diff --git a/read-cache.c b/read-cache.c
index 1ced8c630e..3c71c7d182 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -203,6 +203,19 @@ void fill_stat_cache_info(struct index_state *istate, struct cache_entry *ce, st
 	}
 }
 
+unsigned int ce_mode_from_stat(const struct cache_entry *ce, unsigned int mode)
+{
+	if (!has_symlinks && S_ISREG(mode) &&
+	    ce && S_ISLNK(ce->ce_mode))
+		return ce->ce_mode;
+	if (!trust_executable_bit && S_ISREG(mode)) {
+		if (ce && S_ISREG(ce->ce_mode))
+			return ce->ce_mode;
+		return create_ce_mode(0666);
+	}
+	return create_ce_mode(mode);
+}
+
 static unsigned int st_mode_from_ce(const struct cache_entry *ce)
 {
 	switch (ce->ce_mode & S_IFMT) {
diff --git a/read-cache.h b/read-cache.h
index 043da1f1aa..9088a0724a 100644
--- a/read-cache.h
+++ b/read-cache.h
@@ -5,20 +5,15 @@
 #include "object.h"
 #include "pathspec.h"
 
-static inline unsigned int ce_mode_from_stat(const struct cache_entry *ce,
-					     unsigned int mode)
-{
-	extern int trust_executable_bit, has_symlinks;
-	if (!has_symlinks && S_ISREG(mode) &&
-	    ce && S_ISLNK(ce->ce_mode))
-		return ce->ce_mode;
-	if (!trust_executable_bit && S_ISREG(mode)) {
-		if (ce && S_ISREG(ce->ce_mode))
-			return ce->ce_mode;
-		return create_ce_mode(0666);
-	}
-	return create_ce_mode(mode);
-}
+/*
+ * Determine the appropriate index mode for a file based on its stat()
+ * information and the existing cache entry (if any).
+ *
+ * This function handles degradation for filesystems that lack
+ * symlink support or reliable executable bits.
+ */
+unsigned int ce_mode_from_stat(const struct cache_entry *ce,
+				unsigned int mode);
 
 static inline int ce_to_dtype(const struct cache_entry *ce)
 {