Allow parameter-less CustomOperation

src/Compiler/Checking/AttributeChecking.fs

@@ -207,7 +207,7 @@ let TryBindMethInfoAttribute g (m: range) (AttribInfo(atref, _) as attribSpec) m
         (fun provAttribs -> 
             match provAttribs.PUntaint((fun a -> a.GetAttributeConstructorArgs(provAttribs.TypeProvider.PUntaintNoFailure(id), atref.FullName)), m) with
             | Some args -> f3 args
-            | None -> None)  
+            | None -> None)
 #else
         (fun _provAttribs -> None)
 #endif

src/Compiler/Checking/CheckComputationExpressions.fs

@@ -266,14 +266,22 @@ let TcComputationExpression (cenv: cenv) env (overallTy: OverallTy) tpenv (mWhol
     /// Decide if the builder is an auto-quote builder
     let isAutoQuote = hasMethInfo "Quote"
 
-    let customOperationMethods = 
+    let customOperationMethods =
         AllMethInfosOfTypeInScope ResultCollectionSettings.AllResults cenv.infoReader env.NameEnv None ad IgnoreOverrides mBuilderVal builderTy
-        |> List.choose (fun methInfo -> 
+        |> List.choose (fun methInfo ->
                 if not (IsMethInfoAccessible cenv.amap mBuilderVal ad methInfo) then None else
-                let nameSearch = 
-                    TryBindMethInfoAttribute cenv.g mBuilderVal cenv.g.attrib_CustomOperationAttribute methInfo 
+                let nameSearch =
+                    TryBindMethInfoAttribute cenv.g mBuilderVal cenv.g.attrib_CustomOperationAttribute methInfo
                         IgnoreAttribute // We do not respect this attribute for IL methods
-                        (function Attrib(_, _, [ AttribStringArg msg ], _, _, _, _) -> Some msg | _ -> None)
+                        (fun attr ->
+                            match attr with
+                            | Attrib(_, _, [ AttribStringArg msg ], _, _, _, _) when msg = "" ->
+                                Some methInfo.LogicalName
+                            | Attrib(_, _, [ ], _, _, _, _) ->
+                                Some methInfo.LogicalName
+                            | Attrib(_, _, [ AttribStringArg msg ], _, _, _, _) ->
+                                Some msg
+                            | _ -> None)
                         IgnoreAttribute // We do not respect this attribute for provided methods
 
                 match nameSearch with

src/FSharp.Core/prim-types.fs

@@ -287,6 +287,7 @@ namespace Microsoft.FSharp.Core
         let mutable maintainsVarSpace = false
         let mutable maintainsVarSpaceWithBind = false
         let mutable joinOnWord = ""
+        new() = CustomOperationAttribute("")
         member _.Name = name
         member _.AllowIntoPattern with get() = allowInto and set v = allowInto <- v
         member _.IsLikeZip with get() = isBinary and set v = isBinary <- v

src/FSharp.Core/prim-types.fsi

@@ -420,6 +420,10 @@ namespace Microsoft.FSharp.Core
         /// <returns>CustomOperationAttribute</returns>
         new: name:string -> CustomOperationAttribute
 
+        /// <summary>Create an instance of attribute with empty name</summary>
+        /// <returns>CustomOperationAttribute</returns>
+        new: unit -> CustomOperationAttribute
+
         /// <summary>Get the name of the custom operation when used in a query or other computation expression</summary>
         member Name: string
 

tests/FSharp.Compiler.ComponentTests/Conformance/Expressions/ComputationExpressions/CustomOperations.fs

@@ -0,0 +1,41 @@
+namespace Conformance.Expressions.ComputationExpressions
+
+open Xunit
+open FSharp.Test.Compiler
+
+module CustomOperations =
+
+// it becomes increasingly difficult to use packaged fslib in tests.
+#if !FSHARPCORE_USE_PACKAGE
+    [<Fact>]
+#endif
+    let ``[<CustomOperation>] without explicit name is allowed, uses method name as operation name`` () =
+        FSharp """
+            module CustomOperationTest
+            type CBuilder() =
+                [<CustomOperation>]
+                member this.Foo _ = "Foo"
+                [<CustomOperation>]
+                member this.foo _ = "foo"
+                member this.Yield _ = ()
+                member this.Zero _ = ()
+
+
+            [<EntryPoint>]
+            let main _ =
+                let cb = CBuilder()
+
+                let x = cb { Foo }
+                let y = cb { foo }
+                printfn $"{x}"
+                printfn $"{y}"
+
+                if x <> "Foo" then
+                    failwith "not Foo"
+                if y <> "foo" then
+                    failwith "not foo"
+                0
+        """
+        |> asExe
+        |> compileAndRun
+        |> shouldSucceed

