[Bug bootstrap/111852] New: [14 regression] r14-4339-geaa41a6dc127d8 breaks building with gcc 4.8.5

[Bug bootstrap/111852] New: [14 regression] r14-4339-geaa41a6dc127d8 breaks building with gcc 4.8.5

[seurer at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111852

            Bug ID: 111852
           Summary: [14 regression] r14-4339-geaa41a6dc127d8  breaks
                    building with gcc 4.8.5
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: seurer at gcc dot gnu.org
  Target Milestone: ---

g:eaa41a6dc127d8d8a38646aaadc37681691fc311, r14-4339-geaa41a6dc127d8 

As indicated in
https://gcc.gnu.org/pipermail/gcc-patches/2023-October/632008.html this patch
breaks building with gcc 4.8.5.


commit eaa41a6dc127d8d8a38646aaadc37681691fc311 (HEAD)
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Fri Sep 29 17:55:12 2023 +0100

    Remove poly_int_pod

g++ -v
gcc version 4.8.5 20150623 (Red Hat 4.8.5-44) (GCC) 


g++ -std=gnu++11  -fno-PIE -c   -g -O2     -DIN_GCC    -fno-exceptions
-fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings
-Wcast-qual -Wmissing-format-attribute -Woverloaded-virtual -pedantic
-Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -fno-common 
-DHAVE_CONFIG_H -fno-PIE -I. -I. -I/home/seurer/gcc/git/gcc-test/gcc
-I/home/seurer/gcc/git/gcc-test/gcc/.
-I/home/seurer/gcc/git/gcc-test/gcc/../include 
-I/home/seurer/gcc/git/gcc-test/gcc/../libcpp/include
-I/home/seurer/gcc/git/gcc-test/gcc/../libcody
-I/home/seurer/gcc/git/build/gcc-test/./gmp -I/home/seurer/gcc/git/gcc-test/gmp
-I/home/seurer/gcc/git/build/gcc-test/./mpfr/src
-I/home/seurer/gcc/git/gcc-test/mpfr/src
-I/home/seurer/gcc/git/gcc-test/mpc/src 
-I/home/seurer/gcc/git/gcc-test/gcc/../libdecnumber
-I/home/seurer/gcc/git/gcc-test/gcc/../libdecnumber/dpd -I../libdecnumber
-I/home/seurer/gcc/git/gcc-test/gcc/../libbacktrace
-I/home/seurer/gcc/git/build/gcc-test/./isl/include
-I/home/seurer/gcc/git/gcc-test/isl/include  -o insn-automata.o -MT
insn-automata.o -MMD -MP -MF ./.deps/insn-automata.TPo insn-automata.cc
In file included from insn-automata.cc:14:0:
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:66:26: warning: 'rtx_def::code' is too
small to hold all values of 'enum rtx_code' [enabled by default]
 #define RTX_CODE_BITSIZE 8
                          ^
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:318:33: note: in expansion of macro
'RTX_CODE_BITSIZE'
   ENUM_BITFIELD(rtx_code) code: RTX_CODE_BITSIZE;
                                 ^
g++ -std=gnu++11  -fno-PIE -c   -g -O2     -DIN_GCC    -fno-exceptions
-fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings
-Wcast-qual -Wmissing-format-attribute -Woverloaded-virtual -pedantic
-Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -fno-common 
-DHAVE_CONFIG_H -fno-PIE -I. -I. -I/home/seurer/gcc/git/gcc-test/gcc
-I/home/seurer/gcc/git/gcc-test/gcc/.
-I/home/seurer/gcc/git/gcc-test/gcc/../include 
-I/home/seurer/gcc/git/gcc-test/gcc/../libcpp/include
-I/home/seurer/gcc/git/gcc-test/gcc/../libcody
-I/home/seurer/gcc/git/build/gcc-test/./gmp -I/home/seurer/gcc/git/gcc-test/gmp
-I/home/seurer/gcc/git/build/gcc-test/./mpfr/src
-I/home/seurer/gcc/git/gcc-test/mpfr/src
-I/home/seurer/gcc/git/gcc-test/mpc/src 
-I/home/seurer/gcc/git/gcc-test/gcc/../libdecnumber
-I/home/seurer/gcc/git/gcc-test/gcc/../libdecnumber/dpd -I../libdecnumber
-I/home/seurer/gcc/git/gcc-test/gcc/../libbacktrace
-I/home/seurer/gcc/git/build/gcc-test/./isl/include
-I/home/seurer/gcc/git/gcc-test/isl/include  -o cse.o -MT cse.o -MMD -MP -MF
./.deps/cse.TPo /home/seurer/gcc/git/gcc-test/gcc/cse.cc
In file included from /home/seurer/gcc/git/gcc-test/gcc/cse.cc:25:0:
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:66:26: warning: 'rtx_def::code' is too
small to hold all values of 'enum rtx_code' [enabled by default]
 #define RTX_CODE_BITSIZE 8
                          ^
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:318:33: note: in expansion of macro
'RTX_CODE_BITSIZE'
   ENUM_BITFIELD(rtx_code) code: RTX_CODE_BITSIZE;
                                 ^
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:66:26: warning:
'qty_table_elem::comparison_code' is too small to hold all values of 'enum
rtx_code' [enabled by default]
 #define RTX_CODE_BITSIZE 8
                          ^
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:252:45: note: in expansion of macro
'RTX_CODE_BITSIZE'
   ENUM_BITFIELD(rtx_code) comparison_code : RTX_CODE_BITSIZE;
                                             ^
/home/seurer/gcc/git/gcc-test/gcc/cse.cc: In function 'void
add_to_set(vec<set>*, rtx)':
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::rtl' [-Wmissing-field-initializers]
   struct set entry = {};
                       ^
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::src' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::src_elt' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::src_hash' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::dest_hash' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::inner_dest' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::src_in_memory' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::src_volatile' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::mode' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::src_const_hash' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::src_const' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::src_const_elt' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4236:23: warning: missing initializer
for member 'set::dest_addr_elt' [-Wmissing-field-initializers]
/home/seurer/gcc/git/gcc-test/gcc/cse.cc: In function 'void
cse_insn(rtx_insn*)':
/home/seurer/gcc/git/gcc-test/gcc/cse.cc:4954:19: error: use of deleted
function 'rtx_def::rtx_def()'
    struct rtx_def memory_extend_buf;
                   ^
In file included from /home/seurer/gcc/git/gcc-test/gcc/cse.cc:25:0:
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:313:38: note: 'rtx_def::rtx_def()' is
implicitly deleted because the default definition would be ill-formed:
      chain_prev ("RTX_PREV (&%h)"))) rtx_def {
                                      ^
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:313:38: error: use of deleted function
'rtx_def::u::u()'
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:445:9: note: 'rtx_def::u::u()' is
implicitly deleted because the default definition would be ill-formed:
   union u {
         ^
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:445:9: error: use of deleted function
'rtunion::rtunion()'
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:203:7: note: 'rtunion::rtunion()' is
implicitly deleted because the default definition would be ill-formed:
 union rtunion
       ^
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:207:15: error: union member
'rtunion::rt_subreg' with non-trivial 'poly_int<N, T>::poly_int() [with
unsigned int N = 1u; C = short unsigned int]'
   poly_uint16 rt_subreg;
               ^
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:445:9: error: use of deleted function
'block_symbol::block_symbol()'
   union u {
         ^
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:237:16: note:
'block_symbol::block_symbol()' is implicitly deleted because the default
definition would be ill-formed:
 struct GTY(()) block_symbol {
                ^
/home/seurer/gcc/git/gcc-test/gcc/rtl.h:237:16: error: use of deleted function
'rtunion::rtunion()'
make[2]: *** [cse.o] Error 1

