Report the number of arguments associated with a printf format specifier along with its range

This is needed if one wants to accurately map arguments -> specifiers or
specifiers -> arguments.

A specifier can take 0, 1, 2, or 3 args:

  - printfn "%%"     // 0 args
  - printfn "%*%"    // 1 arg
  - printfn "%*.*%"  // 2 args
  - printfn "%*.*f"  // 3 args

Author: latkin

src/fsharp/CheckFormatStrings.fs

@@ -193,27 +193,30 @@ let parseFormatStringInternal (m:range) g (source: string option) fmt bty cty =
                   checkNoZeroFlag c 
                   checkNoNumericPrefix c
 
-              let collectSpecifierLocation relLine relCol = 
+              let collectSpecifierLocation relLine relCol numStdArgs = 
+                  let numArgsForSpecifier =
+                    numStdArgs + (if widthArg then 1 else 0) + (if precisionArg then 1 else 0)
                   match relLine with
                   | 0 ->
                       specifierLocations.Add(
-                        Range.mkFileIndexRange m.FileIndex 
+                        (Range.mkFileIndexRange m.FileIndex 
                                 (Range.mkPos m.StartLine (startCol + offset)) 
-                                (Range.mkPos m.StartLine (relCol + offset)))
+                                (Range.mkPos m.StartLine (relCol + offset))), numArgsForSpecifier)
                   | _ ->
                       specifierLocations.Add(
-                        Range.mkFileIndexRange m.FileIndex 
+                        (Range.mkFileIndexRange m.FileIndex 
                                 (Range.mkPos (m.StartLine + relLine) startCol) 
-                                (Range.mkPos (m.StartLine + relLine) relCol))
+                                (Range.mkPos (m.StartLine + relLine) relCol)), numArgsForSpecifier)
 
               let ch = fmt.[i]
               match ch with
-              | '%' -> 
+              | '%' ->
+                  collectSpecifierLocation relLine relCol 0
                   parseLoop acc (i+1, relLine, relCol+1) 
 
               | ('d' | 'i' | 'o' | 'u' | 'x' | 'X') ->
                   if info.precision then failwithf "%s" <| FSComp.SR.forFormatDoesntSupportPrecision(ch.ToString())
-                  collectSpecifierLocation relLine relCol
+                  collectSpecifierLocation relLine relCol 1
                   parseLoop ((posi, mkFlexibleIntFormatTypar g m) :: acc) (i+1, relLine, relCol+1)
 
               | ('l' | 'L') ->
@@ -228,59 +231,59 @@ let parseFormatStringInternal (m:range) g (source: string option) fmt bty cty =
                   failwithf "%s" <| FSComp.SR.forLIsUnnecessary()
                   match fmt.[i] with
                   | ('d' | 'i' | 'o' | 'u' | 'x' | 'X') -> 
-                      collectSpecifierLocation relLine relCol
+                      collectSpecifierLocation relLine relCol 1
                       parseLoop ((posi, mkFlexibleIntFormatTypar g m) :: acc)  (i+1, relLine, relCol+1)
                   | _ -> failwithf "%s" <| FSComp.SR.forBadFormatSpecifier()
 
               | ('h' | 'H') ->
                   failwithf "%s" <| FSComp.SR.forHIsUnnecessary()
 
               | 'M' -> 
-                  collectSpecifierLocation relLine relCol
+                  collectSpecifierLocation relLine relCol 1
                   parseLoop ((posi, g.decimal_ty) :: acc) (i+1, relLine, relCol+1)
 
               | ('f' | 'F' | 'e' | 'E' | 'g' | 'G') ->
-                  collectSpecifierLocation relLine relCol
+                  collectSpecifierLocation relLine relCol 1
                   parseLoop ((posi, mkFlexibleFloatFormatTypar g m) :: acc) (i+1, relLine, relCol+1)
 
               | 'b' ->
                   checkOtherFlags ch
-                  collectSpecifierLocation relLine relCol
+                  collectSpecifierLocation relLine relCol 1
                   parseLoop ((posi, g.bool_ty)  :: acc) (i+1, relLine, relCol+1)
 
