Better wording

src/fsharp/CompileOps.fs

@@ -203,7 +203,10 @@ let GetRangeOfDiagnostic(err:PhasedDiagnostic) =
       | SelfRefObjCtor(_,m) -> 
           Some m
 
-      | NotAFunction(_,_,_,mfun,_) -> 
+      | NotAFunction(_,_,mfun,_) -> 
+          Some mfun
+          
+      | NotAFunctionButIndexer(_,_,_,mfun,_) -> 
           Some mfun
 
       | IllegalFileNameChar(_) -> Some rangeCmdArgs
@@ -243,7 +246,7 @@ let GetDiagnosticNumber(err:PhasedDiagnostic) =
       (* DO NOT CHANGE THESE NUMBERS *)
       | ErrorFromAddingTypeEquation _ -> 1
       | FunctionExpected _ -> 2
-      | NotAFunction (_,_,true,_,_)  -> 3217
+      | NotAFunctionButIndexer _ -> 3217
       | NotAFunction _  -> 3
       | FieldNotMutable  _ -> 5
       | Recursion _ -> 6
@@ -742,14 +745,15 @@ let OutputPhasedErrorR (os:StringBuilder) (err:PhasedDiagnostic) =
          os.Append(ParameterlessStructCtorE().Format) |> ignore
       | InterfaceNotRevealed(denv,ity,_) ->
           os.Append(InterfaceNotRevealedE().Format (NicePrint.minimalStringOfType denv ity)) |> ignore
-      | NotAFunction(_,_,hasIndexer,_,marg) ->
-          if hasIndexer then
-              os.Append(FSComp.SR.notAFunctionButMaybeIndexer()) |> ignore
-          elif marg.StartColumn = 0 then 
+      | NotAFunctionButIndexer(_,_,name,_,_) ->
+          match name with
+          | Some name -> os.Append(FSComp.SR.notAFunctionButMaybeIndexerWithName name) |> ignore
+          | _ -> os.Append(FSComp.SR.notAFunctionButMaybeIndexer()) |> ignore
+      | NotAFunction(_,_,_,marg) ->
+          if marg.StartColumn = 0 then
               os.Append(FSComp.SR.notAFunctionButMaybeDeclaration()) |> ignore
           else
               os.Append(FSComp.SR.notAFunction()) |> ignore
-          
       | TyconBadArgs(_,tcref,d,_) -> 
           let exp = tcref.TyparsNoRange.Length
           if exp = 0 then

src/fsharp/FSComp.txt

@@ -1412,5 +1412,7 @@ keywordDescriptionUntypedQuotation,"Delimits a untyped code quotation."
 3216,itemNotFoundInTypeDuringDynamicCodeGen,"%s '%s' not found in type '%s' from assembly '%s'. A possible cause may be a version incompatibility. You may need to explicitly reference the correct version of this assembly to allow all referenced components to use the correct version."
 descriptionWordIs,"is"
 notAFunction,"This value is not a function and cannot be applied."
-3217,notAFunctionButMaybeIndexer,"This value is not a function and cannot be applied. Did you intend to call obj.[index] instead of obj[index]?"
+notAFunctionButMaybeIndexerWithName,"This value is not a function and cannot be applied. Did you intend to access the indexer via %s.[index] instead?"
+notAFunctionButMaybeIndexer,"This expression is not a function and cannot be applied. Did you intend to access the indexer via expr.[index] instead?"
+3217,notAFunctionButMaybeIndexerErrorCode,""
 notAFunctionButMaybeDeclaration,"This value is not a function and cannot be applied. Did you forget to terminate a declaration?"

src/fsharp/TypeChecker.fs

@@ -70,7 +70,8 @@ let mkUnitDelayLambda (g: TcGlobals) m e =
 
 exception BakedInMemberConstraintName of string * range
 exception FunctionExpected of DisplayEnv * TType * range
-exception NotAFunction of DisplayEnv * TType * bool * range * range
+exception NotAFunction of DisplayEnv * TType * range * range
+exception NotAFunctionButIndexer of DisplayEnv * TType * string option * range * range
 exception Recursion of DisplayEnv * Ident * TType * TType  * range
 exception RecursiveUseCheckedAtRuntime of DisplayEnv * ValRef * range
 exception LetRecEvaluatedOutOfOrder of DisplayEnv * ValRef * ValRef * range
@@ -746,7 +747,7 @@ let UnifyFunctionType extraInfo cenv denv mFunExpr ty =
     | Some res -> res
     | None -> 
         match extraInfo with 
-        | Some argm -> error (NotAFunction(denv,ty,false,mFunExpr,argm))
+        | Some argm -> error (NotAFunction(denv,ty,mFunExpr,argm))
         | None ->    error (FunctionExpected(denv,ty,mFunExpr))
 
