問題を解決したと思っていたのですが、別の問題が発生したように見えました。少なくとも、同じ問題が別の形式で発生したようです。その質問への回答で提案されているようにすべてを再構築しようとすると、ビルドの問題でQtCreatorに表示されるものはすべて1行ですcollect2: ld returned 1 exit status
これが私が関連すると思うコンパイル出力のいくつかです：
Running build steps for project Othello-cmd...
Starting: "C:/Qt/2010.05/mingw/bin/mingw32-make.exe" clean -w
[snipped]
C:/Qt/2010.05/mingw/bin/mingw32-make -f Makefile.Release clean
Could Not Find C:\Users\Amos Ng\My Dropbox\School\College\2010.. Fall\CS 3A\Othello-cmd-build-desktop\debug\main.o //this was in red
mingw32-make[1]: Entering directory `C:/Users/Amos Ng/My Dropbox/School/College/2010.. Fall/CS 3A/Othello-cmd-build-desktop'
del release\main.o release\board.o release\player.o release\referee.o release\misc.o release\humanplayer.o release\computerplayer.o release\chatter.o release\chatserver.o release\location.o
mingw32-make[1]: Leaving directory `C:/Users/Amos Ng/My Dropbox/School/College/2010.. Fall/CS 3A/Othello-cmd-build-desktop'
mingw32-make: Leaving directory `C:/Users/Amos Ng/My Dropbox/School/College/2010.. Fall/CS 3A/Othello-cmd-build-desktop'
Could Not Find C:\Users\Amos Ng\My Dropbox\School\College\2010.. Fall\CS 3A\Othello-cmd-build-desktop\release\main.o
//these next 3 lines are in blue
The process "C:/Qt/2010.05/mingw/bin/mingw32-make.exe" exited normally.
Configuration unchanged, skipping qmake step.
Starting: "C:/Qt/2010.05/mingw/bin/mingw32-make.exe" -w
mingw32-make: Entering directory `C:/Users/Amos Ng/My Dropbox/School/College/2010.. Fall/CS 3A/Othello-cmd-build-desktop'
[snipped]
//A bunch of lines similar to
g++ -c -g -frtti -fexceptions -mthreads -Wall -DUNICODE -DQT_LARGEFILE_SUPPORT -DQT_DLL -DQT_CORE_LIB -DQT_THREAD_SUPPORT -I"c:\Qt\2010.05\qt\include\QtCore" -I"c:\Qt\2010.05\qt\include" -I"c:\Qt\2010.05\qt\include\ActiveQt" -I"debug" -I"\\psf\Dropbox\School\College\2010.. Fall\CS 3A\Othello-cmd" -I"." -I"c: "filepath of .o file" "filepath of .cpp file"
g++ -enable-stdcall-fixup -Wl,-enable-auto-import -Wl,-enable-runtime-pseudo-reloc -Wl,-subsystem,console -mthreads -Wl -o debug\Othello-cmd.exe object_script.Othello-cmd.Debug -L"c:\Qt\2010.05\qt\lib" -lQtCored4
//everything's red starting here...
./debug\board.o://psf/Dropbox/School/College/2010.. Fall/CS 3A/Othello-cmd/board.cpp:29: undefined reference to `OPiece::OPiece(int)'
./debug\board.o://psf/Dropbox/School/College/2010.. Fall/CS 3A/Othello-cmd/board.cpp:39: undefined reference to `OPiece::flip()'
./debug\board.o://psf/Dropbox/School/College/2010.. Fall/CS 3A/Othello-cmd/board.cpp:76: undefined reference to `OPiece::display()'
./debug\board.o://psf/Dropbox/School/College/2010.. Fall/CS 3A/Othello-cmd/board.cpp:110: undefined reference to `OPiece::display()'
./debug\board.o://psf/Dropbox/School/College/2010.. Fall/CS 3A/Othello-cmd/board.cpp:159: undefined reference to `OPiece::OPiece(int)'
//couple more lines just like the above
collect2: ld returned 1 exit status
//...finally things are black again
mingw32-make[1]: Leaving directory `C:/Users/Amos Ng/My Dropbox/School/College/2010.. Fall/CS 3A/Othello-cmd-build-desktop'
mingw32-make: Leaving directory `C:/Users/Amos Ng/My Dropbox/School/College/2010.. Fall/CS 3A/Othello-cmd-build-desktop'
//everything's red again
mingw32-make[1]: *** [debug\Othello-cmd.exe] Error 1
mingw32-make: *** [debug] Error 2
The process "C:/Qt/2010.05/mingw/bin/mingw32-make.exe" exited with code %2.
Error while building project Othello-cmd (target: Desktop)
When executing build step 'Make'
このエラーの原因について何か考えはありますか？
編集：デバッグディレクトリ内に「main.o」が見つかったことにも注意してください...
解決策（実際にはそうではありません）：代わりにNetbeansですべてを再コンパイルしました（Macでは、リンカーが異なっていた可能性があります...）。これでプログラムは正常に実行されます...さようならQtCreator