Fix 1749

src/fsharp/IlxGen.fs

@@ -132,20 +132,6 @@ let CountMethodDef = NewCounter "IL method defintitions corresponding to values"
 let CountStaticFieldDef = NewCounter "IL field defintitions corresponding to values"
 let CountCallFuncInstructions = NewCounter "callfunc instructions (indirect calls)"
 
-//-------------------------------------------------------------------------
-// Part of the last-minute tranformation performed by this file
-// is to eliminate variables of static type "unit".  These are
-// utility functions related to this.
-//------------------------------------------------------------------------- 
-
-let BindUnitVars g (mvs:Val list, paramInfos, body) = 
-    match mvs,paramInfos with 
-    | [v],[] -> 
-        assert isUnitTy g v.Type
-        [], mkLet NoSequencePointAtInvisibleBinding v.Range v (mkUnit g v.Range) body 
-    | _ -> mvs,body
-
-
 /// Non-local information related to internals of code generation within an assembly
 type IlxGenIntraAssemblyInfo = 
     { /// A table recording the generated name of the static backing fields for each mutable top level value where 
@@ -155,7 +141,6 @@ type IlxGenIntraAssemblyInfo =
       /// that come from both the signature and the implementation.
       StaticFieldInfo : Dictionary<ILMethodRef, ILFieldSpec> }
 
-//--------------------------------------------------------------------------
 //-------------------------------------------------------------------------- 
 
 /// Indicates how the generated IL code is ultimately emitted 
@@ -4093,6 +4078,7 @@ and GenDelegateExpr cenv cgbuf eenvouter expr (TObjExprMethod((TSlotSig(_,delega
     let ilDelegeeParams,ilDelegeeRet = GenActualSlotsig m cenv envForDelegeeUnderTypars slotsig methTyparsOfOverridingMethod
 
     let numthis = 1
+    let tmvs, body = BindUnitVars cenv.g (tmvs, List.replicate (List.concat slotsig.FormalParams).Length ValReprInfo.unnamedTopArg1, body)
     let envForDelegeeMeth = AddStorageForLocalVals cenv.g (List.mapi (fun i v -> (v,Arg (i+numthis))) tmvs)  envForDelegeeUnderTypars
     let ilMethodBody = CodeGenMethodForExpr cenv cgbuf.mgbuf (SPAlways,[],delegeeMethName,envForDelegeeMeth,1,0,body,(if slotSigHasVoidReturnTy slotsig then discardAndReturnVoid else Return))
     let delegeeInvokeMeth =

src/fsharp/TastOps.fs

@@ -7993,3 +7993,18 @@ let DetectAndOptimizeForExpression g option expr =
 
 // Used to remove Expr.Link for inner expressions in pattern matches
 let (|InnerExprPat|) expr = stripExpr expr
+
+//-------------------------------------------------------------------------
+// One of the tranformations performed by the compiler
+// is to eliminate variables of static type "unit".  These are
+// utility functions related to this.
+//------------------------------------------------------------------------- 
+
+let BindUnitVars g (mvs:Val list, paramInfos:ArgReprInfo list, body) = 
+    match mvs,paramInfos with 
+    | [v],[] -> 
+        assert isUnitTy g v.Type
+        [], mkLet NoSequencePointAtInvisibleBinding v.Range v (mkUnit g v.Range) body 
+    | _ -> mvs,body
+
+

src/fsharp/TastOps.fsi

@@ -1432,3 +1432,5 @@ val mkCoerceIfNeeded : TcGlobals -> tgtTy: TType -> srcTy: TType -> Expr -> Expr
 val (|InnerExprPat|) : Expr -> Expr
 
 val allValsOfModDef : ModuleOrNamespaceExpr -> seq<Val>
+
+val BindUnitVars : TcGlobals -> (Val list * ArgReprInfo list * Expr) -> Val list * Expr

tests/fsharpqa/Source/Conformance/InferenceProcedures/TypeInference/env.lst

@@ -38,4 +38,5 @@
 
 	SOURCE=E_PrettifyForall.fs    SCFLAGS="--test:ErrorRanges --flaterrors"				# E_PrettifyForall.fs
 
-	SOURCE=IgnoreUnitParameters.fs								# IgnoreUnitParameters.fs
+	SOURCE=IgnoreUnitParameters.fs								# IgnoreUnitParameters.fs
+	SOURCE=IgnoreUnitParameters.fs	SCFLAGS="--optimize- -g"							# IgnoreUnitParameters2.fs