#4127 Integer literals beyond unsigned long long range go undiagnosed
1: Sample code that reproduces the problem.
unsigned long long object = 18446744073709551616ULL;
2: Exact command used to run SDCC on this sample code.
sdcc -mz80 --std=c2y -S bug.c
3: SDCC version tested.
SDCC : mcs51/z80/z180/r2k/r2ka/r3ka/r4k/r5k/r6k/sm83/tlcs90/ez80/z80n/r800/ds390/TININative/ds400/hc08/s08/stm8/pdk13/pdk14/pdk15 TD- 4.6.4 #0 (Linux)
published under GNU General Public License (GPL)
Built from clean official SVN r16978 sources on Linux.
4: Observed and expected behaviour.
SDCC exits successfully and emits no diagnostic. A diagnostic is required by
WG14 N3886,
6.4.5.1 paragraph 2:
Each constant shall have a type and the value of a constant shall be in the range of representable
values for its type.
Every constant value must be representable in its type. SDCC silently accepts the value 2^64 written as decimal, hexadecimal or binary with ULL suffix. The implementation provides a 64-bit unsigned long long and advertises __SDCC_BITINT_MAXWIDTH as 64.
5: Additional checks.
GCC 13.3.0, invoked with -std=c2x -pedantic-errors -fsyntax-only, rejects every invalid variant.
Configurations tested: MCS51 default/large/medium/stack-auto, DS390, Z80, Z180,
Rabbit 2000/4000, SM83, TLCS-90, HC08, S08, STM8 default/large, PDK13/14/15,
and eZ80. These are compiler and diagnostic checks, not runtime tests.
Implementation observation: The decimal example is emitted as eight zero bytes in Z80 assembly. sepStrToUll in src/SDCCval.c accumulates digits with unsigned multiplication and addition without overflow checks, allowing wraparound before later type selection. This is a literal-reading failure, not the integer-expression overflow reported in bug [#4093].
Related
Here's a side-by-side comparison of SDCC trunk with GCC 16.2: https://godbolt.org/z/1Kh5dnjEE
Please consider the attached candidate bug fix patch.