From d04ce707d2e084cf3c95b42e10028f09ad19d8a8 Mon Sep 17 00:00:00 2001
From: Emmanuel T Odeke <emmanuel@orijtech.com>
Date: Thu, 13 Feb 2025 22:51:01 +0200
Subject: [PATCH] fix(gnolang): prescriptively reject *ast.(IndexListExpr,
 GoStmt) as unrecognized for Gno

The *ast.IndexListExpr is used for generics but in assignment operations
it is illegal to use. This change returns a proper error and matches
Go's output.
Also *ast.GoStmt is for spawning Go routines but those are forbidden
in Gno, hence reject them prescriptively instead of just spewing
out the raw ast type.

Fixes #3731
Updates #3751
---
 gnovm/pkg/gnolang/go2gno.go                   |  8 ++++++++
 gnovm/tests/files/goroutine_not_supported.gno | 16 ++++++++++++++++
 gnovm/tests/files/parse_indexListExpr.gno     | 16 ++++++++++++++++
 3 files changed, 40 insertions(+)
 create mode 100644 gnovm/tests/files/goroutine_not_supported.gno
 create mode 100644 gnovm/tests/files/parse_indexListExpr.gno

diff --git a/gnovm/pkg/gnolang/go2gno.go b/gnovm/pkg/gnolang/go2gno.go
index b98136b13b5..7a21cc941c8 100644
--- a/gnovm/pkg/gnolang/go2gno.go
+++ b/gnovm/pkg/gnolang/go2gno.go
@@ -441,6 +441,7 @@ func Go2Gno(fs *token.FileSet, gon ast.Node) (n Node) {
 			if len(gon.Recv.List) > 1 {
 				panicWithPos("method has multiple receivers")
 			}
+
 			if len(gon.Recv.List) == 0 {
 				panicWithPos("method has no receiver")
 			}
@@ -478,6 +479,13 @@ func Go2Gno(fs *token.FileSet, gon ast.Node) (n Node) {
 		}
 	case *ast.EmptyStmt:
 		return &EmptyStmt{}
+	case *ast.IndexListExpr:
+		if len(gon.Indices) > 1 {
+			panicWithPos("invalid operation: more than one index"})
+		}
+		panicWithPos("invalid operation: indexList is not permitted in Gno"})
+	case *ast.GoStmt:
+		panicWithPos("goroutines are not permitted"})
 	default:
 		panicWithPos("unknown Go type %v: %s\n",
 			reflect.TypeOf(gon),
diff --git a/gnovm/tests/files/goroutine_not_supported.gno b/gnovm/tests/files/goroutine_not_supported.gno
new file mode 100644
index 00000000000..c9e9d01e010
--- /dev/null
+++ b/gnovm/tests/files/goroutine_not_supported.gno
@@ -0,0 +1,16 @@
+// https://github.com/gnolang/gno/issues/3751
+
+package math
+
+import "testing"
+
+func Add(a, b int) int {
+    return a + b
+}
+
+func TestAdd(t *testing.T) {
+    go Add(1, 1)
+}
+
+// Error:
+// files/goroutine_not_supported.gno:12:5: goroutines are not permitted
diff --git a/gnovm/tests/files/parse_indexListExpr.gno b/gnovm/tests/files/parse_indexListExpr.gno
new file mode 100644
index 00000000000..e876bf88291
--- /dev/null
+++ b/gnovm/tests/files/parse_indexListExpr.gno
@@ -0,0 +1,16 @@
+// https://github.com/gnolang/gno/issues/3731
+
+package main
+
+type node struct {
+	r []int
+}
+
+func (n *node) foo(targ, wndex int) {
+	_ = n.r[targ, wndex]
+}
+
+func main() {}
+
+// ERROR:
+// files/parse_indexListExpr.gno:10:6: invalid operation: more than one index