On Tue, 19 Jan 2016, Patrick Palka wrote:
On Tue, Jan 19, 2016 at 9:56 AM, Jason Merrill <ja...@redhat.com> wrote:
On 01/18/2016 10:55 PM, Patrick Palka wrote:
mark_used is wrongly diagnosing a use of a TEMPLATE_DECL (e.g. the call
to f1 in function f3 of auto-fn29.C below) for having an undeduced
'auto' return type. This doesn't make sense, because an 'auto' used
inside a template doesn't get deduced until after the template is
instantiated. So for a TEMPLATE_DECL we shouldn't diagnose a use of
undeduced 'auto' here. After instantiation, presumably we will call
mark_used on the resulting FUNCTION_DECL which will check for undeduced
auto appropriately.
@@ -5112,7 +5112,9 @@ mark_used (tree decl, tsubst_flags_t complain)
|| DECL_LANG_SPECIFIC (decl) == NULL
|| DECL_THUNK_P (decl))
{
- if (!processing_template_decl && type_uses_auto (TREE_TYPE (decl)))
+ if (!processing_template_decl
+ && TREE_CODE (decl) != TEMPLATE_DECL
+ && type_uses_auto (TREE_TYPE (decl)))
How does a TEMPLATE_DECL get in here? Does it have null DECL_LANG_SPECIFIC?
(In the test case auto-fn29.C,) When instantiating the template
function f3,we call tsubst on the CALL_EXPR "f1 (v);". There, ADL is
performed on the identifier f1 (which is the CALL_EXPR_FN) which
returns the TEMPLATE_DECL f1. Then mark_used is called on this
CALL_EXPR_FN, only if it's a decl.
If in the test case the call to "f1 (v);" is replaced with "Ape::f1
(v);" then the CALL_EXPR_FN is then an OVERLOAD (to the TEMPLATE_DECL
f1), i.e. not a decl, so we don't call mark_used on it in tsubst.
The DECL_LANG_SPECIFIC of this decl is not null.
I'd think mark_used of a TEMPLATE_DECL should return after setting
TREE_USED, there's nothing else to do with it.
Consider it changed.
Here's the updated patch, with mark_used made to return earlier in case
of a TEMPLATE_DECL. Also, auto-fn31.C is now consolidated into
auto-fn29.C since the two test cases were so similar.
-- >8 --
gcc/cp/ChangeLog:
PR c++/69283
PR c++/67835
* decl2.c (mark_used): When given a TEMPLATE_DECL, return after
setting its TREE_USED.
gcc/testsuite/ChangeLog:
PR c++/69283
PR c++/67835
* g++.dg/cpp1y/auto-fn29.C: New test.
* g++.dg/cpp1y/auto-fn30.C: New test.
---
gcc/cp/decl2.c | 4 ++++
gcc/testsuite/g++.dg/cpp1y/auto-fn29.C | 34 ++++++++++++++++++++++++++++++++++
gcc/testsuite/g++.dg/cpp1y/auto-fn30.C | 21 +++++++++++++++++++++
3 files changed, 59 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/cpp1y/auto-fn29.C
create mode 100644 gcc/testsuite/g++.dg/cpp1y/auto-fn30.C
diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index 7d68961..15d7617 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -5068,6 +5068,10 @@ mark_used (tree decl, tsubst_flags_t complain)
/* Set TREE_USED for the benefit of -Wunused. */
TREE_USED (decl) = 1;
+
+ if (TREE_CODE (decl) == TEMPLATE_DECL)
+ return true;
+
if (DECL_CLONED_FUNCTION_P (decl))
TREE_USED (DECL_CLONED_FUNCTION (decl)) = 1;
diff --git a/gcc/testsuite/g++.dg/cpp1y/auto-fn29.C
b/gcc/testsuite/g++.dg/cpp1y/auto-fn29.C
new file mode 100644
index 0000000..f9260e0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/auto-fn29.C
@@ -0,0 +1,34 @@
+// PR c++/69283
+// { dg-do compile { target c++14 } }
+
+namespace Ape {
+ struct Type {};
+
+ template <typename T>
+ auto f1(T const& v){
+ return true;
+ }
+
+ template <typename T>
+ auto f2(T const& v){
+ return f2(v); // { dg-error "auto" }
+ }
+}
+
+namespace Baboon {
+ template <typename T>
+ bool f3(T const& v){
+ return f1(v);
+ }
+
+ template <typename T>
+ bool f4(T const& v){
+ f2(v);
+ }
+}
+
+int main(){
+ Ape::Type x;
+ Baboon::f3(x);
+ Baboon::f4(x);
+}
diff --git a/gcc/testsuite/g++.dg/cpp1y/auto-fn30.C
b/gcc/testsuite/g++.dg/cpp1y/auto-fn30.C
new file mode 100644
index 0000000..e005e6e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/auto-fn30.C
@@ -0,0 +1,21 @@
+// PR c++/67835
+// { dg-do compile { target c++14 } }
+
+template<class Tag, class T>
+auto g(Tag tag, T x) {
+ return f(tag, x);
+}
+
+namespace abc {
+struct tag {};
+
+struct A {};
+
+template<class T>
+auto f(tag, T x) { return x; }
+}
+
+int main() {
+ g(abc::tag(), abc::A());
+ return 0;
+}
--
2.7.0.303.g36d4cae
