https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89761
Bug ID: 89761
Summary: [9.0 Regression] ICE: tree check: expected class
'expression', have 'exceptional'
(argument_pack_select)
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: leni536 at gmail dot com
Target Milestone: ---
The following code triggers an ICE in g++ 9.0.1:
template <int...> struct seq {};
template <bool> struct S {
template <typename Args>
constexpr static void call(Args&&...) {}
};
template <int ...Idx,typename ...Args>
auto foo (seq<Idx...>, Args&& ...args) {
return (S<Idx==sizeof...(args)>::call(args), ...);
}
void bar() {
foo(seq<0,1,2>{}, 1,2,3);
}
I'm not sure about the validity of the code above.
Tested on godbolt.org with "-std=c++17" flag:
<source>: In instantiation of 'auto foo(seq<Idx ...>, Args&& ...) [with int
...Idx = {0, 1, 2}; Args = {int, int, int}]':
<source>:13:28: required from here
<source>:9:20: internal compiler error: tree check: expected class
'expression', have 'exceptional' (argument_pack_select) in tree_operand_check,
at tree.h:3674
9 | return (S<Idx==sizeof...(args)>::call(args), ...);
| ^~~~~~~~~~~~~~~
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://gcc.gnu.org/bugs/> for instructions.
Version:
g++ (Compiler-Explorer-Build) 9.0.1 20190316 (experimental)
