[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662 Jakub Jelinek changed: What|Removed |Added Status|REOPENED|RESOLVED Resolution|--- |FIXED --- Comment #13 from Jakub Jelinek --- Fixed for 7.4+.
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662 --- Comment #12 from Jakub Jelinek --- Author: jakub Date: Fri Jun 22 21:23:03 2018 New Revision: 261962 URL: https://gcc.gnu.org/viewcvs?rev=261962&root=gcc&view=rev Log: Backported from mainline 2018-06-22 Jakub Jelinek PR c++/85662 * g++.dg/ext/offsetof3.C: New test. 2018-05-10 Jakub Jelinek PR c++/85662 * c-common.h (fold_offsetof_1): Removed. (fold_offsetof): Add TYPE argument defaulted to size_type_node and CTX argument defaulted to ERROR_MARK. * c-common.c (fold_offsetof_1): Renamed to ... (fold_offsetof): ... this. Remove wrapper function. Add TYPE argument, convert the pointer constant to TYPE and use size_binop with PLUS_EXPR instead of fold_build_pointer_plus if type is not a pointer type. Adjust recursive calls. * c-fold.c (c_fully_fold_internal): Use fold_offsetof rather than fold_offsetof_1, pass TREE_TYPE (expr) as TYPE to it and drop the fold_convert_loc. * c-typeck.c (build_unary_op): Use fold_offsetof rather than fold_offsetof_1, pass argtype as TYPE to it and drop the fold_convert_loc. * cp-gimplify.c (cp_fold): Use fold_offsetof rather than fold_offsetof_1, pass TREE_TYPE (x) as TYPE to it and drop the fold_convert. * g++.dg/ext/offsetof2.C: New test. Added: branches/gcc-7-branch/gcc/testsuite/g++.dg/ext/offsetof2.C branches/gcc-7-branch/gcc/testsuite/g++.dg/ext/offsetof3.C Modified: branches/gcc-7-branch/gcc/c-family/ChangeLog branches/gcc-7-branch/gcc/c-family/c-common.c branches/gcc-7-branch/gcc/c-family/c-common.h branches/gcc-7-branch/gcc/c/ChangeLog branches/gcc-7-branch/gcc/c/c-fold.c branches/gcc-7-branch/gcc/c/c-typeck.c branches/gcc-7-branch/gcc/cp/ChangeLog branches/gcc-7-branch/gcc/cp/cp-gimplify.c branches/gcc-7-branch/gcc/testsuite/ChangeLog
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662 --- Comment #11 from Jakub Jelinek --- Author: jakub Date: Fri Jun 22 17:26:44 2018 New Revision: 261910 URL: https://gcc.gnu.org/viewcvs?rev=261910&root=gcc&view=rev Log: PR c++/85662 * g++.dg/ext/offsetof3.C: New test. Added: branches/gcc-8-branch/gcc/testsuite/g++.dg/ext/offsetof3.C Modified: branches/gcc-8-branch/gcc/testsuite/ChangeLog
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662 --- Comment #10 from Jakub Jelinek --- Author: jakub Date: Fri Jun 22 17:22:43 2018 New Revision: 261909 URL: https://gcc.gnu.org/viewcvs?rev=261909&root=gcc&view=rev Log: PR c++/85662 * g++.dg/ext/offsetof3.C: New test. Added: trunk/gcc/testsuite/g++.dg/ext/offsetof3.C Modified: trunk/gcc/testsuite/ChangeLog
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662
roland at gnu dot org changed:
What|Removed |Added
Status|RESOLVED|REOPENED
Resolution|FIXED |---
--- Comment #9 from roland at gnu dot org ---
Both my original test case and Jakub's smaller case do hit the bug in gcc 7.
