While discussing issue 2179 at the meeting last week, I noticed that we
were crashing when a partial specialization made a previous
instantiation ambiguous. Fixed thus.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit cb0817f19d7f4ce9878922412c2c1b2d07eb66d7
Author: Jason Merrill <ja...@redhat.com>
Date: Sun Oct 25 05:22:50 2015 -1000
DR 2179
* pt.c (process_partial_specialization): Handle error_mark_node
from most_specialized_partial_spec.
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index ffe02da..2745b40 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -4690,14 +4690,18 @@ process_partial_specialization (tree decl)
: DECL_TEMPLATE_INSTANTIATION (instance))
{
tree spec = most_specialized_partial_spec (instance, tf_none);
- if (spec && TREE_VALUE (spec) == tmpl)
- {
- tree inst_decl = (DECL_P (instance)
- ? instance : TYPE_NAME (instance));
- permerror (input_location,
- "partial specialization of %qD after instantiation "
- "of %qD", decl, inst_decl);
- }
+ tree inst_decl = (DECL_P (instance)
+ ? instance : TYPE_NAME (instance));
+ if (!spec)
+ /* OK */;
+ else if (spec == error_mark_node)
+ permerror (input_location,
+ "declaration of %qD ambiguates earlier template "
+ "instantiation for %qD", decl, inst_decl);
+ else if (TREE_VALUE (spec) == tmpl)
+ permerror (input_location,
+ "partial specialization of %qD after instantiation "
+ "of %qD", decl, inst_decl);
}
}
diff --git a/gcc/testsuite/g++.dg/template/partial-specialization3.C b/gcc/testsuite/g++.dg/template/partial-specialization3.C
new file mode 100644
index 0000000..c5f83bd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/partial-specialization3.C
@@ -0,0 +1,7 @@
+// DR 2179
+
+template <class T1, class T2> class A;
+template <class T> struct A<T, void> { void f(); };
+template <class T> void g(T) { A<char, void>().f(); } // #1
+template<typename T> struct A<char, T> {}; // { dg-error "" }
+A<char, void> f; // #2
