feat: PrevRealm ignores user realms

Fix gnolang#1664

As commented in the IsRealm() method, a better format of user realms
should emerge in the form of `gno.land/u/user_address`, which would
remove the confusion between standard realms and the realm forged under
the MsgRun transaction.

gno.land/cmd/gnoland/testdata/prevrealm.txtar

@@ -0,0 +1,188 @@
+# This tests ensure the consistency of the std.PrevRealm function, in the
+# following situations:
+#
+#
+# | Num | Msg Type |      Call from      | Entry Point     | Result       |
+# |-----|:--------:|:-------------------:|:---------------:|:------------:|
+# | 1   | MsgCall  | wallet direct       | myrlm.A()       | user address |
+# | 2   |          |                     | myrlm.B()       | user address |
+# | 3   |          | through /r/foo      | myrlm.A()       | r/foo        |
+# | 4   |          |                     | myrlm.B()       | r/foo        |
+# | 5   |          | through /p/demo/bar | myrlm.A()       | user address |
+# | 6   |          |                     | myrlm.B()       | user address |
+# | 7   | MsgRun   | wallet direct       | myrlm.A()       | user address |
+# | 8   |          |                     | myrlm.B()       | user address |
+# | 9   |          | through /r/foo      | myrlm.A()       | r/foo        |
+# | 10  |          |                     | myrlm.B()       | r/foo        |
+# | 11  |          | through /p/demo/bar | myrlm.A()       | user address |
+# | 12  |          |                     | myrlm.B()       | user address |
+# | 13  | MsgCall  | wallet direct       | std.PrevRealm() | user address |
+# | 14  | MsgRun   | wallet direct       | std.PrevRealm() | user address |
+
+# Init
+## start a new node
+gnoland start
+
+## deploy myrlm
+gnokey maketx addpkg -pkgdir $WORK/r/myrlm -pkgpath gno.land/r/myrlm -gas-fee 1000000ugnot -gas-wanted 2000000 -broadcast -chainid=tendermint_test test1
+stdout 'OK!'
+
+## deploy r/foo
+gnokey maketx addpkg -pkgdir $WORK/r/foo -pkgpath gno.land/r/foo -gas-fee 1000000ugnot -gas-wanted 2000000 -broadcast -chainid=tendermint_test test1
+stdout 'OK!'
+
+## deploy p/demo/bar
+gnokey maketx addpkg -pkgdir $WORK/p/demo/bar -pkgpath gno.land/p/demo/bar -gas-fee 1000000ugnot -gas-wanted 2000000 -broadcast -chainid=tendermint_test test1
+stdout 'OK!'
+
+env RFOO_ADDR=g1evezrh92xaucffmtgsaa3rvmz5s8kedffsg469
+
+# Test cases
+## 1. MsgCall -> myrlm.A: user address
+gnokey maketx call -pkgpath gno.land/r/myrlm -func A -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1
+stdout ${USER_ADDR_test1}
+
+## 2. MsgCall -> myrealm.B -> myrlm.A: user address
+gnokey maketx call -pkgpath gno.land/r/myrlm -func B -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1
+stdout ${USER_ADDR_test1}
+
+## 3. MsgCall -> r/foo.A -> myrlm.A: r/foo
+gnokey maketx call -pkgpath gno.land/r/foo -func A -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1
+stdout ${RFOO_ADDR}
+
+## 4. MsgCall -> r/foo.B -> myrlm.B -> r/foo.A: r/foo
+gnokey maketx call -pkgpath gno.land/r/foo -func B -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1
+stdout ${RFOO_ADDR}
+
+## 5. MsgCall -> p/demo/bar.A -> myrlm.A: user address
+gnokey maketx call -pkgpath gno.land/p/demo/bar -func A -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1
+stdout ${USER_ADDR_test1}
+
+## 6. MsgCall -> p/demo/bar.B -> myrlm.B -> r/foo.A: user address
+gnokey maketx call -pkgpath gno.land/p/demo/bar -func B -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1
+stdout ${USER_ADDR_test1}
+
+## 7. MsgRun -> myrlm.A: user address
+gnokey maketx run -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1 $WORK/run/myrlmA.gno
+stdout ${USER_ADDR_test1}
+
+## 8. MsgRun -> myrealm.B -> myrlm.A: user address
+gnokey maketx run -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1 $WORK/run/myrlmB.gno
+stdout ${USER_ADDR_test1}
+
+## 9. MsgRun -> r/foo.A -> myrlm.A: r/foo
+gnokey maketx run -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1 $WORK/run/fooA.gno
+stdout ${RFOO_ADDR}
+
+## 10. MsgRun -> r/foo.B -> myrlm.B -> r/foo.A: r/foo
+gnokey maketx run -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1 $WORK/run/fooB.gno
+stdout ${RFOO_ADDR}
+
+## 11. MsgRun -> p/demo/bar.A -> myrlm.A: user address
+gnokey maketx run -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1 $WORK/run/barA.gno
+stdout ${USER_ADDR_test1}
+
+## 12. MsgRun -> p/demo/bar.B -> myrlm.B -> r/foo.A: user address
+gnokey maketx run -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1 $WORK/run/barB.gno
+stdout ${USER_ADDR_test1}
+
+## 13. MsgCall -> std.PrevRealm(): user address
+gnokey maketx call -pkgpath std -func PrevRealm -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1
+stdout ${USER_ADDR_test1}
+
+## 14. MsgRun -> std.PrevRealm(): user address
+gnokey maketx run -gas-fee 100000ugnot -gas-wanted 2000000 -broadcast -chainid tendermint_test test1 $WORK/run/baz.gno
+stdout ${USER_ADDR_test1}
+
+-- r/myrlm/myrlm.gno --
+package myrlm
+
+import "std"
+
+func A() string {
+	return std.PrevRealm().Addr().String()
+}
+
+func B() string {
+	return A()
+}
+-- r/foo/foo.gno --
+package foo
+
+import "gno.land/r/myrlm"
+
+func A() string {
+	return myrlm.A()
+}
+
+func B() string {
+	return myrlm.B()
+}
+-- p/demo/bar/bar.gno --
+package bar
+
+import "gno.land/r/myrlm"
+
+func A() string {
+	return myrlm.A()
+}
+
+func B() string {
+	return myrlm.B()
+}
+-- run/myrlmA.gno --
+package main
+
+import myrlm "gno.land/r/myrlm"
+
+func main() {
+	println(myrlm.A())
+}
+-- run/myrlmB.gno --
+package main
+
+import "gno.land/r/myrlm"
+
+func main() {
+	println(myrlm.B())
+}
+-- run/fooA.gno --
+package main
+
+import "gno.land/r/foo"
+
+func main() {
+	println(foo.A())
+}
+-- run/fooB.gno --
+package main
+
+import "gno.land/r/foo"
+
+func main() {
+	println(foo.B())
+}
+-- run/barA.gno --
+package main
+
+import "gno.land/p/demo/bar"
+
+func main() {
+	println(bar.A())
+}
+-- run/barB.gno --
+package main
+
+import "gno.land/p/demo/bar"
+
+func main() {
+	println(bar.B())
+}
+-- run/baz.gno --
+package main
+
+import "std"
+
+func main() {
+	println(std.PrevRealm().Addr().String())
+}

gnovm/pkg/gnolang/values.go

@@ -816,8 +816,15 @@ type PackageValue struct {
 	fBlocksMap map[Name]*Block
 }
 
+// IsRealm returns true if pv represents a realm.
+// A user realm, forged by the MsgRun transaction, isn't considered as a realm.
+// XXX The user realm format is:
+// PkgPath="gno.land/r/user_address" PkgName="main"
+// A less confusing format could emerge in the future, with the form of
+// PkgPath="gno.land/u/user_address"
 func (pv *PackageValue) IsRealm() bool {
-	return IsRealmPath(pv.PkgPath)
+	return IsRealmPath(pv.PkgPath) &&
+		pv.PkgName != "main" // Discard user realms forged by MsgRun
 }
 
 func (pv *PackageValue) getFBlocksMap() map[Name]*Block {