---
phase: quick-13
plan: 01
subsystem: infra
tags: [build, dead-code-removal, documentation]

requires:
  - phase: none
    provides: standalone cleanup task
provides:
  - Pure Rust extension with no C++ shim or cc build dependency
  - Updated documentation reflecting pure Rust architecture
affects: [build, ci, maintainer-docs]

tech-stack:
  added: []
  patterns: [symbol-visibility-only build.rs]

key-files:
  created: []
  modified:
    - src/lib.rs
    - src/catalog.rs
    - build.rs
    - Cargo.toml
    - README.md
    - TECH-DEBT.md
    - .planning/PROJECT.md

key-decisions:
  - "Removed C++ shim entirely -- was a no-op stub since Phase 11 of v0.2.0"
  - "Kept build.rs for symbol visibility (Linux dynamic-list, macOS exported_symbols_list)"
  - "Deleted duckdb_capi/ vendored headers (1288 files, 130K+ lines) -- only needed for cc compilation"

patterns-established:
  - "build.rs is symbol-visibility-only -- no C++ compilation"

requirements-completed: [QUICK-13]

duration: 5min
completed: 2026-03-03
---

# Quick Task 13: Remove Unused C++ Shim Summary

**Removed no-op C++ shim (1291 files, 130K+ LOC deleted), eliminated cc build dependency, updated all docs to reflect pure Rust architecture**

## Performance

- **Duration:** 5 min
- **Started:** 2026-03-03T15:51:04Z
- **Completed:** 2026-03-03T15:56:00Z
- **Tasks:** 3
- **Files deleted:** 1291 (src/shim/ + duckdb_capi/)
- **Files modified:** 7

## Accomplishments

- Deleted src/shim/ directory (shim.cpp, shim.h, mod.rs) -- no-op stub since v0.2.0 Phase 11
- Deleted duckdb_capi/ vendored DuckDB C++ headers (1288 files)
- Removed extern "C" shim declaration and call from src/lib.rs
- Removed cc::Build block from build.rs, kept symbol visibility section
- Removed cc build-dependency from Cargo.toml
- Updated README, TECH-DEBT.md, and PROJECT.md to reflect pure Rust architecture
- Full test suite passes: cargo test, just test-sql, just test-ducklake-ci

## Task Commits

Each task was committed atomically:

1. **Task 1: Remove C++ shim code and build infrastructure** - `aa42e8c` (feat)
2. **Task 2: Update README and documentation** - `6daf965` (docs)
3. **Task 3: Full test suite verification** - no commit (verification only)

## Files Created/Modified

- `src/shim/shim.cpp` - DELETED: no-op C++ stub
- `src/shim/shim.h` - DELETED: C/C++ header for shim
- `src/shim/mod.rs` - DELETED: Rust module wrapper for shim
- `duckdb_capi/` - DELETED: 1288 vendored DuckDB C++ header files
- `src/lib.rs` - Removed shim module declaration, extern block, and shim call
- `src/catalog.rs` - Removed stale "C++ parser hook" comment
- `build.rs` - Removed cc::Build block; now symbol-visibility-only
- `Cargo.toml` - Removed cc build-dependency
- `Cargo.lock` - Updated to remove cc dependency tree
- `README.md` - "Rust, built on" instead of "Rust with a C++ shim"
- `TECH-DEBT.md` - Updated decisions 1, 5 and deferred items to note shim removal
- `.planning/PROJECT.md` - Updated tech stack, language constraint, validated requirements

## Decisions Made

- Removed C++ shim entirely rather than keeping it for potential future use -- the shim was a no-op since Phase 11, and the architectural limitation (Python DuckDB `-fvisibility=hidden`) means C++ hooks are fundamentally impossible from a loadable extension
- Kept build.rs with symbol visibility configuration -- still needed for the cdylib to restrict exported symbols on Linux and macOS
- Updated TECH-DEBT.md deferred items to mark QUERY-V2-01 and QUERY-V2-03 as architecturally blocked (not just deferred) since the shim approach is no longer viable

## Deviations from Plan

None -- plan executed exactly as written.

## Issues Encountered

None.

## User Setup Required

None -- no external service configuration required.

## Next Phase Readiness

- Extension is now pure Rust with no C++ toolchain requirement for contributors
- Build is simpler (no cc crate compilation step)
- All docs accurately reflect current architecture
