abicheck

abicheck detects breaking changes in C/C++ shared libraries before they reach production. It compares two versions of a shared library — along with their public headers — and reports whether existing binaries will continue to work or break at runtime.

It catches removed or renamed symbols, changed function signatures, struct layout drift, vtable reordering, enum value reassignment, and many more — 254 ABI/API change types in total — that cause crashes, silent data corruption, or linker failures after a library upgrade.

Platforms: Linux (ELF), Windows (PE/COFF), macOS (Mach-O). Binary and header AST analysis on all platforms; debug-info cross-check uses DWARF (Linux, macOS) and PDB (Windows).

Full documentation: abicheck.github.io/abicheck

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Key features

• Reads multiple sources of information. abicheck doesn't rely on a single view of a library. It overlays up to five independent, additive sources — the compiled binary, its debug symbols, its public headers, its build-system data, and (optionally) its sources — and lets the strongest evidence win. Each source finds breaks the weaker ones are blind to, and removes false positives the weaker ones would raise. See How it works below.
• Detects most of what causes ABI/API breaks. 254 change types across functions, variables, structs/classes, enums, unions, typedefs, templates, and platform/linker metadata — removed or renamed symbols, changed signatures and parameter lists, struct/class layout drift, field-offset shifts, vtable reordering, enum value reassignment, qualifier/noexcept/access changes, calling-convention and packing changes, symbol-version and SONAME drift, dependency leaks, and more. Each is classified as BREAKING, API_BREAK, COMPATIBLE_WITH_RISK, or COMPATIBLE. See the Change Kind Reference.
• Cross-platform. Linux (ELF), Windows (PE/COFF), and macOS (Mach-O) binaries, with debug-info cross-checks from DWARF, PDB, BTF, and CTF.
• Built for CI. Deterministic exit codes, SARIF/JSON/Markdown/HTML/JUnit output, snapshot-based baselines, policy profiles and suppressions, and a first-class GitHub Action.
• Public-surface scoping. Filters findings to the library's public ABI surface so internal-only changes don't fail your build — fewer false positives than symbol-only tools.
• More than one library at a time. Compare co-versioned multi-library releases as a single bundle (compare on directory/package inputs), check whether a specific application still works (appcompat), or validate a binary's full dependency stack across sysroots (stack-check).
• Drop-in for existing tools. A compat mode mirrors abi-compliance-checker flags, and migration guides cover ABICC and libabigail.
• Agent- and script-friendly. Structured JSON, a Python API, and an MCP server for AI-driven workflows. Pure Python (3.10+), no heavyweight native toolchain required for binary-only mode.

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How it works — multiple sources of information

abicheck treats compatibility analysis as a question of evidence: the more independent sources you give it about a library, the more it can prove — and the fewer false positives it raises. There are five layers, ordered from the least input to the most. Each one adds facts the previous cannot see; none is complete on its own.

Layer	Source you provide	Read by	What it newly reveals
L0	Just the binary — a stripped .so / .dll / .dylib	ELF/PE/COFF/Mach-O parsers (pyelftools, pefile, macholib)	Exported symbols, SONAME/install-name, symbol versions, visibility, binding, DT_NEEDED/LC_LOAD_DYLIB dependencies
L1	+ Debug symbols — a -g build or sidecar debug file	DWARF, PDB, BTF, CTF	Type layout: struct/class sizes, field offsets, enum values, vtable slots, calling convention, packing/alignment
L2	+ Public headers — -H include/	castxml AST	Source-level API: signatures, overloads, access (public/private), final/explicit/noexcept, templates, default args, public/internal scoping
L3	+ Build system data & options — -p build/	compile DB / CMake / Ninja / Bazel / Make	The flags the library was actually built with: -std, _GLIBCXX_USE_CXX11_ABI, -fvisibility, -fabi-version, toolchain/sysroot, export maps
L4	+ Sources — a build/source pack	per-TU source ABI replay	Facts that never reach the binary: macro/constexpr values, default-argument values, inline/template bodies, uninstantiated templates

The layers are independent and additive, not a fallback chain — abicheck overlays every source you give it and computes one worst-wins verdict, under the authority rule: artifact-backed evidence (L0/L1/L2) is authoritative for the shipped-ABI verdict, while build/source evidence (L3/L4) explains, localizes, scopes, or adds confidence to a finding (and can raise its own source-/API-level findings) but never silently deletes an artifact-proven break.

With less input, abicheck degrades gracefully down the staircase rather than failing — a stripped binary with no headers collapses toward symbol-only checking — and abicheck dump --show-data-sources reports exactly which layers it found. The best input you can give it is old library + new library + matching public headers + debug info + build data. See Evidence & Detectability for what each source can and cannot see, and Architecture for how the layers are reconciled.

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Installation

pip install abicheck
# or
conda install -c conda-forge abicheck

abicheck also needs castxml and a C++ compiler for header AST analysis (the conda-forge package pulls these in automatically). Without them, abicheck still works in binary-only mode. See Getting Started for per-platform setup and cross-compilation.

Naming note: the PyPI package (abicheck) is distinct from distro-packaged tools with similar names (abi-compliance-checker wrappers in Debian devscripts, or abicheck in Fedora's libabigail-tools). Run abicheck --version to confirm — it should print abicheck X.Y.Z (abicheck/abicheck). If there is a conflict, invoke via python -m abicheck.

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Quick start

Compare two library versions:

abicheck compare libfoo.so.1 libfoo.so.2 \
  --old-header include/v1/foo.h --new-header include/v2/foo.h

Save a baseline snapshot at release time, then compare every new build against it:

abicheck dump libfoo.so -H include/foo.h --version 1.0 -o baseline.json
abicheck compare baseline.json ./build/libfoo.so --new-header include/foo.h

Supported output formats: markdown (default), json, sarif, html, and junit.

abicheck compare old.so new.so -H foo.h --format sarif -o report.sarif

See Getting Started for the full tutorial and CLI Usage for the complete command reference.

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Which command do I need?

I want to…	Use
Check whether a library upgrade breaks existing consumers	abicheck compare
Compare a multi-library release (a co-versioned bundle, e.g. oneDAL) as a single bundle	abicheck compare
Check whether my application breaks with a new library version	abicheck appcompat
Validate a binary's full dependency stack across two sysroots	abicheck stack-check
Drop-in replacement for abi-compliance-checker	abicheck compat
Save a reusable ABI baseline snapshot	abicheck dump

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Exit codes

Use these to gate CI pipelines.

Exit code	Verdict	Meaning
0	NO_CHANGE / COMPATIBLE / COMPATIBLE_WITH_RISK	Safe — no binary ABI break
1	SEVERITY_ERROR	Severity-driven error (with --severity-* flags)
2	API_BREAK	Source-level break (recompile needed, binary may still work)
4	BREAKING	Binary ABI break (old binaries will crash or misbehave)
8	REMOVED_LIBRARY	Library removed in new version (multi-library/bundle compare only)

appcompat, stack-check, and compat use the same scheme with per-mode additions — see the full exit code reference.

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GitHub Action

- uses: abicheck/abicheck@v0.3.0
  with:
    old-library: abi-baseline.json
    new-library: build/libfoo.so
    new-header: include/foo.h
    format: sarif
    upload-sarif: true

The action installs Python, castxml, and abicheck automatically. Outputs: verdict, exit-code, report-path. See the GitHub Action docs for matrix builds, cross-compilation, and gating flags (fail-on-breaking, fail-on-api-break).

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Policies and suppressions

Policies classify detected changes (BREAKING, COMPATIBLE, …); suppressions silence known or intentional changes so they don't fail CI.

abicheck compare old.so new.so -H foo.h \
  --policy sdk_vendor \
  --suppress suppressions.yaml

Built-in profiles: strict_abi (default), sdk_vendor, plugin_abi. Custom YAML policies are supported, and the ABICC compat CLI accepts -symbols-list/-types-list whitelist flags.

