Windows CI failing with Rust 1.91: libgit2_sys linking errors via vergen-git2

[jolestar]

Problem

Windows CI builds are failing after upgrading to Rust 1.91.1 with unresolved external symbol errors from libgit2_sys.

Error Details

liblibgit2_sys-bd82eeea6732340b.rlib(f6e81ea219c0b9f3-fs_path.o) : error LNK2019: unresolved external symbol __imp_OpenProcessToken referenced in function current_user_sid
liblibgit2_sys-bd82eeea6732340b.rlib(f6e81ea219c0b9f3-fs_path.o) : error LNK2019: unresolved external symbol __imp_CheckTokenMembership referenced in function git_fs_path_owner_is
liblibgit2_sys-bd82eeea6732340b.rlib(f6e81ea219c0b9f3-rand.o) : error LNK2019: unresolved external symbol __imp_CryptAcquireContextA referenced in function getseed
...
fatal error LNK1120: 15 unresolved externals

All missing symbols are from Windows API:

• advapi32.lib: Registry APIs, Token management, SID operations
• crypt32.lib: Cryptographic functions

Root Cause

1. Dependency Chain: vergen-git2 → libgit2-sys → libgit2 (C library)
2. Build Script Issue: The linking errors occur in the build script compilation phase, not the main binary
3. Chicken-and-Egg Problem:
   • Build scripts need to link libgit2_sys to compile
   • But linking instructions in build.rs only affect the main binary, not build scripts
   • Cannot add system libraries via cargo:rustc-link-lib in build.rs because build.rs hasn't compiled yet

Current Workaround

Temporarily disabled Windows CI in cross-platform checks (PR #3899).

• Tracking in parent issue: Upgrade rust to latest stable version #3777 (Rust 1.91 upgrade)

Potential Solutions

Option 1: Use Static Linking for libgit2

[dependencies.vergen-git2]
features = ["git", "git2"]  # Use bundled git

Option 2: Replace vergen-git2

Alternative crates that don't depend on libgit2:

• vergen (older version without git2 dependency)
• vergen-lib (lightweight alternative)
• Build version info at release time only

Option 3: Conditional Compilation

#[cfg(not(target_os = "windows"))]
use vergen_git2::{...};

#[cfg(target_os = "windows")]
// Use alternative versioning strategy

Option 4: Use vcpkg for libgit2 on Windows

Set up vcpkg to provide pre-built libgit2 with correct system library dependencies.

Option 5: Fix in vergen-git2/libgit2-sys Upstream

• File issue with vergen-git2 repo
• Ensure proper Windows system library linkage in build scripts
• May require changes to libgit2-sys build configuration

Investigation Needed

1. Test vergen-git2 with different feature flags
2. Try alternative versioning crates
3. Check if newer libgit2-sys version fixes Windows linking
4. Evaluate impact of removing git info from Windows builds

Related

• Parent issue: Upgrade rust to latest stable version #3777
• Rust 1.91 upgrade PR: chore: upgrade Rust to 1.91.1 (Part 1 & 2) #3899
• Introduced in: Rust 1.91.1 upgrade from 1.82.0
• First occurred: Windows CI failure in cross-platform check workflow

Priority

Medium - Windows CI is blocked but Linux/macOS builds work fine. Windows developers can still build locally using different configurations.