Bug#1125774: ndpi: FTBFS on arm64: missing symbol

[Emanuele Rocca]

On 2026-01-17 06:15, Andreas Metzler wrote:
> configure:22126: checking for gcry_cipher_checktag in -lgcrypt
> configure:22155: gcc -o conftest -W -Wall -Wno-unused-parameter -Wno-unused-function -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/home/ametzler/NDPI/ndpi-4.2=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -mbranch-protection=standard -I/usr/include/json-c  -Wdate-time -D_FORTIFY_SOURCE=2 -Wl,-z,relro -Wl,-z,now -mbranch-protection=standard conftest.c -lgcrypt  -ljson-c  -ljson-c  >&5
> /usr/lib/gcc/aarch64-linux-gnu/15/../../../aarch64-linux-gnu/libgcrypt.so: warning: GCS is required by -z gcs, but this shared library lacks the necessary property note. The dynamic loader might not enable GCS or refuse to load the program unless all the shared library dependencies have the GCS marking.
> configure:22155: $? = 0
> configure: failed program was:
> [...]
> configure:22167: result: no
> 
> However, taking the snippped "failed program" and running the quoted
> "gcc -o conftest -W ..." on it yields the warning but exits
> successfully. (exit code 0).

Thanks for your analysis, you're right to be very puzzled.

What's happening is that configure.ac uses AC_LANG_WERROR, which means
compiler warnings are considered errors:
https://sources.debian.org/src/ndpi/4.2-2.1/configure.ac#L45

That's why suppressing the GCS warning fixes the build, as Adrian found.