Update to 0.15.19 and use threadsafe-setenv. (#23)

Cargo.toml

@@ -13,7 +13,7 @@ exclude = ["/.github", "ci"]
 keywords = ["linux"]
 
 [dependencies]
-c-gull = { version = "0.15.18", default-features = false, features = ["eyra"] }
+c-gull = { version = "0.15.19", default-features = false, features = ["eyra"] }
 
 [dev-dependencies]
 assert_cmd = "2.0.12"
@@ -33,11 +33,10 @@ which = "5.0.0"
 core_simd = { git = "https://github.com/rust-lang/portable-simd" }
 
 [features]
-default = ["be-std", "lock-environ"]
+default = ["be-std", "threadsafe-setenv"]
 
-# This enables use of an `RwLock` within `getenv`, `setenv`, and related
-# functions, to make them thread-safe.
-lock-environ = ["c-gull/lock-environ"]
+# This makes `setenv` and friends thread-safe by leaking memory.
+threadsafe-setenv = ["c-gull/threadsafe-setenv"]
 
 # Enable logging of program and thread startup and shutdown.
 log = ["c-gull/log"]

README.md

@@ -65,7 +65,7 @@ Other examples include
 Why use Eyra?
 
  - It fixes Rust's [`set_var` unsoundness issue]. The environment-variable
-   implementation uses an `RwLock` internally (it is optional, but enabled by
+   implementation leaks memory internally (it is optional, but enabled by
    default), so `setenv` etc. are thread-safe.
 
  - [Whole-program LTO], including the libc. This sometimes produces smaller