feat: Bound Method Realm support (gnolang#1257)

When a function is called, it's usually enough to get the pkgpath from
where the function is declared, to find out whether we are switching to
a new realm or not.

But when the function is a bound method, and the method and declared
type are defined in a /p/ package, we need to look at the owning
(persisting) pkgpath of the receiver, if any. When one is found, it uses
that.

There are some edge cases to consider, I'm not sure if they are all
fixed, but we will find out.
Here are some that are considered;
1. if the receiver is an unpersisted new object with method, declared in
a p module, it has no realm until it becomes persisted.
2. nil receivers aren't objects, so even if it were stored in a realm,
it would be stored by "reference" from a pointervalue which also is not
an object, so there's no realm to consider even after persistence.
3. if the method from 1 makes any modifications to the /p/ package's
block state, it should result in an error and the tx should fail.
4. if a /p/ declared thing with method gets stored in realm X, it should
be possible for realm Y to call it, and have it modify realm X (e.g. say
realm X attached a closure to the thing).

---------

Signed-off-by: moul <94029+moul@users.noreply.github.com>
Co-authored-by: moul <94029+moul@users.noreply.github.com>

examples/gno.land/p/demo/tests/p_crossrealm/gno.mod

@@ -0,0 +1 @@
+module gno.land/p/demo/tests/p_crossrealm

examples/gno.land/p/demo/tests/p_crossrealm/p_crossrealm.gno

@@ -0,0 +1,24 @@
+package p_crossrealm
+
+type Stringer interface {
+	String() string
+}
+
+type Container struct {
+	A int
+	B Stringer
+}
+
+func (c *Container) Touch() *Container {
+	c.A += 1
+	return c
+}
+
+func (c *Container) Print() {
+	println("A:", c.A)
+	if c.B == nil {
+		println("B: undefined")
+	} else {
+		println("B:", c.B.String())
+	}
+}

examples/gno.land/r/demo/tests/crossrealm/crossrealm.gno

@@ -0,0 +1,29 @@
+package crossrealm
+
+import (
+	"gno.land/p/demo/tests/p_crossrealm"
+	"gno.land/p/demo/ufmt"
+)
+
+type LocalStruct struct {
+	A int
+}
+
+func (ls *LocalStruct) String() string {
+	return ufmt.Sprintf("LocalStruct{%d}", ls.A)
+}
+
+// local is saved locally in this realm
+var local *LocalStruct
+
+func init() {
+	local = &LocalStruct{A: 123}
+}
+
+// Make1 returns a local object wrapped by a p struct
+func Make1() *p_crossrealm.Container {
+	return &p_crossrealm.Container{
+		A: 1,
+		B: local,
+	}
+}

examples/gno.land/r/demo/tests/crossrealm/gno.mod

@@ -0,0 +1,6 @@
+module gno.land/r/demo/tests/crossrealm
+
+require (
+	gno.land/p/demo/tests/p_crossrealm v0.0.0-latest
+	gno.land/p/demo/ufmt v0.0.0-latest
+)

gno.land/pkg/sdk/vm/gas_test.go

@@ -67,7 +67,7 @@ func TestAddPkgDeliverTx(t *testing.T) {
 	gasDeliver := gctx.GasMeter().GasConsumed()
 
 	assert.True(t, res.IsOK())
-	assert.Equal(t, int64(87965), gasDeliver)
+	assert.Equal(t, int64(91825), gasDeliver)
 }
 
 // Enough gas for a failed transaction.

gnovm/cmd/gno/run_test.go

@@ -73,7 +73,7 @@ func TestRunApp(t *testing.T) {
 		},
 		{
 			args:             []string{"run", "-debug-addr", "invalidhost:17538", "../../tests/integ/debugger/sample.gno"},
-			errShouldContain: "listen tcp: lookup invalidhost",
+			errShouldContain: "listen tcp",
 		},
 		{
 			args:                 []string{"run", "../../tests/integ/invalid_assign/main.gno"},

gnovm/cmd/gno/testdata/gno_test/realm_boundmethod.txtar

@@ -0,0 +1,71 @@
+# Set up GNOROOT in the current directory.
+mkdir $WORK/gnovm
+symlink $WORK/gnovm/stdlibs -> $GNOROOT/gnovm/stdlibs
+env GNOROOT=$WORK
+
+gno test -v ./examples/gno.land/r/demo/realm2
+
+stderr '=== RUN   TestDo'
+stderr '--- PASS: TestDo.*'
+
+stderr '=== RUN   file/realm2_filetest.gno'
+stderr '--- PASS: file/realm2_filetest.*'
+
+-- examples/gno.land/p/demo/counter/gno.mod --
+module gno.land/p/demo/counter
+
+-- examples/gno.land/p/demo/counter/counter.gno --
+package counter
+
+type Counter struct {
+	n int
+}
+
+func (c *Counter) Inc() {
+	c.n++
+}
+
+-- examples/gno.land/r/demo/realm1/realm1.gno --
+package realm1
+
+import "gno.land/p/demo/counter"
+
+var c = counter.Counter{}
+
+func GetCounter() *counter.Counter {
+	return &c
+}
+
+-- examples/gno.land/r/demo/realm2/realm2.gno --
+package realm2
+
+import (
+	"gno.land/r/demo/realm1"
+)
+
+func Do() {
+	realm1.GetCounter().Inc()
+}
+
+-- examples/gno.land/r/demo/realm2/realm2_filetest.gno --
+// PKGPATH: gno.land/r/tests
+package tests
+
+import "gno.land/r/demo/realm2"
+
+func main() {
+	realm2.Do()
+	println("OK")
+}
+
+// Output:
+// OK
+
+-- examples/gno.land/r/demo/realm2/realm2_test.gno --
+package realm2
+
+import "testing"
+
+func TestDo(t *testing.T) {
+	Do()
+}

