Minor change

src/fsharp/absil/il.fs

@@ -1614,13 +1614,15 @@ let NoMetadataIdx = -1
 
 [<NoComparison; NoEquality>]
 type ILMethodDef (name: string, attributes: MethodAttributes, implAttributes: MethodImplAttributes, callingConv: ILCallingConv,
-                  parameters: ILParameters, ret: ILReturn, body: MethodBody, isEntryPoint: bool, genericParams: ILGenericParameterDefs,
+                  parameters: ILParameters, ret: ILReturn, body: Lazy<MethodBody>, isEntryPoint: bool, genericParams: ILGenericParameterDefs,
                   securityDeclsStored: ILSecurityDeclsStored, customAttrsStored: ILAttributesStored, metadataIndex: int32) =
 
     new (name, attributes, implAttributes, callingConv, parameters, ret, body, isEntryPoint, genericParams, securityDecls, customAttrs) =
        ILMethodDef (name, attributes, implAttributes, callingConv, parameters, ret, body, isEntryPoint, genericParams,
                     storeILSecurityDecls securityDecls, storeILCustomAttrs customAttrs, NoMetadataIdx)
 
+    member private _.LazyBody = body
+
     // The captured data - remember the object will be as large as the data captured by these members
     member _.Name = name
 
@@ -1634,7 +1636,7 @@ type ILMethodDef (name: string, attributes: MethodAttributes, implAttributes: Me
 
     member _.Return = ret
 
-    member _.Body = body
+    member _.Body = body.Value
 
     member _.SecurityDeclsStored = securityDeclsStored
 
@@ -1648,7 +1650,7 @@ type ILMethodDef (name: string, attributes: MethodAttributes, implAttributes: Me
 
     member x.With (?name: string, ?attributes: MethodAttributes, ?implAttributes: MethodImplAttributes,
                    ?callingConv: ILCallingConv, ?parameters: ILParameters, ?ret: ILReturn,
-                   ?body: MethodBody, ?securityDecls: ILSecurityDecls, ?isEntryPoint: bool,
+                   ?body: Lazy<MethodBody>, ?securityDecls: ILSecurityDecls, ?isEntryPoint: bool,
                    ?genericParams: ILGenericParameterDefs, ?customAttrs: ILAttributes) =
 
         ILMethodDef (name = defaultArg name x.Name,
@@ -1657,7 +1659,7 @@ type ILMethodDef (name: string, attributes: MethodAttributes, implAttributes: Me
                      callingConv = defaultArg callingConv x.CallingConv,
                      parameters = defaultArg parameters x.Parameters,
                      ret = defaultArg ret x.Return,
-                     body = defaultArg body x.Body,
+                     body = defaultArg body x.LazyBody,
                      securityDecls = (match securityDecls with None -> x.SecurityDecls | Some attrs -> attrs),
                      isEntryPoint = defaultArg isEntryPoint x.IsEntryPoint,
                      genericParams = defaultArg genericParams x.GenericParams,
@@ -2938,11 +2940,11 @@ let mkMethodBody (zeroinit, locals, maxstack, code, tag) =
 
 let mkILVoidReturn = mkILReturn ILType.Void
 
-let methBodyNotAvailable = MethodBody.NotAvailable
+let methBodyNotAvailable = notlazy MethodBody.NotAvailable
 
-let methBodyAbstract = MethodBody.Abstract
+let methBodyAbstract = notlazy MethodBody.Abstract
 
-let methBodyNative = MethodBody.Native
+let methBodyNative = notlazy MethodBody.Native
 
 let mkILCtor (access, args, impl) =
     ILMethodDef(name=".ctor",
@@ -2951,7 +2953,7 @@ let mkILCtor (access, args, impl) =
                 callingConv=ILCallingConv.Instance,
                 parameters = args,
                 ret= mkILVoidReturn,
-                body= impl,
+                body= notlazy impl,
                 securityDecls=emptyILSecurityDecls,
                 isEntryPoint=false,
                 genericParams=mkILEmptyGenericParams,
@@ -3000,7 +3002,7 @@ let mkILStaticMethod (genparams, nm, access, args, ret, impl) =
                 securityDecls=emptyILSecurityDecls,
                 isEntryPoint=false,
                 customAttrs = emptyILCustomAttrs,
-                body= impl)
+                body= notlazy impl)
 
 let mkILNonGenericStaticMethod (nm, access, args, ret, impl) =
     mkILStaticMethod (mkILEmptyGenericParams, nm, access, args, ret, impl)
@@ -3016,7 +3018,7 @@ let mkILClassCtor impl =
                 isEntryPoint=false,
                 securityDecls=emptyILSecurityDecls,
                 customAttrs=emptyILCustomAttrs,
-                body= impl)
+                body= notlazy impl)
 
