fix: prevent panic on depinject when input or output struct has an un… (#12786)

…exported fild



## Description

Closes: #1943



---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

depinject/container.go

@@ -446,6 +446,11 @@ func (c *container) build(loc Location, outputs ...interface{}) error {
 
 			for i, output := range outputs {
 				val := reflect.ValueOf(output)
+
+				if !values[i].CanInterface() {
+					return []reflect.Value{}, fmt.Errorf("depinject.Out struct %s on package can't have unexported field", values[i].String())
+
+				}
 				val.Elem().Set(values[i])
 			}
 

depinject/container_test.go

@@ -30,6 +30,15 @@ type KeeperB struct {
 	msgClientA MsgClientA
 }
 
+type KeeperC struct {
+	key        KVStoreKey
+	msgClientA MsgClientA
+}
+
+type KeeperD struct {
+	key KVStoreKey
+}
+
 type Handler struct {
 	Handle func()
 }
@@ -82,6 +91,149 @@ func (ModuleB) Provide(dependencies BDependencies) (BProvides, Handler, error) {
 	}, Handler{}, nil
 }
 
+type ModuleUnexportedDependency struct{}
+
+func (ModuleUnexportedDependency) Provide(dependencies UnexportedFieldCDependencies) (CProvides, Handler, error) {
+	return CProvides{
+		KeeperC: KeeperC{
+			key:        dependencies.key,
+			msgClientA: dependencies.A,
+		},
+		Commands: []Command{{}, {}},
+	}, Handler{}, nil
+}
+
+type UnexportedFieldCDependencies struct {
+	depinject.In
+
+	key KVStoreKey
+	A   MsgClientA
+}
+
+type CProvides struct {
+	depinject.Out
+
+	KeeperC  KeeperC
+	Commands []Command
+}
+
+type ModuleUnexportedProvides struct{}
+
+type CDependencies struct {
+	depinject.In
+
+	Key KVStoreKey
+	A   MsgClientA
+}
+
+type UnexportedFieldCProvides struct {
+	depinject.Out
+
+	keeperC  KeeperC
+	Commands []Command
+}
+
+func (ModuleUnexportedProvides) Provide(dependencies CDependencies) (UnexportedFieldCProvides, Handler, error) {
+	return UnexportedFieldCProvides{
+		keeperC: KeeperC{
+			key:        dependencies.Key,
+			msgClientA: dependencies.A,
+		},
+		Commands: []Command{{}, {}},
+	}, Handler{}, nil
+}
+
+type ModuleD struct{}
+
+type DDependencies struct {
+	depinject.In
+
+	Key     KVStoreKey
+	KeeperC KeeperC
+}
+
+type DProvides struct {
+	depinject.Out
+
+	KeeperD  KeeperD
+	Commands []Command
+}
+
+func (ModuleD) Provide(dependencies DDependencies) (DProvides, Handler, error) {
+	return DProvides{
+		KeeperD: KeeperD{
+			key: dependencies.Key,
+		},
+		Commands: []Command{{}, {}},
+	}, Handler{}, nil
+}
+
+func TestUnexportedField(t *testing.T) {
+	var (
+		handlers map[string]Handler
+		commands []Command
+		a        KeeperA
+		c        KeeperC
+		d        KeeperD
+
+		scenarioConfigProvides = depinject.Configs(
+			depinject.Provide(ProvideMsgClientA),
+			depinject.ProvideInModule("runtime", ProvideKVStoreKey),
+			depinject.ProvideInModule("a", wrapMethod0(ModuleA{})),
+			depinject.ProvideInModule("c", wrapMethod0(ModuleUnexportedProvides{})),
+		)
+
+		scenarioConfigDependency = depinject.Configs(
+			depinject.Provide(ProvideMsgClientA),
+			depinject.ProvideInModule("runtime", ProvideKVStoreKey),
+			depinject.ProvideInModule("a", wrapMethod0(ModuleA{})),
+			depinject.ProvideInModule("c", wrapMethod0(ModuleUnexportedDependency{})),
+		)
+
+		scenarioConfigProvidesDependency = depinject.Configs(
+			depinject.Provide(ProvideMsgClientA),
+			depinject.ProvideInModule("runtime", ProvideKVStoreKey),
+			depinject.ProvideInModule("a", wrapMethod0(ModuleA{})),
+			depinject.ProvideInModule("c", wrapMethod0(ModuleUnexportedProvides{})),
+			depinject.ProvideInModule("d", wrapMethod0(ModuleD{})),
+		)
+	)
+
+	require.ErrorContains(t,
+		depinject.Inject(
+			scenarioConfigProvides,
+			&handlers,
+			&commands,
+			&a,
+			&c,
+		),
+		"depinject.Out struct",
+	)
+
+	require.ErrorContains(t,
+		depinject.Inject(
+			scenarioConfigDependency,
+			&handlers,
+			&commands,
+			&a,
+			&c,
+		),
+		"depinject.In struct",
+	)
+
+	require.ErrorContains(t,
+		depinject.Inject(
+			scenarioConfigProvidesDependency,
+			&handlers,
+			&commands,
+			&a,
+			&c,
+			&d,
+		),
+		"depinject.Out struct",
+	)
+}
+
 var scenarioConfig = depinject.Configs(
 	depinject.Provide(ProvideMsgClientA),
 	depinject.ProvideInModule("runtime", ProvideKVStoreKey),

depinject/struct_args.go

@@ -1,6 +1,7 @@
 package depinject
 
 import (
+	"fmt"
 	"reflect"
 
 	"github.com/pkg/errors"
@@ -74,7 +75,10 @@ func expandStructArgsFn(provider ProviderDescriptor) func(inputs []reflect.Value
 		inputs1 := make([]reflect.Value, len(inParams))
 		for i, in := range inParams {
 			if in.Type.AssignableTo(isInType) {
-				v, n := buildIn(in.Type, inputs[j:])
+				v, n, err := buildIn(in.Type, inputs[j:])
+				if err != nil {
+					return []reflect.Value{}, err
+				}
 				inputs1[i] = v
 				j += n
 			} else {
@@ -158,7 +162,7 @@ func structArgsOutTypes(typ reflect.Type) []ProviderOutput {
 	return res
 }
 
-func buildIn(typ reflect.Type, values []reflect.Value) (reflect.Value, int) {
+func buildIn(typ reflect.Type, values []reflect.Value) (reflect.Value, int, error) {
 	numFields := typ.NumField()
 	j := 0
 	res := reflect.New(typ)
@@ -167,11 +171,18 @@ func buildIn(typ reflect.Type, values []reflect.Value) (reflect.Value, int) {
 		if f.Type.AssignableTo(isInType) {
 			continue
 		}
+		if !res.Elem().Field(i).CanSet() {
+			return reflect.Value{}, 0, fmt.Errorf("depinject.In struct %s on package %s can't have unexported field", res.Elem().String(), f.PkgPath)
+		}
+		if !values[j].CanInterface() {
+			return reflect.Value{}, 0, fmt.Errorf("depinject.Out struct %s on package %s can't have unexported field", res.Elem().String(), f.PkgPath)
+
+		}
 
 		res.Elem().Field(i).Set(values[j])
 		j++
 	}
-	return res.Elem(), j
+	return res.Elem(), j, nil
 }
 
 func extractFromOut(typ reflect.Type, value reflect.Value) []reflect.Value {