now test-cargo-miri will actually work even without a hot cache :D

cargo-miri/bin.rs

@@ -510,7 +510,9 @@ path = "lib.rs"
         if only_setup {
             show_error(format!("failed to run xargo, see error details above"))
         } else {
-            show_error(format!("failed to run xargo; run `cargo miri setup` to see the error details"))
+            show_error(format!(
+                "failed to run xargo; run `cargo miri setup` to see the error details"
+            ))
         }
     }
     if !only_setup {

ci.sh

@@ -21,6 +21,7 @@ function run_tests {
     echo "Testing host architecture"
   fi
 
+  ## ui test suite
   ./miri test --locked
   if [ -z "${MIRI_TEST_TARGET+exists}" ]; then
     # Only for host architecture: tests with optimizations (`-O` is what cargo passes, but crank MIR
@@ -30,15 +31,13 @@ function run_tests {
     MIRIFLAGS="-O -Zmir-opt-level=4" MIRI_SKIP_UI_CHECKS=1 ./miri test --locked -- tests/{pass,panic}
   fi
 
+  ## test-cargo-miri
   # On Windows, there is always "python", not "python3" or "python2".
   if command -v python3 > /dev/null; then
     PYTHON=python3
   else
     PYTHON=python
   fi
-
-  # "miri test" has built the sysroot for us, now this should pass without
-  # any interactive questions.
   ${PYTHON} test-cargo-miri/run-test.py
   echo
 

test-cargo-miri/run-test.py

@@ -25,7 +25,12 @@ def cargo_miri(cmd, quiet = True):
 
 def normalize_stdout(str):
     str = str.replace("src\\", "src/") # normalize paths across platforms
-    return re.sub("finished in \d+\.\d\ds", "finished in $TIME", str)
+    str = re.sub("finished in \d+\.\d\ds", "finished in $TIME", str) # the time keeps changing, obviously
+    return str
+
+def normalize_stderr(str):
+    str = str.replace("Preparing a sysroot for Miri... done\n", "") # remove leading cargo-miri setup output
+    return str
 
 def check_output(actual, path, name):
     expected = open(path).read()
@@ -51,9 +56,8 @@ def test(name, cmd, stdout_ref, stderr_ref, stdin=b'', env={}):
         env=p_env,
     )
     (stdout, stderr) = p.communicate(input=stdin)
-    stdout = stdout.decode("UTF-8")
-    stderr = stderr.decode("UTF-8")
-    stdout = normalize_stdout(stdout)
+    stdout = normalize_stdout(stdout.decode("UTF-8"))
+    stderr = normalize_stderr(stderr.decode("UTF-8"))
 
     stdout_matches = check_output(stdout, stdout_ref, "stdout")
     stderr_matches = check_output(stderr, stderr_ref, "stderr")
@@ -175,10 +179,6 @@ os.environ["RUST_TEST_THREADS"] = "1" # avoid non-deterministic output due to co
 target_str = " for target {}".format(os.environ['MIRI_TEST_TARGET']) if 'MIRI_TEST_TARGET' in os.environ else ""
 print(CGREEN + CBOLD + "## Running `cargo miri` tests{}".format(target_str) + CEND)
 
-if not 'MIRI_SYSROOT' in os.environ:
-    # Make sure we got a working sysroot.
-    # (If the sysroot gets built later when output is compared, that leads to test failures.)
-    subprocess.run(cargo_miri("setup"), check=True)
 test_cargo_miri_run()
 test_cargo_miri_test()
 # Ensure we did not create anything outside the expected target dir.