https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101519
Bug ID: 101519
Summary: Improve diagnostic for template name used as base
class
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: ---
template<typename T> struct A { };
template<typename T> struct B : A { };
a.C:2:35: error: expected class-name before ‘{’ token
2 | template<typename T> struct B : A { };
| ^
While the error is technically correct, it would be more helpful to point out
that a template argument list is expected.
Clang does not better than GCC:
a.C:2:33: error: expected class name
template<typename T> struct B : A { };
^
1 error generated.
But EDG does well:
"a.C", line 2: error: argument list for class template "A" is missing
template<typename T> struct B : A { };
^
"a.C", line 2: error: not a class or struct name
template<typename T> struct B : A { };
^
2 errors detected in the compilation of "a.C".
I think the current error would be fine if it was followed by a note:
note: 'A' is a class template; add a template argument list to use it as a
base-class
