我可以在c ++ / g ++中做到這一點：struct vec3 {     union {        struct {            float x, y, z;        };         float xyz[3];    }; };然后，vec3 v;assert(&v.xyz[0] == &v.x);assert(&v.xyz[1] == &v.y);assert(&v.xyz[2] == &v.z);將工作。用gcc在c語言中如何做到這一點？我有typedef struct {    union {        struct {            float x, y, z;        };        float xyz[3];    };} Vector3;但是我到處都有錯誤，特別是line 5: warning: declaration does not declare anythingline 7: warning: declaration does not declare anything