feat(lib): add usage-rs facade

.github/workflows/test.yml

@@ -89,7 +89,7 @@ jobs:
       matrix:
         include:
           - version: "1.91"
-            crates: usage-argv usage-derive usage-config
+            crates: usage-argv usage-derive usage-config usage-rs
           - version: "1.95"
             crates: usage-lib usage-config-build clap_usage usage-cli
     steps:

Cargo.toml

@@ -5,6 +5,7 @@ members = [
     "config",
     "config-build",
     "derive",
+    "usage-rs",
     "clap_usage",
     "cli",
     "conformance",
@@ -33,6 +34,7 @@ usage-argv = { path = "./argv", version = "5.1.0" }
 usage-config = { path = "./config", version = "5.1.0" }
 usage-derive = { path = "./derive", version = "5.1.0" }
 usage-lib = { path = "./lib", version = "5.1.0", features = ["clap"] }
+usage-rs = { path = "./usage-rs", version = "5.1.0" }
 
 [workspace.metadata.release]
 allow-branch = ["main"]

derive/Cargo.toml

@@ -19,6 +19,7 @@ release = true
 
 [dependencies]
 proc-macro2 = "1"
+proc-macro-crate = "3"
 quote = "1"
 # syn 2 rather than 3, which is already in the tree via clap_derive: nothing here
 # needs the newer API, and matching what is there avoids a second copy.