Function c_build_module_prefixed

internal/cbm/lsp/c_lsp.c:2516–2527

Build " . " into a caller-provided stack buffer, replacing the vsnprintf("%s.%s") path (whose %s does a strlen of both args) that otherwise dominates the kernel cross-file resolve miss cascade. Uses the cached module_qn_len. Returns buf on success, or NULL if the result would not fit (caller falls back to cbm_arena_sprintf). The buffer is only read by the immediate registry looku

// cbm_arena_sprintf). The buffer is only read by the immediate registry lookup — a
// stack lifetime is sufficient (the QN is never retained).
static const char *c_build_module_prefixed(const CLSPContext *ctx, const char *type_qn, char *buf,
                                           size_t bufsz) {
    size_t mlen = ctx->module_qn_len;
    size_t tlen = strlen(type_qn);
    if (mlen + 1 + tlen + 1 > bufsz)
        return NULL; // would truncate → fall back to arena sprintf
    memcpy(buf, ctx->module_qn, mlen);
    buf[mlen] = '.';
    memcpy(buf + mlen + 1, type_qn, tlen);
    buf[mlen + 1 + tlen] = '\0';
    return buf;
}

// FNV-1a over (type_qn, 0xff separator, member_name) for the negative-lookup memo.
// 0 is remapped to 1 so it can serve as the empty-slot sentinel.