Trouble upgrading gettext and probably other formulae depending on icu4c (ld: library not found for -licuuc)

[stormwatch]

Output of brew config

❯ brew config
Password:
HOMEBREW_VERSION: 4.4.14-16-gddbb497
ORIGIN: https://github.com/Homebrew/brew
HEAD: ddbb497f5ad895e4d400a303bde9c149e9ea7b72
Last commit: 4 hours ago
Branch: master
Core tap JSON: 01 Jan 16:37 UTC
Core cask tap JSON: 01 Jan 16:38 UTC
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CASK_OPTS: ["--fontdir=/Library/Fonts"]
HOMEBREW_MAKE_JOBS: 4
HOMEBREW_SORBET_RUNTIME: set
Homebrew Ruby: 3.3.6 => /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/3.3.6/bin/ruby
CPU: quad-core 64-bit broadwell
Clang: 14.0.0 build 1400
Git: 2.37.1 => /Library/Developer/CommandLineTools/usr/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 12.7.6-x86_64
CLT: 14.2.0.0.1.1668646533
Xcode: N/A

Output of brew doctor

Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: Unbrewed dylibs were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae and may need to be deleted.

Unexpected dylibs:
  /usr/local/lib/libMuseSamplerCoreLib.dylib
  /usr/local/lib/libxml2.2.dylib

Warning: Unbrewed header files were found in /usr/local/include.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae and may need to be deleted.

Unexpected header files:
  /usr/local/include/libxml2/libxml/HTMLparser.h
  /usr/local/include/libxml2/libxml/HTMLtree.h
  /usr/local/include/libxml2/libxml/SAX.h
  /usr/local/include/libxml2/libxml/SAX2.h
  /usr/local/include/libxml2/libxml/c14n.h
  /usr/local/include/libxml2/libxml/catalog.h
  /usr/local/include/libxml2/libxml/chvalid.h
  /usr/local/include/libxml2/libxml/debugXML.h
  /usr/local/include/libxml2/libxml/dict.h
  /usr/local/include/libxml2/libxml/encoding.h
  /usr/local/include/libxml2/libxml/entities.h
  /usr/local/include/libxml2/libxml/globals.h
  /usr/local/include/libxml2/libxml/hash.h
  /usr/local/include/libxml2/libxml/list.h
  /usr/local/include/libxml2/libxml/nanoftp.h
  /usr/local/include/libxml2/libxml/nanohttp.h
  /usr/local/include/libxml2/libxml/parser.h
  /usr/local/include/libxml2/libxml/parserInternals.h
  /usr/local/include/libxml2/libxml/pattern.h
  /usr/local/include/libxml2/libxml/relaxng.h
  /usr/local/include/libxml2/libxml/schemasInternals.h
  /usr/local/include/libxml2/libxml/schematron.h
  /usr/local/include/libxml2/libxml/threads.h
  /usr/local/include/libxml2/libxml/tree.h
  /usr/local/include/libxml2/libxml/uri.h
  /usr/local/include/libxml2/libxml/valid.h
  /usr/local/include/libxml2/libxml/xinclude.h
  /usr/local/include/libxml2/libxml/xlink.h
  /usr/local/include/libxml2/libxml/xmlIO.h
  /usr/local/include/libxml2/libxml/xmlautomata.h
  /usr/local/include/libxml2/libxml/xmlerror.h
  /usr/local/include/libxml2/libxml/xmlexports.h
  /usr/local/include/libxml2/libxml/xmlmemory.h
  /usr/local/include/libxml2/libxml/xmlmodule.h
  /usr/local/include/libxml2/libxml/xmlreader.h
  /usr/local/include/libxml2/libxml/xmlregexp.h
  /usr/local/include/libxml2/libxml/xmlsave.h
  /usr/local/include/libxml2/libxml/xmlschemas.h
  /usr/local/include/libxml2/libxml/xmlschemastypes.h
  /usr/local/include/libxml2/libxml/xmlstring.h
  /usr/local/include/libxml2/libxml/xmlunicode.h
  /usr/local/include/libxml2/libxml/xmlversion.h
  /usr/local/include/libxml2/libxml/xmlwriter.h
  /usr/local/include/libxml2/libxml/xpath.h
  /usr/local/include/libxml2/libxml/xpathInternals.h
  /usr/local/include/libxml2/libxml/xpointer.h

Warning: Unbrewed '.la' files were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae and may need to be deleted.

