http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57240
Bug ID: 57240
Summary: decltype() on a template non-type parameter causes
"internal compiler error"
Product: gcc
Version: 4.8.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: scottbaldwin at gmail dot com
GCC 4.8.x (4.8.0 and 4.8.1-20130427) have an "internal compiler error" when
decltype()'s argument is a template non-type parameter.
The following code is a simple demo of the bug. The demo also includes a
"workaround" to show the issue does not occur when the non-type parameter is
"converted" to an equivalent value (i.e., something that is no longer a
template non-type parameter).
---
template<typename _fptype>
struct FuncPointerType { // wrap a function pointer type (for demo
purposes)
typedef _fptype type;
};
void some_func() {} // some function w/ signature of void(void)
template< void(*func_ptr)(void) >
void bug_demo()
{
// crashes w/ "internal compiler error"
using FPT = FuncPointerType< decltype(func_ptr) >; // crashes compiler
in 4.8.0/4.8.1 (works in 4.7.2)
// workaround (if uncommented): pass decltype() an equivalent value
that is not a template nontype parameter
//auto fp = func_ptr;
//using FPT = FuncPointerType< decltype(fp) >; // works fine now
// next line should output "[1]" (if correct)
std::cout << "[" << std::is_same<typename FPT::type,
void(*)(void)>::value << "]" << std::endl;
}
int main() {
bug_demo<some_func>();
return 0;
}
------------
[gcc 4.8.1]
------------
make[1]: compiling [sandbox_cpp11.cpp] (gcc 4.8.1 20130427)
g++ -c sandbox_cpp11.cpp -o dbg-mt/sandbox_cpp11.o -pthread -Wall -Werror
-Wno-unused -Wno-unused-variable -std=c++11 -rdynamic -g3 -O0 -m64 -D__64BIT__
-I./dbg-mt -I. -I.
sandbox_cpp11.cpp: In instantiation of ‘void gcc_bug_demo_1::bug_demo()
[with void (* func_ptr)() = gcc_bug_demo_1::some_func]’:
sandbox_cpp11.cpp:71:23: required from here
sandbox_cpp11.cpp:57:52: internal compiler error: in finish_decltype_type,
at cp/semantics.c:5373
using FPT = FuncPointerType< decltype(func_ptr) >; // crashes compiler
in 4.8.0/4.8.1 (works in 4.7.2)
^
0x5a3680 finish_decltype_type(tree_node*, bool, int)
../../srcdir/gcc/cp/semantics.c:5373
0x5157d0 tsubst(tree_node*, tree_node*, int, tree_node*)
../../srcdir/gcc/cp/pt.c:11812
0x51b352 tsubst_template_args
../../srcdir/gcc/cp/pt.c:9630
0x522010 tsubst_aggr_type
../../srcdir/gcc/cp/pt.c:9827
0x515d45 tsubst(tree_node*, tree_node*, int, tree_node*)
../../srcdir/gcc/cp/pt.c:11190
0x523d36 tsubst_decl
../../srcdir/gcc/cp/pt.c:10648
0x516087 tsubst(tree_node*, tree_node*, int, tree_node*)
../../srcdir/gcc/cp/pt.c:11111
0x518eea tsubst_expr
../../srcdir/gcc/cp/pt.c:12894
0x518cdc tsubst_expr
../../srcdir/gcc/cp/pt.c:12843
0x518f80 tsubst_expr
../../srcdir/gcc/cp/pt.c:13033
0x518433 instantiate_decl(tree_node*, int, bool)
../../srcdir/gcc/cp/pt.c:18910
0x52cb8b instantiate_pending_templates(int)
../../srcdir/gcc/cp/pt.c:19009
0x5445bf cp_write_global_declarations()
../../srcdir/gcc/cp/decl2.c:4043
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.
make[1]: *** [dbg-mt/sandbox_cpp11.o] Error 1
make: *** [objs] Error 2
------------
[gcc 4.8.0]
------------
make[1]: compiling [sandbox_cpp11.cpp] (gcc 4.8.0)
g++ -c sandbox_cpp11.cpp -o dbg-mt/sandbox_cpp11.o -pthread -Wall -Werror
-Wno-unused -Wno-unused-variable -std=c++11 -rdynamic -g3 -O0 -m64 -D__64BIT__
-I./dbg-mt -I. -I.
sandbox_cpp11.cpp: In instantiation of ‘void gcc_bug_demo_1::bug_demo()
[with void (* func_ptr)() = gcc_bug_demo_1::some_func]’:
sandbox_cpp11.cpp:71:23: required from here
sandbox_cpp11.cpp:57:52: internal compiler error: in finish_decltype_type,
at cp/semantics.c:5365
using FPT = FuncPointerType< decltype(func_ptr) >; // crashes compiler
in 4.8.0/4.8.1 (works in 4.7.2)
^
0x5a2ac0 finish_decltype_type(tree_node*, bool, int)
../../srcdir/gcc/cp/semantics.c:5365
0x51e50c tsubst(tree_node*, tree_node*, int, tree_node*)
../../srcdir/gcc/cp/pt.c:11772
0x5217c2 tsubst_template_args
../../srcdir/gcc/cp/pt.c:9607
0x524000 tsubst_aggr_type
../../srcdir/gcc/cp/pt.c:9804
0x51de20 tsubst(tree_node*, tree_node*, int, tree_node*)
../../srcdir/gcc/cp/pt.c:11160
0x51cb16 tsubst_decl
../../srcdir/gcc/cp/pt.c:10625
0x51e157 tsubst(tree_node*, tree_node*, int, tree_node*)
../../srcdir/gcc/cp/pt.c:11081
0x51927a tsubst_expr
../../srcdir/gcc/cp/pt.c:12853
0x51906c tsubst_expr
../../srcdir/gcc/cp/pt.c:12802
0x519310 tsubst_expr
../../srcdir/gcc/cp/pt.c:12992
0x5187c3 instantiate_decl(tree_node*, int, bool)
../../srcdir/gcc/cp/pt.c:18854
0x52d40b instantiate_pending_templates(int)
../../srcdir/gcc/cp/pt.c:18953
0x54416f cp_write_global_declarations()
../../srcdir/gcc/cp/decl2.c:4025
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.
make[1]: *** [dbg-mt/sandbox_cpp11.o] Error 1
make: *** [objs] Error 2
