v.gen.c: fix compilation of `if c_struct_1 != c_struct_2 {`

vlib/v/gen/c/auto_eq_methods.v

@@ -7,7 +7,11 @@ import v.ast
 
 fn (mut g Gen) equality_fn(typ ast.Type) string {
 	g.needed_equality_fns << typ.set_nr_muls(0)
-	return g.typ(g.unwrap_generic(typ).set_nr_muls(0))
+	t1 := g.unwrap_generic(typ)
+	t2 := t1.set_nr_muls(0)
+	st2 := g.typ(t2)
+	res := st2.replace('struct ', '')
+	return res
 }
 
 fn (mut g Gen) gen_equality_fns() {

vlib/v/gen/c/testdata/compare_structs.c.must_have

@@ -0,0 +1,4 @@
+struct Something aaa = (struct Something){.fint = 0,.ff32 = 0,.fchar = 0,};
+struct Something bbb = (struct Something){.fint = 0,.ff32 = 0,.fchar = 0,};
+if (Something_struct_eq(aaa, bbb)) {
+

vlib/v/gen/c/testdata/compare_structs.vv

@@ -0,0 +1,14 @@
+
+struct C.Something {
+	fint int
+	ff32 f32
+	fchar char
+}
+
+fn main() {
+	aaa := C.Something{}
+	bbb := C.Something{}
+	if aaa == bbb {
+		println('ok')
+	}
+}