On Mon, Mar 16, 2020 at 05:12:15PM -0400, Jason Merrill wrote:
> On 3/16/20 10:57 AM, Marek Polacek wrote:
> > Now that convert_like creates an IMPLICIT_CONV_EXPR when it converts
> > something that involves a class in a template, we must be prepared to
> > handle it. In this test, we have a class S and we're converting it
> > to long int& using a user-defined conversion since we're performing
> > -- on it. So cp_build_unary_op/POSTDECREMENT_EXPR calls
> > build_expr_type_conversion which gets the IMPLICIT_CONV_EXPR. Before
> > the convert_like change it got *S::operator long int &(&b) whose type
> > is long int but now it gets IMPLICIT_CONV_EXPR<long int&>(b) whose type
> > is a reference type.
>
> So you need to make sure that your IMPLICIT_CONV_EXPR gets
> convert_from_reference'd at some point.
Perhaps like the following?
Bootstrapped/regtested on x86_64-linux, built Boost/cmcstl2.
-- >8 --
Now that convert_like creates an IMPLICIT_CONV_EXPR when it converts
something that involves a class in a template, we must be prepared to
handle it. In this test, we have a class S and we're converting it
to long int& using a user-defined conversion since we're performing
-- on it. So cp_build_unary_op/POSTDECREMENT_EXPR calls
build_expr_type_conversion which gets the IMPLICIT_CONV_EXPR. Before
the convert_like change it got *S::operator long int &(&b) whose type
is long int but now it gets IMPLICIT_CONV_EXPR<long int&>(b) whose type
is a reference type. But the !MAYBE_CLASS_TYPE_P switch doesn't handle
reference types and so we complain.
Fixed by calling convert_from_reference on the result of convert_like.
PR c++/94190 - wrong no post-decrement operator error in template.
* call.c (build_new_op_1): Use convert_from_reference on the result
of convert_like.
* g++.dg/conversion/op7.C: New test.
---
gcc/cp/call.c | 3 +++
gcc/testsuite/g++.dg/conversion/op7.C | 22 ++++++++++++++++++++++
2 files changed, 25 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/conversion/op7.C
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 1715acc0ec3..d8b28573b95 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -6426,6 +6426,7 @@ build_new_op_1 (const op_location_t &loc, enum tree_code
code, int flags,
{
conv = strip_standard_conversion (conv);
arg1 = convert_like (conv, arg1, complain);
+ arg1 = convert_from_reference (arg1);
}
if (arg2)
@@ -6435,6 +6436,7 @@ build_new_op_1 (const op_location_t &loc, enum tree_code
code, int flags,
{
conv = strip_standard_conversion (conv);
arg2 = convert_like (conv, arg2, complain);
+ arg2 = convert_from_reference (arg2);
}
}
@@ -6445,6 +6447,7 @@ build_new_op_1 (const op_location_t &loc, enum tree_code
code, int flags,
{
conv = strip_standard_conversion (conv);
arg3 = convert_like (conv, arg3, complain);
+ arg3 = convert_from_reference (arg3);
}
}
}
diff --git a/gcc/testsuite/g++.dg/conversion/op7.C
b/gcc/testsuite/g++.dg/conversion/op7.C
new file mode 100644
index 00000000000..c6401d109b4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/conversion/op7.C
@@ -0,0 +1,22 @@
+// PR c++/94190 - wrong no post-decrement operator error in template.
+
+struct S { operator long & (); } b;
+
+template<int> void
+foo ()
+{
+ b--;
+ ++b;
+ --b;
+ b++;
+ !b;
+ ~b;
+ +b;
+ -b;
+}
+
+void
+bar ()
+{
+ foo<0> ();
+}
base-commit: 2691ffe6dbaffb704593dd6220178c28848b3855
--
Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA
