The C frontend disturbs the canonical type hierarchy for typedef unsigned char uint8_t; uint8_t foo[1][0];
./cc1 -quiet t.c -O2 t.c:2:1: internal compiler error: in get_alias_set, at alias.c:710 Please submit a full bug report, with preprocessed source if appropriate. See <http://gcc.gnu.org/bugs.html> for instructions. which is because the C frontend completes the zero-size array element type in grokdeclarator because /* The GCC extension for zero-length arrays differs from ISO flexible array members in that sizeof yields zero. */ so it doesn't get TYPE_STRUCTURAL_EQUALITY. But the built canonical type based on unsigned char[0] doesn't get this treatment and thus will be treated with TYPE_STRUCTURAL_EQUALITY which will trigger the assert. Index: c-decl.c =================================================================== --- c-decl.c (revision 155535) +++ c-decl.c (working copy) @@ -5394,6 +5394,7 @@ grokdeclarator (const struct c_declarato gcc_assert (itype); TYPE_SIZE (type) = bitsize_zero_node; TYPE_SIZE_UNIT (type) = size_zero_node; + SET_TYPE_STRUCTURAL_EQUALITY (type); } if (array_parm_vla_unspec_p) { fixes it. -- Summary: [4.5 Regression] ICE in get_alias_set, at alias.c:710 Product: gcc Version: 4.5.0 Status: UNCONFIRMED Keywords: ice-on-valid-code Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: rguenth at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42570