https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114091
Bug ID: 114091
Summary: gcc/config/aarch64/aarch64.cc has code requiring c++14
instead of c++11, so g++14 bootsrap fails in my
example context
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: markmigm at gmail dot com
Target Milestone: ---
[I'm not sure where gcc/config/aarch64/aarch64.cc fits in the
component alternatives. Feel free to correct that if I got it
wrong.]
gcc bootstrap is based on c++11, which predates the constructors for pair
being constexpr. The gcc/config/aarch64/aarch64.cc specific code can fail
because of using pair constructors where constant expressions are required:
/wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/config/aarch64/aarch64.cc:13095:50:
error: constexpr variable 'tiles' must be initialized by a constant expression
static constexpr std::pair<unsigned int, char> tiles[] = {
^ ~
/wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/config/aarch64/aarch64.cc:13096:5:
note: non-constexpr constructor 'pair<int, char, nullptr>' cannot be used in a
constant expression
{ 0xff, 'b' },
^
This stops the bootstrap in the example context.
This is detected when clang is doing the bootstrapping on FreeBSD.
For reference:
c++ -std=c++11 -fPIC -c -g -DIN_GCC -fno-strict-aliasing -fno-exceptions
-fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings
-Wcast-qual -Wno-format -Wmissing-format-attribute -Wconditionally-supported
-Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros
-Wno-overlength-strings -fno-common -DHAVE_CONFIG_H -fPIC -I. -I.
-I/wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc
-I/wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/.
-I/wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/../include
-I/wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/../libcpp/include
-I/wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/../libcody
-I/usr/local/include
-I/wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/../libdecnumber
-I/wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/../libdecnumber/bid
-I../libdecnumber
-I/wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/../libbacktrace
-DLIBICONV_PLUG -o aarch64.o -MT aarch64.o -MMD -MP -MF ./.deps/aarch64.TPo
/wrkdirs/usr/ports/lang/gcc14-devel/work/gcc-14-20240114/gcc/config/aarch64/aarch64.cc
where clang used its libc++ (its a FreeBSD context):
/usr/include/c++/v1/__utility/pair.h:225:5: note: declared here
225 | pair(_U1&& __u1, _U2&& __u2)
| ^
having -std=c++11 on the command line. That results in lack of
constexpr status in libc++ .
It would appear that until gcc bootstrap intends on being based on
c++14 (or later) that the gcc/config/aarch64/aarch64.cc code
reported is presuming a post-c++11 context when it should not be.
