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

[at445]

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

[gemini-code-assist]

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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[gemini-code-assist]

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.