Add needs-git-hash header to compiletest

This header can be used for tests which check the output of `--version --verbose` commands.

src/bootstrap/test.rs

@@ -1804,6 +1804,10 @@ fn run(self, builder: &Builder<'_>) {
 
         cmd.arg("--channel").arg(&builder.config.channel);
 
+        if !builder.config.ignore_git {
+            cmd.arg("--git-hash");
+        }
+
         if let Some(commit) = builder.config.download_rustc_commit() {
             cmd.env("FAKE_DOWNLOAD_RUSTC_PREFIX", format!("/rustc/{commit}"));
         }

src/tools/compiletest/src/common.rs

@@ -303,6 +303,9 @@ pub struct Config {
     /// The current Rust channel
     pub channel: String,
 
+    /// Whether adding git commit information such as the commit hash has been enabled for building
+    pub git_hash: bool,
+
     /// The default Rust edition
     pub edition: Option<String>,
 

src/tools/compiletest/src/header/needs.rs

@@ -115,6 +115,11 @@ pub(super) fn handle_needs(
             condition: cache.x86_64_dlltool,
             ignore_reason: "ignored when dlltool for x86_64 is not present",
         },
+        Need {
+            name: "needs-git-hash",
+            condition: config.git_hash,
+            ignore_reason: "ignored when git hashes have been omitted for building",
+        },
     ];
 
     let (name, comment) = match ln.split_once([':', ' ']) {

src/tools/compiletest/src/header/tests.rs

@@ -251,6 +251,16 @@ fn debugger() {
     assert!(check_ignore(&config, "// ignore-lldb"));
 }
 
+#[test]
+fn git_hash() {
+    let mut config = config();
+    config.git_hash = false;
+    assert!(check_ignore(&config, "// needs-git-hash"));
+
+    config.git_hash = true;
+    assert!(!check_ignore(&config, "// needs-git-hash"));
+}
+
 #[test]
 fn sanitizers() {
     let mut config = config();

src/tools/compiletest/src/main.rs

@@ -159,6 +159,7 @@ pub fn parse_config(args: Vec<String>) -> Config {
         .optflag("", "nocapture", "")
         .optflag("h", "help", "show this message")
         .reqopt("", "channel", "current Rust channel", "CHANNEL")
+        .optflag("", "git-hash", "run tests which rely on commit version being compiled into the binaries")
         .optopt("", "edition", "default Rust edition", "EDITION");
 
     let (argv0, args_) = args.split_first().unwrap();
@@ -302,6 +303,7 @@ fn make_absolute(path: PathBuf) -> PathBuf {
         rustfix_coverage: matches.opt_present("rustfix-coverage"),
         has_tidy,
         channel: matches.opt_str("channel").unwrap(),
+        git_hash: matches.opt_present("git-hash"),
         edition: matches.opt_str("edition"),
 
         cc: matches.opt_str("cc").unwrap(),