 // --------------------------------------------------------------------
 // Make a virtual method, where the overriding is simply the default
@@ -3040,7 +3042,7 @@ let mkILGenericVirtualMethod (nm, access, genparams, actual_args, actual_ret, im
                 isEntryPoint=false,
                 securityDecls=emptyILSecurityDecls,
                 customAttrs = emptyILCustomAttrs,
-                body= impl)
+                body= notlazy impl)
 
 let mkILNonGenericVirtualMethod (nm, access, args, ret, impl) =
     mkILGenericVirtualMethod (nm, access, mkILEmptyGenericParams, args, ret, impl)
@@ -3056,7 +3058,7 @@ let mkILGenericNonVirtualMethod (nm, access, genparams, actual_args, actual_ret,
                 isEntryPoint=false,
                 securityDecls=emptyILSecurityDecls,
                 customAttrs = emptyILCustomAttrs,
-                body= impl)
+                body= notlazy impl)
 
 let mkILNonGenericInstanceMethod (nm, access, args, ret, impl) =
   mkILGenericNonVirtualMethod (nm, access, mkILEmptyGenericParams, args, ret, impl)
@@ -3076,8 +3078,8 @@ let mdef_code2code f (md: ILMethodDef) =
         | MethodBody.IL il-> il
         | _ -> failwith "mdef_code2code - method not IL"
     let ilCode = ilmbody_code2code f il.Value
-    let b = MethodBody.IL (lazy ilCode)
-    md.With(body = b)
+    let b = MethodBody.IL (notlazy ilCode)
+    md.With(body = notlazy b)
 
 let prependInstrsToCode (instrs: ILInstr list) (c2: ILCode) =
     let instrs = Array.ofList instrs

src/fsharp/absil/il.fsi

@@ -977,12 +977,12 @@ type ILMethodDef =
     /// Functional creation of a value, with delayed reading of some elements via a metadata index
     internal new:
          name: string * attributes: MethodAttributes * implAttributes: MethodImplAttributes * callingConv: ILCallingConv * 
-         parameters: ILParameters * ret: ILReturn * body: MethodBody * isEntryPoint:bool * genericParams: ILGenericParameterDefs * 
+         parameters: ILParameters * ret: ILReturn * body: Lazy<MethodBody> * isEntryPoint:bool * genericParams: ILGenericParameterDefs * 
          securityDeclsStored: ILSecurityDeclsStored * customAttrsStored: ILAttributesStored * metadataIndex: int32 -> ILMethodDef
 
     /// Functional creation of a value, immediate
     new: name: string * attributes: MethodAttributes * implAttributes: MethodImplAttributes * callingConv: ILCallingConv * 
-         parameters: ILParameters * ret: ILReturn * body: MethodBody * isEntryPoint:bool * genericParams: ILGenericParameterDefs * 
+         parameters: ILParameters * ret: ILReturn * body: Lazy<MethodBody> * isEntryPoint:bool * genericParams: ILGenericParameterDefs * 
          securityDecls: ILSecurityDecls * customAttrs: ILAttributes -> ILMethodDef
 
     member Name: string
@@ -1048,7 +1048,7 @@ type ILMethodDef =
     /// Functional update of the value
     member internal 
         With: ?name: string * ?attributes: MethodAttributes * ?implAttributes: MethodImplAttributes * ?callingConv: ILCallingConv * 
-                 ?parameters: ILParameters * ?ret: ILReturn * ?body: MethodBody * ?securityDecls: ILSecurityDecls * ?isEntryPoint:bool * 
+                 ?parameters: ILParameters * ?ret: ILReturn * ?body: Lazy<MethodBody> * ?securityDecls: ILSecurityDecls * ?isEntryPoint:bool * 
                  ?genericParams: ILGenericParameterDefs * ?customAttrs: ILAttributes -> ILMethodDef
     member internal WithSpecialName: ILMethodDef
     member internal WithHideBySig: unit -> ILMethodDef
@@ -1813,9 +1813,9 @@ val internal mkILEmptyGenericParams: ILGenericParameterDefs
 /// Make method definitions.
 val internal mkILMethodBody: initlocals:bool * ILLocals * int * ILCode * ILSourceMarker option -> ILMethodBody
 val internal mkMethodBody: bool * ILLocals * int * ILCode * ILSourceMarker option -> MethodBody
-val internal methBodyNotAvailable: MethodBody 
-val internal methBodyAbstract: MethodBody 
-val internal methBodyNative: MethodBody 
+val internal methBodyNotAvailable: Lazy<MethodBody> 
+val internal methBodyAbstract: Lazy<MethodBody> 
+val internal methBodyNative: Lazy<MethodBody> 
 
