On 9/20/24 5:21 PM, Simon Martin wrote:
The following code triggers an ICE
=== cut here ===
class base {};
class derived : virtual public base {
public:
template<typename Arg> constexpr derived(Arg) {}
};
int main() {
derived obj(1.);
}
=== cut here ===
The problem is that cxx_bind_parameters_in_call ends up attempting to
convert a REAL_CST (the first non artificial parameter) to INTEGER_TYPE
(the type of the __in_chrg parameter), which ICEs.
This patch teaches cxx_bind_parameters_in_call to handle the __in_chrg
and __vtt_parm parameters that {con,de}structors might have.
Note that in the test case, the constructor is not constexpr-suitable,
however it's OK since it's a template according to my read of paragraph
(3) of [dcl.constexpr].
Agreed.
It looks like your patch doesn't correct the mismatching of arguments to
parameters that you describe, but at least for now it should be enough
to set *non_constant_p and return if we see a VTT or in-charge parameter.
Successfully tested on x86_64-pc-linux-gnu.
PR c++/116722
gcc/cp/ChangeLog:
* constexpr.cc (cxx_bind_parameters_in_call): Leave artificial
constructor parameters as is.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/constexpr-ctor22.C: New test.
---
gcc/cp/constexpr.cc | 10 +++++++++-
gcc/testsuite/g++.dg/cpp0x/constexpr-ctor22.C | 15 +++++++++++++++
2 files changed, 24 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-ctor22.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index f6fd059be46..815f93b1d47 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -1871,13 +1871,21 @@ cxx_bind_parameters_in_call (const constexpr_ctx *ctx,
tree t, tree fun,
x = get_nth_callarg (t, i);
/* For member function, the first argument is a pointer to the implied
object. For a constructor, it might still be a dummy object, in
- which case we get the real argument from ctx. */
+ which case we get the real argument from ctx. */
if (i == 0 && DECL_CONSTRUCTOR_P (fun)
&& is_dummy_object (x))
{
x = ctx->object;
x = build_address (x);
}
+ /* Leave the __in_chrg and __vtt_parm parameters of *structors of classes
+ with virtual bases as is. */
+ if ((i == 1 && DECL_HAS_IN_CHARGE_PARM_P (fun))
+ || (i == 2 && DECL_HAS_VTT_PARM_P (fun)))
+ {
+ TREE_VEC_ELT (binds, i) = arg;
+ continue;
+ }
if (TREE_ADDRESSABLE (type))
{
/* Undo convert_for_arg_passing work here. */
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-ctor22.C
b/gcc/testsuite/g++.dg/cpp0x/constexpr-ctor22.C
new file mode 100644
index 00000000000..279f6ec4454
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-ctor22.C
@@ -0,0 +1,15 @@
+// PR c++/116722
+// We're now accepting this in spite of the virtual base class. This is OK
+// according to [dcl.constexpr] 3: "Except for instantiated constexpr functions
+// non-templated constexpr functions shall be constexpr-suitable".
+// { dg-do compile { target c++11 } }
+
+class base {};
+class derived : virtual public base {
+public:
+ template<typename Arg>
+ constexpr derived(Arg) {}
+};
+int main() {
+ derived obj(1.);
+}
