[vcpkg|binarycache] don't use triplet file hash. Hash variables instead.

[Neumann-A]

So I have a a custom triplet with per port customization and this is a problem for the binary cache since if I add a new customization everything will be invalidated, removed and rebuild although only one port was effectively changed.

I thus suggest: Instead of using the file hash of the triplet to determine the hash for the binary cache it would be better to get the variables set by the triplet and use those to define the triplet hash for a port. Since the triplet is already read numerous times for compiler hash checks it shouldn't add a lot of additional overhead.

This would greatly improve my workflow if I have to touch the triplet file.

[ras0219-msft]

This will also need to detect changes to environment variables and I'm not sure how to make

set(ENV{PATH} "$ENV{PATH}:$ENV{SOME_BASE_DIR}/magic")

machine independent without hashing the source code.

[dg0yt]

This will also need to detect changes to environment variables ...

I'm not sure if it is always desired to detect particular changes to environment variables. And even with hashing the source, you don't hash the contents of the $ENV{SOME_BASE_DIR} input.

How about a triplet revision variable (not replacing the hash, but as an input)? It might even be overridden per port...

[autoantwort]

This will also need to detect changes to environment variables and I'm not sure how to make

set(ENV{PATH} "$ENV{PATH}:$ENV{SOME_BASE_DIR}/magic")

machine independent without hashing the source code.

The question is if you always want this. Maybe one changes the env var SOME_BASE_DIR to switch between versions of something, then you want different hashes. Maybe we should add something like set(VCPKG_IGNORE_FOR_HASH "$ENV{SOME_BASE_DIR}") so that the value(s) of VCPKG_IGNORE_FOR_HASH are removed from the value of every variable so that they are not included in the hash.
Or we don't include ENV variables in the hash. If you want to include a value of the env to be hashed you have to set a local variable to the value.

[Neumann-A]

@JackBoosY Why did you mark this as requires:repro?

[autoantwort]

@Neumann-A If you use a selfcompiled vcpkg-tool you can now use microsoft/vcpkg-tool#596

[Osyotr]

Maybe teach VCPKG to also include port-settings/triplet-name.port-name.cmake and hash its content too?

[DownerCase]

Ran into this the other day, added a customization for a single port and was sad to see the world rebuild. Ended up copying the port to be an overlay port instead, which is a rather less ergonomic...

[Neumann-A]

I think nowadays you could solve it with an if checking if a per port customization file exists and VCPKG_HASH_ADDITIONAL_FILES. Of course inserting that logic requires a world rebuild once to introduce the logic.

[redbaron]

@Neumann-A ,

solve it with an if checking if a per port customization file exists

do you propose triplets to implicitly include per-port customisation files ?

[Neumann-A]

@Neumann-A ,

solve it with an if checking if a per port customization file exists

do you propose triplets to implicitly include per-port customisation files ?

Yes and then explicitly add that file to the hash for that port.