Unexpected '.la' files:
  /usr/local/lib/libxml2.la

Warning: Unbrewed '.pc' files were found in /usr/local/lib/pkgconfig.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae and may need to be deleted.

Unexpected '.pc' files:
  /usr/local/lib/pkgconfig/libxml-2.0.pc

Warning: You are using macOS 12.
We (and Apple) do not provide support for this old version.
It is expected behaviour that some formulae will fail to build in this old version.
It is expected behaviour that Homebrew will be buggy and slow.
Do not create any issues about this on Homebrew's GitHub repositories.
Do not create any issues even if you think this message is unrelated.
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Try to figure out the problem yourself and submit a fix as a pull request.
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Description of issue

The build process for gettext fails with:

libtool: link: clang -dynamiclib -o .libs/libgettextlib-0.23.1.dylib .libs/libgettextlib_la-access.o .libs/libgettextlib_la-acl-errno-valid.o .libs/libgettextlib_la-acl-internal.o .libs/libgettextlib_la
-get-permissions.o .libs/libgettextlib_la-set-permissions.o .libs/libgettextlib_la-allocator.o .libs/libgettextlib_la-areadlink.o .libs/libgettextlib_la-argmatch.o .libs/libgettextlib_la-arpa_inet.o .libs
/libgettextlib_la-asyncsafe-spin.o .libs/libgettextlib_la-openat-proc.o .libs/libgettextlib_la-backupfile.o .libs/libgettextlib_la-addext.o .libs/libgettextlib_la-basename-lgpl.o .libs/libgettextlib_la-bc
p47.o .libs/libgettextlib_la-binary-io.o .libs/libgettextlib_la-bitrotate.o .libs/libgettextlib_la-btoc32.o .libs/libgettextlib_la-byteswap.o .libs/libgettextlib_la-c-ctype.o .libs/libgettextlib_la-c-strc
asecmp.o .libs/libgettextlib_la-c-strncasecmp.o .libs/libgettextlib_la-c-strcasestr.o .libs/libgettextlib_la-c-strstr.o .libs/libgettextlib_la-c32_apply_type_test.o .libs/libgettextlib_la-c32_get_type_tes
t.o .libs/libgettextlib_la-c32isalnum.o .libs/libgettextlib_la-c32isalpha.o .libs/libgettextlib_la-c32isblank.o .libs/libgettextlib_la-c32iscntrl.o .libs/libgettextlib_la-c32isdigit.o .libs/libgettextlib_
la-c32isgraph.o .libs/libgettextlib_la-c32islower.o .libs/libgettextlib_la-c32isprint.o .libs/libgettextlib_la-c32ispunct.o .libs/libgettextlib_la-c32isspace.o .libs/libgettextlib_la-c32isupper.o .libs/li
bgettextlib_la-c32isxdigit.o .libs/libgettextlib_la-c32tolower.o .libs/libgettextlib_la-c32width.o .libs/libgettextlib_la-canonicalize.o .libs/libgettextlib_la-canonicalize-lgpl.o .libs/libgettextlib_la-c
areadlinkat.o .libs/libgettextlib_la-chdir-long.o .libs/libgettextlib_la-classpath.o .libs/libgettextlib_la-clean-temp.o .libs/libgettextlib_la-clean-temp-simple.o .libs/libgettextlib_la-cloexec.o .libs/l
ibgettextlib_la-closeout.o .libs/libgettextlib_la-concat-filename.o .libs/libgettextlib_la-copy-file.o .libs/libgettextlib_la-copy-file-range.o .libs/libgettextlib_la-csharpcomp.o .libs/libgettextlib_la-c
sharpexec.o .libs/libgettextlib_la-cygpath.o .libs/libgettextlib_la-dirname.o .libs/libgettextlib_la-basename.o .libs/libgettextlib_la-dirname-lgpl.o .libs/libgettextlib_la-stripslash.o .libs/libgettextli
b_la-error.o .libs/libgettextlib_la-error-progname.o .libs/libgettextlib_la-execute.o .libs/libgettextlib_la-exitfail.o .libs/libgettextlib_la-fatal-signal.o .libs/libgettextlib_la-fd-hook.o .libs/libgett
extlib_la-fd-safer-flag.o .libs/libgettextlib_la-dup-safer-flag.o .libs/libgettextlib_la-file-set.o .libs/libgettextlib_la-filenamecat-lgpl.o .libs/libgettextlib_la-findprog.o .libs/libgettextlib_la-findp
