https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94446
Andrew Benson <abensonca at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |abensonca at gmail dot com --- Comment #2 from Andrew Benson <abensonca at gmail dot com> --- After some more investigation this seems to be related to the following in target-memory.c in function gfc_simplify_sizeof(): case BT_DERIVED: case BT_CLASS: case BT_VOID: case BT_ASSUMED: case BT_PROCEDURE: { /* Determine type size without clobbering the typespec for ISO C binding types. */ gfc_typespec ts; HOST_WIDE_INT size; ts = e->ts; type = gfc_typenode_for_spec (&ts); size = int_size_in_bytes (type); gcc_assert (size >= 0); *siz = size; } return true; The call to gfc_typenode_for_spec() seems to cause the problem. This eventually leads to reaching the following point: #0 gfc_typenode_for_spec(gfc_typespec*, int) () at ../../gcc-git/gcc/fortran/trans-types.c:1177 #1 0x0000000000962502 in gfc_sym_type(gfc_symbol*) () at ../../gcc-git/gcc/fortran/trans-types.c:2247 #2 0x0000000000960858 in gfc_get_function_type(gfc_symbol*, gfc_actual_arglist*) () at ../../gcc-git/gcc/fortran/trans-types.c:3060 #3 0x00000000009611ed in gfc_get_ppc_type (c=<optimized out>) at ../../gcc-git/gcc/fortran/trans-types.c:2430 #4 0x0000000000961b50 in gfc_get_derived_type(gfc_symbol*, int) () at ../../gcc-git/gcc/fortran/trans-types.c:2712 #5 0x0000000000961ae4 in gfc_get_derived_type(gfc_symbol*, int) () at ../../gcc-git/gcc/fortran/trans-types.c:2670 #6 0x0000000000961ae4 in gfc_get_derived_type(gfc_symbol*, int) () at ../../gcc-git/gcc/fortran/trans-types.c:2670 #7 0x0000000000961ae4 in gfc_get_derived_type(gfc_symbol*, int) () at ../../gcc-git/gcc/fortran/trans-types.c:2670 #8 0x0000000000962115 in gfc_typenode_for_spec(gfc_typespec*, int) () at ../../gcc-git/gcc/fortran/trans-types.c:1166 #9 0x00000000008bec61 in gfc_element_size(gfc_expr*, unsigned long*) () at ../../gcc-git/gcc/fortran/target-memory.c:130 #10 0x00000000008bee33 in gfc_target_expr_size(gfc_expr*, unsigned long*) () at ../../gcc-git/gcc/fortran/target-memory.c:166 #11 0x00000000008af4f3 in gfc_simplify_sizeof (x=0x29fd3c0) at ../../gcc-git/gcc/fortran/simplify.c:7492 #12 0x0000000000829eea in do_simplify (specific=specific@entry=0x7ffff75bcc10, e=e@entry=0x29fd5a0) at ../../gcc-git/gcc/fortran/intrinsic.c:4620 #13 0x00000000008350bc in gfc_intrinsic_func_interface(gfc_expr*, int) () at ../../gcc-git/gcc/fortran/intrinsic.c:5013 #14 0x000000000088ec57 in resolve_unknown_f (expr=0x29fd5a0) at ../../gcc-git/gcc/fortran/resolve.c:2918 which is this code: /* If we're dealing with either C_PTR or C_FUNPTR, we modified the type and kind to fit a (void *) and the basetype returned was a ptr_type_node. We need to pass up this new information to the symbol that was declared of type C_PTR or C_FUNPTR. */ if (spec->u.derived->ts.f90_type == BT_VOID) { spec->type = BT_INTEGER; spec->kind = gfc_index_integer_kind; spec->f90_type = BT_VOID; spec->is_c_interop = 1; /* Mark as escaping later. */ } My guess is that this is exactly the "clobbering" that is trying to be avoided in gfc_simplify_sizeof(). As far as I can understand this is occurring because the variable "gsf" in the test case is an argument to a function, so its typespec is being retrieved and modified here. I don't have the understanding to know how to fix this though. The "clobbering" fix was implemented (according to git blame) in this patch: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=48b155b991003487a50ac171ba5ca7c3409ad417 corresponding to PR50004.