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    Suggestion 
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    Resolution: Fixed
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    P3: Somewhat important 
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    None
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    None
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    None
config.summary currently has this output for modules in qtbase:
Qt modules and options: Qt Concurrent .......................... yes Qt D-Bus ............................... yes Qt D-Bus directly linked to libdbus .... no Qt Gui ................................. yes Qt Network ............................. yes Qt Sql ................................. yes Qt Testlib ............................. yes Qt Widgets ............................. yes Qt Xml ................................. yes
A user trying to build qtquickcontrols2, for example, doesn't know that they need qtgraphicaleffects, as there's no indication of that in the build output.
Modules could put this information in their documentation, but it seems like if the build system already has this knowledge, it makes sense to share it in the config.summary. Something like this:
Qt modules and options:
  Qt Concurrent .......................... yes
  Qt D-Bus ............................... yes
  Qt D-Bus directly linked to libdbus .... no
  Qt Gui ................................. yes
  Qt Network ............................. yes
  Qt Quick Controls 2 .................... no
    - Missing qtgraphicaleffects
  Qt Sql ................................. yes
  Qt Testlib ............................. yes
  Qt Widgets ............................. yes
  Qt Xml ................................. yes
config.summary seems like the best place, but really any form of visible build output would help the user if they're grepping through it trying to find out why a module wasn't built.