gnovm/pkg/gnolang/machine.go

@@ -284,14 +284,29 @@ func (m *Machine) runMemPackage(memPkg *std.MemPackage, save, overrides bool) (*
 	}
 	m.SetActivePackage(pv)
 	// run files.
-	m.RunFiles(files.Files...)
-	// maybe save package value and mempackage.
+	updates := m.RunFileDecls(files.Files...)
+	// save package value and mempackage.
+	// XXX save condition will be removed once gonative is removed.
+	var throwaway *Realm
 	if save {
-		// store package values and types
-		m.savePackageValuesAndTypes()
+		// store new package values and types
+		throwaway = m.saveNewPackageValuesAndTypes()
+		if throwaway != nil {
+			m.Realm = throwaway
+		}
+	}
+	// run init functions
+	m.runInitFromUpdates(pv, updates)
+	// save again after init.
+	if save {
+		m.resavePackageValues(throwaway)
 		// store mempackage
 		m.Store.AddMemPackage(memPkg)
+		if throwaway != nil {
+			m.Realm = nil
+		}
 	}
+
 	return pn, pv
 }
 
@@ -494,13 +509,27 @@ func (m *Machine) injectLocOnPanic() {
 	}
 }
 
-// Add files to the package's *FileSet and run them.
-// This will also run each init function encountered.
+// Convenience for tests.
+// Production must not use this, because realm package init
+// must happen after persistence and realm finalization,
+// then changes from init persisted again.
 func (m *Machine) RunFiles(fns ...*FileNode) {
-	m.runFiles(fns...)
+	pv := m.Package
+	if pv == nil {
+		panic("RunFiles requires Machine.Package")
+	}
+	updates := m.runFileDecls(fns...)
+	m.runInitFromUpdates(pv, updates)
+}
+
+// Add files to the package's *FileSet and run decls in them.
+// This will also run each init function encountered.
+// Returns the updated typed values of package.
+func (m *Machine) RunFileDecls(fns ...*FileNode) []TypedValue {
+	return m.runFileDecls(fns...)
 }
 
-func (m *Machine) runFiles(fns ...*FileNode) {
+func (m *Machine) runFileDecls(fns ...*FileNode) []TypedValue {
 	// Files' package names must match the machine's active one.
 	// if there is one.
 	for _, fn := range fns {
@@ -628,11 +657,15 @@ func (m *Machine) runFiles(fns ...*FileNode) {
 		}
 	}
 
-	// Run new init functions.
-	// Go spec: "To ensure reproducible initialization
-	// behavior, build systems are encouraged to present
-	// multiple files belonging to the same package in
-	// lexical file name order to a compiler."
+	return updates
+}
+
+// Run new init functions.
+// Go spec: "To ensure reproducible initialization
+// behavior, build systems are encouraged to present
+// multiple files belonging to the same package in
+// lexical file name order to a compiler."
+func (m *Machine) runInitFromUpdates(pv *PackageValue, updates []TypedValue) {
 	for _, tv := range updates {
 		if tv.IsDefined() && tv.T.Kind() == FuncKind && tv.V != nil {
 			fv, ok := tv.V.(*FuncValue)
@@ -651,7 +684,10 @@ func (m *Machine) runFiles(fns ...*FileNode) {
 
 // Save the machine's package using realm finalization deep crawl.
 // Also saves declared types.
-func (m *Machine) savePackageValuesAndTypes() {
+// This happens before any init calls.
+// Returns a throwaway realm package is not a realm,
+// such as stdlibs or /p/ packages.
+func (m *Machine) saveNewPackageValuesAndTypes() (throwaway *Realm) {
 	// save package value and dependencies.
 	pv := m.Package
 	if pv.IsRealm() {
@@ -664,6 +700,7 @@ func (m *Machine) savePackageValuesAndTypes() {
 		rlm := NewRealm(pv.PkgPath)
 		rlm.MarkNewReal(pv)
 		rlm.FinalizeRealmTransaction(m.ReadOnly, m.Store)
+		throwaway = rlm
 	}
 	// save declared types.
 	if bv, ok := pv.Block.(*Block); ok {
@@ -675,6 +712,25 @@ func (m *Machine) savePackageValuesAndTypes() {
 			}
 		}
 	}
+	return
+}
+
+// Resave any changes to realm after init calls.
+// Pass in the realm from m.saveNewPackageValuesAndTypes()
+// in case a throwaway was created.
+func (m *Machine) resavePackageValues(rlm *Realm) {
+	// save package value and dependencies.
+	pv := m.Package
+	if pv.IsRealm() {
+		rlm = pv.Realm
+		rlm.FinalizeRealmTransaction(m.ReadOnly, m.Store)
+		// re-save package realm info.
+		m.Store.SetPackageRealm(rlm)
+	} else { // use the throwaway realm.
+		rlm.FinalizeRealmTransaction(m.ReadOnly, m.Store)
+	}
+	// types were already saved, and should not change
+	// even after running the init function.
 }
 
