This PR reports a bug where we select a non-const operator function and
then apply it to a const object. That's happening because the
expression 'c[0]' is not dependent, so we figure end up resolving it.
But the lambda capture logic doesn't capture 'c' at that point and we
have a non-const qualified 'c'. At instantiation time we do the capture
and the by-value lambda results in const-qualified captures.
Jason, the orginal test in process_outer_var_ref looked a little funky
-- why not just processing_template_decl? That would satisfy what the
comment says it checking. Anyway changing the test to check DECL's
type-dependency makes the right things happen, and a bootstrap passes.
Could you review please.
nathan
--
Nathan Sidwell
2019-01-16 Nathan Sidwell <nat...@acm.org>
PR c++/86610
* semantics.c (process_outer_var_ref): Only skip dependent types
in templates.
PR c++/86610
* g++.dg/cpp0x/pr86610.C: New.
Index: cp/semantics.c
===================================================================
--- cp/semantics.c (revision 267983)
+++ cp/semantics.c (working copy)
@@ -3438,10 +3438,9 @@ process_outer_var_ref (tree decl, tsubst
}
/* In a lambda within a template, wait until instantiation
- time to implicitly capture. */
+ time to implicitly capture a dependent type. */
if (context == containing_function
- && DECL_TEMPLATE_INFO (containing_function)
- && uses_template_parms (DECL_TI_ARGS (containing_function)))
+ && dependent_type_p (TREE_TYPE (decl)))
return decl;
if (lambda_expr && VAR_P (decl)
Index: testsuite/g++.dg/cpp0x/pr86610.C
===================================================================
--- testsuite/g++.dg/cpp0x/pr86610.C (revision 0)
+++ testsuite/g++.dg/cpp0x/pr86610.C (working copy)
@@ -0,0 +1,31 @@
+// { dg-do run { target c++11 } }
+// PR c++86610 lambda capture inside template
+
+struct C
+{
+ int operator[](int)
+ { return 1; }
+
+ int operator[](int) const
+ { return 0; } // Want this one
+};
+
+int q()
+{
+ C c;
+ return [=] { return c[0]; }();
+}
+
+template <typename T>
+int f()
+{
+ C c;
+ T d;
+ return [=] { return c[0]; }()
+ + [=] { return c[0] + d[0]; }();
+}
+
+int main()
+{
+ return q () + f<C>();
+}
