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  1. Qt
  2. QTBUG-77016

moc resolves symlinks using canonicalFilePath(), breaking relative includes

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    Details

    • Type: Bug
    • Status: Reported
    • Priority: P2: Important
    • Resolution: Unresolved
    • Affects Version/s: 5.12.2
    • Fix Version/s: None
    • Component/s: Build tools: moc
    • Labels:
      None

      Description

      Our build system uses symlinks to create a copy of the directory structure to build, but places all the actual files it wants to use in a flat directory (all file names are hashed). This causes troubles for moc when it is resolving includes, since it removes the symlink info by calling canonicalFilePath() in preprocessor.cpp.

      For example:

      ls -l ./**:
      lrwxrwxrw 1   33 Jul 11 12:20 dir_a/dir_b/file_with_redirect.h -> ../../hashed_file_with_redirect.h
      -rw-r----- 1   23 Jul 11 12:18 dir_a/file_with_symbol.h
      -rw-r----- 1  186 Jul 11 12:18 dir_a/header_to_moc.h
      -rw-r----- 1   33 Jul 11 12:19 hashed_file_with_redirect.h
      

      file_with_redirect.h

      #include "../file_with_symbol.h"
      

      file_with_symbol.h

      #define SYMBOL_DEFINED
      

      header_to_moc.h

      #include <QObject>
      #include "dir_b/file_with_redirect.h"
      
      #ifdef SYMBOL_DEFINED
      
      class TestClass : public QObject {
        Q_OBJECT
        Q_PROPERTY(bool test READ test WRITE setTest)
      };
      
      #endif
      

      And trying to invoke moc:

      moc dir_a/header_to_moc.h -o /tmp/header_to_moc.h
      dir_a/header_to_moc.h:0: Note: No relevant classes found. No output generated.
      

      But if you were to patch preprocessor.cpp:

      @@ -1030,7 +1030,7 @@
      
           if (!fi.exists() || fi.isDir())
               return QByteArray();
      -    return fi.canonicalFilePath().toLocal8Bit();
      +    return fi.filePath().toLocal8Bit();
       }
      
       QByteArray Preprocessor::resolveInclude(const QByteArray &include, const QByteArray &relativeTo)
      @@ -1039,7 +1039,7 @@
               QFileInfo fi;
               fi.setFile(QFileInfo(QString::fromLocal8Bit(relativeTo)).dir(), QString::fromLocal8Bit(include));
               if (fi.exists() && !fi.isDir())
      -            return fi.canonicalFilePath().toLocal8Bit();
      +            return fi.filePath().toLocal8Bit();
           }
      
           auto it = nonlocalIncludePathResolutionCache.find(include);
      

      It picks up the symbol and the class.

      This seems like a similar issue to https://bugreports.qt.io/browse/QTBUG-22655, not sure if there should be some more general cleanup or policy on what to do with symlinks in the build tools.

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            Assignee:
            Unassigned Unassigned
            Reporter:
            cwgthornton Chris Thornton
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              Dates

              Created:
              Updated:

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