https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95871
Bug ID: 95871
Summary: Duplicated error message : "the value is not usable in
a constant expression"
Product: gcc
Version: 11.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: haoxintu at gmail dot com
CC: mpolacek at gcc dot gnu.org
Target Milestone: ---
This code, bug.cc, GCC emits two duplicated error messages in "the value of ‘a’
is not usable in a constant expression".
$cat bug.cc
long a = 10;
enum E { emator_1 = a } enum_var;
$g++ -c bug.cc
bug.cc:2:21: error: the value of ‘a’ is not usable in a constant expression
2 | enum E { emator_1 = a } enum_var;
| ^
bug.cc:1:6: note: ‘long int a’ is not const
1 | long a = 10;
| ^
bug.cc:2:21: error: the value of ‘a’ is not usable in a constant expression
2 | enum E { emator_1 = a } enum_var;
| ^
bug.cc:1:6: note: ‘long int a’ is not const
1 | long a = 10;
| ^
bug.cc:2:21: error: enumerator value for ‘emator_1’ is not an integer constant
2 | enum E { emator_1 = a } enum_var;
|
While in clang
$clang++ -c bug.cc
bug.cc:2:21: error: expression is not an integral constant expression
enum E { emator_1 = a } enum_var;
^
bug.cc:2:21: note: read of non-const variable 'a' is not allowed in a constant
expression
bug.cc:1:6: note: declared here
long a = 10;
^
1 error generated.
I have tested in almost all GCC versions, they all have this issue.
