https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86600
Bug ID: 86600
Summary: Class declaration in the same declarative region as
using declaration - Missing diagnostic message
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: zhonghao at pku dot org.cn
Target Milestone: ---
The following program should give a diagnostic message when trying to compile
it.
namespace X { class A; }
namespace Y { using X::A; class A {}; }
int main() {}
This is because it violates [basic.scope.declarative]/4 in the c++ standard:
http://eel.is/c++draft/basic.scope.declarative#4
The diagnostic message is missing. MSVS gives a diagnostic message for this
program, but clang does not.
Stack overflow post confirming the bug:
http://stackoverflow.com/questions/31220154/class-declaration-in-same-scope-as-using-declaration-compiles-in-gcc-but-not-msv
clang++ also gives an error message:
code0.cpp:3:27: error: declaration conflicts with target of using declaration
already in scope
namespace Y { using X::A; class A {}; }
^
code0.c.cpp:1:21: note: target of using declaration
namespace X { class A; }
^
code0.c.cpp:3:24: note: using declaration
namespace Y { using X::A; class A {}; }
^
1 error generated.
