enabling address sanitization with an empty set of tests reports leaks on Linux w/ Swift 6.2.1 #521
Description
When running swift test on Linux, with address sanitization enabled, I'm getting an error about memory leaks.
This doesn't happen with macOS
Reproduction:
mkdir TempExample
cd TempExample
swift package init
# works in macOS
swift test --sanitize=address
# doesn't work in Linux
container run -it -c 4 -m 8g -v "$(pwd):/src" -w src/ swift:6.2 swift test --sanitize=addressOutput from failure:
[1/1] Planning build
Building for debugging...
[1/1] Write swift-version-24593BA9C3E375BF.txt
Build complete! (0.10s)
Test Suite 'All tests' started at 2025-11-25 21:48:31.247
Test Suite 'debug.xctest' started at 2025-11-25 21:48:31.261
Test Suite 'debug.xctest' passed at 2025-11-25 21:48:31.262
Executed 0 tests, with 0 failures (0 unexpected) in 0.0 (0.0) seconds
Test Suite 'All tests' passed at 2025-11-25 21:48:31.262
Executed 0 tests, with 0 failures (0 unexpected) in 0.0 (0.0) seconds
=================================================================
==62==ERROR: LeakSanitizer: detected memory leaks
Indirect leak of 96 byte(s) in 1 object(s) allocated from:
#0 0xaaaabf578560 in malloc /home/build-user/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:68:3
#1 0xffff9f65329c in swift_slowAlloc (/usr/lib/swift/linux/libswiftCore.so+0x3f329c) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#2 0xffff9f6536b8 in swift_allocObject (/usr/lib/swift/linux/libswiftCore.so+0x3f36b8) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#3 0xffff9de3aa70 in $s6XCTest0A8SuiteRunC4testAc2AC_tcfC (/usr/lib/swift/linux/libXCTest.so+0x2aa70) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#4 0xffff9de3bcc4 in $s6XCTestAAC3runyyF (/usr/lib/swift/linux/libXCTest.so+0x2bcc4) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#5 0xffff9de3707c in $s6XCTest7XCTMain_9arguments9observerss5Int32VSayAA0A4CaseCm04testF5Class_SaySS_yAHKctG8allTeststG_SaySSGSayAA0A11Observation_pGSgtF (/usr/lib/swift/linux/libXCTest.so+0x2707c) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#6 0xffff9de37130 in $s6XCTest7XCTMainys5NeverOSayAA0A4CaseCm04testD5Class_SaySS_yAFKctG8allTeststGF (/usr/lib/swift/linux/libXCTest.so+0x27130) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#7 0xaaaabf5ff7d4 in $s23TempExamplePackageTests6RunnerV4mainyyFZ /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift:543:14
#8 0xaaaabf5ff84c in $s23TempExamplePackageTests6RunnerV5$mainyyFZ /<compiler-generated>
#9 0xaaaabf5ff864 in main /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift
#10 0xffff9db584c0 (/lib/aarch64-linux-gnu/libc.so.6+0x284c0) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#11 0xffff9db58594 in __libc_start_main (/lib/aarch64-linux-gnu/libc.so.6+0x28594) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#12 0xaaaabf4ec32c in _start (/src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.xctest+0x5c32c) (BuildId: 835d26df23c8894a9125db6195006ce0aee2d284)
Indirect leak of 96 byte(s) in 1 object(s) allocated from:
#0 0xaaaabf578560 in malloc /home/build-user/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:68:3
#1 0xffff9f65329c in swift_slowAlloc (/usr/lib/swift/linux/libswiftCore.so+0x3f329c) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#2 0xffff9f6536b8 in swift_allocObject (/usr/lib/swift/linux/libswiftCore.so+0x3f36b8) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#3 0xffff9de3aa70 in $s6XCTest0A8SuiteRunC4testAc2AC_tcfC (/usr/lib/swift/linux/libXCTest.so+0x2aa70) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#4 0xffff9de3bcc4 in $s6XCTestAAC3runyyF (/usr/lib/swift/linux/libXCTest.so+0x2bcc4) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#5 0xffff9de3a280 in $s6XCTest0A5SuiteC7performyyAA0A3RunCF (/usr/lib/swift/linux/libXCTest.so+0x2a280) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#6 0xffff9de3bd10 in $s6XCTestAAC3runyyF (/usr/lib/swift/linux/libXCTest.so+0x2bd10) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#7 0xffff9de3707c in $s6XCTest7XCTMain_9arguments9observerss5Int32VSayAA0A4CaseCm04testF5Class_SaySS_yAHKctG8allTeststG_SaySSGSayAA0A11Observation_pGSgtF (/usr/lib/swift/linux/libXCTest.so+0x2707c) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#8 0xffff9de37130 in $s6XCTest7XCTMainys5NeverOSayAA0A4CaseCm04testD5Class_SaySS_yAFKctG8allTeststGF (/usr/lib/swift/linux/libXCTest.so+0x27130) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#9 0xaaaabf5ff7d4 in $s23TempExamplePackageTests6RunnerV4mainyyFZ /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift:543:14
#10 0xaaaabf5ff84c in $s23TempExamplePackageTests6RunnerV5$mainyyFZ /<compiler-generated>
#11 0xaaaabf5ff864 in main /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift
#12 0xffff9db584c0 (/lib/aarch64-linux-gnu/libc.so.6+0x284c0) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#13 0xffff9db58594 in __libc_start_main (/lib/aarch64-linux-gnu/libc.so.6+0x28594) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#14 0xaaaabf4ec32c in _start (/src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.xctest+0x5c32c) (BuildId: 835d26df23c8894a9125db6195006ce0aee2d284)
Indirect leak of 48 byte(s) in 1 object(s) allocated from:
#0 0xaaaabf578560 in malloc /home/build-user/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:68:3
#1 0xffff9f65329c in swift_slowAlloc (/usr/lib/swift/linux/libswiftCore.so+0x3f329c) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#2 0xffff9f6536b8 in swift_allocObject (/usr/lib/swift/linux/libswiftCore.so+0x3f36b8) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#3 0xffff9de349cc in $s6XCTest11XCTMainMisc_9arguments9observersAA19TestSuiteOrExitCodeOSayAA0A4CaseCm04testK5Class_SaySS_yAHKctG8allTeststG_SaySSGSayAA0A11Observation_pGSgtF crtstuff.c
#4 0xffff9de36fa0 in $s6XCTest7XCTMain_9arguments9observerss5Int32VSayAA0A4CaseCm04testF5Class_SaySS_yAHKctG8allTeststG_SaySSGSayAA0A11Observation_pGSgtF (/usr/lib/swift/linux/libXCTest.so+0x26fa0) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#5 0xffff9de37130 in $s6XCTest7XCTMainys5NeverOSayAA0A4CaseCm04testD5Class_SaySS_yAFKctG8allTeststGF (/usr/lib/swift/linux/libXCTest.so+0x27130) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#6 0xaaaabf5ff7d4 in $s23TempExamplePackageTests6RunnerV4mainyyFZ /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift:543:14
#7 0xaaaabf5ff84c in $s23TempExamplePackageTests6RunnerV5$mainyyFZ /<compiler-generated>
#8 0xaaaabf5ff864 in main /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift
#9 0xffff9db584c0 (/lib/aarch64-linux-gnu/libc.so.6+0x284c0) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#10 0xffff9db58594 in __libc_start_main (/lib/aarch64-linux-gnu/libc.so.6+0x28594) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#11 0xaaaabf4ec32c in _start (/src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.xctest+0x5c32c) (BuildId: 835d26df23c8894a9125db6195006ce0aee2d284)
Indirect leak of 48 byte(s) in 1 object(s) allocated from:
#0 0xaaaabf578560 in malloc /home/build-user/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:68:3
#1 0xffff9f65329c in swift_slowAlloc (/usr/lib/swift/linux/libswiftCore.so+0x3f329c) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#2 0xffff9f6536b8 in swift_allocObject (/usr/lib/swift/linux/libswiftCore.so+0x3f36b8) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#3 0xffff9de34ab8 in $s6XCTest11XCTMainMisc_9arguments9observersAA19TestSuiteOrExitCodeOSayAA0A4CaseCm04testK5Class_SaySS_yAHKctG8allTeststG_SaySSGSayAA0A11Observation_pGSgtF crtstuff.c
#4 0xffff9de36fa0 in $s6XCTest7XCTMain_9arguments9observerss5Int32VSayAA0A4CaseCm04testF5Class_SaySS_yAHKctG8allTeststG_SaySSGSayAA0A11Observation_pGSgtF (/usr/lib/swift/linux/libXCTest.so+0x26fa0) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#5 0xffff9de37130 in $s6XCTest7XCTMainys5NeverOSayAA0A4CaseCm04testD5Class_SaySS_yAFKctG8allTeststGF (/usr/lib/swift/linux/libXCTest.so+0x27130) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#6 0xaaaabf5ff7d4 in $s23TempExamplePackageTests6RunnerV4mainyyFZ /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift:543:14
#7 0xaaaabf5ff84c in $s23TempExamplePackageTests6RunnerV5$mainyyFZ /<compiler-generated>
#8 0xaaaabf5ff864 in main /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift
#9 0xffff9db584c0 (/lib/aarch64-linux-gnu/libc.so.6+0x284c0) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#10 0xffff9db58594 in __libc_start_main (/lib/aarch64-linux-gnu/libc.so.6+0x28594) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#11 0xaaaabf4ec32c in _start (/src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.xctest+0x5c32c) (BuildId: 835d26df23c8894a9125db6195006ce0aee2d284)
Indirect leak of 40 byte(s) in 1 object(s) allocated from:
#0 0xaaaabf578560 in malloc /home/build-user/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:68:3
#1 0xffff9f65329c in swift_slowAlloc (/usr/lib/swift/linux/libswiftCore.so+0x3f329c) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#2 0xffff9f6536b8 in swift_allocObject (/usr/lib/swift/linux/libswiftCore.so+0x3f36b8) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#3 0xffff9f3bbeb4 in $ss22_ContiguousArrayBufferV20_consumeAndCreateNew14bufferIsUnique15minimumCapacity13growForAppendAByxGSb_SiSbtFSS5IndexV_Tg5Tm Swift.o
#4 0xffff9f4ffe14 in $sSa034_makeUniqueAndReserveCapacityIfNotB0yyFyXl_Ts5 (/usr/lib/swift/linux/libswiftCore.so+0x29fe14) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#5 0xffff9de3a9f0 in $s6XCTest0A8SuiteRunC07addTestC0yyAA0aC0CF (/usr/lib/swift/linux/libXCTest.so+0x2a9f0) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#6 0xffff9de3a2a8 in $s6XCTest0A5SuiteC7performyyAA0A3RunCF (/usr/lib/swift/linux/libXCTest.so+0x2a2a8) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#7 0xffff9de3bd10 in $s6XCTestAAC3runyyF (/usr/lib/swift/linux/libXCTest.so+0x2bd10) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#8 0xffff9de3707c in $s6XCTest7XCTMain_9arguments9observerss5Int32VSayAA0A4CaseCm04testF5Class_SaySS_yAHKctG8allTeststG_SaySSGSayAA0A11Observation_pGSgtF (/usr/lib/swift/linux/libXCTest.so+0x2707c) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#9 0xffff9de37130 in $s6XCTest7XCTMainys5NeverOSayAA0A4CaseCm04testD5Class_SaySS_yAFKctG8allTeststGF (/usr/lib/swift/linux/libXCTest.so+0x27130) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#10 0xaaaabf5ff7d4 in $s23TempExamplePackageTests6RunnerV4mainyyFZ /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift:543:14
#11 0xaaaabf5ff84c in $s23TempExamplePackageTests6RunnerV5$mainyyFZ /<compiler-generated>