rog-in.o .libs/libgettextlib_la-float.o .libs/libgettextlib_la-free.o .libs/libgettextlib_la-fstat.o .libs/libgettextlib_la-fstatat.o .libs/libgettextlib_la-fstrcmp.o .libs/libgettextlib_la-ftell.o .libs/
libgettextlib_la-ftello.o .libs/libgettextlib_la-full-write.o .libs/libgettextlib_la-fwriteerror.o .libs/libgettextlib_la-gcd.o .libs/libgettextlib_la-getcwd.o .libs/libgettextlib_la-getcwd-lgpl.o .libs/l
ibgettextlib_la-getdelim.o .libs/libgettextlib_la-getopt.o .libs/libgettextlib_la-getopt1.o .libs/libgettextlib_la-getrandom.o .libs/libgettextlib_la-gettime.o malloc/.libs/libgettextlib_la-scratch_buffer
grow.o malloc/.libs/libgettextlib_la-scratch_buffer_grow_preserve.o malloc/.libs/libgettextlib_la-scratch_buffer_set_array_size.o .libs/libgettextlib_la-hard-locale.o .libs/libgettextlib_la-hash.o .libs/
libgettextlib_la-hash-pjw.o .libs/libgettextlib_la-hash-triple-simple.o .libs/libgettextlib_la-ialloc.o .libs/libgettextlib_la-javacomp.o .libs/libgettextlib_la-javaexec.o .libs/libgettextlib_la-javaversi
on.o .libs/libgettextlib_la-gl_linked_list.o .libs/libgettextlib_la-gl_linkedhash_list.o .libs/libgettextlib_la-gl_list.o .libs/libgettextlib_la-localcharset.o .libs/libgettextlib_la-localename.o .libs/li
bgettextlib_la-localename-unsafe.o .libs/libgettextlib_la-localename-table.o glthread/.libs/libgettextlib_la-lock.o .libs/libgettextlib_la-lstat.o .libs/libgettextlib_la-malloca.o .libs/libgettextlib_la-m
ath.o .libs/libgettextlib_la-mbchar.o .libs/libgettextlib_la-mbrtoc32.o .libs/libgettextlib_la-mbslen.o .libs/libgettextlib_la-mbsrtoc32s.o .libs/libgettextlib_la-mbsstr.o .libs/libgettextlib_la-mbswidth.
o .libs/libgettextlib_la-mbszero.o .libs/libgettextlib_la-mbuiter.o .libs/libgettextlib_la-mbuiterf.o .libs/libgettextlib_la-mem-hash-map.o .libs/libgettextlib_la-mempcpy.o .libs/libgettextlib_la-memrchr.
o .libs/libgettextlib_la-memset_explicit.o .libs/libgettextlib_la-obstack.o glthread/.libs/libgettextlib_la-once.o .libs/libgettextlib_la-open.o .libs/libgettextlib_la-openat.o .libs/libgettextlib_la-open
at-die.o .libs/libgettextlib_la-omp-init.o .libs/libgettextlib_la-pipe-filter-ii.o .libs/libgettextlib_la-pipe-filter-aux.o .libs/libgettextlib_la-pipe2.o .libs/libgettextlib_la-pipe2-safer.o .libs/libget
textlib_la-spawn.o .libs/libgettextlib_la-spawni.o .libs/libgettextlib_la-spawn_faction_addchdir.o .libs/libgettextlib_la-spawn_faction_addclose.o .libs/libgettextlib_la-spawn_faction_adddup2.o .libs/libg
ettextlib_la-spawn_faction_addopen.o .libs/libgettextlib_la-spawn_faction_destroy.o .libs/libgettextlib_la-spawn_faction_init.o .libs/libgettextlib_la-spawnattr_destroy.o .libs/libgettextlib_la-spawnattr
init.o .libs/libgettextlib_la-spawnattr_setflags.o .libs/libgettextlib_la-spawnattr_setpgroup.o .libs/libgettextlib_la-spawnattr_setsigmask.o .libs/libgettextlib_la-spawnp.o .libs/libgettextlib_la-printf-
frexp.o .libs/libgettextlib_la-printf-frexpl.o .libs/libgettextlib_la-progname.o .libs/libgettextlib_la-propername.o .libs/libgettextlib_la-qcopy-acl.o .libs/libgettextlib_la-quotearg.o .libs/libgettextli
b_la-rawmemchr.o .libs/libgettextlib_la-read-file.o .libs/libgettextlib_la-readlink.o .libs/libgettextlib_la-reallocarray.o .libs/libgettextlib_la-safe-read.o .libs/libgettextlib_la-safe-write.o .libs/lib
gettextlib_la-same-inode.o .libs/libgettextlib_la-save-cwd.o .libs/libgettextlib_la-secure_getenv.o .libs/libgettextlib_la-setlocale.o .libs/libgettextlib_la-setlocale_null.o .libs/libgettextlib_la-setloc
