Disable bzip2-sys build script if rust backend is enabled (#125)

* Disable bzip2-sys build script if rust backend is enabled

Currently if one is to enable rust backend without disabling
default features, the bzip2-sys build script would build the
bzip2 again, making it meaningless to enable the feature.

In many cases disabling default-features is hard (breaking
backwards compatibility), so it'd be better to disable the
bzip2-sys bulid-script, if the rust backend is enabled'

It would still pull in cc-rs and pkg-config, but at least
it won't compile the bzip2 c code again.'

Signed-off-by: Jiahao XU <[email protected]>

* Disable bzip2-sys build script if rust backend is enabled

Currently if one is to enable rust backend without disabling
default features, the bzip2-sys build script would build the
bzip2 again, making it meaningless to enable the feature.

In many cases disabling default-features is hard (breaking
backwards compatibility), so it'd be better to disable the
bzip2-sys bulid-script, if the rust backend is enabled'

It would still pull in cc-rs and pkg-config, but at least
it won't compile the bzip2 c code again.'

Signed-off-by: Jiahao XU <[email protected]>

* Disable bzip2-sys build script if rust backend is enabled

Currently if one is to enable rust backend without disabling
default features, the bzip2-sys build script would build the
bzip2 again, making it meaningless to enable the feature.

In many cases disabling default-features is hard (breaking
backwards compatibility), so it'd be better to disable the
bzip2-sys bulid-script, if the rust backend is enabled'

It would still pull in cc-rs and pkg-config, but at least
it won't compile the bzip2 c code again.'

Signed-off-by: Jiahao XU <[email protected]>

---------

Signed-off-by: Jiahao XU <[email protected]>

Author: NobodyXu

Cargo.toml

@@ -22,10 +22,10 @@ publish = true
 bzip2-sys = { version = "0.1.11", path = "bzip2-sys", optional = true }
 
 [dependencies.libbz2-rs-sys]
-version = "0.1.1"
+version = "0.1.3"
 # Don't enable the stdio feature for better portability.
 default-features = false
-features = ["rust-allocator"]
+features = ["rust-allocator", "semver-prefix"]
 optional = true
 
 [dev-dependencies]
@@ -37,7 +37,7 @@ quickcheck = "1.0"
 default = ["dep:bzip2-sys"]
 # Use the pure rust `libbz2-rs-sys` instead of the C FFI bindings of `bzip2-sys`
 # The rust bzip2 implementation is always statically linked.
-libbz2-rs-sys = ["dep:libbz2-rs-sys"]
+libbz2-rs-sys = ["dep:libbz2-rs-sys", "bzip2-sys?/__disabled"]
 # Always build `libbz2` from C source, and statically link it.
 # This flag is only meaningful when `bzip2-sys` is used,
 # and has no effect when `libbz2-rs-sys` is used as the bzip2 implementation.

bzip2-sys/Cargo.toml

@@ -28,3 +28,4 @@ cc = "1.0"
 [features]
 # Enable this feature if you want to have a statically linked bzip2
 static = []
+__disabled = []

bzip2-sys/build.rs

@@ -5,6 +5,11 @@ use std::path::PathBuf;
 use std::{env, fs};
 
 fn main() {
+    // skip building the C library when libbzip2-rs is also used
+    if cfg!(feature = "__disabled") {
+        return;
+    }
+
     let mut cfg = cc::Build::new();
     let target = env::var("TARGET").unwrap();
     cfg.warnings(false);