On Tue, Mar 24, 2015 at 01:14:50AM -0400, Jason Merrill wrote:
Here's my shot at this.
> The problem is that the type is considered dependent in a template but is
> not actually dependent, so we can see the exact same type outside a template
Yeah, I think this is true...
> and it's not dependent. So, this code is creating the difference:
> > /* We can only call value_dependent_expression_p on integral constant
> > expressions; treat non-constant expressions as dependent, too. */
> > if (processing_template_decl
> > && (type_dependent_expression_p (size)
> > || !TREE_CONSTANT (size) || value_dependent_expression_p (size)))
>
> Now that we have instantiation_dependent_expression_p, we should be able to
> use that instead of checking type/value dependency separately.
...but I think there's another place where things go wrong. ISTM that in
build_cplus_array_type we consider all arrays with non-constant index as
dependent (when processing_template_decl) -- but as the testcase shows, this
is not always true. The fix then could look like the following, though I
wouldn't be surprised if this was a wrong way how to go about this.
Bootstrapped/regtested on x86_64-linux. Not a regression, so we might want to
defer this patch to the next stage1.
2015-03-31 Marek Polacek <pola...@redhat.com>
PR c++/65390
* tree.c (build_cplus_array_type): Use dependent_type_p rather than
checking for constness.
* g++.dg/template/pr65390.C: New test.
diff --git gcc/cp/tree.c gcc/cp/tree.c
index ef53aff..97bccc0 100644
--- gcc/cp/tree.c
+++ gcc/cp/tree.c
@@ -822,10 +822,9 @@ build_cplus_array_type (tree elt_type, tree index_type)
if (elt_type == error_mark_node || index_type == error_mark_node)
return error_mark_node;
- bool dependent
- = (processing_template_decl
- && (dependent_type_p (elt_type)
- || (index_type && !TREE_CONSTANT (TYPE_MAX_VALUE (index_type)))));
+ bool dependent = (processing_template_decl
+ && (dependent_type_p (elt_type)
+ || (index_type && dependent_type_p (index_type))));
if (elt_type != TYPE_MAIN_VARIANT (elt_type))
/* Start with an array of the TYPE_MAIN_VARIANT. */
diff --git gcc/testsuite/g++.dg/template/pr65390.C
gcc/testsuite/g++.dg/template/pr65390.C
index e69de29..299d22a 100644
--- gcc/testsuite/g++.dg/template/pr65390.C
+++ gcc/testsuite/g++.dg/template/pr65390.C
@@ -0,0 +1,12 @@
+// PR c++/65390
+// { dg-do compile }
+// { dg-options "" }
+
+template<typename T> struct shared_ptr { };
+
+template<typename T, typename Arg>
+shared_ptr<T> make_shared(Arg) { return shared_ptr<T>(); } // { dg-error
"variably modified type|trying to instantiate" }
+
+void f(int n){
+ make_shared<int[n]>(1); // { dg-error "no matching function" }
+}
Marek
