https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97323
--- Comment #16 from David Binderman <dcb314 at hotmail dot com> --- This C code also seems to generate the same error on 32 bit ARM: void test_incomplete_array_fam() { struct FAM { char c; int data[] }; } void test_single_element_array_possible_fam() { struct FAM { char c; int data[1] }; } dcb@raspberrypi5:~/cvise $ /home/dcb/gcc/results.20241114/bin/gcc -w -g -c fam.c dcb@raspberrypi5:~/cvise $ /home/dcb/gcc/results.20241116/bin/gcc -w -g -c fam.c fam.c: In function ‘test_single_element_array_possible_fam’: fam.c:12:1: error: ‘TYPE_CANONICAL’ is not compatible 12 | } | ^ It seems to go wrong sometime between g:361050589b144913 and g:601a734188f3d2d3, so recent gcc trunk.