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Re: C++ PATCH for c++/41119, 41120
- From: Jason Merrill <jason at redhat dot com>
- To: gcc-patches List <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 19 Aug 2009 13:26:03 -0400
- Subject: Re: C++ PATCH for c++/41119, 41120
- References: <4A8C3596.7060908@redhat.com>
On 08/19/2009 01:25 PM, Jason Merrill wrote:
Synthesizing in the middle of a default argument was problematic because
we don't want to run the garbage collector in the middle of overload
resolution, because the overload candidates aren't marked for GC.
cp_parser_default_argument dealt with this by setting function_depth
around parsing of the default argument, but that didn't cover the case
of synthesizing for initializing a namespace-scope variable. But if
synthesis is the problem, we should set function_depth while
synthesizing, not around the larger scope.
Tested x86_64-pc-linux-gnu, applied to trunk.
2009-08-19 Jason Merrill <jason@redhat.com>
PR c++/41119
PR c++/41120
* decl2.c (mark_used): Increment function_depth during synthesis.
* parser.c (cp_parser_default_argument): Not here.
diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index e4ed963..225cd9d 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -3948,7 +3948,16 @@ mark_used (tree decl)
&& !DECL_THUNK_P (decl)
&& ! DECL_INITIAL (decl))
{
+ /* Synthesizing an implicitly defined member function will result in
+ garbage collection. We must treat this situation as if we were
+ within the body of a function so as to avoid collecting live data
+ on the stack (such as overload resolution candidates).
+
+ ??? Now that inlining is done unit-at-a-time, we ought to defer
+ synthesis like we do templates. */
+ ++function_depth;
synthesize_method (decl);
+ --function_depth;
/* If we've already synthesized the method we don't need to
do the instantiation test below. */
}
diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index e64d0bf..a3e9f0e 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -14615,12 +14615,6 @@ cp_parser_default_argument (cp_parser *parser, bool template_parm_p)
appear in a default argument. */
saved_local_variables_forbidden_p = parser->local_variables_forbidden_p;
parser->local_variables_forbidden_p = true;
- /* The default argument expression may cause implicitly
- defined member functions to be synthesized, which will
- result in garbage collection. We must treat this
- situation as if we were within the body of function so as
- to avoid collecting live data on the stack. */
- ++function_depth;
/* Parse the assignment-expression. */
if (template_parm_p)
push_deferring_access_checks (dk_no_deferred);
@@ -14628,8 +14622,6 @@ cp_parser_default_argument (cp_parser *parser, bool template_parm_p)
= cp_parser_assignment_expression (parser, /*cast_p=*/false, NULL);
if (template_parm_p)
pop_deferring_access_checks ();
- /* Restore saved state. */
- --function_depth;
parser->greater_than_is_operator_p = saved_greater_than_is_operator_p;
parser->local_variables_forbidden_p = saved_local_variables_forbidden_p;
diff --git a/gcc/testsuite/g++.dg/other/gc4.C b/gcc/testsuite/g++.dg/other/gc4.C
new file mode 100644
index 0000000..50c16b3
--- /dev/null
+++ b/gcc/testsuite/g++.dg/other/gc4.C
@@ -0,0 +1,14 @@
+// PR c++/41120
+// { dg-options "--param ggc-min-heapsize=0 --param ggc-min-expand=0" }
+
+struct A
+{
+ A();
+};
+
+struct B
+{
+ A a;
+};
+
+B b;