[WIP]Turn unused value warnings on by default

FSharpBuild.Directory.Build.props

@@ -19,8 +19,8 @@
     <SymStoreDirectory>$(ArtifactsDir)\SymStore</SymStoreDirectory>
     <ProtoOutputPath>$(ArtifactsDir)\Bootstrap</ProtoOutputPath>
     <ValueTupleImplicitPackageVersion>4.4.0</ValueTupleImplicitPackageVersion>
-    <WarningsAsErrors>1182;0025;$(WarningsAsErrors)</WarningsAsErrors>
-    <OtherFlags>$(OtherFlags) --nowarn:3384</OtherFlags>
+    <WarningsAsErrors>0025;$(WarningsAsErrors)</WarningsAsErrors>
+    <OtherFlags>$(OtherFlags) --warnaserror --nowarn:3384</OtherFlags>
   </PropertyGroup>
 
   <!-- nuget -->

src/fsharp/CompilerDiagnostics.fs

@@ -372,7 +372,6 @@ let warningOn err level specificWarnOn =
     List.contains n specificWarnOn ||
     // Some specific warnings are never on by default, i.e. unused variable warnings
     match n with
-    | 1182 -> false // chkUnusedValue - off by default
     | 3180 -> false // abImplicitHeapAllocation - off by default
     | 3517 -> false // optFailedToInlineSuggestedValue - off by default
     | _ -> level >= GetWarningLevel err 

src/fsharp/FSharp.Build/CreateFSharpManifestResourceName.fs

@@ -19,7 +19,7 @@ type CreateFSharpManifestResourceName public () =
                     (linkFileName:string),
                     (rootNamespace:string), (* may be null *)  
                     (dependentUponFileName:string), (* may be null *) 
-                    (binaryStream:System.IO.Stream) (* may be null *)) : string = 
+                    (_binaryStream:System.IO.Stream) (* may be null *)) : string = 
 
         // The Visual CSharp and XBuild CSharp toolchains transform resource names like this:
         //     SubDir\abc.resx --> SubDir.abc.resources

src/fsharp/FSharp.Build/FSharpEmbedResourceText.fs

@@ -356,7 +356,7 @@ open Printf
             printMessage (sprintf "Reading %s" filename)
             let lines = File.ReadAllLines(filename)
                         |> Array.mapi (fun i s -> i,s) // keep line numbers
-                        |> Array.filter (fun (i,s) -> not(s.StartsWith "#"))  // filter out comments
+                        |> Array.filter (fun (_,s) -> not(s.StartsWith "#"))  // filter out comments
 
             printMessage (sprintf "Parsing %s" filename)
             let stringInfos = lines |> Array.map (fun (i,s) -> ParseLine filename i s)
@@ -391,7 +391,7 @@ open Printf
 
             printMessage (sprintf "Generating resource methods for %s" outFilename)
             // gen each resource method
-            stringInfos |> Seq.iter (fun (lineNum, (optErrNum,ident), str, holes, netFormatString) ->
+            stringInfos |> Seq.iter (fun (lineNum, (optErrNum,ident), str, holes, _) ->
                 let formalArgs = new System.Text.StringBuilder()
                 let actualArgs = new System.Text.StringBuilder()
                 let mutable firstTime = true
@@ -428,14 +428,14 @@ open Printf
             // gen validation method
             fprintfn out "    /// Call this method once to validate that all known resources are valid; throws if not"
             fprintfn out "    static member RunStartupValidation() ="
-            stringInfos |> Seq.iter (fun (lineNum, (optErrNum,ident), str, holes, netFormatString) ->
+            stringInfos |> Seq.iter (fun (_, (_,ident), _, _, _) ->
                 fprintfn out "        ignore(GetString(\"%s\"))" ident
             )
             fprintfn out "        ()"  // in case there are 0 strings, we need the generated code to parse
             // gen to resx
             let xd = new System.Xml.XmlDocument()
             xd.LoadXml(xmlBoilerPlateString)
-            stringInfos |> Seq.iter (fun (lineNum, (optErrNum,ident), str, holes, netFormatString) ->
+            stringInfos |> Seq.iter (fun (_, (_,ident), _, _, netFormatString) ->
                 let xn = xd.CreateElement("data")
                 xn.SetAttribute("name",ident) |> ignore
                 xn.SetAttribute("xml:space","preserve") |> ignore

