A default GCC build (Ubuntu 24.04, GCC 13.3.0) fails:

main.c:137:11: error: ignoring return value of 'fscanf' declared with attribute 'warn_unused_result' [-Werror=unused-result]

glibc marks fscanf warn_unused_result, and GCC accepts neither a (void) cast nor WT_IGNORE_RET as suppression. The MongoDB toolchain compiler does not enable the attribute, so Evergreen is unaffected.

This is the only fscanf/scanf call in the tree that ignores its result. Check it instead:

uint64_t lsn;
if (fscanf(fp, "%" SCNu64, &lsn) != 1)
    lsn = 0;