https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109521
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |mpolacek at gcc dot gnu.org
--- Comment #6 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
So we have two "unsigned char [7]" types. They are the same except that one
has TYPE_DEPENDENT_P_VALID set.
One of them comes from the C++ FE: grokfield -> grokdeclarator ->
create_array_type_for_decl etc. This has TYPE_DEPENDENT_P_VALID set.
The other one is created in gimple_fold_builtin_memory_op:
1323 desttype = build_array_type_nelts (unsigned_char_type_node,
1324 tree_to_uhwi (len));
1325 srctype = desttype;
1326 if (src_align > TYPE_ALIGN (srctype))
1327 srctype = build_aligned_type (srctype, src_align);
1328 srcvar = fold_build2 (MEM_REF, srctype, src, off0);
this also answers the question why the problem only happens with "unsigned
char".
Later, we warn in maybe_warn_operand: warning_at -> ... -> print_mem_ref which
tries to display:
MEM <unsigned char[7]> [(char * {ref-all})&D.2870 + 1B]
print_mem_ref calls c_fold_indirect_ref_for_warn with this:
1961 tree cop = build3_loc (loc, COMPONENT_REF, TREE_TYPE
(field),
1962 op, field, NULL_TREE);
1963 off = off - upos;
1964 if (tree ret = c_fold_indirect_ref_for_warn (loc, type,
cop,
1965 off))
1966 return ret;
The type of the MEM_REF is the second type. But COP here is D.2870.pad, and
its type is the first one. Comparing those two in
same_type_ignoring_top_level_qualifiers_p will crash since they are the same
types but their canonical types are not identical.
I don't know what the fix would be.
