Skip to content

gh-96821: Check for -fstrict-overflow only if --with-strict-overflow is passed #139595

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
StanFromIreland wants to merge 4 commits into
base: main
Choose a base branch
from
Open

gh-96821: Check for -fstrict-overflow only if --with-strict-overflow is passed #139595

Show file tree
Hide file tree
Changes from 2 commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
d6448fd
Commit
StanFromIreland Oct 5, 2025
a4180ed
make regen-configure again
StanFromIreland Oct 5, 2025
c5db991
Use `AX_CHECK_COMPILE_FLAG`
StanFromIreland Mar 9, 2026
efc2137
Merge branch 'main' into refactor-autoconf
StanFromIreland Mar 9, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
49 changes: 28 additions & 21 deletions configure
View file
Open in desktop

Some generated files are not rendered by default. Learn more about how customized files appear on GitHub.

55 changes: 29 additions & 26 deletions configure.ac
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2221,28 +2221,6 @@ AC_MSG_RESULT([$BOLT_APPLY_FLAGS])
# compiler and platform. BASECFLAGS tweaks need to be made even if the
# user set OPT.

dnl Historically, some of our code assumed that signed integer overflow
dnl is defined behaviour via twos-complement.
dnl Set STRICT_OVERFLOW_CFLAGS and NO_STRICT_OVERFLOW_CFLAGS depending on compiler support.
dnl Pass the latter to modules that depend on such behaviour.
_SAVE_VAR([CFLAGS])
CFLAGS="-fstrict-overflow -fno-strict-overflow"
AC_CACHE_CHECK([if $CC supports -fstrict-overflow and -fno-strict-overflow],
[ac_cv_cc_supports_fstrict_overflow],
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM([[]], [[]])],
[ac_cv_cc_supports_fstrict_overflow=yes],
[ac_cv_cc_supports_fstrict_overflow=no]
)
)
_RESTORE_VAR([CFLAGS])

AS_VAR_IF([ac_cv_cc_supports_fstrict_overflow], [yes],
[STRICT_OVERFLOW_CFLAGS="-fstrict-overflow"
NO_STRICT_OVERFLOW_CFLAGS="-fno-strict-overflow"],
[STRICT_OVERFLOW_CFLAGS=""
NO_STRICT_OVERFLOW_CFLAGS=""])

AC_MSG_CHECKING([for --with-strict-overflow])
AC_ARG_WITH([strict-overflow],
AS_HELP_STRING(
Expand All @@ -2251,12 +2229,37 @@ AC_ARG_WITH([strict-overflow],
),
[
AS_VAR_IF(
[ac_cv_cc_supports_fstrict_overflow], [no],
[AC_MSG_WARN([--with-strict-overflow=yes requires a compiler that supports -fstrict-overflow])],
[]
[with_strict_overflow], [yes],
[dnl Historically, some of our code assumed that signed integer overflow
dnl is defined behaviour via twos-complement.
dnl Set STRICT_OVERFLOW_CFLAGS and NO_STRICT_OVERFLOW_CFLAGS depending on compiler support.
dnl Pass the latter to modules that depend on such behaviour.
_SAVE_VAR([CFLAGS])
CFLAGS="-fstrict-overflow -fno-strict-overflow"
AC_CACHE_CHECK([if $CC supports -fstrict-overflow and -fno-strict-overflow],
[ac_cv_cc_supports_fstrict_overflow],
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM([[]], [[]])],
[ac_cv_cc_supports_fstrict_overflow=yes],
[ac_cv_cc_supports_fstrict_overflow=no]
)
)

@erlend-aasland erlend-aasland Mar 8, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

We should be fine with using AX_CHECK_COMPILE_FLAG here. (I don't remember why I did not recommend that when we added this code.)

@StanFromIreland StanFromIreland Mar 9, 2026

Copy link
Copy Markdown
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Are you suggesting we just check -fstrict-overflow? Currently it checks both -fstrict-overflow and -fno-strict-overflow.

@StanFromIreland StanFromIreland Mar 9, 2026

Copy link
Copy Markdown
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Using AX_CHECK_COMPILE_FLAG makes it more complicated to follow IMO, but I pushed the change.

@erlend-aasland erlend-aasland May 6, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Sorry, I should've been more specific. Currently, we check for the compile flag first, then we check for the configure flag. Now, you've embedded the compile check into the configure flag check. I suggest keeping the original structure. We should be able to use AX_CHECK_COMPILE_FLAG to check for the compile flag(s), and then use those results when we check for the configure flag.

_RESTORE_VAR([CFLAGS])

AS_VAR_IF([ac_cv_cc_supports_fstrict_overflow], [yes],
[STRICT_OVERFLOW_CFLAGS="-fstrict-overflow"
NO_STRICT_OVERFLOW_CFLAGS="-fno-strict-overflow"],
[AC_MSG_WARN([--with-strict-overflow=yes requires a compiler that supports -fstrict-overflow])
STRICT_OVERFLOW_CFLAGS=""
NO_STRICT_OVERFLOW_CFLAGS=""])
],
[STRICT_OVERFLOW_CFLAGS=""
NO_STRICT_OVERFLOW_CFLAGS="-fno-strict-overflow"]
)
],
[with_strict_overflow=no]
[with_strict_overflow=no
STRICT_OVERFLOW_CFLAGS=""
NO_STRICT_OVERFLOW_CFLAGS="-fno-strict-overflow"]
)
AC_MSG_RESULT([$with_strict_overflow])

Expand Down
Loading