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upstream patch is applied, otherwise the build w/ clang 20 fails with:
> src/mongo/bson/util/bsoncolumnbuilder.h:285:49: error: call to deleted constructor of 'const mongo::TrackingAllocator<void> &'
However, the build still fails with:
> /usr/bin/x86_64-pc-linux-gnu-ld.bfd: build/gentoo/mongo/db/storage/wiredtiger/wiredtiger_record_store.o: in function `mongo::WiredTigerRecordStore::getEarliestOplogTimestamp(mongo::OperationContext*)':
> /usr/lib/gcc/x86_64-pc-linux-gnu/14/include/g++-v14/bits/atomic_base.h:1002:(.text+0x7da9): undefined reference to `__atomic_compare_exchange'
> clang++: error: linker command failed with exit code 1 (use -v to see invocation)
The reason is that Timestamp is a composite type, which requires -latomic
when building with clang++ and libstdc++. Mongodb's SConstruct only
checks for some basic types ('int64_t', 'uint64_t', 'int32_t', 'uint32_t'),
so this case is not detected.
Test case below:
$ cat a.cc
#include <atomic>
struct Timestamp { unsigned int t, i; };
template<typename T> struct AtomicWord {
std::atomic<T> v;
T compareAndSwap(T e, T n) {
v.compare_exchange_strong(e,n); return e;
}
};
int main() {
AtomicWord<Timestamp> x;
Timestamp a{0,0}, b{1,1};
x.compareAndSwap(a,b);
return 0;
}
$ clang++ -stdlib=libstdc++ a.cc
/usr/bin/x86_64-pc-linux-gnu-ld.bfd: /tmp/a-1e3f91.o: in function `std::atomic<Timestamp>::compare_exchange_strong(Timestamp&, Timestamp, std::memory_order, std::memory_order)':
a.cc:(.text._ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_[_ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_]+0x222): undefined reference to `__atomic_compare_exchange'
/usr/bin/x86_64-pc-linux-gnu-ld.bfd: a.cc:(.text._ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_[_ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_]+0x28d): undefined reference to `__atomic_compare_exchange'
/usr/bin/x86_64-pc-linux-gnu-ld.bfd: a.cc:(.text._ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_[_ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_]+0x2f8): undefined reference to `__atomic_compare_exchange'
/usr/bin/x86_64-pc-linux-gnu-ld.bfd: a.cc:(.text._ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_[_ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_]+0x3c1): undefined reference to `__atomic_compare_exchange'
/usr/bin/x86_64-pc-linux-gnu-ld.bfd: a.cc:(.text._ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_[_ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_]+0x42c): undefined reference to `__atomic_compare_exchange'
/usr/bin/x86_64-pc-linux-gnu-ld.bfd: /tmp/a-1e3f91.o:a.cc:(.text._ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_[_ZNSt6atomicI9TimestampE23compare_exchange_strongERS0_S0_St12memory_orderS3_]+0x497): more undefined references to `__atomic_compare_exchange' follow
clang++: error: linker command failed with exit code 1 (use -v to see invocation)
Signed-off-by: Z. Liu <zhixu.liu@gmail.com>
Part-of: https://github.com/gentoo/gentoo/pull/43808
Closes: https://github.com/gentoo/gentoo/pull/43808
Signed-off-by: Sam James <sam@gentoo.org>
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