src/fsharp/FSharp.Build/Fsc.fs

@@ -63,7 +63,6 @@ type public Fsc () as this =
     let mutable tailcalls : bool = true
     let mutable targetProfile : string = null
     let mutable targetType : string = null
-    let mutable toolExe : string = "fsc.exe"
     let defaultToolPath =
         let locationOfThisDll =
             try Some(Path.GetDirectoryName(typeof<Fsc>.Assembly.Location))
@@ -577,7 +576,6 @@ type public Fsc () as this =
             match host with
             | null -> base.ExecuteTool(pathToTool, responseFileCommands, commandLineCommands)
             | _ ->
-                let sources = sources|>Array.map(fun i->i.ItemSpec)
                 let invokeCompiler baseCallDelegate =
                     try
                         let ret =
@@ -590,8 +588,8 @@ type public Fsc () as this =
                     // Do a string compare on the type name to do eliminate a compile time dependency on Microsoft.Build.dll
                     | :? TargetInvocationException as tie when not (isNull tie.InnerException) && (tie.InnerException).GetType().FullName = "Microsoft.Build.Exceptions.BuildAbortedException" ->
                         fsc.Log.LogError(tie.InnerException.Message, [| |])
-                        -1
-                    | e -> reraise()
+                        -1  // ok, this is what happens when VS IDE cancels the build, no need to assert, just log the build-canceled error and return -1 to denote task failed
+                    | _ -> reraise()
 
                 let baseCallDelegate = Func<int>(fun () -> fsc.BaseExecuteTool(pathToTool, responseFileCommands, commandLineCommands) )
                 try

src/fsharp/FSharp.Build/Fsi.fs

@@ -37,15 +37,12 @@ type public Fsi () as this =
     let mutable provideCommandLineArgs = false
     let mutable references : ITaskItem[] = [||]
     let mutable referencePath : string = null
-    let mutable resources : ITaskItem[] = [||]
     let mutable skipCompilerExecution = false
     let mutable sources : ITaskItem[] = [||]
     let mutable loadSources : ITaskItem[] = [||]
     let mutable useSources : ITaskItem[] = [||]
     let mutable tailcalls : bool = true
     let mutable targetProfile : string = null
-    let mutable targetType : string = null
-    let mutable toolExe : string = "fsi.exe"
     let mutable toolPath : string =
         let locationOfThisDll =
             try Some(Path.GetDirectoryName(typeof<Fsi>.Assembly.Location))
@@ -85,11 +82,6 @@ type public Fsi () as this =
             for item in references do
                 builder.AppendSwitchIfNotNull("-r:", item.ItemSpec)
 
-        let referencePathArray = // create a array of strings
-            match referencePath with
-            | null -> null
-            | _ -> referencePath.Split([|';'; ','|], StringSplitOptions.RemoveEmptyEntries)
-
         // NoWarn
         match disabledWarnings with
         | null -> ()
@@ -293,7 +285,6 @@ type public Fsi () as this =
             match host with
             | null -> base.ExecuteTool(pathToTool, responseFileCommands, commandLineCommands)
             | _ ->
-                let sources = sources|>Array.map(fun i->i.ItemSpec)
                 let invokeCompiler baseCallDelegate =
                     try
                         let ret =
@@ -306,8 +297,8 @@ type public Fsi () as this =
                     // Do a string compare on the type name to do eliminate a compile time dependency on Microsoft.Build.dll
                     | :? TargetInvocationException as tie when not (isNull tie.InnerException) && (tie.InnerException).GetType().FullName = "Microsoft.Build.Exceptions.BuildAbortedException" ->
                         fsi.Log.LogError(tie.InnerException.Message, [| |])
-                        -1
-                    | e -> reraise()
+                        -1  // ok, this is what happens when VS IDE cancels the build, no need to assert, just log the build-canceled error and return -1 to denote task failed
+                    | _ -> reraise()
 
                 let baseCallDelegate = Func<int>(fun () -> fsi.BaseExecuteTool(pathToTool, responseFileCommands, commandLineCommands) )
                 try

