[Bug c++/104197] New: clang: gcc/cp/pt.cc:28481:19: warning: predefined identifier is only valid inside function [-Wpredefined-identifier-outside-function]

[Bug c++/104197] New: clang: gcc/cp/pt.cc:28481:19: warning: predefined identifier is only valid inside function [-Wpredefined-identifier-outside-function]

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104197

            Bug ID: 104197
           Summary: clang: gcc/cp/pt.cc:28481:19: warning: predefined
                    identifier is only valid inside function
                    [-Wpredefined-identifier-outside-function]
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
                CC: ppalka at gcc dot gnu.org
  Target Milestone: ---

I noticed the following new warning by clang:

/home/marxin/Programming/gcc/gcc/cp/pt.cc:28481:19: warning: predefined
identifier is only valid inside function
[-Wpredefined-identifier-outside-function]
             int level = current_template_depth + 1)
                         ^
/home/marxin/Programming/gcc/gcc/cp/cp-tree.h:1903:29: note: expanded from
macro 'current_template_depth'
  (current_template_parms ? TMPL_PARMS_DEPTH (current_template_parms) : 0)
                            ^
/home/marxin/Programming/gcc/gcc/cp/cp-tree.h:3802:38: note: expanded from
macro 'TMPL_PARMS_DEPTH'
  ((HOST_WIDE_INT) TREE_INT_CST_LOW (TREE_PURPOSE (NODE)))
                                     ^
/home/marxin/Programming/gcc/gcc/tree.h:1098:29: note: expanded from macro
'TREE_PURPOSE'
#define TREE_PURPOSE(NODE) (TREE_LIST_CHECK (NODE)->list.purpose)
                            ^
./tree-check.h:8:28: note: expanded from macro 'TREE_LIST_CHECK'
#define TREE_LIST_CHECK(t)      TREE_CHECK (t, TREE_LIST)
                                ^
/home/marxin/Programming/gcc/gcc/tree.h:252:39: note: expanded from macro
'TREE_CHECK'
(tree_check ((T), __FILE__, __LINE__, __FUNCTION__, (CODE)))
                                      ^
Is it something we should care about, or is it a false alarm?

[Bug c++/104197] clang: gcc/cp/pt.cc:28481:19: warning: predefined identifier is only valid inside function [-Wpredefined-identifier-outside-function]

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104197

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So the error message comes from the following:

int tree_check(int, int, const char*);
int g(int t = tree_check(1, 1, __FUNCTION__));

[Bug c++/104197] clang: gcc/cp/pt.cc:28481:19: warning: predefined identifier is only valid inside function [-Wpredefined-identifier-outside-function]

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104197

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |build, internal-improvement
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-01-24
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=30811
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Found the bug which talks about how we should be rejecting this PR 30811.

So this is a correct warning which we should deal with.

Confirmed.

[Bug c++/104197] [12 Regression] clang: gcc/cp/pt.cc:28481:19: warning: predefined identifier is only valid inside function [-Wpredefined-identifier-outside-function]

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104197

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |12.0
            Summary|clang:                      |[12 Regression] clang:
                   |gcc/cp/pt.cc:28481:19:      |gcc/cp/pt.cc:28481:19:
                   |warning: predefined         |warning: predefined
                   |identifier is only valid    |identifier is only valid
                   |inside function             |inside function
                   |[-Wpredefined-identifier-ou |[-Wpredefined-identifier-ou
                   |tside-function]             |tside-function]

[Bug c++/104197] [12 Regression] clang: gcc/cp/pt.cc:28481:19: warning: predefined identifier is only valid inside function [-Wpredefined-identifier-outside-function]

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104197

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Something like this will fix the warning:
apinski@xeond:~/src/upstream-gcc-git/gcc/gcc/cp$ git diff
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index bba62a5800a..33969fc646c 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -28477,9 +28477,13 @@ make_args_non_dependent (vec<tree, va_gc> *args)
    by default.  If set_canonical is true, we set TYPE_CANONICAL on it.  */

 static tree
-make_auto_1 (tree name, bool set_canonical,
-            int level = current_template_depth + 1)
+make_auto_1 (tree name, bool set_canonical, bool level0 = false)
 {
+  int level;
+  if (!level0)
+    level = current_template_depth + 1;
+  else
+    level = 0;
   tree au = cxx_make_type (TEMPLATE_TYPE_PARM);
   TYPE_NAME (au) = build_decl (input_location, TYPE_DECL, name, au);
   TYPE_STUB_DECL (au) = TYPE_NAME (au);
@@ -28514,7 +28518,7 @@ make_auto (void)
 tree
 make_template_placeholder (tree tmpl)
 {
-  tree t = make_auto_1 (auto_identifier, false, /*level=*/0);
+  tree t = make_auto_1 (auto_identifier, false, /*level0=*/true);
   CLASS_PLACEHOLDER_TEMPLATE (t) = tmpl;
   /* Our canonical type depends on the placeholder.  */
   TYPE_CANONICAL (t) = canonical_type_parameter (t);

[Bug c++/104197] [12 Regression] clang: gcc/cp/pt.cc:28481:19: warning: predefined identifier is only valid inside function [-Wpredefined-identifier-outside-function]

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104197

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I should mention the use of __FUNCTION__ inside the default argument is
rejected by MSVC which is why I have marked it as a build failure.

[Bug c++/104197] [12 Regression] clang: gcc/cp/pt.cc:28481:19: warning: predefined identifier is only valid inside function [-Wpredefined-identifier-outside-function]

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104197

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1

[Bug c++/104197] [12 Regression] clang: gcc/cp/pt.cc:28481:19: warning: predefined identifier is only valid inside function [-Wpredefined-identifier-outside-function]

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104197

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

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

[Bug c++/104197] [12 Regression] clang: gcc/cp/pt.cc:28481:19: warning: predefined identifier is only valid inside function [-Wpredefined-identifier-outside-function]

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104197

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

https://gcc.gnu.org/g:b1aa2a3cf1ba233ccd5a49fde85a2ca7e5f620e9

commit r12-6847-gb1aa2a3cf1ba233ccd5a49fde85a2ca7e5f620e9
Author: Patrick Palka <ppalka@redhat.com>
Date:   Mon Jan 24 11:47:13 2022 -0500

    c++: Fix non-portable default argument of make_auto_1 [PR104197]

    Avoid using the macro current_template_depth, which expands to an
    expression that uses __FUNCTION__, within the signature of a function.

            PR c++/104197

    gcc/cp/ChangeLog:

            * pt.cc (make_auto_1): Use -1 as a placeholder default argument
            for level.

[Bug c++/104197] [12 Regression] clang: gcc/cp/pt.cc:28481:19: warning: predefined identifier is only valid inside function [-Wpredefined-identifier-outside-function]

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104197

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

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

--- Comment #6 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed.