From 6cfd53bf57e6875aa70dd22f6b2b1b5407c804df Mon Sep 17 00:00:00 2001
From: Henrixounez <30901439+Henrixounez@users.noreply.github.com>
Date: Sun, 11 Apr 2021 23:43:19 +0200
Subject: [PATCH] cgen: generate interfaces after all other typedefs (#9680)

---
 vlib/v/gen/c/cgen.v                            | 11 ++++++++---
 vlib/v/tests/interface_fields_typearray_test.v |  7 +++++++
 2 files changed, 15 insertions(+), 3 deletions(-)
 create mode 100644 vlib/v/tests/interface_fields_typearray_test.v

diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index bafbce455b..e49efbe79c 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -791,9 +791,6 @@ pub fn (mut g Gen) write_typedef_types() {
 					}
 				}
 			}
-			.interface_ {
-				g.write_interface_typesymbol_declaration(typ)
-			}
 			.chan {
 				if typ.name != 'chan' {
 					g.type_definitions.writeln('typedef chan $typ.cname;')
@@ -825,6 +822,14 @@ static inline void __${typ.cname}_pushval($typ.cname ch, $el_stype val) {
 			}
 		}
 	}
+
+	// Generating interfaces after all the common types have been defined
+	// to prevent generating interface struct before definition of field types
+	for typ in g.table.type_symbols {
+		if typ.kind == .interface_ && typ.name !in c.builtins {
+			g.write_interface_typesymbol_declaration(typ)
+		}
+	}
 }
 
 pub fn (mut g Gen) write_interface_typesymbol_declaration(sym ast.TypeSymbol) {
diff --git a/vlib/v/tests/interface_fields_typearray_test.v b/vlib/v/tests/interface_fields_typearray_test.v
new file mode 100644
index 0000000000..74deed07fa
--- /dev/null
+++ b/vlib/v/tests/interface_fields_typearray_test.v
@@ -0,0 +1,7 @@
+struct Test {}
+
+interface Testing {
+	tests []Test
+}
+
+fn test_field_typearray() {}