If you want certainty you'd use Reproducible Builds and know for sure which compiler generates this binary from the given source code. This assumes the code is

If you want certainty you'd use Reproducible Builds and know for sure which compiler generates this binary from the given source code. This assumes the code is open source, you know which specific source code release was used and the author of the binary is making an effort to document the build environment that was used, e.g. through an attached SBOM.