cmake: link terminfo to cpptest/tvm_allvisible when required by LLVM/libedit #18700

at445 · 2026-01-31T09:21:15Z

Summary

Detect and link libtinfo (terminfo) explicitly for cpptest and tvm_allvisible when found.
Prevents link-time failures for test binaries when llvm-config does not export -ltinfo, which can happen with some LLVM packages (observed with LLVM 18 in Ubuntu 24.04.3 LTS (x86_64-linux-gnu) ).

Problem

With USE_LLVM=ON, the build produced undefined references to terminfo symbols (e.g. tgetstr, setupterm) when linking cpptest. ldd /usr/lib/llvm-18/lib/libLLVM-18.so shows it depends on libedit and libtinfo, but llvm-config --libs --link-static did not include -ltinfo, so CMake didn't add it to the final link.

Change

Minimal, portable CMake change:
- find_library(TINFO_LIB tinfo) and, if found, target_link_libraries(cpptest PRIVATE ${TINFO_LIB}) and, when present, target_link_libraries(tvm_allvisible PRIVATE ${TINFO_LIB}).

Reproduction

Steps:
1. cmake -S . -B build-llvm_ON-hide_OFF -DUSE_LLVM=ON -DHIDE_PRIVATE_SYMBOLS=OFF -DUSE_GTEST=ON -DCMAKE_BUILD_TYPE=RelWithDebInfo
2. cmake --build build-llvm_ON-hide_OFF --target cpptest
Expected:
- Before: link errors referencing terminfo symbols and no cpptest binary produced.
- After: cpptest links and is produced.

Rationale

Safer and more portable than relying on consumers to fix package-level llvm-config exports.
No behavioral changes unless tinfo is required and available.

Logs

find more information on attachment
build-llvm_ON-hide_OFF.build.log
build-llvm_ON-hide_OFF.cmake.log
build-llvm_ON-hide_ON.build.log
build-llvm_ON-hide_ON.cmake.log

…libedit\n\nDetect and link libtinfo explicitly to avoid missing terminfo symbols when llvm-config does not export -ltinfo. This fixes cpptest link failures observed with USE_LLVM=ON on some systems (e.g. LLVM 18 packaged without propagating terminfo).\n\nReproduction: cmake -S . -B build-llvm_ON-hide_OFF -DUSE_LLVM=ON -DHIDE_PRIVATE_SYMBOLS=OFF -DUSE_GTEST=ON -DCMAKE_BUILD_TYPE=RelWithDebInfo && cmake --build build-llvm_ON-hide_OFF --target cpptest\n\nVerified: cpptest now links successfully when libtinfo is present on the system and was added as a conditional link target.,

gemini-code-assist · 2026-01-31T09:21:29Z

Summary of Changes

Hello @at445, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a specific build issue encountered when compiling with LLVM, particularly affecting the cpptest and tvm_allvisible targets. It introduces a robust CMake-based solution to explicitly locate and link the libtinfo library, which is sometimes a missing dependency when llvm-config fails to export it. This ensures that these targets can link successfully across various LLVM configurations, enhancing the overall stability of the build system.

Highlights

Terminfo Linking: Explicitly links libtinfo (terminfo) to cpptest and tvm_allvisible targets in CMake when detected.
Build Fix: Resolves link-time failures for test binaries, specifically cpptest, that occur when llvm-config does not export -ltinfo, as observed with LLVM 18 on Ubuntu.
Portability: Improves build portability and reliability by not relying solely on llvm-config to provide all necessary link flags.

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Code Review

This pull request adds logic to link libtinfo when building tests with LLVM to fix link-time failures on some systems. The change is correct in principle. My review includes a suggestion to improve the implementation by making the logic conditional on LLVM being used and by using a more portable CMake command to find the required library. This will improve maintainability and portability.

CMakeLists.txt

…erminfo with Curses

tqchen · 2026-02-03T13:04:35Z

CMakeLists.txt

+    # Ensure we link terminfo when required by LLVM / libedit at link time.
+    find_package(Curses)
+    if(CURSES_FOUND)
+       message(STATUS "Found Curses/terminfo library: ${CURSES_LIBRARIES}")


i think llvm only requires tinfo but not curses library? we do want to avoid dependency bloat in this case

The dependency should also be specified and captured through llvm config in findllm instead of here

i think llvm only requires tinfo but not curses library? we do want to avoid dependency bloat in this case
this is suggested by gemini-code-assist, but I could switch back tinfo if you insist ^_^

You're right, tqchen raises a good point about dependency bloat. While find_package(Curses) often works because libtinfo is frequently bundled with ncurses, explicitly searching for libtinfo is more precise if that's the only required dependency. This helps avoid pulling in unnecessary parts of the Curses library.

My initial suggestion aimed for a common, robust way to find terminal-related libraries, but find_library(TINFO_LIB tinfo) directly addresses the specific missing dependency (libtinfo) as indicated by your problem description. This is a medium severity suggestion to improve precision and minimize dependencies.

Regarding tqchen's second point, ideally, llvm-config should provide all necessary linker flags for its dependencies. If it doesn't include -ltinfo on certain systems, then explicitly finding and linking it as a workaround is a pragmatic approach for now. The long-term solution would involve ensuring FindLLVM.cmake or the llvm-config output itself correctly reports this dependency.

Suggested change

message(STATUS "Found Curses/terminfo library: ${CURSES_LIBRARIES}")

find_library(TINFO_LIB tinfo)

if(TINFO_LIB)

message(STATUS "Found terminfo library: ${TINFO_LIB}")

target_link_libraries(cpptest PRIVATE ${TINFO_LIB})

if(TARGET tvm_allvisible)

target_link_libraries(tvm_allvisible PRIVATE ${TINFO_LIB})

endif()

endif()

The dependency should also be specified and captured through llvm config in findllm instead of here

you are right! I will rethink about it

gemini-code-assist bot reviewed Jan 31, 2026

View reviewed changes

CMakeLists.txt Outdated Show resolved Hide resolved

1. move terminfo linkage into the if(DEFINED LLVM_LIBS)\n 2.replace t…

4c8743f

…erminfo with Curses

tqchen requested changes Feb 3, 2026

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cmake: link terminfo to cpptest/tvm_allvisible when required by LLVM/libedit #18700

cmake: link terminfo to cpptest/tvm_allvisible when required by LLVM/libedit #18700

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-       message(STATUS "Found Curses/terminfo library: ${CURSES_LIBRARIES}")
+    find_library(TINFO_LIB tinfo)
+    if(TINFO_LIB)
+       message(STATUS "Found terminfo library: ${TINFO_LIB}")
+       target_link_libraries(cpptest PRIVATE ${TINFO_LIB})
+       if(TARGET tvm_allvisible)
+          target_link_libraries(tvm_allvisible PRIVATE ${TINFO_LIB})
+       endif()
+    endif()

cmake: link terminfo to cpptest/tvm_allvisible when required by LLVM/libedit #18700

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cmake: link terminfo to cpptest/tvm_allvisible when required by LLVM/libedit #18700

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at445 commented Jan 31, 2026

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