Full references:

• Policy Profiles
• Suppressions (YAML schema, expiry, justification)
• Migrating from ABICC

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Python API

from pathlib import Path
from abicheck.service import run_compare

result, old_snapshot, new_snapshot = run_compare(
    old_input=Path("libfoo.so.1"),
    new_input=Path("libfoo.so.2"),
    old_headers=[Path("include/v1/foo.h")],
    new_headers=[Path("include/v2/foo.h")],
)

print(result.verdict)       # e.g. Verdict.BREAKING
print(len(result.changes))  # number of detected changes

See abicheck.service for the full signature, plus the MCP server integration for AI-agent workflows.

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Examples

The examples/ directory contains 152 real-world ABI/API scenarios (147 single-library cases plus 5 multi-library bundle cases) with ground-truth verdicts. Most are single-library v1/v2 examples with a consumer app; the G20 audit/cross-source cases (143–151) are single-build snapshots demonstrating intra-version cross-checks; bundle/release-level cases use release-style layouts. The full catalog is the development regression corpus; a smaller historical cross-tool subset is kept in the reference docs for release-to-release comparison with libabigail and ABICC.

Current Examples Validation CI runs the full 134-case default/debug catalog and produces 122 PASS / 5 XFAIL / 7 SKIP with no FAIL/ERROR bucket. The same workflow uploads full runtime-smoke results (70 DEMONSTRATED / 47 NO_RUNTIME_SIGNAL / 7 BASELINE_SIGNAL / 10 SKIP) and representative release/stripped/build-source mode-smoke artifacts. See examples/README.md#current-validation-status for the exact commands, execution scope, status, and known stripped-mode backlog.

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Validation snapshot

The main validation target is the full 152-case catalog. To scan it for the current checkout:

python scripts/benchmark_comparison.py --suite all

The command writes benchmark_reports/benchmark_report.json with the selected suite, abicheck version, git commit, tool versions, the ground_truth.json SHA-256, and per-tool accuracy. Cases that require bundle/release harnesses or unavailable compiler features are marked as unscored instead of being folded into single-library verdict accuracy.

For apples-to-apples comparison with libabigail and ABICC, release workflows also run the historical pinned cross-tool subset (case01-case73 + case26b) and attach that report to GitHub Releases:

python scripts/benchmark_comparison.py --suite pinned74

Detection by evidence source

The five sources of information each find breaks the weaker sources are blind to. The --evidence-tiers mode scans the catalog at each level so you can measure what every source unlocks:

python scripts/benchmark_comparison.py --evidence-tiers

Source you provide	Cumulative cases reaching the correct verdict
Just the binary (L0)	42 / 129 (33%)
+ Debug symbols (L1)	105 / 129 (81%)
+ Public headers (L2)	128 / 129 (99%)
+ Build data / sources (L3/L4)	129 / 129 (100%)

More evidence also removes false positives (e.g. header scoping correctly dismisses internal-struct changes). See Evidence & Detectability for what each source reveals and Benchmarking by evidence tier for the methodology.

Per-case matrix, methodology, full-catalog notes, and the pinned cross-tool comparison table: Tool Comparison & Benchmarks.

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Documentation

• Start here: Getting Started
• User guide: CLI Usage · Application compatibility · Output formats · GitHub Action
• Concepts: Verdicts · Architecture · ABI/API Handling & Recommendations · Limitations
• Reference: Change Kinds · Exit Codes · Platforms · Tool Comparison
• Troubleshooting: Troubleshooting guide

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Contributing

See CONTRIBUTING.md for setup, testing, code style, and PR workflow. Project status and roadmap: development/goals.md.

License

Licensed under the Apache License, Version 2.0. See LICENSE and NOTICE.

Copyright 2026 Nikolay Petrov