Embedding CFLAGS makes neomutt unreproducible about neomutt HOT 5 CLOSED

Sorry guys, maybe I didn't give the correct context. What triggers the unreproducibility is recording the CFLAGS used at build time in neomutt's binary. This is done in auto.def:

###############################################################################
# Generate conststrings.c
set conststrings "\
  unsigned char cc_cflags\[\] = {[text2c [expr {
    [get-define want-include-path-in-cflags]
    ? [get-define CFLAGS]
    : [lkill [get-define CFLAGS] {{x} {string equal -length 2 $x {-I}}}]
  }]]};\n\
  unsigned char configure_options\[\] = {[text2c $conf_options]};\n"
if {[catch {set fd [open conststrings.c w]
            puts $fd $conststrings
            close $fd} msg]} {
  user-error "Cannot write conststrings.c: $msg"
}

###############################################################################

And used in version.c:

rstrip_in_place((char *) configure_options);
fprintf(fp, "\n\n%sConfigure options:%s %s\n", col_bold, col_end, (char *) configure_options);

rstrip_in_place((char *) cc_cflags);
fprintf(fp, "\n%sCompilation CFLAGS:%s %s\n", col_bold, col_end, (char *) cc_cflags);

fprintf(fp, "\n%s%s%s\n", col_bold, _("Compile options:"), col_end);
print_compile_options(CompOpts, fp);

Since we use -ffile-prefix-map to allow builds to be reproducible, it is recorded in the binary together with other CFLAGS, but since it can be a bit arbitrary (depending on the build path used) it makes the binary unreproducible.

The proposal here is to only remove -ffile-prefix-map=<some-path> from the CFLAGS recorded in the binary, not at all changing the CFLAGS itself during build time.

There is already something like this in auto.def:

# Misc
  include-path-in-cflags=1  => "Remove include paths from CFLAGS in the output of neomutt -v"

So the proposal would be something like:

include-ffile-prefix-map-in-cflags=1  => "Remove -ffile-prefix-map from CFLAGS in the output of neomutt -v"

from neomutt.

he isn't. these are very much part of the build configuration.

from neomutt.

We don't set that cflag ourselves, but we honour whatever cflags the host environment sets. So I guess if you want a reproducible build, you want to make sure that cflags isn't set. I don't think we should try to outsmart whoever builds neomutt by removing cflags.

from neomutt.

given the purpose of -ffile-prefix-map, i'd be a tad surprised if it caused the build to be non-reproducible. if anything, the specified files are incomplete.

from neomutt.

@charles2910 I guess you're also concerned about paths in the configure options section of -v?

Configure options: CC=clang17 CXX=clang++17 --disable-nls --pgp --disable-idn2 --fmemopen --gpgme --lmdb --ssl --pcre2 --with-ssl=/usr/local --with-ncurses=/usr 

from neomutt.