On 3/3/23 10:18, Jakub Jelinek wrote:
On Thu, Mar 02, 2023 at 11:48:04AM -0500, Jason Merrill wrote:
The stmtexpr19.C testcase used to be rejected as it has a static
variable in statement expression in constexpr context, but as that
static variable is initialized by constant expression, when P2647R1
was implemented we agreed to make it valid.
Now, as reported, the testcase compiles fine, but doesn't actually link
because the static variable isn't defined anywhere, and with -flto ICEs
because of this problem. This is because we never
varpool_node::finalize_decl those vars, the constant expression in which
the DECL_EXPR is present for the static VAR_DECL is folded (constant
evaluated) into just the address of the VAR_DECL.
Would it make sense to define it when we see the DECL_EXPR in constant
evaluation?
So like this?
OK, thanks.
Passes GXX_TESTSUITE_STDS=98,11,14,17,20,2b make check-g++ so far.
2023-03-03 Jakub Jelinek <ja...@redhat.com>
PR c++/108702
* constexpr.cc: Include toplev.h.
(cxx_eval_constant_expression) <case DECL_EXPR>: When seeing a local
static initialized by constant expression outside of a constexpr
function which has been deferred by make_rtl_for_nonlocal_decl,
call rest_of_decl_compilation on it.
* g++.dg/ext/stmtexpr19.C: Use dg-do link rather than dg-do compile.
--- gcc/cp/constexpr.cc.jj 2023-03-03 00:34:44.113679918 +0100
+++ gcc/cp/constexpr.cc 2023-03-03 13:26:57.602871900 +0100
@@ -40,6 +40,7 @@ along with GCC; see the file COPYING3.
#include "attribs.h"
#include "fold-const.h"
#include "intl.h"
+#include "toplev.h"
static bool verify_constant (tree, bool, bool *, bool *);
#define VERIFY_CONSTANT(X) \
@@ -7127,6 +7128,24 @@ cxx_eval_constant_expression (const cons
break;
}
+ /* make_rtl_for_nonlocal_decl could have deferred emission of
+ a local static var, but if it appears in a statement expression
+ which is constant expression evaluated to e.g. just the address
+ of the variable, its DECL_EXPR will never be seen during
+ gimple lowering's record_vars_into as the statement expression
+ will not be in the IL at all. */
+ if (VAR_P (r)
+ && TREE_STATIC (r)
+ && !DECL_REALLY_EXTERN (r)
+ && DECL_FUNCTION_SCOPE_P (r)
+ && !var_in_maybe_constexpr_fn (r)
+ && decl_constant_var_p (r))
+ {
+ varpool_node *node = varpool_node::get (r);
+ if (node == NULL || !node->definition)
+ rest_of_decl_compilation (r, 0, at_eof);
+ }
+
if (AGGREGATE_TYPE_P (TREE_TYPE (r))
|| VECTOR_TYPE_P (TREE_TYPE (r)))
{
--- gcc/testsuite/g++.dg/ext/stmtexpr19.C.jj 2023-02-09 15:52:29.623359240
+0100
+++ gcc/testsuite/g++.dg/ext/stmtexpr19.C 2023-03-03 12:24:20.217186735
+0100
@@ -1,6 +1,6 @@
// PR c++/81073
// { dg-options "" }
-// { dg-do compile { target c++11 } }
+// { dg-do link { target c++11 } }
struct test { const int *addr; };
Jakub
