replace OpCall with OpPreCall

also add comments and small code reorg

stdlibs/stdlibs.go

@@ -287,34 +287,32 @@ func InjectPackage(store gno.Store, pn *gno.PackageNode) {
  // TODO: limit usage in goroutines?
  // TODO: build a new sub-context instead of patching the root one.
  // to support multiple concurrent contexts and advanced flows.
- arg0 := m.LastBlock().GetParams1().TV
- fn := arg0.GetFunc()
-
- ctx := m.Context.(ExecContext)
- ctx.OrigCaller = ctx.OrigPkgAddr
-
- backupContext := m.Context.(ExecContext)
 
+ // Push original context first, so it will be reset after the function
+ // call.
+ m.PushOp(gno.OpSetContext)
  m.PushValue(gno.TypedValue{
- T: &gno.InterfaceType{},
  V: gno.ContextValue{
- Context: backupContext,
+ Context: m.Context,
  },
  })
- m.PushOp(gno.OpSetContext)
 
- cx := gno.Call(gno.FuncT(nil, nil))
- m.PushValue(gno.TypedValue{})
- m.PushFrameCall(cx, fn, gno.TypedValue{})
- m.PushOp(gno.OpCall)
+ // Push a function call, to execute the function in parameter.
+ m.PushOp(gno.OpPrecall)
+ m.PushExpr(gno.Call(gno.FuncT(nil, nil)))
+ tv := m.LastBlock().GetParams1().TV
+ m.PushValue(*tv)
 
+ // Push an alternate context with OrigCaller=OrigPkgAddr, this will
+ // affect the function call above
+ m.PushOp(gno.OpSetContext)
+ ctx := m.Context.(ExecContext)
+ ctx.OrigCaller = ctx.OrigPkgAddr
  m.PushValue(gno.TypedValue{
- T: &gno.InterfaceType{},
  V: gno.ContextValue{
  Context: ctx,
  },
  })
- m.PushOp(gno.OpSetContext)
  },
  )
  pn.DefineNative("GetCallerAt",

tests/files/zrealm_std6.gno

@@ -6,14 +6,16 @@ import (
  "std"
 )
 
-func main() {
- println(std.GetOrigCaller())
- std.ExecAsPkg(func() {
- println(std.GetOrigCaller())
- })
+func printOrigCaller() {
  println(std.GetOrigCaller())
 }
 
+func main() {
+ printOrigCaller()
+ std.ExecAsPkg(printOrigCaller)
+ printOrigCaller()
+}
+
 // Output:
 // g1fahslvxakc058u0wa98ytfc9fd6trhe5qfh9ld
 // g157y5v3k529jyzhjjz4fn49tzzhf4gess6v39xg