expr else
 
         let tagsEqTested = 
           mkCond DebugPointAtBinding.NoneAtSticky m g.bool_ty  

src/fsharp/CheckDeclarations.fs

@@ -4655,14 +4655,13 @@ module TcDeclarations =
 
           | _ ->
             let resInfo = TypeNameResolutionStaticArgsInfo.FromTyArgs synTypars.Length
-            let res = ResolveTypeLongIdent cenv.tcSink cenv.nameResolver ItemOccurence.Binding OpenQualified envForDecls.NameEnv ad longPath resInfo PermitDirectReferenceToGeneratedType.No
             let _, tcref =
-                match res, inSig, longPath with
-                | Result res, _, _ -> res
-                | res, true, [_] ->
+                match ResolveTypeLongIdent cenv.tcSink cenv.nameResolver ItemOccurence.Binding OpenQualified envForDecls.NameEnv ad longPath resInfo PermitDirectReferenceToGeneratedType.No with
+                | Result res -> res
+                | res when inSig && List.isSingleItem longPath ->
                     errorR(Deprecated(FSComp.SR.tcReservedSyntaxForAugmentation(), m))
                     ForceRaise res
-                | res, _, _ -> ForceRaise res
+                | res -> ForceRaise res
             tcref
 
         let isInterfaceOrDelegateOrEnum = 

src/fsharp/ConstraintSolver.fs

@@ -1699,13 +1699,11 @@ and SolveMemberConstraint (csenv: ConstraintSolverEnv) ignoreUnresolvedOverload
                           | "?>="  | "?>"  | "?<="  | "?<"  | "?="  | "?<>" 
                           | ">=?"  | ">?"  | "<=?"  | "<?"  | "=?"  | "<>?" 
                           | "?>=?" | "?>?" | "?<=?" | "?<?" | "?=?" | "?<>?" ->
-                             match tys with
-                             | [_] -> FSComp.SR.csTypeDoesNotSupportOperatorNullable(tyString, opName)
-                             | _ -> FSComp.SR.csTypesDoNotSupportOperatorNullable(tyString, opName)
-                          | _ -> 
-                             match tys with
-                             | [_] -> FSComp.SR.csTypeDoesNotSupportOperator(tyString, opName)
-                             | _ -> FSComp.SR.csTypesDoNotSupportOperator(tyString, opName)
+                             if List.isSingleItem tys then FSComp.SR.csTypeDoesNotSupportOperatorNullable(tyString, opName)
+                             else FSComp.SR.csTypesDoNotSupportOperatorNullable(tyString, opName)
+                          | _ ->
+                             if List.isSingleItem tys then FSComp.SR.csTypeDoesNotSupportOperator(tyString, opName)
+                             else FSComp.SR.csTypesDoNotSupportOperator(tyString, opName)
                       return! ErrorD(ConstraintSolverError(err, m, m2))
 
           | _ -> 

src/fsharp/MethodOverrides.fs

@@ -164,7 +164,7 @@ module DispatchSlotChecking =
         match vsl with 
         | [thisv] :: vs -> 
             // Check for empty variable list from a () arg
-            let vs = match vs, argInfos with | [_], [] -> [] | _ -> vs
+            let vs = if List.isSingleItem vs && argInfos.IsEmpty then [] else vs
             let implKind = 
                 if isInterfaceTy g implty then 
                     CanImplementAnyInterfaceSlot 

src/fsharp/Optimizer.fs

@@ -3314,7 +3314,7 @@ and StripPreComputationsFromComputedFunction g f0 args mkApp =
             fs, (remake >> (fun innerExprR -> Expr.DebugPoint (dp, innerExprR)))
 
         | _ -> 
-            [f], (fun newExprs -> (assert (match newExprs with [_] -> true | _ -> false)); List.head newExprs)
+            [f], (fun newExprs -> (assert (List.isSingleItem newExprs)); List.head newExprs)
 
     match strip f0 with 
     | [f], remake -> 

src/fsharp/TypedTreeOps.fs

@@ -2851,7 +2851,7 @@ module SimplifyTypes =
             simplify &&
             isTTyparCoercesToType tpc && 
             Zset.contains tp singletons && 
-            match tp.Constraints with [_] -> true | _ -> false)
+            List.isSingleItem tp.Constraints)
         let inplace = inplace |> List.map (function tp, TyparConstraint.CoercesTo(ty, _) -> tp, ty | _ -> failwith "not isTTyparCoercesToType")
 