 let ReportImplicitlyIgnoredBoolExpression denv m ty expr =
@@ -8222,14 +8223,21 @@ and Propagate cenv overallTy env tpenv (expr: ApplicableExpr) exprty delayed =
                 let mArg = arg.Range
                 match arg with
                 | SynExpr.CompExpr _ -> ()
-                | SynExpr.ArrayOrListOfSeqExpr _ ->
+                | SynExpr.ArrayOrListOfSeqExpr (_,_,_) ->
                     // 'delayed' is about to be dropped on the floor, first do rudimentary checking to get name resolutions in its body
                     RecordNameAndTypeResolutions_IdeallyWithoutHavingOtherEffects_Delayed cenv env tpenv delayed
-                    error (NotAFunction(denv,overallTy,IsIndexerType cenv.g cenv.amap expr.Type,mExpr,mArg)) 
+                    if IsIndexerType cenv.g cenv.amap expr.Type then
+                        match expr.Expr with
+                        | Expr.Val (d,_,_) ->
+                            error (NotAFunctionButIndexer(denv,overallTy,Some d.DisplayName,mExpr,mArg))
+                        | _ ->
+                            error (NotAFunctionButIndexer(denv,overallTy,None,mExpr,mArg))
+                    else
+                        error (NotAFunction(denv,overallTy,mExpr,mArg))
                 | _ ->
                     // 'delayed' is about to be dropped on the floor, first do rudimentary checking to get name resolutions in its body
                     RecordNameAndTypeResolutions_IdeallyWithoutHavingOtherEffects_Delayed cenv env tpenv delayed
-                    error (NotAFunction(denv,overallTy,false,mExpr,mArg)) 
+                    error (NotAFunction(denv,overallTy,mExpr,mArg))
 
     propagate delayed expr.Range exprty
 
@@ -8315,7 +8323,7 @@ and TcFunctionApplicationThen cenv overallTy env tpenv mExprAndArg expr exprty (
             let bodyOfCompExpr,tpenv = TcComputationOrSequenceExpression cenv env overallTy mFunExpr (Some(expr.Expr,exprty)) tpenv comp
             TcDelayed cenv overallTy env tpenv mExprAndArg (MakeApplicableExprNoFlex cenv bodyOfCompExpr) (tyOfExpr cenv.g bodyOfCompExpr) ExprAtomicFlag.NonAtomic delayed 
         | _ -> 
-            error (NotAFunction(denv,overallTy,false,mFunExpr,mArg)) 
+            error (NotAFunction(denv,overallTy,mFunExpr,mArg)) 
 
 //-------------------------------------------------------------------------
 // TcLongIdentThen : Typecheck "A.B.C<D>.E.F ... " constructs

src/fsharp/TypeChecker.fsi

@@ -63,7 +63,8 @@ val TypeCheckOneSigFile :
 
 exception BakedInMemberConstraintName of string * range
 exception FunctionExpected of DisplayEnv * TType * range
-exception NotAFunction of DisplayEnv * TType * bool * range * range
+exception NotAFunction of DisplayEnv * TType * range * range
+exception NotAFunctionButIndexer of DisplayEnv * TType * string option * range * range
 exception Recursion of DisplayEnv * Ast.Ident * TType * TType * range
 exception RecursiveUseCheckedAtRuntime of DisplayEnv * ValRef * range
 exception LetRecEvaluatedOutOfOrder of DisplayEnv * ValRef * ValRef * range

tests/fsharpqa/Source/Warnings/SuggestToUseIndexer.fs

 // #Warnings
-//<Expects status="Error" span="(6,9)" id="FS3217">This value is not a function and cannot be applied. But the given value has an indexer. Did you intend to call obj.[index] instead of obj[index]?</Expects>
+//<Expects status="Error" span="(6,9)" id="FS3217">This value is not a function and cannot be applied. Did you intend to access the indexer via d.[index] instead?</Expects>
 //<Expects status="Error" span="(8,9)" id="FS3217">This value is not a function and cannot be applied.$</Expects>
+//<Expects status="Error" span="(12,9)" id="FS3217">This value is not a function and cannot be applied. Did you intend to access the indexer via expr.[index] instead?"</Expects>
 
 let d = [1,1] |> dict
 let y = d[1]
 
 let z = d[|1|]
 
+let f() = d
+let y = (f())[1]
+
 exit 0
\ No newline at end of file