Issue 1048: Mixed [non-]designated initializer behavior

Authors: Aaron Ballman
Date: 2026-04-22
Submitted against: C23
Status: Open

Consider the following code:

#include <stdio.h>

struct {
    char str[16];
} hello = {
    "hello world",
    .str[6] = 'W',
    "ORLD"
};

int main(void) {
    printf("hello.str = \"%s\"\n", hello.str);

    printf("raw bytes: ");
    for (int i = 0; i < 16; i++) {
        printf("%d ", (unsigned char)hello.str[i]);
    }
    printf("\n");

    return 0;
}

What should this program output?

• SDCC, TCC, cc65 diagnose as too many initializers
• EDG, Compcert reject due to conversion from char * to char which results in truncation (with assigning "ORLD" to str[7] presumably)
• Clang, MSVC accept and produce "hello WORLD"
• GCC accepts and produces "ORLD"
• Chibicc accepts and produces "hello Wl@@"

Which, if any, of these behaviors is the expected one? I can see a reading of the standard that allows for any of the first three behaviors depending on how you interpret C23 6.7.11p18-19.