src/fsharp/FSharp.Build/MapSourceRoots.fs

@@ -122,7 +122,7 @@ type MapSourceRoots () =
 
                     for root in mappedSourceRoots do
                         match root.GetMetadata SourceControl with
-                        | HasValue v when isSourceControlled -> mapNestedRootIfEmpty root
+                        | HasValue _ when isSourceControlled -> mapNestedRootIfEmpty root
                         | NullOrEmpty when not isSourceControlled -> mapNestedRootIfEmpty root
                         | _ -> ()
 

src/fsharp/FSharp.Compiler.Server.Shared/FSharpInteractiveServer.fs

@@ -37,7 +37,7 @@ type internal FSharpInteractiveServer() =
         LifetimeServices.RenewOnCallTime      <- TimeSpan(7,0,0,0);
         LifetimeServices.SponsorshipTimeout   <- TimeSpan(7,0,0,0);
         ChannelServices.RegisterChannel(chan,false);
-        let objRef = RemotingServices.Marshal(server,"FSIServer") 
+        RemotingServices.Marshal(server,"FSIServer") |> ignore
         ()
 
     static member StartClient(channelName) =

tests/FSharp.Build.UnitTests/FSharp.Build.UnitTests.fsproj

@@ -8,6 +8,7 @@
     <OutputType>Library</OutputType>
     <DisableImplicitFSharpCoreReference>true</DisableImplicitFSharpCoreReference>
     <UnitTestType>nunit</UnitTestType>
+    <NoWarn>$(NoWarn);1182</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>

tests/FSharp.Compiler.ComponentTests/ErrorMessages/UnsupportedAttributes.fs

@@ -20,6 +20,7 @@ type C() =
     member _.G() = ()
         """
         |> FSharp
+        |> withOptions ["--nowarn:1182"]
         |> typecheck
         |> shouldFail
         |> withResults [

tests/FSharp.Compiler.ComponentTests/ErrorMessages/WarnExpressionTests.fs

@@ -70,7 +70,7 @@ let changeProperty() =
     [<Fact>]
     let ``Don't Warn If Property Without Setter``() =
         FSharp """
-type MyClass(property1 : int) =
+type MyClass(_property1 : int) =
     member val Property2 = "" with get
 
 let x = MyClass(1)

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/BasicTypeAndModuleDefinitions/RecordTypes/Overload_Equals.fs

@@ -4,9 +4,9 @@
 
 type R =
     { x: int }
-    member this.Equals(s:char) = true
+    member this.Equals(_:char) = true
     // member this.Equals(s:R) = 1.
-    member this.Equals(?s:char) = true
+    member this.Equals(?_s:char) = true
 
 #if INTERACTIVE
 exit 0;;

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/BasicTypeAndModuleDefinitions/RecordTypes/Overload_GetHashCode.fs

@@ -3,9 +3,9 @@
 // Overloading of GetHashCode()
 type R =
     { x: int }
-    member this.GetHashCode(s:char) =  1
+    member this.GetHashCode(_s:char) =  1
     //member this.GetHashCode() = 1.
-    member this.GetHashCode(?s:char) = 1 
+    member this.GetHashCode(?_s:char) = 1 
 
 #if INTERACTIVE
 exit 0;;

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/BasicTypeAndModuleDefinitions/RecordTypes/Overload_ToString.fs

@@ -4,9 +4,9 @@
 
 type R =
     { x: int }
-    member this.ToString(s:char) = true
+    member this.ToString(_s:char) = true
     member this.ToString() =       true
-    member this.ToString(?s:char) = true
+    member this.ToString(?_s:char) = true
 
 #if INTERACTIVE
 exit 0;;

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/BasicTypeAndModuleDefinitions/UnionTypes/Overload_Equals.fs

@@ -3,9 +3,9 @@
 // Overloading of Equals()
 
 type DU = | A
-          member this.Equals(s:char) = true
+          member this.Equals(_s:char) = true
           //member this.Equals(s:DU) = 1.
-          member this.Equals(?s:char) = true
+          member this.Equals(?_s:char) = true
 
 #if INTERACTIVE
 exit 0;;

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/BasicTypeAndModuleDefinitions/UnionTypes/Overload_GetHashCode.fs

