https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68049
Bug ID: 68049
Summary: template instantiation involving may_alias defines
symbol twice
Product: gcc
Version: 5.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: kretz at kde dot org
Target Milestone: ---
The following testcase fails to compile at -O0, but works at -O1 and higher
(-std=c++11 is the only required compiler flag):
template <typename T> struct Bar
{
using type = T;
};
template <typename T> struct Foo
{
typedef typename Bar<T>::type alias_type [[gnu::may_alias]];
alias_type operator()() { return {}; }
};
template <typename T> void print(T) {}
int main()
{
print(Foo<int>()());
print(0);
return 0;
}
The template instantiation of print(T) is done twice:
/tmp/ccDEkoML.s: Assembler messages:
/tmp/ccDEkoML.s:69: Error: symbol `_Z5printIiEvT_' is already defined
With a recent GCC 6 snapshot I get:
failure.cpp:19:1: error: Two symbols with same comdat_group are not linked by
the same_comdat_group list.
}
^
_Z5printIiEvT_/3 (void print(T) [with T = int]) @0x7faa000d75c0
Type: function definition analyzed
Visibility: public weak comdat comdat_group:_Z5printIiEvT_ one_only
previous sharing asm name: 2
References:
Referring:
First run: 0
Function flags: body
Called by: main/0 (1.00 per call)
Calls:
_Z5printIiEvT_/2 (void print(T) [with T = Bar<int>::type]) @0x7faa000d7450
Type: function definition analyzed
Visibility: public weak comdat comdat_group:_Z5printIiEvT_ one_only
next sharing asm name: 3
References:
Referring:
First run: 0
Function flags: body
Called by: main/0 (1.00 per call)
Calls:
failure.cpp:19:1: internal compiler error: symtab_node::verify failed
0x90a6e9 symtab_node::verify_symtab_nodes()
../.././gcc/symtab.c:1126
0x91d3d5 symbol_table::compile()
../.././gcc/cgraphunit.c:2377
0x920162 symbol_table::compile()
../.././gcc/cgraphunit.c:2536
0x920162 symbol_table::finalize_compilation_unit()
../.././gcc/cgraphunit.c:2562
