Add ability to ignore git when building rust.

Some users of the build system change the git sha on every build due to
utilizing git to push changes to a remote server. This allows them to
simply configure that away instead of depending on custom patches to
rustbuild.

Author: Mark-Simulacrum

src/bootstrap/channel.rs

@@ -21,6 +21,7 @@ use std::process::Command;
 use build_helper::output;
 
 use Build;
+use config::Config;
 
 // The version number
 pub const CFG_RELEASE_NUM: &str = "1.21.0";
@@ -41,9 +42,9 @@ struct Info {
 }
 
 impl GitInfo {
-    pub fn new(dir: &Path) -> GitInfo {
+    pub fn new(config: &Config, dir: &Path) -> GitInfo {
         // See if this even begins to look like a git dir
-        if !dir.join(".git").exists() {
+        if config.ignore_git || !dir.join(".git").exists() {
             return GitInfo { inner: None }
         }
 

src/bootstrap/config.rs

@@ -54,6 +54,7 @@ pub struct Config {
     pub extended: bool,
     pub sanitizers: bool,
     pub profiler: bool,
+    pub ignore_git: bool,
 
     pub on_fail: Option<String>,
     pub stage: Option<u32>,
@@ -258,6 +259,7 @@ struct Rust {
     optimize_tests: Option<bool>,
     debuginfo_tests: Option<bool>,
     codegen_tests: Option<bool>,
+    ignore_git: Option<bool>,
 }
 
 /// TOML representation of how each build target is configured.
@@ -289,6 +291,7 @@ impl Config {
         config.rust_codegen_units = 1;
         config.channel = "dev".to_string();
         config.codegen_tests = true;
+        config.ignore_git = false;
         config.rust_dist_src = true;
 
         config.on_fail = flags.on_fail;
@@ -406,6 +409,7 @@ impl Config {
             set(&mut config.use_jemalloc, rust.use_jemalloc);
             set(&mut config.backtrace, rust.backtrace);
             set(&mut config.channel, rust.channel.clone());
+            set(&mut config.ignore_git, rust.ignore_git);
             config.rustc_default_linker = rust.default_linker.clone();
             config.rustc_default_ar = rust.default_ar.clone();
             config.musl_root = rust.musl_root.clone().map(PathBuf::from);

src/bootstrap/config.toml.example

@@ -254,6 +254,9 @@
 # saying that the FileCheck executable is missing, you may want to disable this.
 #codegen-tests = true
 
+# Flag indicating whether git info will be retrieved from .git automatically.
+#ignore-git = false
+
 # =============================================================================
 # Options for specific targets
 #

src/bootstrap/lib.rs

@@ -299,9 +299,9 @@ impl Build {
             }
             None => false,
         };
-        let rust_info = channel::GitInfo::new(&src);
-        let cargo_info = channel::GitInfo::new(&src.join("src/tools/cargo"));
-        let rls_info = channel::GitInfo::new(&src.join("src/tools/rls"));
+        let rust_info = channel::GitInfo::new(&config, &src);
+        let cargo_info = channel::GitInfo::new(&config, &src.join("src/tools/cargo"));
+        let rls_info = channel::GitInfo::new(&config, &src.join("src/tools/rls"));
 
         Build {
             initial_rustc: config.initial_rustc.clone(),

src/bootstrap/tool.rs

@@ -109,7 +109,7 @@ impl Step for ToolBuild {
 
         cargo.env("CFG_RELEASE_CHANNEL", &build.config.channel);
 
-        let info = GitInfo::new(&dir);
+        let info = GitInfo::new(&build.config, &dir);
         if let Some(sha) = info.sha() {
             cargo.env("CFG_COMMIT_HASH", sha);
         }