[Bug bootstrap/111852] [14 regression] r14-4339-geaa41a6dc127d8 breaks building with gcc 4.8.5

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111852

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sayle at gcc dot gnu.org
   Target Milestone|---                         |14.0

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
There's a duplicate and a patch floating around.

[Bug bootstrap/111852] [14 regression] r14-4339-geaa41a6dc127d8 breaks building with gcc 4.8.5

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111852

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

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

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Reduced testcase
struct poly_int {
  poly_int() = default;
  template <typename> poly_int();
};
union rtunion {
  poly_int rt_subregrt_rtx;
};
struct rtx_def {
  rtunion fld;
};
void cse_insn() { rtx_def memory_extend_buf; }
which got fixed with r5-3834 as part of PR63362 fix.

[Bug bootstrap/111852] [14 regression] r14-4339-geaa41a6dc127d8 breaks building with gcc 4.8.5

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111852

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:bc4bd69faf986326f6b0fd0400cdd6871577afd1

commit r14-4722-gbc4bd69faf986326f6b0fd0400cdd6871577afd1
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Oct 18 17:01:26 2023 +0200

    cse: Workaround GCC < 5 bug in cse_insn [PR111852]

    Before the r5-3834 commit for PR63362, GCC 4.8-4.9 refuses to compile
    cse.cc which contains a variable with rtx_def type, because rtx_def
    contains a union with poly_uint16 element.  poly_int template has
    defaulted default constructor and a variadic template constructor which
    could have empty parameter pack. GCC < 5 treated it as non-trivially
    constructible class and deleted rtunion and rtx_def default constructors.

    For the cse_insn purposes, all we need is a variable with size and
alignment
    of rtx_def, not necessarily rtx_def itself, which we then memset to 0 and
    fill in like rtx is normally allocated from heap, so this patch for
    GCC_VERSION < 5000 uses an unsigned char array of the right size/alignment.

    2023-10-18  Jakub Jelinek  <jakub@redhat.com>

            PR bootstrap/111852
            * cse.cc (cse_insn): Add workaround for GCC 4.8-4.9, instead of
            using rtx_def type for memory_extend_buf, use unsigned char
            arrayy with size of rtx_def and its alignment.

[Bug bootstrap/111852] [14 regression] r14-4339-geaa41a6dc127d8 breaks building with gcc 4.8.5

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111852

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

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

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Should be worked around now.

[Bug bootstrap/111852] [14 regression] r14-4339-geaa41a6dc127d8 breaks building with gcc 4.8.5

[seurer at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111852

--- Comment #5 from seurer at gcc dot gnu.org ---
Yup, thanks!

In another 4.8.5 breakage PR someone mentioned removing that as the minimum
required compiler level.  Has there been any more discussion of that?

[Bug bootstrap/111852] [14 regression] r14-4339-geaa41a6dc127d8 breaks building with gcc 4.8.5

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111852

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
In several gcc ml (or gcc-patches, don't remember) threads it was discussed
whether we should switch to C++14 as the implementation language, that would
bump to the bootstrap compiler requirement to GCC 5 (core language features,
maybe GCC 6 if we need full library side, certainly GCC 6 switched to
-std=gnu++14 by default).
Today on IRC this was discussed again, and I think Richi proposed switching
just for GCC 15, not 14.