From 8d093951eae76fe9cd1e9fa947d62c7338456279 Mon Sep 17 00:00:00 2001
From: Bryce Kwon <bryce@brycekwon.com>
Date: Sun, 6 Sep 2026 14:41:26 -1000
Subject: Report ignored config keys on stderr

---
 source/cgit.c         | 16 ++++++++++++----
 tests/t0205-config.sh | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+), 4 deletions(-)
 create mode 100755 tests/t0205-config.sh

diff --git a/source/cgit.c b/source/cgit.c
index 23521f5..730e2c6 100644
--- a/source/cgit.c
+++ b/source/cgit.c
@@ -695,6 +695,10 @@ static void apply_config(const char *name, const char *value)
 		add_mimetype(arg, value);
 	else if (!strcmp(name, "include"))
 		config_file_parse(cgit_expand_macros(value), apply_config);
+	else if (skip_prefix(name, "repo.", &arg))
+		fprintf(stderr, "[cgit] Ignoring %s before any repo.url\n", name);
+	else
+		fprintf(stderr, "[cgit] Unknown config key: %s\n", name);
 }
 
 /*
@@ -1223,16 +1227,20 @@ void cgit_repo_config(struct cgit_repo *repo, const char *name, const char *valu
 		repo->hide = atoi(value);
 	else if (!strcmp(name, "ignore"))
 		repo->ignore = atoi(value);
-	else if (ctx.cfg.enable_filter_overrides) {
-		if (!strcmp(name, "about-filter"))
+	else if (!strcmp(name, "about-filter") || !strcmp(name, "commit-filter") ||
+		 !strcmp(name, "source-filter") || !strcmp(name, "email-filter")) {
+		if (!ctx.cfg.enable_filter_overrides)
+			fprintf(stderr, "[cgit] Ignoring repo %s: enable-filter-overrides is not set\n", name);
+		else if (!strcmp(name, "about-filter"))
 			repo->about_filter = cgit_new_filter(value, ABOUT);
 		else if (!strcmp(name, "commit-filter"))
 			repo->commit_filter = cgit_new_filter(value, COMMIT);
 		else if (!strcmp(name, "source-filter"))
 			repo->source_filter = cgit_new_filter(value, SOURCE);
-		else if (!strcmp(name, "email-filter"))
+		else
 			repo->email_filter = cgit_new_filter(value, EMAIL);
-	}
+	} else
+		fprintf(stderr, "[cgit] Unknown repo config key: %s\n", name);
 }
 
 int cmd_main(int argc, const char **argv)
diff --git a/tests/t0205-config.sh b/tests/t0205-config.sh
new file mode 100755
index 0000000..a7d32f4
--- /dev/null
+++ b/tests/t0205-config.sh
@@ -0,0 +1,53 @@
+#!/bin/sh
+
+# Checks what the configuration parser reports on stderr. A key it does not
+# know, a repo key before any repository and a filter override without its
+# enabling flag are each ignored with a warning naming the key, and a config
+# cgit fully understands stays silent.
+
+test_description='Check configuration diagnostics'
+. ./setup.sh
+
+test_expect_success 'set up configs' '
+	{
+		echo "virtual-root=/" &&
+		echo "cache-size=0" &&
+		echo "no-such-key=1" &&
+		echo "repo.url=diag" &&
+		echo "repo.path=$PWD/repos/foo/.git" &&
+		echo "repo.no-such-repo-key=1"
+	} >diagrc &&
+	{
+		echo "virtual-root=/" &&
+		echo "cache-size=0" &&
+		echo "repo.desc=early" &&
+		echo "repo.url=diag" &&
+		echo "repo.path=$PWD/repos/foo/.git" &&
+		echo "repo.about-filter=exec:/bin/true"
+	} >earlyrc
+'
+
+test_expect_success 'unknown keys are reported and the page still renders' '
+	CGIT_CONFIG="$PWD/diagrc" QUERY_STRING="url=diag/" cgit >tmp 2>err &&
+	grep "Status: 200" tmp &&
+	grep "Unknown config key: no-such-key" err &&
+	grep "Unknown repo config key: no-such-repo-key" err
+'
+
+test_expect_success 'a repo key before any repo.url is reported' '
+	CGIT_CONFIG="$PWD/earlyrc" QUERY_STRING="url=diag/" cgit >tmp 2>err &&
+	grep "Status: 200" tmp &&
+	grep "Ignoring repo.desc before any repo.url" err
+'
+
+test_expect_success 'a filter override without its flag is reported' '
+	grep "Ignoring repo about-filter: enable-filter-overrides is not set" err
+'
+
+test_expect_success 'a fully understood config stays silent' '
+	cgit_url "foo/" >tmp 2>err &&
+	grep "Status: 200" tmp &&
+	! grep "\[cgit\]" err
+'
+
+test_done
-- 
cgit v2.8.0