[GitHub] [arrow] nealrichardson commented on a change in pull request #8756: ARROW-10541: [C++] Add re2 library to core arrow / ARROW_WITH_RE2

[GitBox <gi...@apache.org>]

nealrichardson commented on a change in pull request #8756:
URL: https://github.com/apache/arrow/pull/8756#discussion_r529726847



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File path: cpp/cmake_modules/DefineOptions.cmake
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@@ -363,6 +363,8 @@ if("${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
 
   define_option(ARROW_WITH_UTF8PROC
                 "Build with support for Unicode properties using the utf8proc library" ON)
+  define_option(ARROW_WITH_RE2
+                "Build with support for regular expressions using the re2 library" ON)

Review comment:
       I find this confusing. I understand how it works--if ARROW_COMPUTE is on, these are on too unless you set them to OFF--but it looks like they're always built by default, unlike the compression libs listed above.
   
   Maybe it's irrelevant that it looks confusing here. Or maybe at least we should add a comment here explaining how the default is really ON iff ARROW_COMPUTE is ON too. Or is it possible to define the default option here to be literally whatever ARROW_COMPUTE is, like `define_option(ARROW_WITH_RE2 "..." ARROW_COMPUTE)`?




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