This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[C++ PATCH] [PR86648] use auto identifier for class placeholder templates


dwarf2out recognizes unspecified auto types by the identifier.  C++
template class placeholders are unspecified auto types that take the
identifier of the class rather than those used by preexisting auto
types, so dwarf2out ICEs when it finds one of those.  Alas, they may
be visible to dwarf2out, since the types of e.g. static data members
of templates are only deduced at member instantiation, i.e., if the
data member is actually referenced, but the data member is added as a
field, still with unspecified auto placeholder type, when the
enclosing class is instantiated.

I've changed placeholder creator to use an auto identifier instead,
which allowed dropping the placeholder test in C++'s is_auto (alas, it
can't be used in dwarf2out, think LTO).  To avoid losing information
in error messages and dumps and whatnot, I've added code to recognize
placeholders for template classes say A and print them out as
A<...auto...>.

Regstrapped on x86_64- and i686-linux-gnu.  Ok to install?


for  gcc/cp/ChangeLog

	PR c++/86648
        * pt.c (make_template_placeholder): Use auto_identifier.
        (is_auto): Drop CLASS_PLACEHOLDER_TEMPLATE test.
        * error.c (dump_type): Handle template placeholders.
        * cxx-pretty-print.c (pp_cx_unqualified_id): Likewise.

for  gcc/testsuite/ChangeLog

	PR c++/86648
        * gcc.dg/cpp1z/pr86648.C: New.

---
 gcc/cp/cxx-pretty-print.c            |   10 +++++++++-
 gcc/cp/error.c                       |    8 ++++++++
 gcc/cp/pt.c                          |    5 ++---
 gcc/testsuite/g++.dg/cpp1z/pr86648.C |    5 +++++
 4 files changed, 24 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp1z/pr86648.C

diff --git a/gcc/cp/cxx-pretty-print.c b/gcc/cp/cxx-pretty-print.c
index b79ff5137aa1..c173760f0425 100644
--- a/gcc/cp/cxx-pretty-print.c
+++ b/gcc/cp/cxx-pretty-print.c
@@ -187,7 +187,15 @@ pp_cxx_unqualified_id (cxx_pretty_printer *pp, tree t)
 
     case TEMPLATE_TYPE_PARM:
     case TEMPLATE_TEMPLATE_PARM:
-      if (TYPE_IDENTIFIER (t))
+      if (template_placeholder_p (t)
+	  && DECL_P (CLASS_PLACEHOLDER_TEMPLATE (t))
+	  && TYPE_IDENTIFIER (TREE_TYPE (CLASS_PLACEHOLDER_TEMPLATE (t))))
+	{
+	  t = TREE_TYPE (CLASS_PLACEHOLDER_TEMPLATE (t));
+	  pp_cxx_unqualified_id (pp, TYPE_IDENTIFIER (t));
+	  pp_string (pp, "<...auto...>");
+	}
+      else if (TYPE_IDENTIFIER (t))
 	pp_cxx_unqualified_id (pp, TYPE_IDENTIFIER (t));
       else
 	pp_cxx_canonical_template_parameter (pp, t);
diff --git a/gcc/cp/error.c b/gcc/cp/error.c
index f9b0b9987174..e2f039d1f09e 100644
--- a/gcc/cp/error.c
+++ b/gcc/cp/error.c
@@ -546,6 +546,14 @@ dump_type (cxx_pretty_printer *pp, tree t, int flags)
       pp_cxx_cv_qualifier_seq (pp, t);
       if (tree c = PLACEHOLDER_TYPE_CONSTRAINTS (t))
 	pp_cxx_constrained_type_spec (pp, c);
+      else if (template_placeholder_p (t)
+	       && DECL_P (CLASS_PLACEHOLDER_TEMPLATE (t))
+	       && TYPE_IDENTIFIER (TREE_TYPE (CLASS_PLACEHOLDER_TEMPLATE (t))))
+	{
+	  t = TREE_TYPE (CLASS_PLACEHOLDER_TEMPLATE (t));
+	  pp_cxx_tree_identifier (pp, TYPE_IDENTIFIER (t));
+	  pp_string (pp, "<...auto...>");
+	}
       else if (TYPE_IDENTIFIER (t))
 	pp_cxx_tree_identifier (pp, TYPE_IDENTIFIER (t));
       else
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 18b093e7d2d2..04bf4cd238e9 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -26433,7 +26433,7 @@ make_auto (void)
 tree
 make_template_placeholder (tree tmpl)
 {
-  tree t = make_auto_1 (DECL_NAME (tmpl), true);
+  tree t = make_auto_1 (auto_identifier, true);
   CLASS_PLACEHOLDER_TEMPLATE (t) = tmpl;
   return t;
 }
@@ -27364,8 +27364,7 @@ is_auto (const_tree type)
 {
   if (TREE_CODE (type) == TEMPLATE_TYPE_PARM
       && (TYPE_IDENTIFIER (type) == auto_identifier
-	  || TYPE_IDENTIFIER (type) == decltype_auto_identifier
-	  || CLASS_PLACEHOLDER_TEMPLATE (type)))
+	  || TYPE_IDENTIFIER (type) == decltype_auto_identifier))
     return true;
   else
     return false;
diff --git a/gcc/testsuite/g++.dg/cpp1z/pr86648.C b/gcc/testsuite/g++.dg/cpp1z/pr86648.C
new file mode 100644
index 000000000000..20ee4c8c0d44
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/pr86648.C
@@ -0,0 +1,5 @@
+// { dg-do compile { target c++17 } }
+
+template <typename> class A;
+template <class T> struct B { static A a{T::a}; };
+void foo () { B<int> a; }


-- 
Alexandre Oliva, freedom fighter   https://FSFLA.org/blogs/lxo
Be the change, be Free!         FSF Latin America board member
GNU Toolchain Engineer                Free Software Evangelist
Hay que enGNUrecerse, pero sin perder la terGNUra jamás-GNUChe


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]