#include <stdint.h>\n\n#define INIT_UINT32 1\n#define INIT_INT32 2\n\n#define INIT INIT_INT32\n\ntypedef union\n{\n uint32_t a;\n int32_t b;\n} Foo_t;\n\n/* Why does this compile... */\nstatic Foo_t foo_static = INIT == INIT_INT32 ?\n (Foo_t){ .a = UINT32_MAX} : (Foo_t){ .b = INT32_MAX };\n\n/* but this doesn't? */\nstatic Foo_t foo_static_array[] =\n{\n INIT == INIT_INT32 ? (Foo_t){ .a = UINT32_MAX} : (Foo_t){ .b = INT32_MAX }\n};\n\nint main(void)\n{\n}\n编译时，使用复合文字的 foo_static 条件初始化成功，但使用复合文字的 foo_static_array 条件初始化失败。以下是编译错误。
\n$ gcc test.c\ntest.c:4:21: error: initializer element is not constant\n 4 | #define INIT_INT32 2\n | …