Fix bug in seekReadMethodDefAsMethodDataUncached (#1704)

seekReadMethodDefAsMethodDataUncached didn't honour the total parameter
count of both the type object and the method object. If there was only
one, then the correct result would have been achieved, but when both
were specific it caused corruption of the resultant MethodData
structure.

src/absil/il.fs

@@ -1908,12 +1908,12 @@ let gparam_of_gactual (_ga:ILType) = mkILSimpleTypar "T"
 
 let mkILFormalTypars (x: ILGenericArgsList) = List.map gparam_of_gactual x
 
-let mkILFormalGenericArgs (gparams:ILGenericParameterDefs)  =
-    List.mapi (fun n _gf -> mkILTyvarTy (uint16 n)) gparams
+let mkILFormalGenericArgs numtypars (gparams:ILGenericParameterDefs)  =
+    List.mapi (fun n _gf -> mkILTyvarTy (uint16 (numtypars + n))) gparams
  
-let mkILFormalBoxedTy tref gparams = mkILBoxedTy tref (mkILFormalGenericArgs gparams)
+let mkILFormalBoxedTy tref gparams = mkILBoxedTy tref (mkILFormalGenericArgs 0 gparams)
 
-let mkILFormalNamedTy bx tref gparams = mkILNamedTy bx tref (mkILFormalGenericArgs gparams)
+let mkILFormalNamedTy bx tref gparams = mkILNamedTy bx tref (mkILFormalGenericArgs 0 gparams)
 
 // -------------------------------------------------------------------- 
 // Operations on class etc. defs.

src/absil/il.fsi

@@ -1686,7 +1686,7 @@ val mkILFormalBoxedTy: ILTypeRef -> ILGenericParameterDef list -> ILType
 val mkILFormalNamedTy: ILBoxity -> ILTypeRef -> ILGenericParameterDef list -> ILType
 
 val mkILFormalTypars: ILType list -> ILGenericParameterDefs
-val mkILFormalGenericArgs: ILGenericParameterDefs -> ILGenericArgsList
+val mkILFormalGenericArgs: int -> ILGenericParameterDefs -> ILGenericArgsList
 val mkILSimpleTypar : string -> ILGenericParameterDef
 /// Make custom attributes.
 val mkILCustomAttribMethRef: 

src/absil/ilread.fs

@@ -2222,8 +2222,6 @@ and seekReadMethodDefAsMethodData ctxt idx =
    ctxt.seekReadMethodDefAsMethodData idx
 and seekReadMethodDefAsMethodDataUncached ctxtH idx =
    let ctxt = getHole ctxtH
-   let (_code_rva, _implflags, _flags, nameIdx, typeIdx, _paramIdx) = seekReadMethodRow ctxt idx
-   let nm = readStringHeap ctxt nameIdx
    // Look for the method def parent. 
    let tidx = 
      seekReadIndexedRow (ctxt.getNumRows TableNames.TypeDef,
@@ -2235,15 +2233,25 @@ and seekReadMethodDefAsMethodDataUncached ctxtH idx =
                                         elif methodsIdx <= idx && idx < endMethodsIdx then 0 
                                         else -1),
                             true,fst)
-   // Read the method def signature. 
-   let _generic,_genarity,cc,retty,argtys,varargs = readBlobHeapAsMethodSig ctxt 0 typeIdx
-   if varargs <> None then dprintf "ignoring sentinel and varargs in ILMethodDef token signature"
-   // Create a formal instantiation if needed 
-   let finst = mkILFormalGenericArgs (seekReadGenericParams ctxt 0 (tomd_TypeDef,tidx))
-   let minst = mkILFormalGenericArgs (seekReadGenericParams ctxt finst.Length (tomd_MethodDef,idx))
+   // Create a formal instantiation if needed
+   let typeGenericArgs = seekReadGenericParams ctxt 0 (tomd_TypeDef, tidx)
+   let typeGenericArgsCount = typeGenericArgs.Length
+
+   let methodGenericArgs = seekReadGenericParams ctxt typeGenericArgsCount (tomd_MethodDef, idx)
+    
+   let finst = mkILFormalGenericArgs 0 typeGenericArgs
+   let minst = mkILFormalGenericArgs typeGenericArgsCount methodGenericArgs
    // Read the method def parent. 
    let enclTyp = seekReadTypeDefAsType ctxt AsObject (* not ok: see note *) finst tidx
    // Return the constituent parts: put it together at the place where this is called. 
+
+   let (_code_rva, _implflags, _flags, nameIdx, typeIdx, _paramIdx) = seekReadMethodRow ctxt idx
+   let nm = readStringHeap ctxt nameIdx
+
+   // Read the method def signature. 
+   let _generic,_genarity,cc,retty,argtys,varargs = readBlobHeapAsMethodSig ctxt typeGenericArgsCount typeIdx
+   if varargs <> None then dprintf "ignoring sentinel and varargs in ILMethodDef token signature"
+
    MethodData(enclTyp, cc, nm, argtys, retty, minst)
 
