Switch to git-testament rather than old build.rs

Rather than the previous not-very-informative version string
which was generated by build.rs and then not updated unless
build.rs was touched, use the new `git-testament` crate which
does a more complete job at compile time via a proc-macro.

Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

Cargo.toml

@@ -16,8 +16,6 @@ keywords = ["rustup", "multirust", "install", "proxy"]
 
 license = "MIT OR Apache-2.0"
 
-build = "build.rs"
-
 [features]
 
 default = ["curl-backend", "reqwest-backend"]
@@ -51,6 +49,8 @@ toml = "0.4"
 url = "1.1.0"
 wait-timeout = "0.1.5"
 openssl = { version = '0.10.15', optional = true }
+git-testament = { git = "https://github.com/kinnison/git-testament" }
+lazy_static = "1.0.0"
 
 [target."cfg(windows)".dependencies]
 winapi = { version = "0.3", features = ["jobapi", "jobapi2", "processthreadsapi", "psapi", "synchapi", "winuser"] }

src/rustup-cli/common.rs

@@ -3,6 +3,8 @@
 use crate::errors::*;
 use crate::self_update;
 use crate::term2;
+use git_testament::git_testament;
+use lazy_static::lazy_static;
 use rustup::{Cfg, Notification, Toolchain, UpdateStatus};
 use rustup_utils::notify::NotificationLevel;
 use rustup_utils::utils;
@@ -402,11 +404,22 @@ pub fn list_overrides(cfg: &Cfg) -> Result<()> {
     Ok(())
 }
 
+git_testament!(TESTAMENT);
+
+lazy_static! {
+    static ref VERSION_STRING: String = {
+        let testament_string = format!("{}", TESTAMENT);
+        let pkg_version = env!("CARGO_PKG_VERSION");
+        if &testament_string[..pkg_version.len()] == pkg_version {
+            testament_string
+        } else {
+            format!("{} really {}", pkg_version, testament_string)
+        }
+    };
+}
+
 pub fn version() -> &'static str {
-    concat!(
-        env!("CARGO_PKG_VERSION"),
-        include_str!(concat!(env!("OUT_DIR"), "/commit-info.txt"))
-    )
+    VERSION_STRING.as_ref()
 }
 
 pub fn report_error(e: &Error) {