@@ -3,9 +3,9 @@
 // Overloading of GetHashCode()
 
 type DU = | A
-            member this.GetHashCode(s:char) =  1
+            member this.GetHashCode(_s:char) =  1
             //member this.GetHashCode() = 1.
-            member this.GetHashCode(?s:char) = 1 
+            member this.GetHashCode(?_s:char) = 1 
 
 #if INTERACTIVE
 exit 0;;

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/BasicTypeAndModuleDefinitions/UnionTypes/Overload_ToString.fs

@@ -3,9 +3,9 @@
 // Overloading of ToString()
 
 type DU = | A
-          member this.ToString(s:char) = true
+          member this.ToString(_s:char) = true
           member this.ToString() =       true
-          member this.ToString(?s:char) = true
+          member this.ToString(?_s:char) = true
 
 #if INTERACTIVE
 exit 0;;

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/LexicalAnalysis/Shift/Generics/RightShift001.fs

@@ -9,4 +9,4 @@
 type ID<'T> =
     static member id (x:'T) = x
 
-let f x = ID<ID<int>>.id  (* ok *)
+let f _x = ID<ID<int>>.id  (* ok *)

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/LexicalAnalysis/Shift/Generics/RightShift002.fs

@@ -9,4 +9,4 @@
 type ID<'T> =
     static member id (x:'T) = x
 
-let f x = ID<ID<int>> .id  (* ok *)
+let f _x = ID<ID<int>> .id  (* ok *)

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/LexicalFiltering/HashLight/IndentationWithComputationExpression01.fs

@@ -10,7 +10,7 @@ async {
                     return 5 
                 }
               )
-    let! b = a
-    for i in 1..10000 do
+    let! _b = a
+    for _ in 1..10000 do
         ()
 } |> Async.RunSynchronously

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/ObjectOrientedTypeDefinitions/StructTypes/Overload_Equals.fs

@@ -4,9 +4,9 @@
 
 [<Struct>]
 type S3 =
-    member this.Equals(s:char) = true
+    member this.Equals(_s:char) = true
     //member this.Equals(s:S3) = 1.
-    member this.Equals(?s:char) = true
+    member this.Equals(?_s:char) = true
 
 #if INTERACTIVE
 ;;

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/ObjectOrientedTypeDefinitions/StructTypes/Overload_GetHashCode.fs

@@ -4,9 +4,9 @@
 
 [<Struct>]
 type S2 =
-    member this.GetHashCode(s:char) =  1
+    member this.GetHashCode(_s:char) =  1
     //member this.GetHashCode() = 1.
-    member this.GetHashCode(?s:char) = 1 
+    member this.GetHashCode(?_s:char) = 1 
 
 #if INTERACTIVE
 ;;

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/ObjectOrientedTypeDefinitions/StructTypes/Overload_ToString.fs

@@ -4,9 +4,9 @@
 
 [<Struct>]
 type S1 =
-    member this.ToString(s:char) = true
+    member this.ToString(_s:char) = true
     member this.ToString() =       true
-    member this.ToString(?s:char) = true
+    member this.ToString(?_s:char) = true
 
 #if INTERACTIVE
 exit 0;;

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/UnitsOfMeasure/Basic/Stats.fs

@@ -18,7 +18,7 @@ let variance xs = let m = mean xs in meanMap (fun x -> sqr (x-m)) xs
 let sdeviation xs = sqrt (variance xs)
 
 let skewness xs = 
-  let n = float (List.length xs)
+  let _n = float (List.length xs)
   let m = mean xs
   let s = sdeviation xs
   meanMap (fun x -> cube(x-m)) xs / (cube s)

tests/FSharp.Compiler.ComponentTests/resources/tests/Conformance/UnitsOfMeasure/TypeChecker/GenericSubType01.fs

@@ -5,7 +5,7 @@
 
 type SC< [<Measure>] 'u>() = class end
 type TC< [<Measure>] 'u>() = inherit SC<'u>()
-let wff (x:SC<'u>) = ()
+let wff (_x:SC<'u>) = ()
 
 
 let wgg (x:TC<'v>) = wff x      // OK

tests/FSharp.Compiler.Private.Scripting.UnitTests/FSharp.Compiler.Private.Scripting.UnitTests.fsproj