I just tested the current gcc-7-branch: commit
c66c7f7b6f41118cef03ece0c367554eb38c3d65
On x86_64-linux-gnu:
$ ../../gcc/configure --enable-languages=c,c++,lto
$ make all-gcc
$ ./gcc/xgcc -Bgcc/ -O2 -S bar.cc
bar.cc:3:1: error: non-constant condition for static assertion
static_assert (__builtin_offsetof (T, f.x[31 - 1]) == __builtin_offsetof (T,
f.x[30]), "");
^
bar.cc:3:1: error: value ‘8’ of type ‘T*’ is not a constant expression
[Exit 1]
$ cat bar.cc
struct S { unsigned long x[31]; };
struct T { bool b; S f; };
static_assert (__builtin_offsetof (T, f.x[31 - 1]) == __builtin_offsetof (T,
f.x[30]), "");
$
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662 Jakub Jelinek changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED --- Comment #8 from Jakub Jelinek --- Fixed for 8.2+. As I said, can't reproduce with GCC 7.
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662 --- Comment #7 from Jakub Jelinek --- Author: jakub Date: Wed May 30 07:20:58 2018 New Revision: 260916 URL: https://gcc.gnu.org/viewcvs?rev=260916&root=gcc&view=rev Log: Backported from mainline 2018-05-10 Jakub Jelinek PR c++/85662 * c-common.h (fold_offsetof_1): Removed. (fold_offsetof): Add TYPE argument defaulted to size_type_node and CTX argument defaulted to ERROR_MARK. * c-common.c (fold_offsetof_1): Renamed to ... (fold_offsetof): ... this. Remove wrapper function. Add TYPE argument, convert the pointer constant to TYPE and use size_binop with PLUS_EXPR instead of fold_build_pointer_plus if type is not a pointer type. Adjust recursive calls. * c-fold.c (c_fully_fold_internal): Use fold_offsetof rather than fold_offsetof_1, pass TREE_TYPE (expr) as TYPE to it and drop the fold_convert_loc. * c-typeck.c (build_unary_op): Use fold_offsetof rather than fold_offsetof_1, pass argtype as TYPE to it and drop the fold_convert_loc. * cp-gimplify.c (cp_fold): Use fold_offsetof rather than fold_offsetof_1, pass TREE_TYPE (x) as TYPE to it and drop the fold_convert. * g++.dg/ext/offsetof2.C: New test. Added: branches/gcc-8-branch/gcc/testsuite/g++.dg/ext/offsetof2.C Modified: branches/gcc-8-branch/gcc/c-family/ChangeLog branches/gcc-8-branch/gcc/c-family/c-common.c branches/gcc-8-branch/gcc/c-family/c-common.h branches/gcc-8-branch/gcc/c/ChangeLog branches/gcc-8-branch/gcc/c/c-fold.c branches/gcc-8-branch/gcc/c/c-typeck.c branches/gcc-8-branch/gcc/cp/ChangeLog branches/gcc-8-branch/gcc/cp/cp-gimplify.c branches/gcc-8-branch/gcc/testsuite/ChangeLog
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662 --- Comment #6 from roland at gnu dot org --- Thanks for the fix. What's the status on backporting this to 8 and/or 7?
