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  1. Qt
  2. QTBUG-102162

Unnecessary rebuilding of targets when moc executable changes - on _next_ rebuild

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Details

    • Bug
    • Resolution: Unresolved
    • P3: Somewhat important
    • None
    • 6.4.0 FF
    • Build System: CMake, Build tools: moc
    • None
    • Linux/X11

    Description

      • Given an existing build of qtbase.
      • When modifying qbuffer.cpp.
      • Then a second ninja tst_qbuffer rebuilds all QtCore TUs that #include the moc file (= all)

      To reproduce:

      $ path/to/srcdir/configure ...
$ ninja src/all
$ ninja tst_qbuffer
$ echo >> path/to/srcdir/src/corelib/io/qbuffer.cpp
$ ninja tst_qbuffer
(rebuilds qbuffer.o in bootstrap, re-links libbootstrap.a, moc, rebuilds qbuffer.o in QtCore, relinks Qt6Core, relinks tst_qbuffer)
(as expected)
$ echo >> path/to/srcdir/tests/auto/corelib/io/qbuffer/tst_qbuffer.cpp
$ ninja tst_qbuffer
(rebuilds all of QtCore's .o's)
(expected: only rebuilds tst_qbuffer)

      I don't know whether this is a moc problem or an automoc one. In any case, I'd expect that the moc files are left unchanged if their re-writing would not change their content.

      Environment:

      • Ubuntu 20.04
      • cmake 3.21.1
      • local branch off of 344e0e7141667686a7e093aa76441bf2c43b6633
      $ cat config.opt
-opensource
-confirm-license
-release
-force-debug-info
-separate-debug-info
-c++std
c++2a
-developer-build
-sctp
-pch
-sanitize
address
-sanitize
undefined

      Attachments

        Issue Links

          duplicates

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-92269 Build claims to be done when it isn't, unnecessary rebuilds of Core after touching bootstrap source files

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-95099 [FTBFS] Qt6CoreToolsTargets.cmake not found with -DQT_FORCE_FIND_TOOLS=ON

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Closed

          Suggestion - Public suggestions QTBUG-99683 Make it possible to build the tools in a non-cross-compilation build when QT_FORCE_FIND_TOOLS is also set

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Closed
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          Activity

            People

              qtbuildsystem Qt Build System Team
              mmutz Marc Mutz
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              Dates

                Created:
                Updated:

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