tests/FSharp.Compiler.ComponentTests/FSharp.Compiler.ComponentTests.fsproj

@@ -31,53 +31,77 @@
       <Link>FsUnit.fs</Link>
     </Compile>
     <Compile Include="Conformance\BasicGrammarElements\AccessibilityAnnotations\Basic\Basic.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\AccessibilityAnnotations\OnOverridesAndIFaceImpl\OnOverridesAndIFaceImpl.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\AccessibilityAnnotations\OnTypeMembers\OnTypeMembers.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\AccessibilityAnnotations\PermittedLocations\PermittedLocations.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\CustomAttributes\AttributeInheritance\AttributeInheritance.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\CustomAttributes\AttributeUsage\AttributeUsage.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\AccessibilityAnnotations\OnOverridesAndIFaceImpl\OnOverridesAndIFaceImpl.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\AccessibilityAnnotations\OnTypeMembers\OnTypeMembers.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\AccessibilityAnnotations\PermittedLocations\PermittedLocations.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\CustomAttributes\AttributeInheritance\AttributeInheritance.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\CustomAttributes\AttributeUsage\AttributeUsage.fs" />
     <Compile Include="Conformance\BasicGrammarElements\CustomAttributes\Basic\Basic.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\CustomAttributes\ImportedAttributes\ImportedAttributes.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\CustomAttributes\ArgumentsOfAllTypes\ArgumentsOfAllTypes.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\CustomAttributes\ImportedAttributes\ImportedAttributes.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\CustomAttributes\ArgumentsOfAllTypes\ArgumentsOfAllTypes.fs" />
     <Compile Include="Conformance\BasicGrammarElements\DelegateTypes\DelegateDefinition.fs" />
     <Compile Include="Conformance\BasicGrammarElements\EntryPoint\EntryPoint.fs" />
     <Compile Include="Conformance\BasicGrammarElements\Events\Basic\Basic.fs" />
     <Compile Include="Conformance\BasicGrammarElements\ExceptionDefinitions\ExceptionDefinitions.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\ExplicitObjectConstructors\ExplicitObjectConstructors.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\ExplicitObjectConstructors\ExplicitObjectConstructors.fs" />
     <Compile Include="Conformance\BasicGrammarElements\FieldMembers\FieldMembers.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\ImplicitObjectConstructors\ImplicitObjectConstructors.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\ImplicitObjectConstructors\ImplicitObjectConstructors.fs" />
     <Compile Include="Conformance\BasicGrammarElements\ImportDeclarations\ImportDeclarations.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\InterfaceSpecificationsAndImplementations\InterfaceSpecificationsAndImplementations.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\InterfaceSpecificationsAndImplementations\InterfaceSpecificationsAndImplementations.fs" />
     <Compile Include="Conformance\BasicGrammarElements\LetBindings\Basic\Basic.fs" />
     <Compile Include="Conformance\BasicGrammarElements\LetBindings\TypeFunctions\TypeFunctions.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\LetBindings\ActivePatternBindings\ActivePatternBindings.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\LetBindings\ExplicitTypeParameters\ExplicitTypeParameters.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\LetBindings\ActivePatternBindings\ActivePatternBindings.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\LetBindings\ExplicitTypeParameters\ExplicitTypeParameters.fs" />
     <Compile Include="Conformance\BasicGrammarElements\MemberDefinitions\MemberDefinitions.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\MemberDefinitions\ImplementingDispatchSlots\ImplementingDispatchSlots.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\MemberDefinitions\MethodsAndProperties\MethodsAndProperties.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\MemberDefinitions\NamedArguments\NamedArguments.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\MemberDefinitions\OptionalArguments\OptionalArguments.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\MemberDefinitions\OptionalDefaultParamArgs\OptionalDefaultParamArgs.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\MemberDefinitions\OverloadingMembers\OverloadingMembers.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\MemberDefinitions\ImplementingDispatchSlots\ImplementingDispatchSlots.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\MemberDefinitions\MethodsAndProperties\MethodsAndProperties.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\MemberDefinitions\NamedArguments\NamedArguments.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\MemberDefinitions\OptionalArguments\OptionalArguments.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\MemberDefinitions\OptionalDefaultParamArgs\OptionalDefaultParamArgs.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\MemberDefinitions\OverloadingMembers\OverloadingMembers.fs" />
     <Compile Include="Conformance\BasicGrammarElements\MethodResolution.fs" />
     <Compile Include="Conformance\BasicGrammarElements\ModuleAbbreviations\ModuleAbbreviations.fs" />
     <Compile Include="Conformance\BasicGrammarElements\ModuleDefinitions\ModuleDefinitions.fs" />
     <Compile Include="Conformance\BasicGrammarElements\NamespaceDeclGroups\NamespaceDeclGroups.fs" />
     <Compile Include="Conformance\BasicGrammarElements\NullRepresentations\NullRepresentations.fs" />
     <Compile Include="Conformance\BasicGrammarElements\OperatorNames\OperatorNames.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\PrecedenceAndOperators\PrecedenceAndOperators.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\PrecedenceAndOperators\PrecedenceAndOperators.fs" />
     <Compile Include="Conformance\BasicGrammarElements\StaticLet\StaticLetInUnionsAndRecords.fs" />
     <Compile Include="Conformance\BasicGrammarElements\TypeAbbreviations\TypeAbbreviations.fs" />
-    <Compile Include="Conformance\BasicGrammarElements\TypeAbbreviations\WarnForAutoOpenAttributeAlias.fs" />
+    <Compile
+      Include="Conformance\BasicGrammarElements\TypeAbbreviations\WarnForAutoOpenAttributeAlias.fs" />
     <Compile Include="Conformance\BasicGrammarElements\ValueRestriction\ValueRestriction.fs" />
     <Compile Include="Conformance\BasicGrammarElements\UseBindings\UseBindings.fs" />
-	<Compile Include="Conformance\Constraints\Unmanaged.fs" />
-    <Compile Include="Conformance\GeneratedEqualityHashingComparison\Attributes\Diags\Attributes_Diags.fs" />
-    <Compile Include="Conformance\GeneratedEqualityHashingComparison\Attributes\Legacy\Attributes_Legacy.fs" />
+    <Compile Include="Conformance\Constraints\Unmanaged.fs" />
+    <Compile
+      Include="Conformance\GeneratedEqualityHashingComparison\Attributes\Diags\Attributes_Diags.fs" />
+    <Compile
+      Include="Conformance\GeneratedEqualityHashingComparison\Attributes\Legacy\Attributes_Legacy.fs" />
     <Compile Include="Conformance\GeneratedEqualityHashingComparison\Basic\Basic.fs" />
     <Compile Include="Conformance\GeneratedEqualityHashingComparison\IComparison\IComparison.fs" />
-    <Compile Include="Conformance\Expressions\ApplicationExpressions\BasicApplication\BasicApplication.fs" />
+    <Compile
+      Include="Conformance\Expressions\ApplicationExpressions\BasicApplication\BasicApplication.fs" />
     <Compile Include="Conformance\Expressions\BindingExpressions\BindingExpressions.fs" />
+    <Compile Include="Conformance\Expressions\ComputationExpressions\CustomOperations.fs" />
     <Compile Include="Conformance\Expressions\ObjectExpressions\ObjectExpressions.fs" />
     <Compile Include="Conformance\Expressions\ControlFlowExpressions\PatternMatching\PatternMatching.fs" />
     <Compile Include="Conformance\Expressions\ControlFlowExpressions\SequenceIteration\SequenceIteration.fs" />

