Bootstrap fail, gcc-13-20221030 on macOS 13

[Simon Wright <simon.j.wright@mac.com>]

The boot compiler is GCC 12.1.0.

Configuration fails because the C compiler can’t produce an executable. I don’t have the log, but the errors were like

configure:3943: gcc -c -g  conftest.c >&5
<built-in>: error: unknown value '13.0.0' of '-mmacosx-version-min'

I tried setting CFLAGS and CXXFLAGS as here:

export CFLAGS=-mmacosx-version-min=12.0.0
export CXXFLAGS=-mmacosx-version-min=12.0.0

$GCC_SRC/configure                                                      \
  --prefix=$PREFIX                                                      \
  --without-libiconv-prefix                                             \
  --disable-libmudflap                                                  \
  --disable-libstdcxx-pch                                               \
  --disable-libsanitizer                                                \
  --disable-libcc1                                                      \
  --disable-libcilkrts                                                  \
  --disable-multilib                                                    \
  --disable-nls                                                         \
  --enable-languages=c,c++,ada                                          \
  --host=$BUILD                                                         \
  --target=$BUILD                                                       \
  --build=$BUILD                                                        \
  --without-isl                                                         \
  --with-build-sysroot="$(xcrun --show-sdk-path)"                       \
  --with-sysroot=                                                       \
  --with-specs="%{!sysroot=*:--sysroot=%:if-exists-else($XCODE $CLU)}"  \
  --with-build-config=no                                                \
  --enable-bootstrap                                                    \
  CFLAGS=-mmacosx-version-min=12.0.0                                    \
  CXXFLAGS=-mmacosx-version-min=12.0.0 

(having checked that this flag was needed to avoid the error in a standard-alone compilation) but the configure now failed in fixincludes/. It seems that sometimes the CFLAGS setting is used and sometimes it isn’t??? See lines 3674, 3744, 3800, 3857, 3905 below and then 3943

configure:3652: checking whether the C compiler works
configure:3674: gcc -mmacosx-version-min=12.0.0   conftest.c  >&5
configure:3678: $? = 0
configure:3726: result: yes
configure:3729: checking for C compiler default output file name
configure:3731: result: a.out
configure:3737: checking for suffix of executables
configure:3744: gcc -o conftest -mmacosx-version-min=12.0.0   conftest.c  >&5
configure:3748: $? = 0
configure:3770: result: 
configure:3792: checking whether we are cross compiling
configure:3800: gcc -o conftest -mmacosx-version-min=12.0.0   conftest.c  >&5
configure:3804: $? = 0
configure:3811: ./conftest
configure:3815: $? = 0
configure:3830: result: no
configure:3835: checking for suffix of object files
configure:3857: gcc -c -mmacosx-version-min=12.0.0  conftest.c >&5
configure:3861: $? = 0
configure:3882: result: o
configure:3886: checking whether we are using the GNU C compiler
configure:3905: gcc -c -mmacosx-version-min=12.0.0  conftest.c >&5
configure:3905: $? = 0
configure:3914: result: yes
configure:3923: checking whether gcc accepts -g
configure:3943: gcc -c -g  conftest.c >&5
<built-in>: error: unknown value '13.0.0' of '-mmacosx-version-min'
configure:3943: $? = 1
configure: failed program was:
| /* confdefs.h */
| #define PACKAGE_NAME "fixincludes"
| #define PACKAGE_TARNAME "fixincludes"
| #define PACKAGE_VERSION " "
| #define PACKAGE_STRING "fixincludes  "
| #define PACKAGE_BUGREPORT ""
| #define PACKAGE_URL ""
| /* end confdefs.h.  */
| 
| int
| main ()
| {
| 
|   ;
|   return 0;
| }