I had to make one more change, replace `guint` with `gsize` in `what_len` and `replacement_len`: ```C static gboolean replace_str(gchar **where, const gchar *what, gsize what_len, const gchar *replacement, gsize replacement_len) ``` because otherwise ```C gchar *str = g_malloc(where_len + (replacement_len - what_len) + 1); ``` may underflow.
Interestingly, only meson unit tests failed and not the autotools ones - not sure why.