https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116198
Bug ID: 116198
Summary: Wdeprecated-enum-enum-conversion triggers inside
extern "C"
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: rsaxvc at gmail dot com
Target Milestone: ---
deprecated-enum-enum-conversion warnings apply to C code compiled by G++,
should they? I'm assuming if this code would not trigger a warning in C, it
shouldn't trigger a warning in extern "C". Here's a minimal contrived example:
#include <stdlib.h>
extern "C"{
enum {TWO = 2};
enum {ONE = 1};
void * triggerDeprecatedEnumConversion() {
return malloc(ONE | TWO);
}
}
When the above code is compiled with g++ 12.2.0, -Wall -Wextra -O2 -std=c++23,
triggers this warning:
<source>: In function 'void* triggerDeprecatedEnumConversion()':
<source>:17:27: warning: bitwise operation between different enumeration
types '<unnamed enum>' and '<unnamed enum>' is deprecated
[-Wdeprecated-enum-enum-conversion]
17 | return malloc(ONE | TWO);
| ~~~~^~~~~
One real-world use-case this impacts occurs in LVGL, which uses separate enums
for different parts of a bitfield that are then combined in functions in a
header, so every C++ file that includes those headers triggers this warning.
Related discussion here: https://github.com/lvgl/lvgl/issues/5119
Specific compiler version:
xtensa-esp32s3-elf-c++.exe (crosstool-NG esp-12.2.0_20230208) 12.2.0
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