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3/26/2015 UndocumentedQmake

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UndocumentedQmakeLastUpdate:20060829

InJuly2006,Ichangedjobs,andnolongeruseQtatwork.IintendtodabbleabitwithQt,butIwon'tbespendinganythinglikeasmuchtimewithitaspreviously.SoIdon'texpecttobeaddingmuchtothispagefromnowon.

Ifyou'reusingQt,thenthechancesareyouuseqmake.It'spossibletointegrateQtintoothermakesystems,butformostpeople,it'salotofhardworkforlittlegain.Personally,Ifindqmakequitegood,butithasonebigproblem.Thedocumentationisincomplete.Inadditiontothedocumentationavailableinassistant,I'vefounditinvaluabletosearchthroughtheqmakesourcecodetofindouthowthingsaredone,andalsotodiscoverundocumentedfeatures.Thiswebpageisintendedtodocumentsomeofthesefeatures.ThecurrentversionofQtatthetimeofwritingwasQt3.3.4.

MyexperienceofQt4isquitelimited.However,Idohavetheimpressionthatqmakehasbeensubstantiallyrewritten,andthatthedocumentationismoreexhaustive

TheotherthingthatI'vefoundinvaluableistostudytheqmake.conffilesin$QTDIR/mkspecsattentively.Fromstudyingthesefiles,youcanseehowqmakedoesthingsbydefault,andyoucanadaptthemtoyouneedsifrequired.

I'vetestedmostofthesethingsonSolaris,LinuxandHPUX.Ijustaboutgotmostthingstowork,withsomedifficulty,onWindows2000usingcygwin.

Using$$ORIGIN

MostunicesallowyoutospecifytheRPATHforapplications.Thisispartofthepaththatwillbesearchedfordynamiclibraries.Inaddition,youcanspecifyarelativepathwiththe$ORIGINvariable.Thisisnotanenvironmentvariable,itispartoftheapplication'sRPATH.Forinstance,saytheapplicationisinstalledin/opt/foo/bin/fooappandtherearedynamiclibrariesin/opt/foo/lib.Youcouldspecifytheabsolutepath(/opt/foo/lib)intheapplication.Oralternativelyyoucouldspecifytherelativepathwith$ORIGIN/../lib.Enoughbackground.Howdoyouactuallydothis?OnSolariswithSunStudio,itwouldbeachievedbyaddingR$ORIGIN/../libtothelinkcommand.(g++usesWl,rpath,insteadofR).Theqmakevariableforthisis,naturally,QMAKE_RPATH.Sowhatistheproblem?Well,themakefileneedstocontain'R$$ORIGIN/../lib'(twodollarssothatitdoesn'ttake$ORIGINforamakeMACRO).

IfyouareusingQt3.3.8(andIguess4.x,butIhaven'tchecked),thenyoucansimplyuse\$$ORIGIN.ButifyouareusinganolderversionofQt(I'vecheckedthiswith3.1.1),thenyouhaveaproblem.$$ORIGINlookslikeavariabletoqmake.I'vetriedallsortsofthingstoescapethedollars,($$$$ORIGIN,\$\$ORIGIN,singlequotes,doublequotes...).Butalwayseitherthe$$ORIGINistreatedasavariableanddisappears,orelsetheescapingistooefficient,andtheescapecharactersendupinthegeneratedmakefile.OnesolutionistosetanORIGINenvironmentvariable:

exportORIGIN=\$\$ORIGIN

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andthenusethatintheprojectfile:

QMAKE_LFLAGS=L/bar/build/libR$$(ORIGIN)/../liblibrary=stlport4

Anotherpossibility,abitcleaner,istobeattheqmakevariablesattheirowngame:

DOLLAR=$QMAKE_LFLAGS=L/bar/build/libR$${DOLLAR}$${DOLLAR}ORIGIN/../liblibrary=stlport4

Thefirstcurlybracesaren'tstrictlynecessary.Justimagineexplainingthatbytelephonesupport,"minusrdollardollardollardollardollardollar".Hmm!

