Hello, This is a bug report regarding llvm ports. This has been confirmed for versions 19-22.
When compiling with -fexperimental-library on OpenBSD, clang tries to link -lc++experimental, but OpenBSD's libcxx is named libec++experimental.a, causing a linker error. The library is built as libec++experimental.a due to OpenBSD's "ec++" naming convention, but clang's OpenBSD toolchain is hardcoded to request -lc++experimental, causing the linker error. The following section likely needs to be fixed. Related code: https://github.com/llvm/llvm-project/blob/llvmorg-22.1.8/clang/lib/Driver/ToolChains/OpenBSD.cpp#L353C1-L362C2 void OpenBSD::AddCXXStdlibLibArgs(const ArgList &Args, ArgStringList &CmdArgs) const { bool Profiling = Args.hasArg(options::OPT_pg); CmdArgs.push_back(Profiling ? "-lc++_p" : "-lc++"); if (Args.hasArg(options::OPT_fexperimental_library)) CmdArgs.push_back("-lc++experimental"); CmdArgs.push_back(Profiling ? "-lc++abi_p" : "-lc++abi"); CmdArgs.push_back(Profiling ? "-lpthread_p" : "-lpthread"); } Steps to reproduce: $ doas pkg_add llvm%22 libcxx%22 $ echo "#include <syncstream>\nint main(){}" > test.cpp $ clang++-22 -v -std=c++20 -fexperimental-library test.cpp clang version 22.1.8 Target: amd64-unknown-openbsd7.9 Thread model: posix InstalledDir: /usr/local/llvm22/bin "/usr/local/llvm22/bin/clang-22" -cc1 -triple amd64-unknown-openbsd7.9 -emit-obj -dumpdir a- -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name test.cpp -mrelocation-model pic -pic-level 1 -pic-is-pie -mframe-pointer=all -relaxed-aliasing -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/tmp -v -fcoverage-compilation-dir=/tmp -resource-dir /usr/local/llvm22/lib/clang/22 -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/llvm22/lib/clang/22/include -internal-externc-isystem /usr/include -std=c++20 -fdeprecated-macro -fexperimental-library -ferror-limit 19 -fmessage-length=132 -femulated-tls -fwrapv -D_RET_PROTECTOR -ret-protector -fcf-protection=branch -fno-jump-tables -fgnuc-version=4.2.1 -fno-implicit-modules -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -faddrsig -fdwarf2-cfi-asm -o /tmp/test-480167.o -x c++ test.cpp clang -cc1 version 22.1.8 based upon LLVM 22.1.8 default target amd64-unknown-openbsd7.9 #include "..." search starts here: #include <...> search starts here: /usr/include/c++/v1 /usr/local/llvm22/lib/clang/22/include /usr/include End of search list. "/usr/bin/ld" -e __start --eh-frame-hdr -dynamic-linker /usr/libexec/ld.so -o a.out /usr/lib/crt0.o /usr/lib/crtbegin.o -L/usr/lib /tmp/test-480167.o -lc++ -lc++experimental -lc++abi -lpthread -lm -lcompiler_rt -lc -lcompiler_rt /usr/lib/crtend.o ld: error: unable to find library -lc++experimental clang++: error: linker command failed with exit code 1 (use -v to see invocation) System Info: $ sysctl -n kern.version OpenBSD 7.9-current (GENERIC.MP) #2: Fri Jun 12 12:08:26 MDT 2026 [email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP $ cat /var/db/installed.BUILDINFO Build date: 1781288383 - Fri Jun 12 18:19:43 UTC 2026 ports tree version: current Note: I previously contacted the maintainers about this issue without receiving a response, so I'm posting to the public list. -c2qd diff --git a/devel/llvm/19/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp b/devel/llvm/19/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp index 55dc701f8f8..5a046c1cb92 100644 --- a/devel/llvm/19/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp +++ b/devel/llvm/19/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp @@ -21,3 +21,12 @@ Index: clang/lib/Driver/ToolChains/OpenBSD.cpp ToolChain.addProfileRTLibs(Args, CmdArgs); const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath()); +@@ -365,7 +378,7 @@ void OpenBSD::AddCXXStdlibLibArgs(const ArgList &Args, + + CmdArgs.push_back(Profiling ? "-lc++_p" : "-lc++"); + if (Args.hasArg(options::OPT_fexperimental_library)) +- CmdArgs.push_back("-lc++experimental"); ++ CmdArgs.push_back("-lec++experimental"); + CmdArgs.push_back(Profiling ? "-lc++abi_p" : "-lc++abi"); + CmdArgs.push_back(Profiling ? "-lpthread_p" : "-lpthread"); + } diff --git a/devel/llvm/20/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp b/devel/llvm/20/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp index 9ec59adf692..0f201dbcd84 100644 --- a/devel/llvm/20/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp +++ b/devel/llvm/20/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp @@ -21,3 +21,12 @@ Index: clang/lib/Driver/ToolChains/OpenBSD.cpp ToolChain.addProfileRTLibs(Args, CmdArgs); const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath()); +@@ -366,7 +379,7 @@ void OpenBSD::AddCXXStdlibLibArgs(const ArgList &Args, + + CmdArgs.push_back(Profiling ? "-lc++_p" : "-lc++"); + if (Args.hasArg(options::OPT_fexperimental_library)) +- CmdArgs.push_back("-lc++experimental"); ++ CmdArgs.push_back("-lec++experimental"); + CmdArgs.push_back(Profiling ? "-lc++abi_p" : "-lc++abi"); + CmdArgs.push_back(Profiling ? "-lpthread_p" : "-lpthread"); + } diff --git a/devel/llvm/21/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp b/devel/llvm/21/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp index b7aa7dae11d..451c411dc09 100644 --- a/devel/llvm/21/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp +++ b/devel/llvm/21/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp @@ -21,3 +21,12 @@ Index: clang/lib/Driver/ToolChains/OpenBSD.cpp ToolChain.addProfileRTLibs(Args, CmdArgs); const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath()); +@@ -356,7 +369,7 @@ void OpenBSD::AddCXXStdlibLibArgs(const ArgList &Args, + + CmdArgs.push_back(Profiling ? "-lc++_p" : "-lc++"); + if (Args.hasArg(options::OPT_fexperimental_library)) +- CmdArgs.push_back("-lc++experimental"); ++ CmdArgs.push_back("-lec++experimental"); + CmdArgs.push_back(Profiling ? "-lc++abi_p" : "-lc++abi"); + CmdArgs.push_back(Profiling ? "-lpthread_p" : "-lpthread"); + } diff --git a/devel/llvm/22/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp b/devel/llvm/22/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp index b7aa7dae11d..451c411dc09 100644 --- a/devel/llvm/22/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp +++ b/devel/llvm/22/patches/patch-clang_lib_Driver_ToolChains_OpenBSD_cpp @@ -21,3 +21,12 @@ Index: clang/lib/Driver/ToolChains/OpenBSD.cpp ToolChain.addProfileRTLibs(Args, CmdArgs); const char *Exec = Args.MakeArgString(ToolChain.GetLinkerPath()); +@@ -356,7 +369,7 @@ void OpenBSD::AddCXXStdlibLibArgs(const ArgList &Args, + + CmdArgs.push_back(Profiling ? "-lc++_p" : "-lc++"); + if (Args.hasArg(options::OPT_fexperimental_library)) +- CmdArgs.push_back("-lc++experimental"); ++ CmdArgs.push_back("-lec++experimental"); + CmdArgs.push_back(Profiling ? "-lc++abi_p" : "-lc++abi"); + CmdArgs.push_back(Profiling ? "-lpthread_p" : "-lpthread"); + }