 val internal mkILCtor: ILMemberAccess * ILParameter list * MethodBody -> ILMethodDef
 val internal mkILClassCtor: MethodBody -> ILMethodDef

src/fsharp/absil/ilmorph.fs

@@ -227,7 +227,7 @@ let mdef_ty2ty_ilmbody2ilmbody ilg fs (md: ILMethodDef)  =
     let ftye' = ftye (Some md) 
     let body' = morphILMethodBody (filmbody (Some md))  md.Body 
     md.With(genericParams=gparams_ty2ty ftye' md.GenericParams,
-            body= body',
+            body= notlazy body',
             parameters = List.map (param_ty2ty ilg ftye') md.Parameters,
             ret = return_ty2ty ilg ftye' md.Return,
             customAttrs=cattrs_ty2ty ilg ftye' md.CustomAttrs)

src/fsharp/absil/ilread.fs

@@ -2494,6 +2494,7 @@ and seekReadConstant (ctxt: ILMetadataReader) idx =
   | _ -> ILFieldInit.Null
 
 and seekReadImplMap (ctxt: ILMetadataReader) nm midx = 
+ lazy
    MethodBody.PInvoke
       (lazy 
             let mdv = ctxt.mdfile.GetView()
@@ -2797,6 +2798,7 @@ and seekReadMethodRVA (pectxt: PEReader) (ctxt: ILMetadataReader) (_idx, nm, _in
 #else
 and seekReadMethodRVA (pectxt: PEReader) (ctxt: ILMetadataReader) (idx, nm, _internalcall, noinline, aggressiveinline, numtypars) rva = 
 #endif
+ lazy
   let pev = pectxt.pefile.GetView()
   let baseRVA = pectxt.anyV2P("method rva", rva)
   // ": reading body of method "+nm+" at rva "+string rva+", phys "+string baseRVA

src/fsharp/ilx/EraseClosures.fs

@@ -322,7 +322,7 @@ let convMethodBody thisClo = function
 
 let convMethodDef thisClo (md: ILMethodDef)  =
     let b' = convMethodBody thisClo (md.Body)
-    md.With(body=b')
+    md.With(body=notlazy b')
 
 // -------------------------------------------------------------------- 
 // Make fields for free variables of a type abstraction.

tests/FSharp.Compiler.Service.Tests/SurfaceArea.netstandard.fs

@@ -616,7 +616,7 @@ FSharp.Compiler.AbstractIL.IL+ILMethodDef: System.Reflection.MethodImplAttribute
 FSharp.Compiler.AbstractIL.IL+ILMethodDef: System.Reflection.MethodImplAttributes get_ImplAttributes()
 FSharp.Compiler.AbstractIL.IL+ILMethodDef: System.String Name
 FSharp.Compiler.AbstractIL.IL+ILMethodDef: System.String get_Name()
-FSharp.Compiler.AbstractIL.IL+ILMethodDef: Void .ctor(System.String, System.Reflection.MethodAttributes, System.Reflection.MethodImplAttributes, ILCallingConv, Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.AbstractIL.IL+ILParameter], ILReturn, MethodBody, Boolean, Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.AbstractIL.IL+ILGenericParameterDef], ILSecurityDecls, ILAttributes)
+FSharp.Compiler.AbstractIL.IL+ILMethodDef: Void .ctor(System.String, System.Reflection.MethodAttributes, System.Reflection.MethodImplAttributes, ILCallingConv, Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.AbstractIL.IL+ILParameter], ILReturn, System.Lazy`1[FSharp.Compiler.AbstractIL.IL+MethodBody], Boolean, Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.AbstractIL.IL+ILGenericParameterDef], ILSecurityDecls, ILAttributes)
 FSharp.Compiler.AbstractIL.IL+ILMethodDefs: ILMethodDef[] AsArray
 FSharp.Compiler.AbstractIL.IL+ILMethodDefs: ILMethodDef[] get_AsArray()
 FSharp.Compiler.AbstractIL.IL+ILMethodDefs: Microsoft.FSharp.Collections.FSharpList`1[FSharp.Compiler.AbstractIL.IL+ILMethodDef] AsList