On 7/20/23 15:51, Marek Polacek wrote:
On Thu, Jul 20, 2023 at 02:37:07PM -0400, Jason Merrill wrote:
On 7/20/23 14:13, Marek Polacek wrote:
On Wed, Jul 19, 2023 at 10:11:27AM -0400, Patrick Palka wrote:
On Tue, 18 Jul 2023, Marek Polacek via Gcc-patches wrote:
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk and branches?
Looks reasonable to me.
Thanks.
Though I wonder if we could also fix this by not checking potentiality
at all in this case? The problematic call to is_rvalue_constant_expression
happens from cp_parser_constant_expression with 'allow_non_constant' != 0
and with 'non_constant_p' being a dummy out argument that comes from
cp_parser_functional_cast, so the result of is_rvalue_constant_expression
is effectively unused in this case, and we should be able to safely elide
it when 'allow_non_constant && non_constant_p == nullptr'.
Sounds plausible. I think my patch could be applied first since it
removes a tiny bit of code, then I can hopefully remove the flag below,
then maybe go back and optimize the call to is_rvalue_constant_expression.
Does that sound sensible?
Relatedly, ISTM the member cp_parser::non_integral_constant_expression_p
is also effectively unused and could be removed?
It looks that way. Seems it's only used in cp_parser_constant_expression:
10806 if (allow_non_constant_p)
10807 *non_constant_p = parser->non_integral_constant_expression_p;
but that could be easily replaced by a local var. I'd be happy to see if
we can actually do away with it. (I wonder why it was introduced and when
it actually stopped being useful.)
It was for the C++98 notion of constant-expression, which was more of a
parser-level notion, and has been supplanted by the C++11 version. I'm
happy to remove it, and therefore remove the is_rvalue_constant_expression
call.
Wonderful. I'll do that next.
-- >8 --
is_really_empty_class is liable to crash when it gets an incomplete
or dependent type. Since r11-557, we pass the yet-uninstantiated
class type S<0> of the PARM_DECL s to is_really_empty_class -- because
of the potential_rvalue_constant_expression -> is_rvalue_constant_expression
change in cp_parser_constant_expression. Here we're not parsing
a template so we did not check COMPLETE_TYPE_P as we should.
PR c++/110106
gcc/cp/ChangeLog:
* constexpr.cc (potential_constant_expression_1): Check COMPLETE_TYPE_P
even when !processing_template_decl.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/noexcept80.C: New test.
---
gcc/cp/constexpr.cc | 2 +-
gcc/testsuite/g++.dg/cpp0x/noexcept80.C | 12 ++++++++++++
2 files changed, 13 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept80.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 6e8f1c2b61e..1f59c5472fb 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -9116,7 +9116,7 @@ potential_constant_expression_1 (tree t, bool want_rval,
bool strict, bool now,
if (now && want_rval)
{
tree type = TREE_TYPE (t);
- if ((processing_template_decl && !COMPLETE_TYPE_P (type))
+ if (!COMPLETE_TYPE_P (type)
|| dependent_type_p (type)
There shouldn't be a problem completing the type here, so it seems to me
that we're missing a call to complete_type_p, at least when
!processing_template_decl. Probably need to move the dependent_type_p check
up as a result.
Like so?
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
OK.
-- >8 --
is_really_empty_class is liable to crash when it gets an incomplete
or dependent type. Since r11-557, we pass the yet-uninstantiated
class type S<0> of the PARM_DECL s to is_really_empty_class -- because
of the potential_rvalue_constant_expression -> is_rvalue_constant_expression
change in cp_parser_constant_expression. Here we're not parsing
a template so we did not check COMPLETE_TYPE_P as we should.
It should work to complete the type before checking COMPLETE_TYPE_P.
PR c++/110106
gcc/cp/ChangeLog:
* constexpr.cc (potential_constant_expression_1): Try to complete the
type when !processing_template_decl.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/noexcept80.C: New test.
---
gcc/cp/constexpr.cc | 5 +++--
gcc/testsuite/g++.dg/cpp0x/noexcept80.C | 12 ++++++++++++
2 files changed, 15 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/noexcept80.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 6e8f1c2b61e..fb94f3cefcb 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -9116,8 +9116,9 @@ potential_constant_expression_1 (tree t, bool want_rval,
bool strict, bool now,
if (now && want_rval)
{
tree type = TREE_TYPE (t);
- if ((processing_template_decl && !COMPLETE_TYPE_P (type))
- || dependent_type_p (type)
+ if (dependent_type_p (type)
+ || !COMPLETE_TYPE_P (processing_template_decl
+ ? type : complete_type (type))
|| is_really_empty_class (type, /*ignore_vptr*/false))
/* An empty class has no data to read. */
return true;
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept80.C
b/gcc/testsuite/g++.dg/cpp0x/noexcept80.C
new file mode 100644
index 00000000000..3e90af747e2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept80.C
@@ -0,0 +1,12 @@
+// PR c++/110106
+// { dg-do compile { target c++11 } }
+
+template<int> struct S
+{
+};
+
+struct G {
+ G(S<0>);
+};
+
+void y(S<0> s) noexcept(noexcept(G{s}));
base-commit: 4b8878fbf7b74ea5c3405c9f558df0517036f131