 func (m *Machine) RunFunc(fn Name) {
@@ -815,6 +871,13 @@ func (m *Machine) RunStatement(s Stmt) {
 // NOTE: to support realm persistence of types, must
 // first require the validation of blocknode locations.
 func (m *Machine) RunDeclaration(d Decl) {
+	if fd, ok := d.(*FuncDecl); ok && fd.Name == "init" {
+		// XXX or, consider running it, but why would this be needed?
+		// from a repl there is no need for init() functions.
+		// Also, there are complications with realms, where
+		// the realm must be persisted before init(), and persisted again.
+		panic("Machine.RunDeclaration cannot be used for init functions")
+	}
 	// Preprocess input using package block.  There should only
 	// be one block right now, and it's a *PackageNode.
 	pn := m.LastBlock().GetSource(m.Store).(*PackageNode)
@@ -1738,8 +1801,23 @@ func (m *Machine) PushFrameCall(cx *CallExpr, fv *FuncValue, recv TypedValue) {
 	if pv == nil {
 		panic(fmt.Sprintf("package value missing in store: %s", fv.PkgPath))
 	}
-	m.Package = pv
 	rlm := pv.GetRealm()
+	if rlm == nil && recv.IsDefined() {
+		obj := recv.GetFirstObject(m.Store)
+		if obj == nil {
+			// could be a nil receiver.
+			// just ignore.
+		} else {
+			recvOID := obj.GetObjectInfo().ID
+			if !recvOID.IsZero() {
+				// override the pv and rlm with receiver's.
+				recvPkgOID := ObjectIDFromPkgID(recvOID.PkgID)
+				pv = m.Store.GetObject(recvPkgOID).(*PackageValue)
+				rlm = pv.GetRealm() // done
+			}
+		}
+	}
+	m.Package = pv
 	if rlm != nil && m.Realm != rlm {
 		m.Realm = rlm // enter new realm
 	}

gnovm/pkg/gnolang/ownership.go

@@ -328,11 +328,6 @@ func (oi *ObjectInfo) GetIsTransient() bool {
 func (tv *TypedValue) GetFirstObject(store Store) Object {
 	switch cv := tv.V.(type) {
 	case PointerValue:
-		// TODO: in the future, consider skipping the base if persisted
-		// ref-count would be 1, e.g. only this pointer refers to
-		// something in it; in that case, ignore the base.  That will
-		// likely require maybe a preparation step in persistence
-		// ( or unlikely, a second type of ref-counting).
 		return cv.GetBase(store)
 	case *ArrayValue:
 		return cv

gnovm/pkg/gnolang/realm.go

@@ -73,9 +73,16 @@ func PkgIDFromPkgPath(path string) PkgID {
 	return PkgID{HashBytes([]byte(path))}
 }
 
+// Returns the ObjectID of the PackageValue associated with path.
 func ObjectIDFromPkgPath(path string) ObjectID {
+	pkgID := PkgIDFromPkgPath(path)
+	return ObjectIDFromPkgID(pkgID)
+}
+
+// Returns the ObjectID of the PackageValue associated with pkgID.
+func ObjectIDFromPkgID(pkgID PkgID) ObjectID {
 	return ObjectID{
-		PkgID:   PkgIDFromPkgPath(path),
+		PkgID:   pkgID,
 		NewTime: 1, // by realm logic.
 	}
 }

gnovm/tests/files/zrealm_crossrealm14.gno

@@ -0,0 +1,17 @@
+// PKGPATH: gno.land/r/crossrealm_test
+package crossrealm_test
+
+import (
+	crossrealm "gno.land/r/demo/tests/crossrealm"
+)
+
+func main() {
+	// even though we are running within a realm,
+	// we aren't storing the result of crossrealm.Make1(),
+	// so this should print fine.
+	crossrealm.Make1().Touch().Print()
+}
+
+// Output:
+// A: 2
+// B: LocalStruct{123}

gnovm/tests/imports.go

@@ -89,6 +89,7 @@ func TestStore(rootDir, filesPath string, stdin io.Reader, stdout, stderr io.Wri
 				// pkg := gno.NewPackageNode(gno.Name(memPkg.Name), memPkg.Path, nil)
 				// pv := pkg.NewPackage()
 				// m2.SetActivePackage(pv)
+				// XXX remove second arg 'false' and remove all gonative stuff.
 				return m2.RunMemPackage(memPkg, false)
 			}
 		}