next-20250826 gcc-8 compiler_types.h:572:38: error: call to '__compiletime_assert_478' declared with attribute error: FIELD_PREP: value too large for the field

[Naresh Kamboju <naresh.kamboju@linaro.org>]

The following build warnings / errors noticed on arm riscv mips with
gcc-8 toolchain but gcc-13 build pass for the following configs.

Regression Analysis:
- New regression? yes
- Reproducibility? yes

First seen on next-20250826
Good: next-20250825
Bad: next-20250826 to next-20250828

Build regression: next-20250826 gcc-8 compiler_types.h:572:38: error:
call to '__compiletime_assert_478' declared with attribute error:
FIELD_PREP: value too large for the field

Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>

arm:
  build:
    * gcc-8-integrator_defconfig
    * gcc-8-omap1_defconfig
    * gcc-8-footbridge_defconfig

riscv:
  build:
    * gcc-8-defconfig
    * gcc-8-lkftconfig-hardening

mips:
    * cavium_octeon_defconfig
    * malta_defconfig
    * defconfig

## Build log
drivers/pci/pci.c: In function 'pcie_set_readrq':
include/linux/compiler_types.h:572:38: error: call to
'__compiletime_assert_478' declared with attribute error: FIELD_PREP:
value too large for the field
  _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
                                      ^

Anders bisected this and found,
# first bad commit:
  [cbc654d18d3743cff70b2dafb64c903b8cd01f2b]
  bitops: Add __attribute_const__ to generic ffs()-family implementations


## Source
* Kernel version: 6.17.0-rc3-next-20250828
* Git tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/next/linux-next.git
* Git describe: next-20250828
* Architectures: arm riscv mips
* Toolchains: gcc-8
* Kconfigs: integrator_defconfig, omap1_defconfig, footbridge_defconfig

## Build
* Build log: https://qa-reports.linaro.org/api/testruns/29694807/log_file/
* Build details:
https://regressions.linaro.org/lkft/linux-next-master/next-20250828/build/gcc-8-footbridge_defconfig/
* Build error details:
https://regressions.linaro.org/lkft/linux-next-master/next-20250828/log-parser-build-gcc/gcc-compiler-include_linux_compiler_types_h-error-call-to-__compiletime_assert_-declared-with-attribute-error-field_prep-value-too-large-for-the-field/history/
* Build plan: https://tuxapi.tuxsuite.com/v1/groups/linaro/projects/lkft/builds/31u6OUKGnkxZYEIbLMDV9Fi1OgZ
* Build link: https://storage.tuxsuite.com/public/linaro/lkft/builds/31u6OUKGnkxZYEIbLMDV9Fi1OgZ/
* Kernel config:
https://storage.tuxsuite.com/public/linaro/lkft/builds/31u6OUKGnkxZYEIbLMDV9Fi1OgZ/config

--
Linaro LKFT
https://lkft.linaro.org