[PATCH v2] checkkconfigsymbols: resolve revisions before resetting the tree

[Erkan Erdem]

The commit comparison resets the current branch to commit_a before
resolving commit_b. If the second revision is HEAD or the current branch
name, it then resolves to the first revision. For example, --diff
HEAD^..HEAD compares the parent with itself and silently misses newly
undefined symbols. The same problem affects --commit with the current
branch name.

Resolve and verify both revisions as commits before the first reset.
This keeps their meaning stable throughout the comparison and rejects
invalid endpoints before changing the working tree.

Keep lookup diagnostics separate from the resolved hashes. Use the
resolved range for --find too, since resetting also updates ORIG_HEAD.

Fixes: b1a3f243485f ("checkkconfigsymbols.py: make it Git aware")
Link: https://lore.kernel.org/20210901145212.478066-1-arielmarcovitch@xxxxxxxxx/
Assisted-by: LLM
Signed-off-by: Erkan Erdem <hexvalid@xxxxxxxxx>
---

Changes in v2, addressing Julian Braha's review:
- Submit this fix independently of the unrelated Kconfig input fix.
- No code changes from v1.
- Include the original Git-awareness author and contributors to the
  previous HEAD-reference fix in Cc.

v1: https://lore.kernel.org/all/20260905123237.40670-2-hexvalid@xxxxxxxxx/

An AI coding assistant found the issue, prepared the fix and changelog,
and ran the original verification. The same assistant prepared this
standalone v2 submission.

Validation:
- The code is unchanged from v1, which passed 15 actual-CLI cases in
  disposable Git repositories, including HEAD-relative ranges, branch
  names, hashes, tags, annotated tags, ambiguous names, --commit,
  --find, ORIG_HEAD and invalid or non-commit endpoints.
- Those checks verified HEAD, current branch, index and tracked file
  contents after every invocation.
- The script in mainline df2908090cda368b01ff43709f51890076c56157 still
  matches the original pre-fix file; this patch applies independently.

 scripts/checkkconfigsymbols.py | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/scripts/checkkconfigsymbols.py b/scripts/checkkconfigsymbols.py
index 36c920e71..e0a1a631b 100755
--- a/scripts/checkkconfigsymbols.py
+++ b/scripts/checkkconfigsymbols.py
@@ -150,6 +150,13 @@ def print_undefined_symbols():
             undefined_a = {}
             undefined_b = {}
 
+        commit_a = execute(["git", "rev-parse", "--verify", commit_a + "^{commit}"],
+                           stderr=None).strip()
+        commit_b = execute(["git", "rev-parse", "--verify", commit_b + "^{commit}"],
+                           stderr=None).strip()
+        if args.diff:
+            args.diff = commit_a + ".." + commit_b
+
         # get undefined items before the commit
         reset(commit_a)
         undefined_a, _ = check_symbols(args.ignore)
@@ -223,10 +230,10 @@ def red(string):
     return "\033[31m%s\033[0m" % string if COLOR else string
 
 
-def execute(cmd):
+def execute(cmd, stderr=subprocess.STDOUT):
     """Execute %cmd and return stdout.  Exit in case of error."""
     try:
-        stdout = subprocess.check_output(cmd, stderr=subprocess.STDOUT, shell=False)
+        stdout = subprocess.check_output(cmd, stderr=stderr, shell=False)
         stdout = stdout.decode(errors='replace')
     except subprocess.CalledProcessError as fail:
         exit(fail)

base-commit: 4d7d9486c04d917265f64c55bd23b2cc4fe7749c
-- 
2.50.1 (Apple Git-155)