On 3/9/20 1:40 PM, Jason Merrill wrote:
On 3/9/20 12:31 PM, Martin Sebor wrote:
On 2/28/20 1:24 PM, Jason Merrill wrote:
On 2/28/20 12:45 PM, Martin Sebor wrote:
On 2/28/20 9:58 AM, Jason Merrill wrote:
On 2/24/20 6:58 PM, Martin Sebor wrote:
-Wredundant-tags doesn't consider type declarations that are also
the first uses of the type, such as in 'void f (struct S);' and
issues false positives for those. According to the reported that's
making it harder to use the warning to clean up LibreOffice.
The attached patch extends -Wredundant-tags to avoid these false
positives by relying on the same class_decl_loc_t::class2loc mapping
as -Wmismatched-tags. The patch also somewhat improves the detection
of both issues in template declarations (though more work is still
needed there).
+ a new entry for it and return unless it's a declaration
+ involving a template that may need to be diagnosed by
+ -Wredundant-tags. */
*rdl = class_decl_loc_t (class_key, false, def_p);
- return;
+ if (TREE_CODE (decl) != TEMPLATE_DECL)
+ return;
How can the first appearance of a class template be redundant?
I'm not sure I correctly understand the question. The comment says
"involving a template" (i.e., not one of the first declaration of
a template). The test case that corresponds to this test is:
template <class> struct S7 { };
struct S7<void> s7v; // { dg-warning "\\\[-Wredundant-tags" }
where DECL is the TEPLATE_DECL of S7<void>.
As I mentioned, more work is still needed to handle templates right
because some redundant tags are still not diagnosed. For example:
template <class> struct S7 { };
template <class T>
using U = struct S7<T>; // missing warning
When we get here for an instance of a template, it doesn't make sense
to treat it as a new type.
If decl is a template and type_decl is an instance of that template,
do we want to (before the lookup) change type_decl to the template or
the corresponding generic TYPE_DECL, which should already be in the
table?
I'm struggling with how to do this. Given type (a RECORD_TYPE) and
type_decl (a TEMPLATE_DECL) representing the use of a template, how
do I get the corresponding template (or its explicit or partial
specialization) in the three cases below?
1) Instance of the primary:
template <class> class A;
struct A<int> a;
2) Instance of an explicit specialization:
template <class> class B;
template <> struct B<int>;
class B<int> b;
3) Instance of a partial specialization:
template <class> class C;
template <class T> struct C<T*>;
class C<int*> c;
By trial and (lots of) error I figured out that in both (1) and (2),
but not in (3), TYPE_MAIN_DECL (TYPE_TI_TEMPLATE (type)) returns
the template's type_decl.
Is there some function to call to get it in (3), or even better,
in all three cases?
I think you're looking for most_general_template.
I don't think that's quite what I'm looking for. At least it doesn't
return the template or its specialization in all three cases above.
In (2) and (3) it won't distinguish between specializations of B or
C on different types. In (2), the function returns the same result
for both:
template <> struct B<int>;
template <> struct B<char>;
In (3), it similarly returns the same result for both of
template <class T> struct C<T*>;
template <class T> struct C<const T>;
even though they are declarations of distinct types.
What I missing?
Martin