ale-lock.o .libs/libgettextlib_la-setlocale_null-unlocked.o .libs/libgettextlib_la-sf-istream.o .libs/libgettextlib_la-sh-quote.o .libs/libgettextlib_la-sig-handler.o .libs/libgettextlib_la-sockets.o .lib
s/libgettextlib_la-spawn-pipe.o .libs/libgettextlib_la-stat.o .libs/libgettextlib_la-stat-time.o .libs/libgettextlib_la-stdlib.o .libs/libgettextlib_la-strchrnul.o .libs/libgettextlib_la-strerror.o .libs/
libgettextlib_la-strerror-override.o .libs/libgettextlib_la-striconv.o .libs/libgettextlib_la-striconveh.o .libs/libgettextlib_la-striconveha.o .libs/libgettextlib_la-string-buffer.o .libs/libgettextlib_l
a-string-buffer-printf.o .libs/libgettextlib_la-string-desc.o .libs/libgettextlib_la-string-desc-contains.o .libs/libgettextlib_la-strnlen1.o .libs/libgettextlib_la-strtol.o .libs/libgettextlib_la-strtoul
.o .libs/libgettextlib_la-supersede.o .libs/libgettextlib_la-sys_socket.o .libs/libgettextlib_la-tempname.o glthread/.libs/libgettextlib_la-threadlib.o .libs/libgettextlib_la-timespec.o glthread/.libs/lib
gettextlib_la-tls.o .libs/libgettextlib_la-tmpdir.o .libs/libgettextlib_la-trim.o unicase/.libs/libgettextlib_la-cased.o unicase/.libs/libgettextlib_la-ignorable.o unicase/.libs/libgettextlib_la-special-c
asing.o unicase/.libs/libgettextlib_la-tocasefold.o unicase/.libs/libgettextlib_la-u8-casemap.o unilbrk/.libs/libgettextlib_la-lbrktables.o unilbrk/.libs/libgettextlib_la-ulc-common.o uninorm/.libs/libget
textlib_la-decompose-internal.o uninorm/.libs/libgettextlib_la-decomposition-table.o .libs/libgettextlib_la-unistd.o .libs/libgettextlib_la-dup-safer.o .libs/libgettextlib_la-fd-safer.o .libs/libgettextli
b_la-pipe-safer.o .libs/libgettextlib_la-unlink.o .libs/libgettextlib_la-utime.o .libs/libgettextlib_la-utimens.o .libs/libgettextlib_la-vaszprintf.o .libs/libgettextlib_la-aszprintf.o .libs/libgettextlib
_la-vsnzprintf.o .libs/libgettextlib_la-wait-process.o .libs/libgettextlib_la-wctype-h.o .libs/libgettextlib_la-wcwidth.o .libs/libgettextlib_la-wmempcpy.o .libs/libgettextlib_la-xmalloc.o .libs/libgettex
tlib_la-xalloc-die.o .libs/libgettextlib_la-xconcat-filename.o .libs/libgettextlib_la-xerror.o .libs/libgettextlib_la-gl_xlist.o .libs/libgettextlib_la-xmalloca.o .libs/libgettextlib_la-xmemdup0.o .libs/l
ibgettextlib_la-xreadlink.o .libs/libgettextlib_la-xsetenv.o .libs/libgettextlib_la-xsize.o .libs/libgettextlib_la-xstrerror.o .libs/libgettextlib_la-xstriconv.o .libs/libgettextlib_la-xstriconveh.o .libs
/libgettextlib_la-xstring-buffer.o .libs/libgettextlib_la-xstring-buffer-printf.o .libs/libgettextlib_la-xstring-desc.o .libs/libgettextlib_la-xvasprintf.o .libs/libgettextlib_la-xasprintf.o .libs/acl_ent
ries.o .libs/asnprintf.o .libs/fnmatch.o .libs/fopen.o .libs/mbsrtoc32s-state.o .libs/memmem.o .libs/printf-args.o .libs/printf-parse.o .libs/strerror_r.o .libs/strstr.o .libs/vasnprintf.o ../../gettext
-runtime/intl/.libs/libintl.dylib -lpthread -L/usr/local/opt/libunistring/lib -lunistring /usr/local/lib/libxml2.dylib -L/usr/local/opt/libxml2/lib -L/usr/local/opt/readline/lib -L/usr/local/opt/icu4c@76/
lib -L/usr/lib -L/usr/local/Cellar/icu4c@76/76.1_1/lib -lz -licuuc -liconv -g -O2 -Wl,-framework -Wl,CoreFoundation -Wl,-framework -Wl,CoreServices -Wl,-framework -Wl,CoreFoundation -Wl,-framework -Wl,Co
reServices -install_name /usr/local/Cellar/gettext/0.23.1/lib/libgettextlib-0.23.1.dylib -Wl,-single_module
ld: library not found for -licuuc
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[5]: *** [libgettextlib.la] Error 1
make[4]: *** [all] Error 2
make[3]: *** [all-recursive] Error 1
make[2]: *** [all] Error 2
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2

