feat(gnovm): sync code AssignStmt - ValueDecl (#3017)

This PR aims at fixing this issue
[1958](#1958)

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pull request. -->

<details><summary>Contributors' checklist...</summary>

- [ ] Added new tests, or not needed, or not feasible
- [ ] Provided an example (e.g. screenshot) to aid review or the PR is
self-explanatory
- [ ] Updated the official documentation or not needed
- [ ] No breaking changes were made, or a `BREAKING CHANGE: xxx` message
was included in the description
- [ ] Added references to related issues and PRs
- [ ] Provided any useful hints for running manual tests
</details>

---------

Co-authored-by: hieu.ha <[email protected]>
Co-authored-by: Mikael VALLENET <[email protected]>

gnovm/tests/files/assign25c.gno

@@ -0,0 +1,15 @@
+package main
+
+import "fmt"
+
+func f() (a, b int) {
+	return 1, 2
+}
+
+func main() {
+	x, y, z := 1, f()
+	fmt.Println(x, y, z)
+}
+
+// Error:
+// main/files/assign25c.gno:10:2: assignment mismatch: 3 variable(s) but 2 value(s)

gnovm/tests/files/assign25d.gno

@@ -0,0 +1,15 @@
+package main
+
+import "fmt"
+
+func f() (a, b int) {
+	return 1, 2
+}
+
+func main() {
+	x, y, z := f(), 1, 2, 3
+	fmt.Println(x, y, z)
+}
+
+// Error:
+// main/files/assign25d.gno:10:2: assignment mismatch: 3 variable(s) but 4 value(s)

gnovm/tests/files/assign32.gno

@@ -0,0 +1,22 @@
+package main
+
+func foo() int {
+	return 2
+}
+
+func main() {
+	var mp map[string]int = map[string]int{"idx": 4}
+	var sl []int = []int{4, 5, 6}
+	arr := [1]int{7}
+ 	var num interface{} = 5
+
+	a, b, c, d, e, f, g := int(1), foo(), 3, mp["idx"], num.(int), sl[2], arr[0]
+	println(a, b, c, d, e, f, g)
+
+	var h, i, j, k, l, m, n int = int(1), foo(), 3, mp["idx"], num.(int), sl[2], arr[0]
+	println(h, i, j, k, l, m, n)
+}
+
+// Output:
+// 1 2 3 4 5 6 7
+// 1 2 3 4 5 6 7

gnovm/tests/files/assign33.gno

@@ -0,0 +1,13 @@
+package main
+
+func foo() (int, bool) {
+	return 1, true
+}
+
+func main() {
+	var a, b int = foo()
+	println(a, b)
+}
+
+// Error:
+// main/files/assign33.gno:8:6: cannot use foo<VPBlock(3,0)>() (value of type bool) as int value in assignment

gnovm/tests/files/assign34.gno

@@ -0,0 +1,14 @@
+package main
+
+func foo() (int, bool) {
+	return 1, true
+}
+
+func main() {
+	var a, b = foo()
+	println(a, b)
+}
+
+// Output:
+// 1 true
+

gnovm/tests/files/assign35.gno

@@ -0,0 +1,14 @@
+package main
+
+func foo() (int, bool) {
+	return 1, true
+}
+
+func main() {
+	a, b := 2, foo()
+
+	println(a, b)
+}
+
+// Error:
+// main/files/assign35.gno:8:2: multiple-value foo<VPBlock(3,0)> (value of type [int bool]) in single-value context

gnovm/tests/files/assign36.gno

@@ -0,0 +1,19 @@
+package main
+
+import "fmt"
+
+func f() (int) {
+	return 2
+}
+
+func main() {
+	var a, b, c = 1, f(), 3
+	fmt.Println(a, b, c)
+
+	x, y, z := 1, f(), 3
+	fmt.Println(x, y, z)
+}
+
+// Output:
+// 1 2 3
+// 1 2 3

gnovm/tests/files/var22c.gno

@@ -0,0 +1,15 @@
+package main
+
+import "fmt"
+
+func f() (a, b int) {
+	return 1, 2
+}
+
+func main() {
+	var x, y, z = 1, f()
+	fmt.Println(x, y, z)
+}
+
+// Error:
+// main/files/var22c.gno:10:6: missing init expr for z<!VPUverse(0)>