 
@@ -2267,7 +2275,7 @@ and seekReadFieldDefAsFieldSpecUncached ctxtH idx =
    // Read the field signature. 
    let retty = readBlobHeapAsFieldSig ctxt 0 typeIdx
    // Create a formal instantiation if needed 
-   let finst = mkILFormalGenericArgs (seekReadGenericParams ctxt 0 (tomd_TypeDef,tidx))
+   let finst = mkILFormalGenericArgs 0 (seekReadGenericParams ctxt 0 (tomd_TypeDef,tidx))
    // Read the field def parent. 
    let enclTyp = seekReadTypeDefAsType ctxt AsObject (* not ok: see note *) finst tidx
    // Put it together. 

src/absil/ilx.fs

@@ -143,7 +143,7 @@ type IlxUnionInfo =
 
 let destTyFuncApp = function Apps_tyapp (b,c) -> b,c | _ -> failwith "destTyFuncApp"
 
-let mkILFormalCloRef gparams csig = IlxClosureSpec.Create(csig, mkILFormalGenericArgs gparams)
+let mkILFormalCloRef gparams csig = IlxClosureSpec.Create(csig, mkILFormalGenericArgs 0 gparams)
 
 let actualTypOfIlxUnionField (cuspec : IlxUnionSpec) idx fidx =
   instILType cuspec.GenericArgs (cuspec.FieldDef idx fidx).Type

src/fsharp/IlxGen.fs

@@ -3462,7 +3462,7 @@ and GenMethodImpl cenv eenv (useMethodImpl,(TSlotSig(nameOfOverridenMethod,_,_,_
         let eenvForOverrideBy = AddTyparsToEnv methTyparsOfOverridingMethod eenv 
         let ilParamsOfOverridingMethod,ilReturnOfOverridingMethod = GenActualSlotsig m cenv eenvForOverrideBy slotsig methTyparsOfOverridingMethod
         let ilOverrideMethGenericParams = GenGenericParams cenv eenvForOverrideBy methTyparsOfOverridingMethod 
-        let ilOverrideMethGenericArgs = mkILFormalGenericArgs ilOverrideMethGenericParams
+        let ilOverrideMethGenericArgs = mkILFormalGenericArgs 0 ilOverrideMethGenericParams
         let ilOverrideBy = mkILInstanceMethSpecInTy(ilTyForOverriding, nameOfOverridingMethod, typesOfILParams ilParamsOfOverridingMethod, ilReturnOfOverridingMethod.Type, ilOverrideMethGenericArgs)
         { Overrides = OverridesSpec(ilOverrideMethRef,ilOverrideTy)
           OverrideBy = ilOverrideBy })
@@ -3607,7 +3607,7 @@ and GenSequenceExpr cenv (cgbuf:CodeGenBuffer) eenvouter (nextEnumeratorValRef:V
     let ilCloLambdas = Lambdas_return ilCloRetTyInner 
     let cloref = IlxClosureRef(ilCloTypeRef, ilCloLambdas, ilCloFreeVars)
     let ilxCloSpec = IlxClosureSpec.Create(cloref, GenGenericArgs m eenvouter.tyenv cloFreeTyvars)
-    let formalClospec = IlxClosureSpec.Create(cloref, mkILFormalGenericArgs ilCloGenericParams)
+    let formalClospec = IlxClosureSpec.Create(cloref, mkILFormalGenericArgs 0 ilCloGenericParams)
 
     let getFreshMethod = 
         let _,mbody =
@@ -4080,7 +4080,7 @@ and GenDelegateExpr cenv cgbuf eenvouter expr (TObjExprMethod((TSlotSig(_,delega
     let takenNames = List.map nameOfVal tmvs
     let (cloAttribs,_,_,cloFreeTyvars,cloFreeVars,ilDelegeeTypeRef,ilCloFreeVars,eenvinner) = GetIlxClosureFreeVars cenv m None eenvouter takenNames expr
     let ilDelegeeGenericParams = GenGenericParams cenv eenvinner cloFreeTyvars
-    let ilDelegeeGenericActualsInner = mkILFormalGenericArgs ilDelegeeGenericParams
+    let ilDelegeeGenericActualsInner = mkILFormalGenericArgs 0 ilDelegeeGenericParams
 
     // Create a new closure class with a single "delegee" method that implements the delegate. 
     let delegeeMethName = "Invoke"