On 12/11/2015 05:10 AM, Richard Biener wrote:
On Thu, Dec 10, 2015 at 11:03 PM, Jason Merrill <ja...@redhat.com> wrote:
The C++ front end uses a temporary hash table to remember specializations of
local variables during template instantiations. In a nested function such
as a lambda or local class member function, we need to retain the elements
from the enclosing function's local_specializations table; otherwise the
testcase crashes because we don't find a local specialization for the
non-captured use of 'args' in the decltype.
This patch addresses that by making a copy of the enclosing
local_specializations table if it exists; to enable that I've added copy
constructors to hash_table and hash_map.
Tested x86_64-pc-linux-gnu. OK for trunk?
I don't think you can copy the elements with memcpy they may be C++ classes
that are not copyable.
True. Fixed thus:
+ for (size_t i = 0; i < size; ++i)
+ {
+ value_type &entry = h.m_entries[i];
+ if (is_deleted (entry))
+ mark_deleted (m_entries[i]);
+ else if (!is_empty (entry))
+ m_entries[i] = entry;
+ }
Also watch out for the bool gather_mem_stats = true
to bool gather_mem_stats = GATHER_STATISTICS change if that crosses your
change.
OK.
I also think copying hash tables should be discouraged ;) I wonder if you
can get around the copying by adding a generation count (to easily "backtrack")
instead.
I considered having a chain of tables to check, to handle generations,
but I figured that the tables in question were small enough (only
containing local variables for a single function) that a simple copy was
reasonable.
Jason
commit ae8c23201f9a057516f081d4d9fde1fb3281153f
Author: Jason Merrill <ja...@redhat.com>
Date: Thu Dec 10 15:37:50 2015 -0500
PR c++/68309
gcc/
* hash-table.h: Add copy constructor.
* hash-map.h: Add copy constructor.
gcc/cp/
* pt.c (instantiate_decl): Copy local_specializations for nested
function.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 60cc94c..a45e6df 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -21725,8 +21725,13 @@ instantiate_decl (tree d, int defer_ok,
template from within the body of another. */
saved_local_specializations = local_specializations;
- /* Set up the list of local specializations. */
- local_specializations = new hash_map<tree, tree>;
+ /* Set up the list of local specializations, copying the current
+ list if there is one. */
+ if (local_specializations)
+ local_specializations
+ = new hash_map<tree, tree> (*local_specializations);
+ else
+ local_specializations = new hash_map<tree, tree>;
/* Set up context. */
if (DECL_OMP_DECLARE_REDUCTION_P (code_pattern)
diff --git a/gcc/hash-map.h b/gcc/hash-map.h
index b83708c..9b3d1e9 100644
--- a/gcc/hash-map.h
+++ b/gcc/hash-map.h
@@ -110,6 +110,11 @@ public:
bool gather_mem_stats = true CXX_MEM_STAT_INFO)
: m_table (n, ggc, gather_mem_stats, HASH_MAP_ORIGIN PASS_MEM_STAT) {}
+ hash_map (const hash_map &h, bool ggc = false,
+ bool gather_mem_stats = true CXX_MEM_STAT_INFO)
+ : m_table (h.m_table, ggc, gather_mem_stats,
+ HASH_MAP_ORIGIN PASS_MEM_STAT) {}
+
/* Create a hash_map in ggc memory. */
static hash_map *create_ggc (size_t size, bool gather_mem_stats = true
CXX_MEM_STAT_INFO)
diff --git a/gcc/hash-table.h b/gcc/hash-table.h
index 192be30..e3f9dbd 100644
--- a/gcc/hash-table.h
+++ b/gcc/hash-table.h
@@ -364,6 +364,10 @@ public:
explicit hash_table (size_t, bool ggc = false, bool gather_mem_stats = true,
mem_alloc_origin origin = HASH_TABLE_ORIGIN
CXX_MEM_STAT_INFO);
+ hash_table (const hash_table &, bool ggc = false,
+ bool gather_mem_stats = true,
+ mem_alloc_origin origin = HASH_TABLE_ORIGIN
+ CXX_MEM_STAT_INFO);
~hash_table ();
/* Create a hash_table in gc memory. */
@@ -580,6 +584,34 @@ hash_table<Descriptor, Allocator>::hash_table (size_t size, bool ggc, bool
}
template<typename Descriptor, template<typename Type> class Allocator>
+hash_table<Descriptor, Allocator>::hash_table (const hash_table &h, bool ggc,
+ bool gather_mem_stats,
+ mem_alloc_origin origin
+ MEM_STAT_DECL) :
+ m_n_elements (h.m_n_elements), m_n_deleted (h.m_n_deleted),
+ m_searches (0), m_collisions (0), m_ggc (ggc),
+ m_gather_mem_stats (gather_mem_stats)
+{
+ size_t size = h.m_size;
+
+ if (m_gather_mem_stats)
+ hash_table_usage.register_descriptor (this, origin, ggc
+ FINAL_PASS_MEM_STAT);
+
+ m_entries = alloc_entries (size PASS_MEM_STAT);
+ for (size_t i = 0; i < size; ++i)
+ {
+ value_type &entry = h.m_entries[i];
+ if (is_deleted (entry))
+ mark_deleted (m_entries[i]);
+ else if (!is_empty (entry))
+ m_entries[i] = entry;
+ }
+ m_size = size;
+ m_size_prime_index = h.m_size_prime_index;
+}
+
+template<typename Descriptor, template<typename Type> class Allocator>
hash_table<Descriptor, Allocator>::~hash_table ()
{
for (size_t i = m_size - 1; i < m_size; i--)
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-variadic3.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-variadic3.C
new file mode 100644
index 0000000..76b6b3f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-variadic3.C
@@ -0,0 +1,9 @@
+// PR c++/68309
+// { dg-do compile { target c++11 } }
+
+template <class... Ts> void f(Ts...);
+template <class T> T g(T);
+template <typename... Ts> void print(Ts... args) {
+ [&] { f(g<decltype(args)>(args)...); }();
+}
+int main() { print(5.2); }
