[Bug c++/100101] New: [11 Regression] ICE with -Wzero-as-null-pointer-constant

[Bug c++/100101] New: [11 Regression] ICE with -Wzero-as-null-pointer-constant

[reichelt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100101

            Bug ID: 100101
           Summary: [11 Regression] ICE with
                    -Wzero-as-null-pointer-constant
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: reichelt at gcc dot gnu.org
  Target Milestone: ---

Compiling the following valid code snippet with
"-Wzero-as-null-pointer-constant" triggers an assertion on trunk.
This is a recent regression from within the last month.

==============================================================================
template <typename T> struct A
{
    template <typename U> static char foo(U*, int* = 0);
    static const bool value = sizeof(foo(static_cast<T*>(nullptr))) > 0;
};

template <bool b> struct B
{
    static const bool value = b;
};

template <typename T> struct C
{
    typedef B<A<T>::value> type;
};

template <typename T>
void bar() noexcept(A<T>::value && C<T>::type::value) {}

void baz()
{
  bar<void>();
}
==============================================================================

'
Internal compiler error: Error reporting routines re-entered.
0x8cfbf8 convert_default_arg(tree_node*, tree_node*, tree_node*, int, int)
        ../../gcc/gcc/cp/call.c:8348
0x8dc177 build_over_call
        ../../gcc/gcc/cp/call.c:9230
0x8da248 build_new_method_call_1
        ../../gcc/gcc/cp/call.c:10783
0x8db2af build_new_method_call(tree_node*, tree_node*, vec<tree_node*, va_gc,
vl_embed>**, tree_node*, int, tree_node**, int)
        ../../gcc/gcc/cp/call.c:10858
0xae76dd finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**, bool,
bool, int)
        ../../gcc/gcc/cp/semantics.c:2751
0xa99115 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        ../../gcc/gcc/cp/pt.c:20484
0xa969ec tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        ../../gcc/gcc/cp/pt.c:19958
0xa957f3 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        ../../gcc/gcc/cp/pt.c:19876
0xaa0e48 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        ../../gcc/gcc/cp/pt.c:19164
0xaaaa06 instantiate_decl(tree_node*, bool, bool)
        ../../gcc/gcc/cp/pt.c:26117
0x98fc9a maybe_instantiate_decl(tree_node*)
        ../../gcc/gcc/cp/decl2.c:5460
0x990ff8 maybe_instantiate_decl(tree_node*)
        ../../gcc/gcc/cp/decl2.c:5663
0x990ff8 mark_used(tree_node*, int)
        ../../gcc/gcc/cp/decl2.c:5689
0xa951f0 tsubst_qualified_id
        ../../gcc/gcc/cp/pt.c:16466
0xa96ee8 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        ../../gcc/gcc/cp/pt.c:19914
0xaa0e48 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        ../../gcc/gcc/cp/pt.c:19164
0xab59ce tsubst_template_args(tree_node*, tree_node*, int, tree_node*)
        ../../gcc/gcc/cp/pt.c:13384
0xabed23 tsubst_aggr_type
        ../../gcc/gcc/cp/pt.c:13587
0xa9dd10 tsubst_decl
        ../../gcc/gcc/cp/pt.c:14847
0xacc3dd instantiate_class_template_1
        ../../gcc/gcc/cp/pt.c:12031
Please submit a full bug report, [etc.]

[Bug c++/100101] [11 Regression] ICE with -Wzero-as-null-pointer-constant

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100101

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |ppalka at gcc dot gnu.org
             Status|UNCONFIRMED                 |NEW
   Target Milestone|---                         |11.0
   Last reconfirmed|                            |2021-04-15
     Ever confirmed|0                           |1

--- Comment #1 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Seems to have started with r11-7953.

[Bug c++/100101] [11 Regression] ICE with -Wzero-as-null-pointer-constant

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100101

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
                 CC|                            |jakub at gcc dot gnu.org

[Bug c++/100101] [11 Regression] ICE with -Wzero-as-null-pointer-constant

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100101

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So maybe find_typenames doesn't want to walk into TYPE_RAISES_EXCEPTIONS?

[Bug c++/100101] [11 Regression] ICE with -Wzero-as-null-pointer-constant

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100101

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
In particular it is the TYPENAME_TYPE type seen in bar's noexcept expression.

Does find_typenames_r ever want to walk into expressions?
I.e. couldn't the fix be
  if (EXPR_P (*tp))
    *walk_subtrees = 0;
?

[Bug c++/100101] [11 Regression] ICE with -Wzero-as-null-pointer-constant

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100101

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jason at gcc dot gnu.org

[Bug c++/100101] [11 Regression] ICE with -Wzero-as-null-pointer-constant

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100101

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
--- gcc/cp/error.c.jj   2021-02-25 23:27:46.561918450 +0100
+++ gcc/cp/error.c      2021-04-15 19:10:38.389850343 +0200
@@ -1554,10 +1554,12 @@ find_typenames_r (tree *tp, int *walk_su
     /* Add the typename without any cv-qualifiers.  */
     mv = TYPE_MAIN_VARIANT (*tp);

-  if (PACK_EXPANSION_P (*tp))
+  if (PACK_EXPANSION_P (*tp) || EXPR_P (*tp))
     {
       /* Don't mess with parameter packs since we don't remember
-        the pack expansion context for a particular typename.  */
+        the pack expansion context for a particular typename.
+        Similarly, don't walk into expressions such as
+        those inside of TYPE_RAISES_EXCEPTIONS.  */
       *walk_subtrees = false;
       return NULL_TREE;
     }
passed make check-c++-all and fixes the testcase.

[Bug c++/100101] [11 Regression] ICE with -Wzero-as-null-pointer-constant

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100101

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:2efbbba16a0630fac8cadcd6d9e0ffaabfadb79f

commit r11-8201-g2efbbba16a0630fac8cadcd6d9e0ffaabfadb79f
Author: Jason Merrill <jason@redhat.com>
Date:   Thu Apr 15 13:38:54 2021 -0400

    c++: noexcept error recursion [PR100101]

    Here instantiating the noexcept-specifier for bar<void>() means
    instantiating A<void>::value, which complains about the conversion from 0
to
    int* in the default argument of foo.  Since my patch for PR99583, printing
    the error context involves looking at C<void>::type, which again wants to
    instantiate A<void>::value, which breaks.  For now at least, let's break
    this recursion by avoiding looking into the noexcept-specifier in
    find_typenames, and limit that to just the uses_parameter_packs case that
    PR99583 cares about.

    gcc/cp/ChangeLog:

            PR c++/100101
            PR c++/99583
            * pt.c (find_parameter_packs_r) [FUNCTION_TYPE]: Walk into
            TYPE_RAISES_EXCEPTIONS here.
            * tree.c (cp_walk_subtrees): Not here.

    gcc/testsuite/ChangeLog:

            PR c++/100101
            * g++.dg/cpp0x/noexcept67.C: New test.

[Bug c++/100101] [11 Regression] ICE with -Wzero-as-null-pointer-constant

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100101

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed.