all-patches/dtc: fix host-dtc build with GCC 16; cover in gcc-compat CI#2179
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Starting with GCC 15 and especially GCC 16 + recent glibc, the _Generic
wrappers for memchr()/strchr()/strrchr() in <string.h> return a
const-qualified pointer when the input is const-qualified. host-dtc 1.7.0
builds with -Werror, so the two existing const-discarding assignments in
libfdt/fdt_overlay.c and fdtput.c become hard build errors on any host
with GCC 16 (Arch + glibc 2.40+, Debian sid, future gcc:16 docker image).
Add general/package/all-patches/dtc/0001-fix-const-discarding-gcc16.patch:
* libfdt/fdt_overlay.c: retype the local 'sep' to const char* (only
read through, never used to write), split 'endptr' into its own
non-const declaration so strtoul() still has a writable char**.
* fdtput.c: drop the const from create_node()'s 'node_name' parameter;
the function genuinely writes through it (*p = '\0';), so the const
was always a lie about effects on the caller. All callers pass
plain char* from argv, so no caller change is needed.
Wire GCC 16 into the matrix in .github/workflows/gcc-compat.yml so the
fix has CI coverage going forward.
Locally verified by full from-scratch builds under GCC 16.1.1 on Arch
(no other patches needed):
* BOARD=hi3516cv6xx_ultimate -> firmware.bin 10112K/16384K (5:06)
* BOARD=gk7205v200_lite -> rootfs.squashfs 5040K/5120K (7:52)
The latter is the same board that gcc-compat.yml builds in CI.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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…for GCC 16
CI's GCC 16 matrix entry surfaced a host-cmake-3.28.3 bootstrap link
failure that did not appear on my local Arch GCC 16.1.1 build (Arch's
host-cmake was system-provided so buildroot's host-cmake never had to
bootstrap there):
cmake.cxx:(.text+0xbfee): undefined reference to
'cmGlobalGhsMultiGenerator::cmGlobalGhsMultiGenerator(cmake*)'
cmake.cxx:(.text+0xce91): undefined reference to
'cmGlobalGhsMultiGenerator::GetDocumentation()'
collect2: error: ld returned 1 exit status
The single use of cmGlobalGhsMultiGenerator in cmake.cxx (line 3014) is
already gated by '#if !defined(CMAKE_BOOTSTRAP)', so the GHS Multi
generator is intentionally excluded from the bootstrap build. But the
matching '#include "cmGlobalGhsMultiGenerator.h"' on line 132 is only
gated by host OS — not by CMAKE_BOOTSTRAP. Older GCCs never ODR-used the
inline NewFactory() so the
'cmGlobalGeneratorSimpleFactory<cmGlobalGhsMultiGenerator>' template
specialization wasn't emitted. Under GCC 16 the specialization is
emitted anyway (more aggressive vague-linkage emission /
speculative-devirtualization), and the bootstrap link fails because
cmGlobalGhsMultiGenerator.cxx is correctly excluded from the bootstrap
source list.
Wrap the include in the same CMAKE_BOOTSTRAP guard as the use site —
same pattern as the existing cmGlobalXCodeGenerator block immediately
below. Non-bootstrap host-cmake builds are unaffected. Still present on
cmake master at the time of writing (cmake/cmake@v3.31.0).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Follow-up to the GCC 14/15 host-compat work (#2018, #1978, #1996, #2003). With GCC 16 on the host (GCC 16.1.1 on Arch + glibc 2.40+, Debian sid, future `gcc:16` docker image), `<string.h>`'s `_Generic` wrappers for `memchr`/`strchr`/`strrchr` now return a const-qualified pointer when the input is const-qualified. host-dtc 1.7.0 builds with `-Werror`, so two existing const-discarding assignments become hard errors:
```
libfdt/fdt_overlay.c:446: error: assignment discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
fdtput.c:235: error: assignment discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
```
Test plan
Locally verified by full from-scratch builds under GCC 16.1.1 on Arch (no other patches needed beyond what's already in master):
🤖 Generated with Claude Code