Environment variables

I've set some variables in Fish shell:

set -gx CPPFLAGS "-I/usr/local/opt/libxml2/include -I/usr/local/opt/readline/include -I/usr/local/opt/icu4c@76/include"
set -gx LDFLAGS "-L/usr/local/opt/libxml2/lib -L/usr/local/opt/readline/lib -L/usr/local/opt/icu4c@76/lib"
set -gx PKG_CONFIG_PATH "/usr/local/opt/libxml2/lib/pkgconfig:/usr/local/opt/readline/lib/pkgconfig:/usr/local/opt/icu4c@76/lib/pkgconfig"
set -gx ICU_ROOT /usr/local/opt/icu4c

Aliases

Since this is a shared machine, brew always runs as the original user:
alias brew 'sudo --set-home --preserve-env --user=originalUser brew'.

Just in case I've tested if environment variables are preserved, and they are:

> sudo --set-home --preserve-env --user=originalUser bash -c 'echo $LDFLAGS'
-L/usr/local/opt/libxml2/lib -L/usr/local/opt/readline/lib -L/usr/local/opt/icu4c@76/lib

Things I'm going to try next:

brew reinstall libxml2

I've compiled libxml2 manually because the formula was failing to build, but just tried again and this time it worked. Most likely, this is the source of my problems.

Use the clang provided by brew's llvm

I doubt this would change things.

build gettext manually

Workaround and last resource

[stormwatch]

After reinstalling libxml2 properly via brew reinstall libxml2, brew upgrade gettext worked too.

Moral: Mess with homebrew at your own peril.