https://gcc.gnu.org/g:1853b02d8c127740055242123db2d32cf9476ea9
commit r15-7822-g1853b02d8c127740055242123db2d32cf9476ea9
Author: Jakub Jelinek <ja...@redhat.com>
Date: Wed Mar 5 06:41:00 2025 +0100
c++: Apply/diagnose attributes when instatiating
ARRAY/POINTER/REFERENCE_TYPE [PR118787]
The following testcase IMO in violation of the P2552R3 paper doesn't
pedwarn on alignas applying to dependent types or alignas with dependent
argument.
tsubst was just ignoring TYPE_ATTRIBUTES.
The following patch fixes it for the POINTER/REFERENCE_TYPE and
ARRAY_TYPE cases, but perhaps we need to do the same also for other
types (INTEGER_TYPE/REAL_TYPE and the like). I guess I'll need to
construct more testcases.
2025-03-05 Jakub Jelinek <ja...@redhat.com>
PR c++/118787
* pt.cc (tsubst) <case ARRAY_TYPE>: Use return t; only if it doesn't
have any TYPE_ATTRIBUTES. Call apply_late_template_attributes.
<case POINTER_TYPE, case REFERENCE_TYPE>: Likewise. Formatting fix.
* g++.dg/cpp0x/alignas22.C: New test.
Diff:
---
gcc/cp/pt.cc | 24 +++++++++++++++++++-----
gcc/testsuite/g++.dg/cpp0x/alignas22.C | 23 +++++++++++++++++++++++
2 files changed, 42 insertions(+), 5 deletions(-)
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 62d91a2dd159..c09a934580f2 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -16865,7 +16865,9 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
tree in_decl)
case POINTER_TYPE:
case REFERENCE_TYPE:
{
- if (type == TREE_TYPE (t) && TREE_CODE (type) != METHOD_TYPE)
+ if (type == TREE_TYPE (t)
+ && TREE_CODE (type) != METHOD_TYPE
+ && TYPE_ATTRIBUTES (t) == NULL_TREE)
return t;
/* [temp.deduct]
@@ -16935,9 +16937,9 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
tree in_decl)
A,' while an attempt to create the type type rvalue reference to
cv T' creates the type T"
*/
- r = cp_build_reference_type
- (TREE_TYPE (type),
- TYPE_REF_IS_RVALUE (t) && TYPE_REF_IS_RVALUE (type));
+ r = cp_build_reference_type (TREE_TYPE (type),
+ TYPE_REF_IS_RVALUE (t)
+ && TYPE_REF_IS_RVALUE (type));
else
r = cp_build_reference_type (type, TYPE_REF_IS_RVALUE (t));
r = cp_build_qualified_type (r, cp_type_quals (t), complain);
@@ -16946,6 +16948,11 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
tree in_decl)
/* Will this ever be needed for TYPE_..._TO values? */
layout_type (r);
+ if (!apply_late_template_attributes (&r, TYPE_ATTRIBUTES (t),
+ /*flags=*/0,
+ args, complain, in_decl))
+ return error_mark_node;
+
return r;
}
case OFFSET_TYPE:
@@ -17020,7 +17027,9 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
tree in_decl)
/* As an optimization, we avoid regenerating the array type if
it will obviously be the same as T. */
- if (type == TREE_TYPE (t) && domain == TYPE_DOMAIN (t))
+ if (type == TREE_TYPE (t)
+ && domain == TYPE_DOMAIN (t)
+ && TYPE_ATTRIBUTES (t) == NULL_TREE)
return t;
/* These checks should match the ones in create_array_type_for_decl.
@@ -17059,6 +17068,11 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
tree in_decl)
TYPE_USER_ALIGN (r) = 1;
}
+ if (!apply_late_template_attributes (&r, TYPE_ATTRIBUTES (t),
+ /*flags=*/0,
+ args, complain, in_decl))
+ return error_mark_node;
+
return r;
}
diff --git a/gcc/testsuite/g++.dg/cpp0x/alignas22.C
b/gcc/testsuite/g++.dg/cpp0x/alignas22.C
new file mode 100644
index 000000000000..e7929774c3c0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/alignas22.C
@@ -0,0 +1,23 @@
+// PR c++/118787
+// { dg-do compile { target c++11 } }
+// { dg-options "-pedantic" }
+
+template <typename T, int N>
+void foo (T & alignas (N)); // { dg-warning "'alignas' on a type
other than class" }
+template <typename T, int N>
+void bar (T (&)[N] alignas (N)); // { dg-warning "'alignas' on a type
other than class" }
+template <typename T, int N>
+using U = T * alignas (N); // { dg-warning "'alignas' on a type
other than class" }
+template <typename T, int N>
+using V = T[N] alignas (N); // { dg-warning "'alignas' on a type
other than class" }
+
+void
+baz ()
+{
+ int x alignas (4) = 0;
+ foo <int, 4> (x);
+ int y alignas (4) [4];
+ bar <int, 4> (y);
+ U <int, 4> u;
+ V <int, 4> v;
+}
