Add libtinfo5 compatibility patch for LLVM < 19 on Ubuntu 24.04+

[Copilot]

LLVM < 19 depends on libtinfo.so.5, which is absent from Ubuntu 24.04+ (replaced by libtinfo6). This causes build failures: error while loading shared libraries: libtinfo.so.5: cannot open shared object file.

Changes

Added patch libtinfo5_fix.patch to toolchains_llvm 1.6.0.envoy:

• toolchain/internal/repo.bzl: Downloads libtinfo5 from Ubuntu 22.04 archives (amd64/aarch64) and extracts libtinfo.so.5.9 when:

  • OS is Linux
  • LLVM major version < 19
  • Architecture is amd64 or aarch64
  • Gracefully skips unsupported architectures

• toolchain/cc_wrapper.sh.tpl: Prepends LD_LIBRARY_PATH with toolchain's lib directory on Linux:

  if [[ "$(uname -s)" == "Linux" ]]; then
    export LD_LIBRARY_PATH="${toolchain_path_prefix}lib:${LD_LIBRARY_PATH}"
  fi

Updated source.json: Added patch with SHA256 checksum.

Details

.deb archives sourced from Ubuntu 22.04:

• amd64: http://security.ubuntu.com/ubuntu/pool/universe/n/ncurses/libtinfo5_6.3-2ubuntu0.1_amd64.deb
• arm64: http://ports.ubuntu.com/pool/universe/n/ncurses/libtinfo5_6.3-2ubuntu0.1_arm64.deb

Verified checksums match upstream package database.

Upstream tracking: bazel-contrib/toolchains_llvm#528

Original prompt

Problem

LLVM versions < 19 distributed via toolchains_llvm depend on libtinfo.so.5, which is not available on Ubuntu 24.04+ (only libtinfo6 is present). This causes builds to fail with:

error while loading shared libraries: libtinfo.so.5: cannot open shared object file: No such file or directory

This is tracked upstream at bazel-contrib/toolchains_llvm#528

Solution

Add a patch to the existing toolchains_llvm registry entry at bazel-registry/modules/toolchains_llvm/1.6.0.envoy/ that:

1. Modifies toolchain/internal/repo.bzl to download and extract libtinfo5 from Ubuntu 22.04 archives when:

   • OS is Linux
   • LLVM major version < 19
   • Architecture is amd64 or aarch64

2. Modifies toolchain/cc_wrapper.sh.tpl to prepend LD_LIBRARY_PATH with the toolchain's lib directory on Linux, so the injected library is found.

Implementation Details

Patch file to create: bazel-registry/modules/toolchains_llvm/1.6.0.envoy/patches/libtinfo5_fix.patch

The patch should:

For toolchain/cc_wrapper.sh.tpl - Add after the clang existence check (around line 87):

# Inject libtinfo5 path if present to fix issues on Ubuntu 24.04+
if [[ "$(uname -s)" == "Linux" ]]; then
  export LD_LIBRARY_PATH="${toolchain_path_prefix}lib:${LD_LIBRARY_PATH}"
fi

For toolchain/internal/repo.bzl - Add after updated_attrs = _download_llvm(rctx) (around line 438):

    # Inject libtinfo5 for older LLVMs on Linux
    # LLVM < 19 depends on libtinfo.so.5 which is missing on Ubuntu 24.04+
    if os == "linux" and major_llvm_version < 19:
        libtinfo_map = {
            "amd64": {
                "url": "http://security.ubuntu.com/ubuntu/pool/universe/n/ncurses/libtinfo5_6.3-2ubuntu0.1_amd64.deb",
                "sha256": "ab89265d8dd18bda6a29d7c796367d6d9f22a39a8fa83589577321e7caf3857b",
                "path": "./lib/x86_64-linux-gnu/libtinfo.so.5.9"
            },
            "aarch64": {
                "url": "http://ports.ubuntu.com/pool/universe/n/ncurses/libtinfo5_6.3-2ubuntu0.1_arm64.deb",
                "sha256": "be34705c5d2952298f480b4b571b382e7c921d65195889e6870b55ad834ce02c",
                "path": "./lib/aarch64-linux-gnu/libtinfo.so.5.9"
            }
        }
        
        arch_info = libtinfo_map.get(rctx.os.arch)
        
        if arch_info:
            print("DEBUG: Injecting libtinfo5 compatibility lib for " + rctx.os.arch)
            rctx.download(
                url = arch_info["url"],
                sha256 = arch_info["sha256"],
                output = "libtinfo5.deb",
            )
            rctx.execute(["ar", "x", "libtinfo5.deb", "data.tar.xz"])
            rctx.execute(["tar", "-xf", "data.tar.xz", "--strip-components=3", "-C", "lib", arch_info["path"]])
            rctx.execute(["ln", "-s", "libtinfo.so.5.9", "lib/libtinfo.so.5"])

Update source.json

After creating the patch file, update bazel-registry/modules/toolchains_llvm/1.6.0.envoy/source.json to include the new patch. The SHA256 of the patch file must be calculated correctly.

CRITICAL INSTRUCTIONS

1. SHA256 checksums for the .deb files are VERIFIED - use exactly:

   • amd64: ab89265d8dd18bda6a29d7c796367d6d9f22a39a8fa83589577321e7caf3857b
   • arm64: be34705c5d2952298f480b4b571b382e7c921d65195889e6870b55ad834ce02c

2. The patch file's SHA256 for source.json must be calculated AFTER creating the patch file - do not use a placeholder.

3. The patch must be a valid unified diff that applies cleanly to toolchains_llvm v1.6.0.

4. Reference the actual source files from https://github.com/bazel-contrib/toolchains_llvm at tag v1.6.0 to get correct line numbers for the patch.

5. The logic must be safe - if the architecture is not in the map, it should skip gracefully (no error).

This pull request was created from Copilot chat.

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