               | 'c' ->
                   checkOtherFlags ch
-                  collectSpecifierLocation relLine relCol
+                  collectSpecifierLocation relLine relCol 1
                   parseLoop ((posi, g.char_ty)  :: acc) (i+1, relLine, relCol+1)
 
               | 's' ->
                   checkOtherFlags ch
-                  collectSpecifierLocation relLine relCol
+                  collectSpecifierLocation relLine relCol 1
                   parseLoop ((posi, g.string_ty)  :: acc) (i+1, relLine, relCol+1)
 
               | 'O' ->
                   checkOtherFlags ch
-                  collectSpecifierLocation relLine relCol
+                  collectSpecifierLocation relLine relCol 1
                   parseLoop ((posi, NewInferenceType ()) :: acc) (i+1, relLine, relCol+1)
 
               | 'A' ->
                   match info.numPrefixIfPos with
                   | None     // %A has BindingFlags=Public, %+A has BindingFlags=Public | NonPublic
                   | Some '+' -> 
-                      collectSpecifierLocation relLine relCol
+                      collectSpecifierLocation relLine relCol 1
                       parseLoop ((posi, NewInferenceType ()) :: acc)  (i+1, relLine, relCol+1)
                   | Some _   -> failwithf "%s" <| FSComp.SR.forDoesNotSupportPrefixFlag(ch.ToString(), (Option.get info.numPrefixIfPos).ToString())
 
               | 'a' ->
                   checkOtherFlags ch
                   let xty = NewInferenceType () 
                   let fty = bty --> (xty --> cty)
-                  collectSpecifierLocation relLine relCol
+                  collectSpecifierLocation relLine relCol 1
                   parseLoop ((Option.map ((+)1) posi, xty) ::  (posi, fty) :: acc) (i+1, relLine, relCol+1)
 
               | 't' ->
                   checkOtherFlags ch
-                  collectSpecifierLocation relLine relCol
+                  collectSpecifierLocation relLine relCol 1
                   parseLoop ((posi, bty --> cty) :: acc)  (i+1, relLine, relCol+1)
 
               | c -> failwithf "%s" <| FSComp.SR.forBadFormatSpecifierGeneral(String.make 1 c) 

src/fsharp/CheckFormatStrings.fsi

@@ -13,6 +13,6 @@ open Microsoft.FSharp.Compiler.Tast
 open Microsoft.FSharp.Compiler.TcGlobals
 open Microsoft.FSharp.Compiler.AbstractIL.Internal 
 
-val ParseFormatString : Range.range -> TcGlobals -> source: string option -> fmt: string -> bty: TType -> cty: TType -> dty: TType -> (TType * TType) * Range.range list
+val ParseFormatString : Range.range -> TcGlobals -> source: string option -> fmt: string -> bty: TType -> cty: TType -> dty: TType -> (TType * TType) * (Range.range * int) list
 
 val TryCountFormatStringArguments : m:Range.range -> g:TcGlobals -> fmt:string -> bty:TType -> cty:TType -> int option

src/fsharp/NameResolution.fs

@@ -1105,7 +1105,7 @@ type ITypecheckResultsSink =
     abstract NotifyEnvWithScope : range * NameResolutionEnv * AccessorDomain -> unit
     abstract NotifyExprHasType : pos * TType * Tastops.DisplayEnv * NameResolutionEnv * AccessorDomain * range -> unit
     abstract NotifyNameResolution : pos * Item * Item * ItemOccurence * Tastops.DisplayEnv * NameResolutionEnv * AccessorDomain * range -> unit
-    abstract NotifyFormatSpecifierLocation : range -> unit
+    abstract NotifyFormatSpecifierLocation : range * int -> unit
     abstract CurrentSource : string option
 
 let (|ValRefOfProp|_|) (pi : PropInfo) = pi.ArbitraryValRef
@@ -1301,7 +1301,7 @@ type TcResolutions
 
