[Bug fortran/82976] [8 Regression] Error: non-trivial conversion at assignment since r254526

["marxin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82976

--- Comment #4 from Martin Liška <marxin at gcc dot gnu.org> ---
So for following GIMPLE stmt:

$ (gdb) p debug_gimple_stmt(stmt)
_54 = 0;

RHS (kind == 1) is created here:

(gdb) bt
#0  make_int_cst (len=1, ext_len=1) at ../../gcc/tree.c:2286
#1  0x000000000139516a in build_new_int_cst (type=0x7ffff6827b28, cst=...) at
../../gcc/tree.c:1280
#2  0x0000000001395ef3 in wide_int_to_tree (type=0x7ffff6827b28, pcst=...) at
../../gcc/tree.c:1529
#3  0x0000000001010b84 in set_min_and_max_values_for_integral_type
(type=0x7ffff6827b28, precision=8, sgn=UNSIGNED) at
../../gcc/stor-layout.c:2680
#4  0x0000000001010cfa in fixup_unsigned_type (type=0x7ffff6827b28) at
../../gcc/stor-layout.c:2711
#5  0x0000000001010016 in make_unsigned_type (precision=8) at
../../gcc/stor-layout.c:2538
#6  0x00000000013b4983 in build_common_tree_nodes (signed_char=false) at
../../gcc/tree.c:9562
#7  0x000000000091167e in gfc_init_decl_processing () at
../../gcc/fortran/f95-lang.c:506
#8  0x0000000000910f2a in gfc_init () at ../../gcc/fortran/f95-lang.c:242
#9  0x0000000001020600 in lang_dependent_init (name=0x7fffffffe202
"/home/marxin/Programming/gcc/gcc/testsuite/gfortran.dg/realloc_on_assign_16.f90")
at ../../gcc/toplev.c:1819
#10 0x0000000001020b37 in do_compile () at ../../gcc/toplev.c:2045
#11 0x0000000001020e84 in toplev::main (this=0x7fffffffdc6e, argc=16,
argv=0x7fffffffdd68) at ../../gcc/toplev.c:2194
#12 0x0000000001c3e1d2 in main (argc=16, argv=0x7fffffffdd68) at
../../gcc/main.c:39

LHS here:

(gdb) bt
#0  make_ssa_name_fn (fn=0x7ffff69c10b0, var=0x7ffff6833348,
stmt=0x7ffff662aa00, version=0) at ../../gcc/tree-ssanames.c:313
#1  0x00000000012ee868 in copy_ssa_name_fn (fn=0x7ffff69c10b0,
name=0x7ffff661a750, stmt=0x7ffff662aa00) at ../../gcc/tree-ssanames.c:691
#2  0x00000000012eeccf in duplicate_ssa_name_fn (fn=0x7ffff69c10b0,
name=0x7ffff661a750, stmt=0x7ffff662aa00) at ../../gcc/tree-ssanames.c:752
#3  0x00000000010dc1a0 in duplicate_ssa_name (var=0x7ffff661a750,
stmt=0x7ffff662aa00) at ../../gcc/tree-ssanames.h:134
#4  0x00000000010e3605 in create_new_def_for (old_name=0x7ffff661a750,
stmt=0x7ffff662aa00, def=0x7ffff662aa40) at ../../gcc/tree-into-ssa.c:2949
#5  0x0000000001079665 in gimple_duplicate_bb (bb=0x7ffff661bea0) at
../../gcc/tree-cfg.c:6186
#6  0x0000000000a76d6c in duplicate_block (bb=0x7ffff661bea0, e=0x0, after=0x0)
at ../../gcc/cfghooks.c:1077
#7  0x00000000012cc659 in create_block_for_threading (bb=0x7ffff661bea0,
rd=0x2a8c950, count=0, duplicate_blocks=0x7fffffffd6e0) at
../../gcc/tree-ssa-threadupdate.c:336
#8  0x00000000012cde44 in ssa_create_duplicates (slot=0x2c3be30,
local_info=0x7fffffffd6d0) at ../../gcc/tree-ssa-threadupdate.c:1124
#9  0x00000000012d182d in hash_table<redirection_data,
xcallocator>::traverse_noresize<ssa_local_info_t*,
&(ssa_create_duplicates(redirection_data**, ssa_local_info_t*))>
(this=0x2c3bdf0, argument=0x7fffffffd6d0) at ../../gcc/hash-table.h:969
#10 0x00000000012d0d0f in hash_table<redirection_data,
xcallocator>::traverse<ssa_local_info_t*,
&(ssa_create_duplicates(redirection_data**, ssa_local_info_t*))>
(this=0x2c3bdf0, argument=0x7fffffffd6d0) at ../../gcc/hash-table.h:990
#11 0x00000000012ce4e0 in thread_block_1 (bb=0x7ffff661bea0, noloop_only=true,
joiners=false) at ../../gcc/tree-ssa-threadupdate.c:1387
#12 0x00000000012ce5b6 in thread_block (bb=0x7ffff661bea0, noloop_only=true) at
../../gcc/tree-ssa-threadupdate.c:1431
#13 0x00000000012d03a4 in thread_through_all_blocks
(may_peel_loop_headers=false) at ../../gcc/tree-ssa-threadupdate.c:2298
#14 0x00000000011afcb9 in (anonymous namespace)::pass_dominator::execute
(this=0x2aa0470, fun=0x7ffff69c10b0) at ../../gcc/tree-ssa-dom.c:749
#15 0x0000000000ef7b1f in execute_one_pass (pass=0x2aa0470) at
../../gcc/passes.c:2497
#16 0x0000000000ef7e70 in execute_pass_list_1 (pass=0x2aa0470) at
../../gcc/passes.c:2586
#17 0x0000000000ef7ea1 in execute_pass_list_1 (pass=0x2a9e270) at
../../gcc/passes.c:2587
#18 0x0000000000ef7ef9 in execute_pass_list (fn=0x7ffff69c10b0, pass=0x2a9e090)
at ../../gcc/passes.c:2597
#19 0x0000000000ab8076 in cgraph_node::expand (this=0x7ffff69d3170) at
../../gcc/cgraphunit.c:2139
#20 0x0000000000ab86b2 in expand_all_functions () at
../../gcc/cgraphunit.c:2275
#21 0x0000000000ab9206 in symbol_table::compile (this=0x7ffff6817100) at
../../gcc/cgraphunit.c:2623
#22 0x0000000000ab947b in symbol_table::finalize_compilation_unit
(this=0x7ffff6817100) at ../../gcc/cgraphunit.c:2716
#23 0x000000000101e4c8 in compile_file () at ../../gcc/toplev.c:480
#24 0x0000000001020b97 in do_compile () at ../../gcc/toplev.c:2059
#25 0x0000000001020e84 in toplev::main (this=0x7fffffffdc6e, argc=16,
argv=0x7fffffffdd68) at ../../gcc/toplev.c:2194
#26 0x0000000001c3e1d2 in main (argc=16, argv=0x7fffffffdd68) at
../../gcc/main.c:39

Is it helpful information, or should I investigate more?
Which is the problematic type?