On Mar 23, 2018, Jason Merrill <ja...@redhat.com> wrote:
> On Fri, Mar 23, 2018 at 3:38 PM, Alexandre Oliva <aol...@redhat.com> wrote:
>> + /* Concepts allows 'auto' in template arguments, even multiple
>> + 'auto's in a single argument.
> I think that's only intended for class templates;
Aah, that explains a lot! Dang, it was so close!
It actually makes sense; was there any discussion about standardizing
this, with reasons to reject this construct, or is it just that we
aren't there yet? I wouldn't be surprised if it were to appear in some
future version of C++.
> we should reject 'auto' as a template argument for function or
> variable templates.
Is this (in the patch below) the best spot to test for it?
[PR c++/84979] reject auto in explicit tmpl args for tmpl-fn
With concepts, we accept auto in explicit template arguments, but we
should only accept them for template classes. Passing them to
template functions is not allowed. So, reject it.
Regstrapping on i686- and x86-64-linux-gnu, after a successful make
check-c++-all. Ok to install if it passes?
for gcc/cp/ChangeLog
PR c++/84979
* semantics.c (finish_id_expression): Reject template args
referencing auto for template fns.
for gcc/testsuite/ChangeLog
PR c++/84979
* g++.dg/concepts/pr84979.C: New.
---
gcc/cp/semantics.c | 11 +++++++++--
gcc/testsuite/g++.dg/concepts/pr84979.C | 9 +++++++++
2 files changed, 18 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/concepts/pr84979.C
diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 035e39515748..9b33234c8b73 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -3528,8 +3528,15 @@ finish_id_expression (tree id_expression,
/* If we have a template-id, then no further lookup is
required. If the template-id was for a template-class, we
will sometimes have a TYPE_DECL at this point. */
- else if (TREE_CODE (decl) == TEMPLATE_ID_EXPR
- || TREE_CODE (decl) == TYPE_DECL)
+ else if (TREE_CODE (decl) == TEMPLATE_ID_EXPR)
+ {
+ if (flag_concepts && type_uses_auto (decl))
+ {
+ *error_msg = "invalid use of %<auto%> in template argument for
template function";
+ return error_mark_node;
+ }
+ }
+ else if (TREE_CODE (decl) == TYPE_DECL)
;
/* Look up the name. */
else
diff --git a/gcc/testsuite/g++.dg/concepts/pr84979.C
b/gcc/testsuite/g++.dg/concepts/pr84979.C
new file mode 100644
index 000000000000..c70b3756f2b8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/concepts/pr84979.C
@@ -0,0 +1,9 @@
+// { dg-do compile { target c++11 } }
+// { dg-options "-fconcepts" }
+
+template<typename> void foo() {}
+
+void bar()
+{
+ foo<auto>(); // { dg-error "invalid|no match" }
+}
--
Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/ FSF Latin America board member
Free Software Evangelist|Red Hat Brasil GNU Toolchain Engineer
