please excuse the AI slop.

tldr, deterministic builds are hard to achieve across platforms. there are entire OSs designed to eliminate these problems

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Even when a project aims for deterministic builds, several factors can cause different build outputs with different hashes:

Timestamps and Metadata

Build timestamps embedded in binaries, archives, or metadata files

File modification times preserved in archives (tar, zip)

Version control metadata like Git commit timestamps

Compiler-generated timestamps in debug info or headers

Build Environment Variations

Different compiler versions producing slightly different output

Different toolchain versions (linker, assembler, archiver)

Operating system differences affecting system libraries or build tools

CPU architecture flags causing different optimization paths

Locale and timezone settings affecting sorting or formatting

Build Path Dependencies

Absolute paths embedded in debug symbols or error messages

Source directory location captured in compilation metadata

Build directory paths affecting relative path calculations

Username or hostname included in build metadata

Non-Deterministic Operations

Random number generation during build processes

Parallel builds with race conditions in file ordering

Hash map or set iteration with non-deterministic ordering

Filesystem directory listing order varying across systems

Dependency Issues

Floating dependency versions pulling different package versions

Transitive dependencies resolved differently over time

Mirror or CDN variations in downloaded dependencies

Solutions

To achieve reproducible builds, projects typically need to:

Strip timestamps or use fixed values

Normalize file ordering and permissions

Pin all dependency versions

Use consistent toolchain versions

Sanitize embedded paths