SafeInt broken with 18.1.3 (1ubuntu1)

[dcleblanc]

This project:
https://github.com/dcleblanc/SafeInt

Previously compiled with an earlier version of clang (sorry, I don't have a record - about 2 years ago) . See the cpp98_clang branch where I've brought some things up to date and attempted to make it work by disabling optimizations.

[EugeneZelenko]

Could you please try 21 or main branch? Only most recent release is maintained.

[dcleblanc]

Ok, sure will do. Hang on From: EugeneZelenko ***@***.***> Sent: Saturday, November 8, 2025 6:36 PM To: llvm/llvm-project ***@***.***> Cc: David LeBlanc ***@***.***>; Author ***@***.***> Subject: Re: [llvm/llvm-project] SafeInt broken with 18.1.3 (1ubuntu1) (Issue #167194) [https://avatars.githubusercontent.com/u/9355329?s=20&v=4]EugeneZelenko left a comment (llvm/llvm-project#167194)<#167194 (comment)> Could you please try 21 or main branch? Only most recent release is maintained. — Reply to this email directly, view it on GitHub<#167194 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AHX6YL2SRIZWFMD3R6J5DLL332R7JAVCNFSM6AAAAACLRXIEFCVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTKMBXGM3DCMRZGE>. You are receiving this because you authored the thread.Message ID: ***@***.******@***.***>>

[dcleblanc]

Hi Eugene, Yes, v21 fails the same way. Version is 21.1.5. Repro has been seen on 16, 17, 18. This library can give compilers a work-out, it is fairly popular, you might consider adding it to your tests. Please let me know if there’s a work-around or anything I can do to help you diagnose it. From: EugeneZelenko ***@***.***> Sent: Saturday, November 8, 2025 6:36 PM To: llvm/llvm-project ***@***.***> Cc: David LeBlanc ***@***.***>; Author ***@***.***> Subject: Re: [llvm/llvm-project] SafeInt broken with 18.1.3 (1ubuntu1) (Issue #167194) [https://avatars.githubusercontent.com/u/9355329?s=20&v=4]EugeneZelenko left a comment (llvm/llvm-project#167194)<#167194 (comment)> Could you please try 21 or main branch? Only most recent release is maintained. — Reply to this email directly, view it on GitHub<#167194 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AHX6YL2SRIZWFMD3R6J5DLL332R7JAVCNFSM6AAAAACLRXIEFCVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTKMBXGM3DCMRZGE>. You are receiving this because you authored the thread.Message ID: ***@***.******@***.***>>

[dcleblanc]

An update - a very simple repro:

1. Navigate to SafeInt/Test directory
2. clang++ CompileTest.cpp

It says:
realloc(): invalid pointer

[keinflue]

An update - a very simple repro:

1. Navigate to SafeInt/Test directory

2. clang++ CompileTest.cpp

It says: realloc(): invalid pointer

That just generates a bunch of errors for me until the limit is reached. Cause is code in the function MoveRegression which is only valid at namespace scope. See https://godbolt.org/z/v7Yn7aYPh.

[keinflue]

If you meant this to be done on the cpp98_clang branch, then it compiles fine for me although it takes a while: https://godbolt.org/z/1Tjbvr9j9

[dcleblanc]

In the cpp98_clang branch, MoveRegression should have an #if 0 around it. I'm not sure what's up with that, it's a separate issue. That came in because of this - dcleblanc/SafeInt#50

BTW, I am getting a crash with simply:

clang++ CompileTest.cpp

in both cpp98_clang and master

[keinflue]

I'm not sure what's up with that, it's a separate issue.

Neither including standard library headers nor defining class templates inside a function is allowed. They must both be placed at namespace scope.

BTW, I am getting a crash with simply:

Unfortunately I can't reproduce that. What exactly is the full error message? Normally there is an error handler that will print a stack trace when clang crashes.

[dcleblanc]

I would appreciate any insight into the problem in MoveRegression that you might have, and I'll be glad to take your advice on making a cleaner repro out of it. The story was (if I remember correctly) that once I did some work to properly support move, then it broke an n-1 version of gcc. I've no idea how the person reporting the bug came up with that as a repro, it seems to be odd code to me, I stuck it where it is in order not to re-introduce the problem.

