AIX build breaks with "field 'dtoa' has incomplete type"

[ayappanec]

Bug report

Bug description:

AIX build starts failing with the below error recently. Looks like some recent commits introduced some changes which caused the issue I guess.

gcc -pthread -c -fno-strict-overflow -Wimplicit-fallthrough -fstack-protector-strong -Wtrampolines -Wsign-compare -DNDEBUG -g -O3 -Wall -std=c11 -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wstrict-prototypes -Werror=implicit-function-declaration -fvisibility=hidden -I./Include/internal -I./Include/internal/mimalloc -I. -I./Include -DPy_BUILD_CORE -o Parser/pegen.o Parser/pegen.c
In file included from ./Include/internal/pycore_runtime.h:17,
 from ./Include/internal/pycore_pystate.h:12,
 from Parser/pegen.c:3:
./Include/internal/pycore_interp.h:246:24: error: field 'dtoa' has incomplete type
 246 | struct _dtoa_state dtoa;
 | ^~~~
gmake: *** [Makefile:3035: Parser/pegen.o] Error 1

CPython versions tested on:

CPython main branch

Operating systems tested on:

Other

Linked PRs

• gh-121045: Use link test to check whether -fstack-protector-strong works #121258

[ronaldoussoren]

This is a duplicate of #119447

[ayappanec]

The actual problem here is that check for "x87-style double rounding" is failed ( which sets X87_DOUBLE_ROUNDING and that in turn sets _PY_SHORT_FLOAT_REPR to 0).

Check for "x87-style double rounding" is failed because gcc compiler don't support "-fstack-protector-strong" in AIX.
configure:23929: gcc -pthread -maix64 -fno-strict-overflow -fstack-protector-strong -Wtrampolines -Wsign-compare -o conftest conftest.c -lintl -ldl >&5
collect2: fatal error: library libssp_nonshared not found
compilation terminated.
configure:23929: $? = 1

Even though there is configure check for "-fstack-protector-strong" , it actually requires a link/run test rather than a compile test.
configure:9610: checking whether C compiler accepts -fstack-protector-strong
configure:9630: gcc -pthread -maix64 -c -Werror -fstack-protector-strong conftest.c >&5
configure:9630: $? = 0
configure:9639: result: yes

The simple fix here would be to change "ac_fn_c_try_compile" to "ac_fn_c_try_run" for "-fstack-protector-strong" test. I will send a PR soon for this.

Issue #119447 is with xlc compiler. There also I see the check for "x87-style double rounding" failing which could be for a different reason because "-fstack-protector-strong" is not introduced that time.

[ayappanec]

I see #120975 introduced "-fstack-protector-strong" through AX_CHECK_COMPILE_FLAG in configure.ac. Any option to make it as run/link (-o) test rather than compile (-c) test through Autoconf macro ?. I am not sure whether we can use AX_CHECK_LINK_FLAG.