Reimplement git version generation ourselves

This allows us to remove two dependency crates

Cargo.toml

@@ -34,7 +34,6 @@ num-traits = "0.2.15"
 once_cell = "1.17.0"
 rand = { version = "0.8.5", features = ["small_rng"] }
 widestring = "1.0.2"
-git-version = "0.3"
 terminfo = { git = "https://github.com/meh/rust-terminfo", rev = "870327dd79beaecf50db09a15931d5ee1de2a24d" }
 
 [dev-dependencies]

build.rs

@@ -24,6 +24,8 @@ fn main() {
             .unwrap(),
     );
 
+    rsconf::set_env_value("FISH_BUILD_VERSION", &get_version(build_dir));
+
     rsconf::rebuild_if_path_changed("src/libc.c");
     cc::Build::new()
         .file("src/libc.c")
@@ -193,3 +195,27 @@ fn setup_paths() {
     rsconf::set_env_value("DOCDIR", docdir.to_str().unwrap());
     rsconf::rebuild_if_env_changed("DOCDIR");
 }
+
+fn get_version(build_dir: &str) -> String {
+    use std::fs::read_to_string;
+    use std::process::Command;
+
+    if let Ok(var) = std::env::var("FISH_BUILD_VERSION") {
+        return var;
+    }
+
+    let path = PathBuf::from(build_dir).join("version");
+    if let Ok(strver) = read_to_string(path) {
+        return strver.to_string();
+    }
+
+    let args = &["describe", "--always", "--dirty=-dirty"];
+    if let Ok(output) = Command::new("git").args(args).output() {
+        let rev = String::from_utf8_lossy(&output.stdout).trim().to_string();
+        if !rev.is_empty() {
+            return rev;
+        }
+    }
+
+    "unknown".to_string()
+}

src/lib.rs

@@ -22,10 +22,7 @@
 #![allow(clippy::too_many_arguments)]
 #![allow(clippy::uninlined_format_args)]
 
-pub const BUILD_VERSION: &str = match option_env!("FISH_BUILD_VERSION") {
-    Some(v) => v,
-    None => git_version::git_version!(args = ["--always", "--dirty=-dirty"], fallback = "unknown"),
-};
+pub const BUILD_VERSION: &str = env!("FISH_BUILD_VERSION");
 
 #[macro_use]
 pub mod common;