lint: Move commit range printing to test_runner

Having a single test_runner for all logic improves the consistency and
UX.

Author: MarcoFalke

ci/lint/06_script.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 #
-# Copyright (c) 2018-2022 The Bitcoin Core developers
+# Copyright (c) 2018-present The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -9,22 +9,13 @@ export LC_ALL=C
 set -ex
 
 if [ -n "$CIRRUS_PR" ]; then
-  COMMIT_RANGE="HEAD~..HEAD"
+  export COMMIT_RANGE="HEAD~..HEAD"
   if [ "$(git rev-list -1 HEAD)" != "$(git rev-list -1 --merges HEAD)" ]; then
     echo "Error: The top commit must be a merge commit, usually the remote 'pull/${PR_NUMBER}/merge' branch."
     false
   fi
-else
-  # Otherwise, assume that a merge commit exists. This merge commit is assumed
-  # to be the base, after which linting will be done. If the merge commit is
-  # HEAD, the range will be empty.
-  COMMIT_RANGE="$( git rev-list --max-count=1 --merges HEAD )..HEAD"
 fi
-export COMMIT_RANGE
 
-echo
-git log --no-merges --oneline "$COMMIT_RANGE"
-echo
 RUST_BACKTRACE=1 "${LINT_RUNNER_PATH}/test_runner"
 
 if [ "$CIRRUS_REPO_FULL_NAME" = "bitcoin/bitcoin" ] && [ "$CIRRUS_PR" = "" ] ; then

test/lint/test_runner/src/main.rs

@@ -180,7 +180,17 @@ fn get_git_root() -> PathBuf {
 
 /// Return the commit range, or panic
 fn commit_range() -> String {
-    env::var("COMMIT_RANGE").unwrap()
+    // Use the env var, if set. E.g. COMMIT_RANGE='HEAD~n..HEAD' for the last 'n' commits.
+    env::var("COMMIT_RANGE").unwrap_or_else(|_| {
+        // Otherwise, assume that a merge commit exists. This merge commit is assumed
+        // to be the base, after which linting will be done. If the merge commit is
+        // HEAD, the range will be empty.
+        format!(
+            "{}..HEAD",
+            check_output(git().args(["rev-list", "--max-count=1", "--merges", "HEAD"]))
+                .expect("check_output failed")
+        )
+    })
 }
 
 /// Return all subtree paths
@@ -673,6 +683,10 @@ fn main() -> ExitCode {
     };
 
     let git_root = get_git_root();
+    let commit_range = commit_range();
+    let commit_log = check_output(git().args(["log", "--no-merges", "--oneline", &commit_range]))
+        .expect("check_output failed");
+    println!("Checking commit range ({commit_range}):\n{commit_log}\n");
 
     let mut test_failed = false;
     for linter in linters_to_run {