But that's not the current issue, especially since at the time, clang dealt with everything correctly, only thing that was broken was gcc. Since it is currently #if 0, I'll sort that out on another day. If once I make it correctly standard it still blows up, we can look into that then.

I have a theory about this one, though - I started chopping away at CompileTest.cpp and found that if I eliminated a bunch of the code in CompileType, it didn't crash. So I took out the code that was working, only to find that the code that was previously not crashing was now crashing. This code is only supposed to compile, but what strikes me is that the optimizer is going to have a bad day because all of it will end up discarded. For example, the code under the comment Test Constructors are all unused variables.

When I try this on Godbolt, at least for me, it often times out. We're hitting resource constraints. The memory on my Linux VM is only 16GB. I might be running out of memory. The crash is in realloc, which could confirm that. Let me get a capture of the crash.

What I am thinking to try as a workaround is to move chunks of this code into other compilation units, make life easier on the compiler.

[dcleblanc]

Crash text:

david@Phineas:~/src/SafeInt/Test$ git checkout master
Switched to branch 'master'
Your branch is ahead of 'origin/master' by 1 commit.
  (use "git push" to publish your local commits)
david@Phineas:~/src/SafeInt/Test$ clang++ CompileTest.cpp 
realloc(): invalid pointer
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: /usr/lib/llvm-21/bin/clang -cc1 -triple x86_64-pc-linux-gnu -emit-obj -dumpdir a- -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name CompileTest.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/home/david/src/SafeInt/Test -fcoverage-compilation-dir=/home/david/src/SafeInt/Test -resource-dir /usr/lib/llvm-21/lib/clang/21 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/backward -internal-isystem /usr/lib/llvm-21/lib/clang/21/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/14/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -ferror-limit 19 -fmessage-length=146 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/CompileTest-671568.o -x c++ CompileTest.cpp
1.      <eof> parser at end of file
2.      CompileTest.cpp:192:6: instantiating function definition 'CompileType<char>'
3.      CompileTest.cpp:33:6: instantiating function definition 'CompiledMixedType<char, unsigned long long>'
 #0 0x00007be7723d37ff llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/usr/lib/llvm-21/bin/../lib/libLLVM.so.21.1+0xbd37ff)
 #1 0x00007be7723d10b7 llvm::sys::RunSignalHandlers() (/usr/lib/llvm-21/bin/../lib/libLLVM.so.21.1+0xbd10b7)
 #2 0x00007be7723d45da (/usr/lib/llvm-21/bin/../lib/libLLVM.so.21.1+0xbd45da)
 #3 0x00007be771045330 (/lib/x86_64-linux-gnu/libc.so.6+0x45330)
 #4 0x00007be77109eb2c __pthread_kill_implementation ./nptl/pthread_kill.c:44:76
 #5 0x00007be77109eb2c __pthread_kill_internal ./nptl/pthread_kill.c:78:10
 #6 0x00007be77109eb2c pthread_kill ./nptl/pthread_kill.c:89:10
 #7 0x00007be77104527e raise ./signal/../sysdeps/posix/raise.c:27:6
 #8 0x00007be7710288ff abort ./stdlib/abort.c:81:7
 #9 0x00007be7710297b6 _IO_acquire_lock_fct ./libio/libioP.h:979:6
#10 0x00007be7710297b6 _IO_peekc_locked ./libio/peekc.c:37:3
#11 0x00007be7710a8ff5 ./malloc/malloc.c:5772:3
#12 0x00007be7710ae49c __libc_realloc ./malloc/malloc.c:3493:19
#13 0x00007be772360e50 llvm::SmallVectorBase<unsigned int>::grow_pod(void*, unsigned long, unsigned long) (/usr/lib/llvm-21/bin/../lib/libLLVM.so.21.1+0xb60e50)
#14 0x00007be77a7f1906 (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x9f1906)
#15 0x00007be77aab01fd (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0xcb01fd)
#16 0x00007be772323496 llvm::FoldingSetBase::FindNodeOrInsertPos(llvm::FoldingSetNodeID const&, void*&, llvm::FoldingSetBase::FoldingSetInfo const&) (/usr/lib/llvm-21/bin/../lib/libLLVM.so.21.1+0xb23496)
#17 0x00007be77aa66681 clang::ASTContext::getPointerType(clang::QualType) const (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0xc66681)
