__attribute__((section)) is silently ignored, breaking section-based registration

The section attribute has no effect: the data is emitted, but not into the named section, and no diagnostic is produced.

__attribute__((section("mysection"), used))
static const char blob[16] = "HELLO_SECTION";
const char *get(void) { return blob; }

$ clang -c -o sect.o sect.c        # Fil-C
$ readelf -S sect.o | grep -c mysection     -> 0
$ strings sect.o | grep -c HELLO_SECTION    -> 1

$ gcc -c -o sect.o sect.c          # system GCC 13.3, same source
$ readelf -S sect.o | grep -c mysection     -> 1
$ strings sect.o | grep -c HELLO_SECTION    -> 1

Impact: any library that registers things by placing records in a named section and walking it later stops working, with no build-time indication. Concretely, it breaks Qt's entire plugin system -- Q_PLUGIN_METADATA puts plugin metadata in a .qtmetadata section and Qt locates plugins by scanning for it, so every plugin is rejected as "not a Qt plugin" and no GUI application can start at all. Test registries and similar _start/_stop designs would fail the same way.

A diagnostic on an unsupported section attribute would be much easier to diagnose than the silent miscompile, if honouring it is not practical.