On Wed, 26 Feb 2025 at 10:19, Thomas Schwinge wrote:
>
> In particular, 'GLIBCXX_ENABLE_CXX_FLAGS' shouldn't overwrite
> 'EXTRA_CXX_FLAGS'
> (and prepend any additional '--enable-cxx-flags=[...]').
This seems good, but why prepend instead of append here?
If there are important flags passed down from top-level configure that
shouldn't be replaced by the libstdc++ --enable-cxx-flags option, can
we mention that in the new comment in acinclude.m4?
>
> libstdc++-v3/
> * acinclude.m4 (GLIBCXX_ENABLE_CXX_FLAGS): Prepend any additional
> flags to 'EXTRA_CXX_FLAGS'.
> * configure: Regenerate.
> * configure.host: Document 'EXTRA_CFLAGS', 'EXTRA_CXX_FLAGS'.
> ---
> libstdc++-v3/acinclude.m4 | 3 ++-
> libstdc++-v3/configure | 3 ++-
> libstdc++-v3/configure.host | 4 ++++
> 3 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
> index b3423d7957a..3287dab3b89 100644
> --- a/libstdc++-v3/acinclude.m4
> +++ b/libstdc++-v3/acinclude.m4
> @@ -3269,7 +3269,8 @@ AC_DEFUN([GLIBCXX_ENABLE_CXX_FLAGS], [dnl
> done
> fi
>
> - EXTRA_CXX_FLAGS="$enable_cxx_flags"
> + # Prepend the additional flags.
> + EXTRA_CXX_FLAGS="$enable_cxx_flags $EXTRA_CXX_FLAGS"
> AC_MSG_RESULT($EXTRA_CXX_FLAGS)
> AC_SUBST(EXTRA_CXX_FLAGS)
> ])
> diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
> index e115ee55739..ba908577a66 100755
> --- a/libstdc++-v3/configure
> +++ b/libstdc++-v3/configure
> @@ -19452,7 +19452,8 @@ fi
> done
> fi
>
> - EXTRA_CXX_FLAGS="$enable_cxx_flags"
> + # Prepend the additional flags.
> + EXTRA_CXX_FLAGS="$enable_cxx_flags $EXTRA_CXX_FLAGS"
> { $as_echo "$as_me:${as_lineno-$LINENO}: result: $EXTRA_CXX_FLAGS" >&5
> $as_echo "$EXTRA_CXX_FLAGS" >&6; }
>
> diff --git a/libstdc++-v3/configure.host b/libstdc++-v3/configure.host
> index 45f55b250ce..1e84c78af30 100644
> --- a/libstdc++-v3/configure.host
> +++ b/libstdc++-v3/configure.host
> @@ -61,6 +61,10 @@
> #
> # It possibly modifies the following variables:
> #
> +# EXTRA_CFLAGS extra flags to pass when compiling C code
> +#
> +# EXTRA_CXX_FLAGS extra flags to pass when compiling C++ code
> +#
> # OPT_LDFLAGS extra flags to pass when linking the library, of
> # the form '-Wl,blah'
> # (defaults to empty in acinclude.m4)
> --
> 2.34.1
>