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662 --- Comment #5 from Jakub Jelinek --- Author: jakub Date: Thu May 10 17:40:28 2018 New Revision: 260119 URL: https://gcc.gnu.org/viewcvs?rev=260119&root=gcc&view=rev Log: PR c++/85662 * c-common.h (fold_offsetof_1): Removed. (fold_offsetof): Add TYPE argument defaulted to size_type_node and CTX argument defaulted to ERROR_MARK. * c-common.c (fold_offsetof_1): Renamed to ... (fold_offsetof): ... this. Remove wrapper function. Add TYPE argument, convert the pointer constant to TYPE and use size_binop with PLUS_EXPR instead of fold_build_pointer_plus if type is not a pointer type. Adjust recursive calls. * c-fold.c (c_fully_fold_internal): Use fold_offsetof rather than fold_offsetof_1, pass TREE_TYPE (expr) as TYPE to it and drop the fold_convert_loc. * c-typeck.c (build_unary_op): Use fold_offsetof rather than fold_offsetof_1, pass argtype as TYPE to it and drop the fold_convert_loc. * cp-gimplify.c (cp_fold): Use fold_offsetof rather than fold_offsetof_1, pass TREE_TYPE (x) as TYPE to it and drop the fold_convert. * g++.dg/ext/offsetof2.C: New test. Added: trunk/gcc/testsuite/g++.dg/ext/offsetof2.C Modified: trunk/gcc/c-family/ChangeLog trunk/gcc/c-family/c-common.c trunk/gcc/c-family/c-common.h trunk/gcc/c/ChangeLog trunk/gcc/c/c-fold.c trunk/gcc/c/c-typeck.c trunk/gcc/cp/ChangeLog trunk/gcc/cp/cp-gimplify.c trunk/gcc/testsuite/ChangeLog
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662 Richard Biener changed: What|Removed |Added Keywords||rejects-valid Priority|P3 |P2
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662 --- Comment #4 from roland at gnu dot org --- That fix (applied to trunk) works for my test case and for the original real-world case I reduced it from. Will it be backported to 7 and 8? Thanks for the quick work as usual, Jakub!
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662 Jakub Jelinek changed: What|Removed |Added Status|NEW |ASSIGNED Assignee|unassigned at gcc dot gnu.org |jakub at gcc dot gnu.org --- Comment #3 from Jakub Jelinek --- Created attachment 44076 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44076&action=edit gcc8-pr85662.patch Untested fix.
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662
Jakub Jelinek changed:
What|Removed |Added
CC||jason at gcc dot gnu.org
--- Comment #2 from Jakub Jelinek ---
In any case, I think the problem is related to the delayed folding, C++
constexpr handling not liking pointer constants and fold_offsetof_1 done as
pointer addition rather than integer addition. With delayed folding and
fold_build_pointer_plus called by fold_offsetof_1 the nested expressions aren't
really folded. We could easily fix it up by doing a cp_fold (together with
recursive cp_fold_r though, because cp_fold isn't fully recursive) on the
result of fold_offsetof in the C++ FE, that way we'd get a constant whenever
possible.
On the other side, we wouldn't then reject __builtin_offsetof used with not
valid constexpr expressions in the second argument (say out of bound array
access etc. subtracted from itself).
Say:
constexpr int a[5];
struct S { int b, c[5]; };
constexpr int d = __builtin_offsetof (S, c[(&a[6] - &a[6]) + 2]);
Another possibility is in fold_offsetof_1, if we detect the TREE_CONSTANT base,
if it is a pointer typed INTEGER_CST, build corresponding sizetype INTEGER_CST
instead and use normal PLUS_EXPR folding (or do we actually want any folding at
all?) instead of fold_build_pointer_plus.
[Bug c++/85662] [8/9 Regression] "error: non-constant condition for static assertion" from __builtin_offsetof in C++
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85662
Jakub Jelinek changed:
What|Removed |Added
Status|UNCONFIRMED |NEW
Last reconfirmed||2018-05-05
CC||jakub at gcc dot gnu.org
Version|unknown |8.0
Target Milestone|--- |8.2
Summary|regression since 6: "error: |[8/9 Regression] "error:
|non-constant condition for |non-constant condition for
|static assertion" from |static assertion" from
|__builtin_offsetof in C++ |__builtin_offsetof in C++
Ever confirmed|0 |1
--- Comment #1 from Jakub Jelinek ---
Weird, I can only reproduce it starting with r247495 and can't reproduce with
gcc 7.
Better testcase that doesn't really depend on the actual structure layout and
sizes:
struct S { unsigned long x[31]; };
struct T { bool b; S f; };
static_assert (__builtin_offsetof (T, f.x[31 - 1]) == __builtin_offsetof (T,
f.x[30]), "");
Using 30 instead of 31-1 makes it go away, and the problem is that something
creates or keeps around 8 as pointer constant.