#18 0x00007be77b89b0db clang::Sema::AddConversionCandidate(clang::CXXConversionDecl*, clang::DeclAccessPair, clang::CXXRecordDecl*, clang::Expr*, clang::QualType, clang::OverloadCandidateSet&, bool, bool, bool, bool) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1a9b0db)
#19 0x00007be77b88e995 (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1a8e995)
#20 0x00007be77b8b95c3 (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1ab95c3)
#21 0x00007be77b889067 (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1a89067)
#22 0x00007be77b8964db (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1a964db)
#23 0x00007be77b89cafb clang::Sema::AddBuiltinCandidate(clang::QualType*, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, unsigned int) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1a9cafb)
#24 0x00007be77b8a01a5 (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1aa01a5)
#25 0x00007be77b89f307 clang::Sema::AddBuiltinOperatorCandidates(clang::OverloadedOperatorKind, clang::SourceLocation, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1a9f307)
#26 0x00007be77b8af3a0 clang::Sema::CreateOverloadedBinOp(clang::SourceLocation, clang::BinaryOperatorKind, clang::UnresolvedSetImpl const&, clang::Expr*, clang::Expr*, bool, bool, clang::FunctionDecl*) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1aaf3a0)
#27 0x00007be77ba4849a (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1c4849a)
#28 0x00007be77ba3bfb8 (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1c3bfb8)
#29 0x00007be77ba3f9de (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1c3f9de)
#30 0x00007be77ba2ed48 (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1c2ed48)
#31 0x00007be77ba40db4 (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1c40db4)
#32 0x00007be77ba2ecc9 clang::Sema::SubstStmt(clang::Stmt*, clang::MultiLevelTemplateArgumentList const&) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1c2ecc9)
#33 0x00007be77ba7f033 clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1c7f033)
#34 0x00007be77ba81fa4 clang::Sema::PerformPendingInstantiations(bool, bool) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1c81fa4)
#35 0x00007be77ba7f176 clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1c7f176)
#36 0x00007be77ba81fa4 clang::Sema::PerformPendingInstantiations(bool, bool) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x1c81fa4)
#37 0x00007be77b3bfd28 clang::Sema::ActOnEndOfTranslationUnitFragment(clang::TUFragmentKind) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x15bfd28)
#38 0x00007be77b3c01b9 clang::Sema::ActOnEndOfTranslationUnit() (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x15c01b9)
#39 0x00007be77aa3fcd8 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0xc3fcd8)
#40 0x00007be77a97d19e clang::ParseAST(clang::Sema&, bool, bool) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0xb7d19e)
#41 0x00007be77c57b392 clang::FrontendAction::Execute() (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x277b392)
#42 0x00007be77c4f1df4 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x26f1df4)
#43 0x00007be77c60303c clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/usr/lib/llvm-21/bin/../lib/libclang-cpp.so.21.1+0x280303c)
#44 0x0000562522112fab cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/usr/lib/llvm-21/bin/clang+0x13fab)
#45 0x000056252210fcb4 (/usr/lib/llvm-21/bin/clang+0x10cb4)
#46 0x000056252210f07e clang_main(int, char**, llvm::ToolContext const&) (/usr/lib/llvm-21/bin/clang+0x1007e)
#47 0x000056252211d1f3 main (/usr/lib/llvm-21/bin/clang+0x1e1f3)
#48 0x00007be77102a1ca __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:74:3
#49 0x00007be77102a28b call_init ./csu/../csu/libc-start.c:128:20
#50 0x00007be77102a28b __libc_start_main ./csu/../csu/libc-start.c:347:5
#51 0x000056252210d9b5 _start (/usr/lib/llvm-21/bin/clang+0xe9b5)
clang++: error: unable to execute command: Aborted (core dumped)
clang++: error: clang frontend command failed due to signal (use -v to see invocation)
Ubuntu clang version 21.1.5 (++20251023083335+45afac62e373-1~exp1~20251023083454.54)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/lib/llvm-21/bin
clang++: note: diagnostic msg: 
********************