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I'm a bit new to Rust and ran into an issue where I'd like to make a feature of my crate that designates which features of a dependent crate should be included.

More specifically, I'm using the image-rs crate, which defines features for which image formats the library should support.

I'd like to have a feature of my crate that specifies to compile additional image format features of the image-rs crate. For example:

# Cargo.toml
[dependencies]
image = { version = "^0.23.6", features = ["png", "jpeg"] }

[features]
# I dont know the syntax to include image in my feature with specific image crate featres.
extra-image-formats = [ "image {features = [jpeg, png, gif, webp]}" ]

Is this supported? It would be nice; I hoped to have the default include commonly used image formats from the image-rs crate, but opt-in for more image formats (at the cost of a larger binary and longer compile due to all the extra decoders and encoders).

Thanks in advance!

catleeball
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1 Answers1

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As described in the cargo book, you can use crate/feature to refer to features of dependencies. Your example would therefore look like this:

# Cargo.toml
[dependencies]
image = { version = "^0.23.6", features = ["png", "jpeg"] }

[features]
extra-image-formats = [ "image/jpeg", "image/png", "image/gif", "image/webp" ]
apetranzilla
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  • Thanks! I think I misunderstood that initially, I wasn't sure what it meant by reexport, but it makes sense now. – catleeball Jul 18 '20 at 19:45