https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114218
Bug ID: 114218
Summary: -Wdr could show constant values
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: sjames at gcc dot gnu.org
Target Milestone: ---
It'd be a nice UX improvement if -Wodr showed the differing constant values
rather than just the identifier.
(This came up in the wild https://github.com/alsaplayer/alsaplayer/issues/28).
a.h:
```
#ifndef MAGIC_NUMBER
#define MAGIC_NUMBER 42
#endif
struct number_storage {
int MY_NUMBERS[MAGIC_NUMBER];
};
```
b.cxx:
```
#include "a.h"
struct number_storage collection_1;
```
c.cxx
```
#define MAGIC_NUMBER 100
#include "a.h"
struct number_storage collection_2;
int main() {
}
```
```
$ g++ b.cxx c.cxx -Wall -Wextra -flto
a.h:5:8: warning: type ‘struct number_storage’ violates the C++ One Definition
Rule [-Wodr]
5 | struct number_storage {
| ^
a.h:5:8: note: a different type is defined in another translation unit
5 | struct number_storage {
| ^
a.h:6:13: note: the first difference of corresponding definitions is field
‘MY_NUMBERS’
6 | int MY_NUMBERS[MAGIC_NUMBER];
| ^
a.h:6:13: note: a field of same name but different type is defined in another
translation unit
6 | int MY_NUMBERS[MAGIC_NUMBER];
| ^
a.h:5:8: note: array types have different bounds
5 | struct number_storage {
| ^
```