#12 0xaaaabf5ff864 in main /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift
#13 0xffff9db584c0 (/lib/aarch64-linux-gnu/libc.so.6+0x284c0) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#14 0xffff9db58594 in __libc_start_main (/lib/aarch64-linux-gnu/libc.so.6+0x28594) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#15 0xaaaabf4ec32c in _start (/src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.xctest+0x5c32c) (BuildId: 835d26df23c8894a9125db6195006ce0aee2d284)
Indirect leak of 40 byte(s) in 1 object(s) allocated from:
#0 0xaaaabf578560 in malloc /home/build-user/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:68:3
#1 0xffff9f65329c in swift_slowAlloc (/usr/lib/swift/linux/libswiftCore.so+0x3f329c) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#2 0xffff9f6536b8 in swift_allocObject (/usr/lib/swift/linux/libswiftCore.so+0x3f36b8) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#3 0xffff9f3bbeb4 in $ss22_ContiguousArrayBufferV20_consumeAndCreateNew14bufferIsUnique15minimumCapacity13growForAppendAByxGSb_SiSbtFSS5IndexV_Tg5Tm Swift.o
#4 0xffff9f4ffe14 in $sSa034_makeUniqueAndReserveCapacityIfNotB0yyFyXl_Ts5 (/usr/lib/swift/linux/libswiftCore.so+0x29fe14) (BuildId: 20ba6bf673eefe7dbaa48fe92b80636e7d10d7fc)
#5 0xffff9de34aec in $s6XCTest11XCTMainMisc_9arguments9observersAA19TestSuiteOrExitCodeOSayAA0A4CaseCm04testK5Class_SaySS_yAHKctG8allTeststG_SaySSGSayAA0A11Observation_pGSgtF crtstuff.c
#6 0xffff9de36fa0 in $s6XCTest7XCTMain_9arguments9observerss5Int32VSayAA0A4CaseCm04testF5Class_SaySS_yAHKctG8allTeststG_SaySSGSayAA0A11Observation_pGSgtF (/usr/lib/swift/linux/libXCTest.so+0x26fa0) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#7 0xffff9de37130 in $s6XCTest7XCTMainys5NeverOSayAA0A4CaseCm04testD5Class_SaySS_yAFKctG8allTeststGF (/usr/lib/swift/linux/libXCTest.so+0x27130) (BuildId: 0247c17b45dc5c03a92075e2ba612195d9a12d2a)
#8 0xaaaabf5ff7d4 in $s23TempExamplePackageTests6RunnerV4mainyyFZ /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift:543:14
#9 0xaaaabf5ff84c in $s23TempExamplePackageTests6RunnerV5$mainyyFZ /<compiler-generated>
#10 0xaaaabf5ff864 in main /src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.derived/runner.swift
#11 0xffff9db584c0 (/lib/aarch64-linux-gnu/libc.so.6+0x284c0) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#12 0xffff9db58594 in __libc_start_main (/lib/aarch64-linux-gnu/libc.so.6+0x28594) (BuildId: d6c205bda1b6e91815f8fef45bdf56bc2239c37e)
#13 0xaaaabf4ec32c in _start (/src/.build/aarch64-unknown-linux-gnu/debug/TempExamplePackageTests.xctest+0x5c32c) (BuildId: 835d26df23c8894a9125db6195006ce0aee2d284)
SUMMARY: AddressSanitizer: 368 byte(s) leaked in 6 allocation(s).
◇ Test run started.
↳ Testing Library Version: 6.2.1 (c9d57c83568b06d)
↳ Target Platform: aarch64-unknown-linux-gnu
◇ Test example() started.
✔ Test example() passed after 0.001 seconds.
✔ Test run with 1 test in 0 suites passed after 0.001 seconds.If you disable XCTests, the leak error report goes away.
A similar error is reported with Swift:6.1 and Swift:6.0 release images. (adjusting the Swift tools version down to 6.0 to enable the checks)
container run -it -c 4 -m 8g -v "$(pwd):/src" -w src/ swift:6.1 swift test --sanitize=addresscontainer run -it -c 4 -m 8g -v "$(pwd):/src" -w src/ swift:6.0 swift test --sanitize=address
and on the latest nightly main branch build:container run -it -c 4 -m 8g -v "$(pwd):/src" -w src/ swiftlang/swift:nightly swift test --sanitize=address