 
 /// Represents container for all name resolutions that were met so far when typechecking some particular file
-type TcSymbolUses(g, capturedNameResolutions : ResizeArray<CapturedNameResolution>, formatSpecifierLocations: range[]) = 
+type TcSymbolUses(g, capturedNameResolutions : ResizeArray<CapturedNameResolution>, formatSpecifierLocations: (range * int)[]) = 
 
     member this.GetUsesOfSymbol(item) = 
         [| for cnr in capturedNameResolutions do
@@ -1367,8 +1367,8 @@ type TcResultsSinkImpl(g, ?source: string) =
                     capturedNameResolutions.Add(CapturedNameResolution(endPos,item,occurenceType,denv,nenv,ad,m)) 
                     capturedMethodGroupResolutions.Add(CapturedNameResolution(endPos,itemMethodGroup,occurenceType,denv,nenv,ad,m)) 
 
-        member sink.NotifyFormatSpecifierLocation(m) = 
-            capturedFormatSpecifierLocations.Add(m)
+        member sink.NotifyFormatSpecifierLocation(m, numArgs) = 
+            capturedFormatSpecifierLocations.Add((m, numArgs))
 
         member sink.CurrentSource = source
 

src/fsharp/NameResolution.fsi

@@ -233,15 +233,15 @@ type internal TcSymbolUses =
 
     member GetAllUsesOfSymbols : unit -> (Item * ItemOccurence * DisplayEnv * range)[]
 
-    member GetFormatSpecifierLocations : unit -> range[]
+    member GetFormatSpecifierLocations : unit -> (range * int)[]
 
 
 /// An abstract type for reporting the results of name resolution and type checking
 type ITypecheckResultsSink =
     abstract NotifyEnvWithScope   : range * NameResolutionEnv * AccessorDomain -> unit
     abstract NotifyExprHasType    : pos * TType * DisplayEnv * NameResolutionEnv * AccessorDomain * range -> unit
     abstract NotifyNameResolution : pos * Item * Item * ItemOccurence * DisplayEnv * NameResolutionEnv * AccessorDomain * range -> unit
-    abstract NotifyFormatSpecifierLocation : range -> unit
+    abstract NotifyFormatSpecifierLocation : range * int -> unit
     abstract CurrentSource : string option
 
 type internal TcResultsSinkImpl =

src/fsharp/TypeChecker.fs

@@ -1739,7 +1739,7 @@ let MakeAndPublishSimpleVals cenv env m names mergeNamesInOneNameresEnv =
                             if not m.IsSynthetic then
                                 nameResolutions.Add(pos, a, b, occurence, denv, nenv, ad, m)
                         member this.NotifyExprHasType(_, _, _, _, _, _) = assert false // no expr typings in MakeSimpleVals
-                        member this.NotifyFormatSpecifierLocation _ = ()
+                        member this.NotifyFormatSpecifierLocation(_, _) = ()
                         member this.CurrentSource = None } 
 
                 use _h = WithNewTypecheckResultsSink(sink, cenv.tcSink)
@@ -6314,8 +6314,8 @@ and TcConstStringExpr cenv overallTy env m tpenv s  =
         match cenv.tcSink.CurrentSink with 
         | None -> () 
         | Some sink  -> 
-            for specifierLocation in specifierLocations do
-                sink.NotifyFormatSpecifierLocation specifierLocation
+            for specifierLocation,numArgs in specifierLocations do
+                sink.NotifyFormatSpecifierLocation(specifierLocation, numArgs)
 
         UnifyTypes cenv env m aty aty'
         UnifyTypes cenv env m ety ety'

src/fsharp/vs/service.fsi

@@ -259,8 +259,8 @@ type FSharpCheckFileResults =
     /// <summary>Get any extra colorization info that is available after the typecheck</summary>
     member GetExtraColorizationsAlternate : unit -> (range * FSharpTokenColorKind)[]
 
-    /// <summary>Get the locations of format specifiers</summary>
-    member GetFormatSpecifierLocations : unit -> range[]
+    /// <summary>Get the locations of and number of arguments associated with format specifiers</summary>
+    member GetFormatSpecifierLocations : unit -> (range*int)[]
 
     /// Get all textual usages of all symbols throughout the file
     member GetAllUsesOfAllSymbolsInFile : unit -> Async<FSharpSymbolUse[]>