tests/projects/Sample_Local_Compiler_and_FSLib/LocalCompilerAndFslib.fsproj

@@ -0,0 +1,23 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <LangVersion>preview</LangVersion>
+    <DisableImplicitFSharpCoreReference>true</DisableImplicitFSharpCoreReference>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <DisableAutoSetFscCompilerPath>true</DisableAutoSetFscCompilerPath>
+    <DotnetFscCompilerPath>$(MSBuildThisFileDirectory)../../../artifacts/bin/fsc/Debug/net8.0/fsc.dll</DotnetFscCompilerPath>
+    <Fsc_DotNET_DotnetFscCompilerPath>$(MSBuildThisFileDirectory)../../../artifacts/bin/fsc/Debug/net8.0/fsc.dll</Fsc_DotNET_DotnetFscCompilerPath>
+    <FSharpPreferNetFrameworkTools>False</FSharpPreferNetFrameworkTools>
+    <FSharpPrefer64BitTools>True</FSharpPrefer64BitTools>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Reference Include="$(MSBuildThisFileDirectory)../../../artifacts/bin/FSharp.Core/Debug/netstandard2.0/FSharp.Core.dll" />
+    <Compile Include="Program.fs" />
+  </ItemGroup>
+
+</Project>

tests/projects/Sample_Local_Compiler_and_FSLib/Program.fs

@@ -0,0 +1,25 @@
+module Program
+
+type CBuilder() =
+    [<CustomOperation>]
+    member this.Foo _ = "Foo"
+    [<CustomOperation>]
+    member this.foo _ = "foo"
+    member this.Yield _ = ()
+    member this.Zero _ = ()
+
+
+[<EntryPoint>]
+let main _ =
+    let cb = CBuilder()
+
+    let x = cb { Foo }
+    let y = cb { foo }
+    printfn $"{x}"
+    printfn $"{y}"
+
+    if x <> "Foo" then
+        failwith "not Foo"
+    if y <> "foo" then
+        failwith "not foo"
+    0