Add --no-capture as a bootstrap argument

src/bootstrap/src/core/build_steps/test.rs

@@ -1829,6 +1829,10 @@ NOTE: if you're sure you want to do this, please open an issue as to why. In the
             cmd.arg("--force-rerun");
         }
 
+        if builder.config.cmd.no_capture() {
+            cmd.arg("--nocapture");
+        }
+
         let compare_mode =
             builder.config.cmd.compare_mode().or_else(|| {
                 if builder.config.test_compare_mode { self.compare_mode } else { None }

src/bootstrap/src/core/builder/tests.rs

@@ -637,6 +637,7 @@ mod dist {
             run: None,
             only_modified: false,
             extra_checks: None,
+            no_capture: false,
         };
 
         let build = Build::new(config);
@@ -702,6 +703,7 @@ mod dist {
             run: None,
             only_modified: false,
             extra_checks: None,
+            no_capture: false,
         };
         // Make sure rustfmt binary not being found isn't an error.
         config.channel = "beta".to_string();

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

@@ -388,6 +388,9 @@ pub enum Subcommand {
         /// enable this to generate a Rustfix coverage file, which is saved in
         /// `/<build_base>/rustfix_missing_coverage.txt`
         rustfix_coverage: bool,
+        #[arg(long)]
+        /// don't capture stdout/stderr of tests
+        no_capture: bool,
     },
     /// Build and run some test suites *in Miri*
     Miri {
@@ -563,6 +566,13 @@ impl Subcommand {
         }
     }
 
+    pub fn no_capture(&self) -> bool {
+        match *self {
+            Subcommand::Test { no_capture, .. } => no_capture,
+            _ => false,
+        }
+    }
+
     pub fn rustfix_coverage(&self) -> bool {
         match *self {
             Subcommand::Test { rustfix_coverage, .. } => rustfix_coverage,