https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109876
--- Comment #10 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
So I have
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -27969,6 +27969,13 @@ value_dependent_expression_p (tree expression)
else if (TYPE_REF_P (TREE_TYPE (expression)))
/* FIXME cp_finish_decl doesn't fold reference initializers. */
return true;
+ /* We have a constexpr variable and we're processing a template. When
+ there's lifetime extension involved (for which finish_compound_literal
+ used to create a temporary), we'll not be able to evaluate the
+ variable until instantiating, so pretend it's value-dependent. */
+ else if (DECL_DECLARED_CONSTEXPR_P (expression)
+ && !TREE_CONSTANT (expression))
+ return true;
return false;
case DYNAMIC_CAST_EXPR:
but that breaks
struct foo { };
template <const foo & F> void fnc() { }
void
test()
{
static constexpr foo a;
fnc<a>();
}
with:
$ ./cc1plus -quiet nontype-auto16.C
nontype-auto16.C:6:31: warning: ‘void fnc() [with const foo& F = a]’ used but
never defined
6 | template <const foo & F> void fnc() { }
| ^~~
nontype-auto16.C:13:1: internal compiler error: Segmentation fault
13 | }
| ^
0x19a5624 crash_signal
/home/mpolacek/src/gcc/gcc/toplev.cc:314
0x7fe161facb1f ???
/usr/src/debug/glibc-2.36-9.fc37.x86_64/signal/../sysdeps/unix/sysv/linux/x86_64/libc_sigaction.c:0
0xcbfe74 tree_check(tree_node const*, char const*, int, char const*, tree_code)
/home/mpolacek/src/gcc/gcc/tree.h:3795
0x12c2224 symbol_table::decl_assembler_name_hash(tree_node const*)
/home/mpolacek/src/gcc/gcc/symtab.cc:84
The warning is obviously wrong and the cause for the ICE, I'd say. test isn't
a function template but uses_template_parms / verify_unstripped_args set p_t_d,
so we still reach the new code.
