fftools/ffprobe: Use proper enum type

This is a bit cleaner as int need not be the underlying type
of an enum if a smaller type can hold all its values.
Also declare the children_ids array as const as it never changes.

Reviewed-by: Stefano Sabatini <stefasab@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

fftools/ffprobe.c

@@ -161,22 +161,6 @@ static int find_stream_info  = 1;
 
 #define SECTION_MAX_NB_CHILDREN 10
 
-struct section {
-    int id;             ///< unique id identifying a section
-    const char *name;
-
-#define SECTION_FLAG_IS_WRAPPER      1 ///< the section only contains other sections, but has no data at its own level
-#define SECTION_FLAG_IS_ARRAY        2 ///< the section contains an array of elements of the same type
-#define SECTION_FLAG_HAS_VARIABLE_FIELDS 4 ///< the section may contain a variable number of fields with variable keys.
-                                           ///  For these sections the element_name field is mandatory.
-    int flags;
-    int children_ids[SECTION_MAX_NB_CHILDREN+1]; ///< list of children section IDS, terminated by -1
-    const char *element_name; ///< name of the contained element, if provided
-    const char *unique_name;  ///< unique section name, in case the name is ambiguous
-    AVDictionary *entries_to_show;
-    int show_all_entries;
-};
-
 typedef enum {
     SECTION_ID_NONE = -1,
     SECTION_ID_CHAPTER,
@@ -229,6 +213,22 @@ typedef enum {
     SECTION_ID_SUBTITLE,
 } SectionID;
 
+struct section {
+    int id;             ///< unique id identifying a section
+    const char *name;
+
+#define SECTION_FLAG_IS_WRAPPER      1 ///< the section only contains other sections, but has no data at its own level
+#define SECTION_FLAG_IS_ARRAY        2 ///< the section contains an array of elements of the same type
+#define SECTION_FLAG_HAS_VARIABLE_FIELDS 4 ///< the section may contain a variable number of fields with variable keys.
+                                           ///  For these sections the element_name field is mandatory.
+    int flags;
+    const SectionID children_ids[SECTION_MAX_NB_CHILDREN+1]; ///< list of children section IDS, terminated by -1
+    const char *element_name; ///< name of the contained element, if provided
+    const char *unique_name;  ///< unique section name, in case the name is ambiguous
+    AVDictionary *entries_to_show;
+    int show_all_entries;
+};
+
 static struct section sections[] = {
     [SECTION_ID_CHAPTERS] =           { SECTION_ID_CHAPTERS, "chapters", SECTION_FLAG_IS_ARRAY, { SECTION_ID_CHAPTER, -1 } },
     [SECTION_ID_CHAPTER] =            { SECTION_ID_CHAPTER, "chapter", 0, { SECTION_ID_CHAPTER_TAGS, -1 } },
@@ -3688,8 +3688,7 @@ static inline void mark_section_show_entries(SectionID section_id,
 
     section->show_all_entries = show_all_entries;
     if (show_all_entries) {
-        SectionID *id;
-        for (id = section->children_ids; *id != -1; id++)
+        for (const SectionID *id = section->children_ids; *id != -1; id++)
             mark_section_show_entries(*id, show_all_entries, entries);
     } else {
         av_dict_copy(&section->entries_to_show, entries, 0);
@@ -4072,11 +4071,10 @@ static const OptionDef real_options[] = {
 
 static inline int check_section_show_entries(int section_id)
 {
-    int *id;
     struct section *section = &sections[section_id];
     if (sections[section_id].show_all_entries || sections[section_id].entries_to_show)
         return 1;
-    for (id = section->children_ids; *id != -1; id++)
+    for (const SectionID *id = section->children_ids; *id != -1; id++)
         if (check_section_show_entries(*id))
             return 1;
     return 0;