add explicit stage fields to Config

Signed-off-by: onur-ozkan <work@onurozkan.dev>

src/bootstrap/src/core/config/config.rs

@@ -218,6 +218,8 @@ pub struct Config {
     pub stderr_is_tty: bool,
 
     pub on_fail: Option<String>,
+    pub explicit_stage_from_cli: bool,
+    pub explicit_stage_from_config: bool,
     pub stage: u32,
     pub keep_stage: Vec<u32>,
     pub keep_stage_std: Vec<u32>,
@@ -2323,6 +2325,14 @@ impl Config {
         config.compiletest_diff_tool = compiletest_diff_tool;
 
         let download_rustc = config.download_rustc_commit.is_some();
+        config.explicit_stage_from_cli = flags.stage.is_some();
+        config.explicit_stage_from_config = test_stage.is_some()
+            || build_stage.is_some()
+            || doc_stage.is_some()
+            || dist_stage.is_some()
+            || install_stage.is_some()
+            || check_stage.is_some()
+            || bench_stage.is_some();
         // See https://github.com/rust-lang/compiler-team/issues/326
         config.stage = match config.cmd {
             Subcommand::Check { .. } => flags.stage.or(check_stage).unwrap_or(0),