https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68518
Bug ID: 68518
Summary: ICE on invalid code using lambda in variadic template
in tsubst_copy, at cp/pt.c:12997
Product: gcc
Version: 5.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: Caspar at Kielwein dot de
Target Milestone: ---
Created attachment 36820
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36820&action=edit
preprocessed code that triggers the ice
The following code (with invalid use of constexpr) causes an internal compiler
error.
#include <type_traits>
template<class... dummy> constexpr bool void_check(dummy...) {return 0;}
template<class source_t,class sink_t>
struct connection {
source_t source;
sink_t sink;
template<class param>
auto operator()(const param& p)
-> typename std::enable_if<void_check(source, sink) == 0,
decltype(sink(source(p)))>::type {
return sink(source(p));
}
};
template<class source_t,class sink_t>
auto connect(const source_t& source, const sink_t& sink){
return connection<source_t, sink_t>{source, sink};
}
auto increment = [](int i) -> int {return i+1;};
auto give_one = [](void) ->int {return 1;};
auto one_plus_one = connect(give_one, increment);
I could reproduce it with 4.8, 4.9, 5.2.1 and development snapshot:
gcc version 5.2.1 20151117 (GCC)
both locally and on https://gcc.godbolt.org/
clang rejects the code: error: non-type template argument is not a constant
expression
gcc "-std=gnu++14" -save-temps gcc_bug_check.cpp
gcc_bug_check.cpp: In instantiation of ‘struct connection<<lambda()>,
<lambda(int)> >’:
gcc_bug_check.cpp:20:50: required from ‘auto connect(const source_t&, const
sink_t&) [with source_t = <lambda()>; sink_t = <lambda(int)>]’
gcc_bug_check.cpp:25:48: required from here
gcc_bug_check.cpp:12:40: internal compiler error: in tsubst_copy, at
cp/pt.c:12997
-> typename std::enable_if<void_check(source, sink) == 0,
^
0x657131 tsubst_copy
../../gcc-5-20151117/gcc/cp/pt.c:12997
0x647f68 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
../../gcc-5-20151117/gcc/cp/pt.c:15741
0x6483e1 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
../../gcc-5-20151117/gcc/cp/pt.c:14791
0x648c28 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
../../gcc-5-20151117/gcc/cp/pt.c:14772
0x648831 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
../../gcc-5-20151117/gcc/cp/pt.c:15523
0x649185 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
../../gcc-5-20151117/gcc/cp/pt.c:15234
0x649047 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
../../gcc-5-20151117/gcc/cp/pt.c:14931
0x650562 tsubst_expr
../../gcc-5-20151117/gcc/cp/pt.c:14553
0x6514ec tsubst_template_arg
../../gcc-5-20151117/gcc/cp/pt.c:9811
0x655b99 tsubst_template_args
../../gcc-5-20151117/gcc/cp/pt.c:10372
0x6560c4 tsubst_aggr_type
../../gcc-5-20151117/gcc/cp/pt.c:10569
0x64ad69 tsubst(tree_node*, tree_node*, int, tree_node*)
../../gcc-5-20151117/gcc/cp/pt.c:12543
0x65549b tsubst_function_type
../../gcc-5-20151117/gcc/cp/pt.c:11739
0x64b174 tsubst(tree_node*, tree_node*, int, tree_node*)
../../gcc-5-20151117/gcc/cp/pt.c:12482
0x6578de tsubst_decl
../../gcc-5-20151117/gcc/cp/pt.c:10960
0x64b484 tsubst(tree_node*, tree_node*, int, tree_node*)
../../gcc-5-20151117/gcc/cp/pt.c:11955
0x6582cf tsubst_decl
../../gcc-5-20151117/gcc/cp/pt.c:10807
0x64b484 tsubst(tree_node*, tree_node*, int, tree_node*)
../../gcc-5-20151117/gcc/cp/pt.c:11955
0x662db1 instantiate_class_template_1
../../gcc-5-20151117/gcc/cp/pt.c:9470
0x662db1 instantiate_class_template(tree_node*)
../../gcc-5-20151117/gcc/cp/pt.c:9792
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
