Cabal v2-build: Undefined symbols for architecture x86_64

Question

Cabal suddenly stopped building my project. Nothing much changed in the project itself since the last successful build, I guess only OS updates were installed.

The error I get on cabal v2-build is:

Undefined symbols for architecture x86_64:
  "_u_errorName_70", referenced from:
      ___hs_u_errorName in libHStxt-c-0.7.1.0-21406b30.a(text_icu.o)
  "_ucnv_close_70", referenced from:
      ___hs_ucnv_close in libHStxt-c-0.7.1.0-21406b30.a(text_icu.o)
  "_ucnv_fromUChars_70", referenced from:
      ___hs_ucnv_fromUChars in libHStxt-c-0.7.1.0-21406b30.a(text_icu.o)
  "_ucnv_getMaxCharSize_70", referenced from:
      ___get_max_bytes_for_string in libHStxt-c-0.7.1.0-21406b30.a(text_icu.o)
  "_ucnv_open_70", referenced from:
      ___hs_ucnv_open in libHStxt-c-0.7.1.0-21406b30.a(text_icu.o)
  "_ucnv_setFallback_70", referenced from:
      ___hs_ucnv_setFallback in libHStxt-c-0.7.1.0-21406b30.a(text_icu.o)
  "_ucnv_toUChars_70", referenced from:
      ___hs_ucnv_toUChars in libHStxt-c-0.7.1.0-21406b30.a(text_icu.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
`gcc' failed in phase `Linker'. (Exit code: 1)

Additionally, cabal repl stopped working as well:

<command line>: dlopen(/Users/user/.cabal/store/ghc-8.10.7/lib/libHStxt-c-0.7.1.0-21406b30-ghc8.10.7.dylib, 0x0005): Library not loaded: '/usr/local/opt/icu4c/lib/libicuuc.70.dylib'
  Referenced from: '/Users/user/.cabal/store/ghc-8.10.7/lib/libHStxt-c-0.7.1.0-21406b30-ghc8.10.7.dylib'
  Reason: tried: '/usr/local/opt/icu4c/lib/libicuuc.70.dylib' (no such file), '/usr/local/lib/libicuuc.70.dylib' (no such file), '/usr/lib/libicuuc.70.dylib' (no such file), '/usr/local/Cellar/icu4c/71.1/lib/libicuuc.70.dylib' (no such file), '/usr/local/lib/libicuuc.70.dylib' (no such file), '/usr/lib/libicuuc.70.dylib' (no such file)
Error: cabal: repl failed for exe:appname from
appname-1.0.0

I am on ghc 8.10.7 , macOS Monterey 12.6.1 and cabal --version outputs

cabal-install version 3.8.1.0
compiled using version 3.8.1.0 of the Cabal library

Version of icu4c is 71.1, it is installed using brew .

How could I make the project compile successfully again?

Answer 1

Well, it looks like the text-icu package got built against icu4u version 70, and then your system upgraded to version 71. Unless you feel like downgrading icu4u , you should try deleting the package store (that is, ~/.cabal/store/ghc-<version>/ ). The next run of cabal v2-build in your project will then go and rebuild all its dependencies, including the packages rendered "stale" by your system upgrade. Note that deleting the store may break installed executables.