Install icu4c version 63 with Homebrew

brew 管理多版本php时, 遇到icu4c版本过高导致php@56无法正常启动, 报错信息:

dyld: Library not loaded: /usr/local/opt/icu4c/lib/libicui18n.64.dylib
  Referenced from: /usr/local/opt/php@5.6/sbin/php-fpm
  Reason: image not found

在stackoverflow找到类似解决方法如下:

把下文中63版本改成这次报错的64版本即可解决

https://stackoverflow.com/questions/55826221/install-icu4c-version-63-with-homebrew

Solution:

1) cd to Homebrew's formula directory

cd $(brew --prefix)/Homebrew/Library/Taps/homebrew/homebrew-core/Formula

2) Find desired commit (version 63 for icu4c) to checkout

git log --follow icu4c.rb

3) Checkout to a new branch

git checkout -b icu4c-63 e7f0f10dc63b1dc1061d475f1a61d01b70ef2cb7

4) Reinstall the library with the new version

brew reinstall ./icu4c.rb

5) Switch to the reinstalled version

brew switch icu4c 63.1

6) Checkout back to master

git checkout master

Sources:

Homebrew install specific version of formula?

http://hanxue-it.blogspot.com/2018/08/macos-homebrew-installing-older-version-of-software.html

Bonus for those who ended up using this more than once:

# zsh
function hiicu63() {
  local last_dir=$(pwd)

  cd $(brew --prefix)/Homebrew/Library/Taps/homebrew/homebrew-core/Formula
  git checkout icu4c-63
  brew reinstall ./icu4c.rb
  brew switch icu4c 63.1
  git checkout master

  cd $last_dir
}