The installer uses v55.1:

https://github.com/libbitcoin/libbitcoin/blob/master/install.sh#L36

I'm not sure if this is the absolute minimum. The dependency is indirect
(via boost), and I don't recall what is documented or if I tested all
available options. But I usually do attempt to work with the lowest
possible dependency version.

However, the version itself may not be sufficient. I had little luck
getting preinstalled versions of ICU to work on either OSX or Ubuntu. On
Windows boost uses native Unicode features, so there is no ICU
dependency.) It seems that the normalization features are not always
installed.

Compounding this issue is that boost ICU discovery is a bit of a hack,
and it assumes an ICU directory structure that's outdated. There is a
hack (to the boost installer) in the install.sh to overcome this.

Compounding this even further is that the boost-locale build with ICU
required, will compile even if these normalization APIs are missing. And
then invoking the boost normalization API will also succeed, but it will
not perform the normalization - just passing the text straight thorough.
So we have a unit test to verify, bust also a first-run test to ensure
the API is linked and working properly. Otherwise people could lose
money by mismatching passphrases in the case where they didn't
run/notice unit test failures.

I spent at least a week on getting the ICU dependency reliable on across
all platforms. It's a nightmare I don't plan to revisit for some time :).

e

On 12/14/2015 09:53 AM, mlmikael wrote:
> (As for me I use http://icu-project.org/apiref/icu4c/ version 55.1 .)
>
> On 2015-12-15 01:46, mlmikael wrote:
>> "libbitcoin"'s README.md mentions that libICU is "not typically
>> preinstalled at a sufficient level".
>>
>> (https://github.com/libbitcoin/libbitcoin/blob/version2/README.md)
>>
>> How can I determine if my OS' bundled libICU is satisfactory?
>>
>> Thanks!
>> Mlmikael
>>
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