cgen: fix generation of a missing return in return if cond { x } else { return missing } (fix #22838) (#22839)

Author: felipensp

vlib/v/gen/c/cgen.v

@@ -1958,6 +1958,8 @@ fn (mut g Gen) stmts_with_tmp_var(stmts []ast.Stmt, tmp_var string) bool {
 							}
 						}
 					}
+				} else if stmt is ast.Return {
+					g.stmt(stmt)
 				}
 			} else {
 				g.set_current_pos_as_last_stmt_pos()

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

@@ -0,0 +1,10 @@
+VV_LOCAL_SYMBOL _result_string main__empty(string s) {
+_result_string _t2; /* if prepend */
+if ((s).len != 0) {
+_result_ok(&(string[]) { s }, (_result*)(&_t2), sizeof(string));
+} else {
+return (_result_string){ .is_error=true, .err=_v_error(_SLIT("empty")), .data={EMPTY_STRUCT_INITIALIZATION} };
+}
+_result_string _t1 =  _t2;
+return _t1;
+}

vlib/v/gen/c/testdata/if_else_return.out

@@ -0,0 +1 @@
+expected error empty

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

@@ -0,0 +1,21 @@
+fn empty(s string) !string {
+	return if s != '' {
+		s
+	} else {
+		return error('empty')
+	}
+}
+
+fn main() {
+	str_1 := empty('something') or {
+		assert false, 'something is not empty!'
+		return
+	}
+	assert str_1 == 'something'
+
+	str_2 := empty('') or {
+		println('expected error ${err}')
+		return
+	}
+	assert false, 'invalid accepted ${str_2}'
+}