@@ -8,6 +8,7 @@
     <DisableImplicitFSharpCoreReference>true</DisableImplicitFSharpCoreReference>
     <UnitTestType>xunit</UnitTestType>
     <ExcludeFromSourceBuild>true</ExcludeFromSourceBuild>
+    <NoWarn>$(NoWarn);1182</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>

tests/FSharp.Compiler.Private.Scripting.UnitTests/FSharpScriptTests.fs

@@ -418,7 +418,7 @@ let y = 2
             foundInner <- foundInner || name = "inner")
         let code = @"
 let x =
-    let inner = 1
+    let _inner = 1
     ()
 "
         script.Eval(code) |> ignoreValue

tests/FSharp.Compiler.Service.Tests/FSharp.Compiler.Service.Tests.fsproj

@@ -4,7 +4,7 @@
     <OutputType>Exe</OutputType>
     <TargetFrameworks Condition="'$(OS)' != 'Unix'">net472;net5.0</TargetFrameworks>
     <TargetFrameworks Condition="'$(OS)' == 'Unix'">net5.0</TargetFrameworks>
-    <NoWarn>$(NoWarn);44;75;</NoWarn>
+    <NoWarn>$(NoWarn);44;75;1182;</NoWarn>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <GenerateProgramFile>false</GenerateProgramFile>
     <DisableImplicitFSharpCoreReference>true</DisableImplicitFSharpCoreReference>

tests/FSharp.Compiler.UnitTests/FSharp.Compiler.UnitTests.fsproj

@@ -9,7 +9,7 @@
     <DisableImplicitFSharpCoreReference>true</DisableImplicitFSharpCoreReference>
     <DefineConstants>$(DefineConstants);ASSUME_PREVIEW_FSHARP_CORE</DefineConstants>
     <UnitTestType>xunit</UnitTestType>
-    <NoWarn>$(NoWarn);57;3186;1104</NoWarn>
+    <NoWarn>$(NoWarn);57;3186;1104;1182;</NoWarn>
   </PropertyGroup>
 
     <ItemGroup>

tests/FSharp.Core.UnitTests/FSharp.Core.UnitTests.fsproj

@@ -6,6 +6,7 @@
     <TargetFrameworks>net5.0;net472</TargetFrameworks>
     <TargetFrameworks Condition="'$(OS)' == 'Unix'">net5.0</TargetFrameworks>
     <OutputType>Library</OutputType>
+    <NoWarn>$(NoWarn);1182</NoWarn>
 
     <AssemblyName>FSharp.Core.UnitTests</AssemblyName>
     <PackageId>Microsoft.FSharp.Core.UnitTests</PackageId>

tests/benchmarks/CompilerServiceBenchmarks/FSharp.Compiler.Benchmarks.fsproj

@@ -4,6 +4,7 @@
     <OutputType>Exe</OutputType>
     <TargetFramework>net5.0</TargetFramework>
     <DisableImplicitFSharpCoreReference>true</DisableImplicitFSharpCoreReference>
+    <NoWarn>$(NoWarn);1182</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>

tests/benchmarks/MicroPerf/MicroPerf.fsproj

@@ -11,6 +11,8 @@
     <OtherFlags>$(OtherFlags) --langversion:preview</OtherFlags>
     <OtherFlags>$(OtherFlags) --define:PREVIEW</OtherFlags>
 
+    <NoWarn>$(NoWarn);1182</NoWarn>
+
     <!-- By default this project will compile with the proto compiler -->
     <!-- Uncommenting this will build with a previous installed compiler  -->
     <!--

tests/benchmarks/TaskPerf/TaskPerf.fsproj

@@ -13,6 +13,9 @@
 	<OtherFlags>$(OtherFlags) --nowarn:3511 --nowarn:3513</OtherFlags>
 	<OtherFlags>$(OtherFlags) --langversion:preview</OtherFlags>
 	<OtherFlags>$(OtherFlags) --define:PREVIEW</OtherFlags>
+
+	<NoWarn>$(NoWarn);1182</NoWarn>
+
   </PropertyGroup>
 
   <ItemGroup>