Better error message when abstract member impl is wrong - fixes #1203

dotnet · May 31, 2016 · 6a54b7f · 6a54b7f
1 parent 02b490d
commit 6a54b7f
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Showing 4 changed files with 22 additions and 5 deletions.
diff --git a/src/fsharp/FSComp.txt b/src/fsharp/FSComp.txt
@@ -588,8 +588,8 @@ tcExpressionWithIfRequiresParenthesis,"This list or array expression includes an
 765,tcExtraneousFieldsGivenValues,"Extraneous fields have been given values"
 766,tcObjectExpressionsCanOnlyOverrideAbstractOrVirtual,"Only overrides of abstract and virtual members may be specified in object expressions"
 767,tcNoAbstractOrVirtualMemberFound,"The member '%s' does not correspond to any abstract or virtual method available to override or implement"
-768,tcArgumentArityMismatch,"The member '%s' does not accept the correct number of arguments, %d arguments are expected"
-769,tcArgumentArityMismatchOneOverload,"The member '%s' does not accept the correct number of arguments. One overload accepts %d arguments."
+768,tcArgumentArityMismatch,"The member '%s' does not accept the correct number of arguments. %d argument(s) are expected. The required signature is '%s'."
+769,tcArgumentArityMismatchOneOverload,"The member '%s' does not accept the correct number of arguments. One overload accepts %d arguments. The required signature is '%s'."
 770,tcSimpleMethodNameRequired,"A simple method name is required here"
 771,tcPredefinedTypeCannotBeUsedAsSuperType,"The types System.ValueType, System.Enum, System.Delegate, System.MulticastDelegate and System.Array cannot be used as super types in an object expression or class"
 772,tcNewMustBeUsedWithNamedType,"'new' must be used with a named type"

diff --git a/src/fsharp/TypeChecker.fs b/src/fsharp/TypeChecker.fs
@@ -6036,16 +6036,20 @@ and GetNameAndArityOfObjExprBinding _cenv _env b =
         lookPat pat
 
 
-and FreshenObjExprAbstractSlot cenv (_env: TcEnv) implty virtNameAndArityPairs (bind,bindAttribs,bindName,absSlots:(_ * MethInfo) list) = 
+and FreshenObjExprAbstractSlot cenv (env: TcEnv) implty virtNameAndArityPairs (bind,bindAttribs,bindName,absSlots:(_ * MethInfo) list) = 
     let (NormalizedBinding (_,_,_,_,_,_,synTyparDecls,_,_,_,mBinding,_)) = bind 
     match absSlots with 
     | [] when not (CompileAsEvent cenv.g bindAttribs) -> 
         let absSlotsByName = List.filter (fst >> fst >> (=) bindName) virtNameAndArityPairs
 
         match absSlotsByName with 
         | []              -> errorR(Error(FSComp.SR.tcNoAbstractOrVirtualMemberFound(bindName),mBinding))
-        | [(_,absSlot:MethInfo)]     -> errorR(Error(FSComp.SR.tcArgumentArityMismatch(bindName, (List.sum absSlot.NumArgs)),mBinding))
-        | (_,absSlot:MethInfo) :: _  -> errorR(Error(FSComp.SR.tcArgumentArityMismatchOneOverload(bindName, (List.sum absSlot.NumArgs)),mBinding))
+        | [(_,absSlot:MethInfo)]     ->
+            let signature = (NicePrint.stringOfMethInfo cenv.amap mBinding env.DisplayEnv absSlot).Replace("abstract ","")
+            errorR(Error(FSComp.SR.tcArgumentArityMismatch(bindName, List.sum absSlot.NumArgs, signature),mBinding))
+        | (_,absSlot:MethInfo) :: _  ->
+            let signature = (NicePrint.stringOfMethInfo cenv.amap mBinding env.DisplayEnv absSlot).Replace("abstract ","")
+            errorR(Error(FSComp.SR.tcArgumentArityMismatchOneOverload(bindName, List.sum absSlot.NumArgs, signature),mBinding))
 
         None
 

diff --git a/tests/fsharpqa/Source/Warnings/TupleInAbstractMethod.fs b/tests/fsharpqa/Source/Warnings/TupleInAbstractMethod.fs
@@ -0,0 +1,12 @@
+// #Warnings
+//<Expects status="Error" span="(9,16)" id="FS0768">The member 'Function' does not accept the correct number of arguments. 1 argument(s) are expected. The required signature is 'member IInterface.Function : (int32 * int32) -> unit'.</Expects>
+
+type IInterface =
+    abstract Function : (int32 * int32) -> unit
+
+let x = 
+  { new IInterface with
+        member this.Function (i, j) = ()
+  }
+
+exit 0
diff --git a/tests/fsharpqa/Source/Warnings/env.lst b/tests/fsharpqa/Source/Warnings/env.lst
@@ -2,6 +2,7 @@
 	SOURCE=WarnIfMissingElseBranch.fs # WarnIfMissingElseBranch.fs
 	SOURCE=ReturnInsteadOfReturnBang.fs # ReturnInsteadOfReturnBang.fs
 	SOURCE=YieldInsteadOfYieldBang.fs # YieldInsteadOfYieldBang.fs
+	SOURCE=TupleInAbstractMethod.fs # TupleInAbstractMethod.fs
 	SOURCE=CommaInRecCtor.fs # CommaInRecCtor.fs
 	SOURCE=ValidCommaInRecCtor.fs # ValidCommaInRecCtor.fs
 	SOURCE=ElseBranchHasWrongType.fs # ElseBranchHasWrongType.fs