https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101524
Bug ID: 101524
Summary: Improve diagnostic for incorrect definition of
namespace alias
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: diagnostic
Severity: enhancement
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: redi at gcc dot gnu.org
Target Milestone: ---
This is an incorrect attempt to define a namespace alias:
namespace x { namespace y { } }
using z = x::y;
GCC correctly says:
alias.C:2:14: error: ‘y’ in namespace ‘x’ does not name a type
2 | using z = x::y;
| ^
alias.C:1:25: note: ‘x::y’ declared here
1 | namespace x { namespace y { } }
| ^
It might be nice in this case (where a using-declaration names a namespace, not
a type) to offer a fix-it to make it a namespace alias:
note: did you mean to define a namespace alias?
2 | using z = x::y;
| ^~~~~
| namespace
The suggestion won't always be correct, maybe the user meant to define a
typedef for a type x::Y or x::yo and the x::y was a typo. And given how rarely
namespace aliases are used, maybe that's more likely. But maybe it's worth
doing.
