@Zergling_man >if someone takes free software, compiles it, and gives you the result without telling you where it comes from, is it proprietary?
If they do not provide the source code in the same way when you ask, or they have included a written offer that they will follow through with, that is proprietary software - as if the user does not have the source code, they do not have freedoms 1, 2 & 3.

For copyleft licenses like the GPLv2 & GPLv3 such act is copyright infringement.

>If you then find where it comes from, compile it yourself and get hash match on the result, does it suddenly become free?
Yes, if you manage to find the complete corresponding source code yourself and manage to extract or guess the configuration and compile that into a corresponding binary (you are very unlikely to arrive at an exact hash due to compiler version differences etc, when it comes to compiling the same binary from the same sources, but that doesn't matter, as either executable functions identically), you have freedom again, as you have the 4 freedoms again.

But that is quite a stretch, as when people and businesses distribute GPLv2{+,-only} and/or GPLv3{+,-only} software, they typically apply a custom configuration or write their own build scripts and often make some patches, all of which you need to get a corresponding binary.

Alas, some businesses like dumping the original sources without including the build scripts and claim they are GPLv2-compliant, even though they do not comply with any of the below 3 crucial requirements; "The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the ****scripts**** used to control ****compilation**** and ****installation of the executable****. "

Of course, when you check the incomplete sources more carefully, you find that certain libraries have GPLv3 components that are enabled by default.