         { singletons = singletons
@@ -9275,8 +9275,8 @@ type Entity with
 
             let argInfos = ArgInfosOfMember g vref 
             match argInfos with
-            | [argInfo] ->
-                List.lengthsEqAndForall2 (typeEquiv g) (List.map fst argInfo) argtys &&  
+            | [argInfos] ->
+                List.lengthsEqAndForall2 (typeEquiv g) (List.map fst argInfos) argtys &&  
                 membInfo.MemberFlags.IsOverrideOrExplicitImpl
             | _ -> false) 
 
@@ -9290,7 +9290,7 @@ type Entity with
 
             let argInfos = ArgInfosOfMember g vref
             match argInfos with
-            | [argInfo] -> List.lengthsEqAndForall2 (typeEquiv g) (List.map fst argInfo) argtys
+            | [argInfos] -> List.lengthsEqAndForall2 (typeEquiv g) (List.map fst argInfos) argtys
             | _ -> false) 
 
 

src/fsharp/absil/illib.fs

@@ -473,6 +473,11 @@ module List =
         | [] -> true
         | h::t -> t |> List.forall (fun h2 -> h = h2)
 
+    let isSingleItem l =
+        match l with
+        | [_] -> true
+        | _ -> false
+
 module ResizeArray =
 
     /// Split a ResizeArray into an array of smaller chunks.

src/fsharp/absil/illib.fsi

@@ -206,6 +206,8 @@ module internal List =
 
     val internal allEqual: xs:'T list -> bool when 'T: equality
 
+    val isSingleItem: xs: 'T list -> bool
+
 module internal ResizeArray =
 
     /// Split a ResizeArray into an array of smaller chunks.

src/fsharp/infos.fs

@@ -2159,7 +2159,7 @@ type PropInfo =
             // A getter has signature  { OptionalObjectType } -> Unit -> PropertyType
             // A getter indexer has signature  { OptionalObjectType } -> TupledIndexerArguments -> PropertyType
             match ArgInfosOfMember g vref with
-            | [_ :: _] -> true
+            | [argInfos] -> not (List.isEmpty argInfos)
             | _ -> false
         | FSProp(g, _, _, Some vref) ->
             // A setter has signature  { OptionalObjectType } -> PropertyType -> Void

src/fsharp/symbols/Exprs.fs

@@ -512,13 +512,13 @@ module FSharpExprConvert =
         let g = cenv.g
         if g.langVersion.SupportsFeature(Features.LanguageFeature.WitnessPassing) && not env.suppressWitnesses then 
             let witnessExprs = 
-                match ConstraintSolver.CodegenWitnessesForTyparInst cenv.tcValF g cenv.amap m tps tyargs, tyargs with
+                match ConstraintSolver.CodegenWitnessesForTyparInst cenv.tcValF g cenv.amap m tps tyargs with
                 // There is a case where optimized code makes expressions that do a shift-left on the 'char'
                 // type.  There is no witness for this case.  This is due to the code
                 //    let inline HashChar (x:char) = (# "or" (# "shl" x 16 : int #) x : int #)
                 // in FSharp.Core. 
-                | ErrorResult _, [_]  when vref.LogicalName =  "op_LeftShift" -> []
-                | res, _ -> CommitOperationResult res
+                | ErrorResult _  when vref.LogicalName = "op_LeftShift" && List.isSingleItem tyargs -> []
+                | res -> CommitOperationResult res
             let env = { env with suppressWitnesses = true }
             witnessExprs |> List.map (fun arg -> 
                 match arg with