public inbox for gcc-cvs@sourceware.org
help / color / mirror / Atom feed
* [gcc r13-4390] c++: explicit specialization and trailing requirements [PR107864]
@ 2022-11-29 14:55 Patrick Palka
0 siblings, 0 replies; only message in thread
From: Patrick Palka @ 2022-11-29 14:55 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:36cabc257dfb7dd4f7625896891f6c5b195a0241
commit r13-4390-g36cabc257dfb7dd4f7625896891f6c5b195a0241
Author: Patrick Palka <ppalka@redhat.com>
Date: Tue Nov 29 09:55:21 2022 -0500
c++: explicit specialization and trailing requirements [PR107864]
Here we're crashing when using the explicit specialization of the
function template g with trailing requirements ultimately because
earlier decls_match (called indirectly from register_specialization) for
for the explicit specialization returned false since the template has
trailing requirements whereas the specialization doesn't.
In r12-2230-gddd25bd1a7c8f4, we fixed a similar issue concerning template
requirements instead of trailing requirements. We could extend that fix
to ignore trailing requirement mismatches for explicit specializations
as well, but it seems cleaner to just propagate constraints from the
specialized template to the specialization when declaring an explicit
specialization so that decls_match will naturally return true in this
case. And it looks like determine_specialization already does this,
albeit inconsistently (only when specializing a non-template member
function of a class template as in cpp2a/concepts-explicit-spec4.C).
So this patch makes determine_specialization consistently propagate
constraints from the specialized template to the specialization, which
in turn lets us get rid of the function_requirements_equivalent_p special
case added by r12-2230.
PR c++/107864
gcc/cp/ChangeLog:
* decl.cc (function_requirements_equivalent_p): Don't check
DECL_TEMPLATE_SPECIALIZATION.
* pt.cc (determine_specialization): Propagate constraints when
specializing a function template too. Simplify by using
add_outermost_template_args.
gcc/testsuite/ChangeLog:
* g++.dg/concepts/explicit-spec1a.C: New test.
Diff:
---
gcc/cp/decl.cc | 4 +---
gcc/cp/pt.cc | 19 ++++++++-----------
gcc/testsuite/g++.dg/concepts/explicit-spec1a.C | 11 +++++++++++
3 files changed, 20 insertions(+), 14 deletions(-)
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 544efdc9914..238e72f90da 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -956,9 +956,7 @@ static bool
function_requirements_equivalent_p (tree newfn, tree oldfn)
{
/* In the concepts TS, the combined constraints are compared. */
- if (cxx_dialect < cxx20
- && (DECL_TEMPLATE_SPECIALIZATION (newfn)
- <= DECL_TEMPLATE_SPECIALIZATION (oldfn)))
+ if (cxx_dialect < cxx20)
{
tree ci1 = get_constraints (oldfn);
tree ci2 = get_constraints (newfn);
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index fbf498ad16a..2d8e4fdd4b5 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -2482,17 +2482,14 @@ determine_specialization (tree template_id,
}
/* It was a specialization of a template. */
- targs = DECL_TI_ARGS (DECL_TEMPLATE_RESULT (TREE_VALUE (templates)));
- if (TMPL_ARGS_HAVE_MULTIPLE_LEVELS (targs))
- {
- *targs_out = copy_node (targs);
- SET_TMPL_ARGS_LEVEL (*targs_out,
- TMPL_ARGS_DEPTH (*targs_out),
- TREE_PURPOSE (templates));
- }
- else
- *targs_out = TREE_PURPOSE (templates);
- return TREE_VALUE (templates);
+ tree tmpl = TREE_VALUE (templates);
+ *targs_out = add_outermost_template_args (tmpl, TREE_PURPOSE (templates));
+
+ /* Propagate the template's constraints to the declaration. */
+ if (tsk != tsk_template)
+ set_constraints (decl, get_constraints (tmpl));
+
+ return tmpl;
}
/* Returns a chain of parameter types, exactly like the SPEC_TYPES,
diff --git a/gcc/testsuite/g++.dg/concepts/explicit-spec1a.C b/gcc/testsuite/g++.dg/concepts/explicit-spec1a.C
new file mode 100644
index 00000000000..ec678740cb8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/explicit-spec1a.C
@@ -0,0 +1,11 @@
+// A version of explicit-spec1.C where the template g has trailing instead of
+// template requirements.
+// PR c++/107864
+// { dg-do compile { target concepts } }
+
+template<typename T> concept C = __is_class(T);
+struct Y { int n; } y;
+template<class T> void g(T) requires C<T> { }
+int called;
+template<> void g(Y) { called = 3; }
+int main() { g(y); }
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2022-11-29 14:55 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-11-29 14:55 [gcc r13-4390] c++: explicit specialization and trailing requirements [PR107864] Patrick Palka
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).