Updated freshness on several docs, and made some minor updates to the content.
PiperOrigin-RevId: 604993985
diff --git a/docs/upb/style-guide.md b/docs/upb/style-guide.md
index e02571b..9aa09ae 100644
--- a/docs/upb/style-guide.md
+++ b/docs/upb/style-guide.md
@@ -2,7 +2,7 @@
<!--*
# Document freshness: For more information, see go/fresh-source.
-freshness: { owner: 'haberman' reviewed: '2022-05-08' }
+freshness: { owner: 'haberman' reviewed: '2024-02-05' }
*-->
Since upb is written in pure C, we supplement the
@@ -47,19 +47,31 @@
### Private Functions and Members
-Since we do not have `private` in C++, we use a leading underscore convention
-to mark internal functions and variables that should only be accessed from
-upb:
+Since we do not have `private` in C++, we use the `UPB_PRIVATE()` macro to mark
+internal functions and variables that should only be accessed from upb:
```c++
// Internal-only function.
-int64_t _upb_Int64_FromLL();
+int64_t UPB_PRIVATE(upb_Int64_FromLL)();
// Internal-only members. Underscore prefixes are only necessary when the
// structure is defined in a header file.
typedef struct {
- const int32_t* _values; // List of values <0 or >63
- uint64_t _mask; // Bits are set for acceptable value 0 <= x < 64
- int _value_count;
+ const int32_t* UPB_PRIVATE(values);
+ uint64_t UPB_PRIVATE(mask);
+ int UPB_PRIVATE(value_count);
} upb_MiniTableEnum;
+
+// Using these members in an internal function.
+int upb_SomeFunction(const upb_MiniTableEnum* e) {
+ return e->UPB_PRIVATE(value_count);
+}
```
+
+This prevents users from accessing these symbols, because `UPB_PRIVATE()`
+is defined in `port_def.inc` and undefined in `port_undef.inc`, and these
+textual headers are not accessible by users.
+
+It is only necessary to use `UPB_PRIVATE()` for things defined in headers.
+For symbols in `.c` files, it is sufficient to mark private functions with
+`static`.