QMAKE_EXTRA_WIN_TARGETS,QMAKE_EXTRA_WIN_COMPILERS

ThedocumentationcoversQMAKE_EXTRA_UNIX_TARGETSandQMAKE_EXTRA_UNIX_COMPILERS,butnottheirWINcounterparts.ThesecertainlydoexistforWindowsaswell.

No.inheaderincludepath

Add"no_include_pwd"toCONFIGandI"."willnolongerbeaddedtoINCPATH.Youmightwanttodothis,forinstance,ifyouhaveafilelikestring.hinyourproject,butyouwanttoincludethesystemversionbydefault.

NoeliminationofduplicateentriesinLIBS

Add"no_smart_library_merge"toCONFIG.

Escaping'{'and'}'inaprojectfile

Fromqtinterestmailinglist

First,echo${0##*/}isthecorrectthingtouse.

GettingpathsforMSSDKandDDK


Ithinkthatthisisalsoonan'undocumentedQt'wiki.

#FindtheSDKSYSTEM_CMD=$$quote(regqueryHKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MicrosoftSDK\Directories/v"InstallDir")SYSTEM_RET=$$system($${SYSTEM_CMD})FORLOOP=8910111213141516for(i,FORLOOP):SDKPATH+=$$member(SYSTEM_RET,$${i})SDKPATH=$$quote($${SDKPATH})



#FindthenewestDDKcontainingheaders/libsfor$${DDK_TARGET}DDK_TARGET=w2kSYSTEM_CMD=$$quote(regqueryHKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WINDDK)SYSTEM_RET=$$system($${SYSTEM_CMD})FORLOOP=12111098765for(i,FORLOOP){REG_CURENTRY=$$member(SYSTEM_RET,$${i})count(REG_CURENTRY,1){SYSTEM_CMD2=$$quote(regquery$${REG_CURENTRY}/v"LFNDirectory")SYSTEM_RET2=$$system($${SYSTEM_CMD2})FORLOOP2=789101112131415CURDDKPATH=for(j,FORLOOP2){CURDDKPATH+=$$member(SYSTEM_RET2,$${j})}CURDDKPATH=$$quote($${CURDDKPATH})exists($${CURDDKPATH}/inc/$${DDK_TARGET}):DDKPATH=$$quote($${CURDDKPATH})}}

Settingsystemdependentoptions

Theexistingqmakesupportissufficientformostneeds,inparticular,thevalueoftheQMAKESPECenvironmentvariable.Thereare,however,afewcaseswherethismightnotbeenough,e.g.,ifyouneedtodistinguishbetweenLinuxonx86andPPC,orbetweenSolarisonSPARCandx86.Asanexample,onUnixsystems(possiblyincludingWindowswithcygwin),thenyoucoulduse

SYSTEM=$$system(unamesp|sed's//_/g')

Analternative[Qt3.3andlater]istouseproperties.Foreachsystemthatyouuse,youwouldissueacommandlike

qmakesetSYSTEMLinuxPPC

Youcouldthenuseinyourprojectfilesomethinglike

CONFIG+=$$[SYSTEM]

LinuxPPC{message(LinuxonPPC)}

Theoneslightdrawbackofthisapproachisthatitrequireseachusertoperformthe'qmakeset'steptocorrectlyconfiguretheirenvironment.Usuallythiswouldfallslightlyoutofthescopeofasourcemanagementsystem.Thusyouwouldnotbeabletodosomethinglike"checkout&make".Ifyoudotakethissortofapproach,thenyoucanprotectyourselfagainsterrorslikethepropertynotbeingsetlikethis:

isEmpty($$[FOO]){



error(YoumustrunqmakesetFOOwhateverbeforerunningqmake)}

AddingtoINCPATHafter$QTDIR/include

Inyour.profile,add

QMAKE_INCDIR_QT+=my/path

NotlinkingwiththeoutputofQMAKE_EXTRA_UNIX_COMPILERS

qmakeassumesthattheoutputoftheextracompilersisdestinedtobelinkedintothefinallibraryorapplication.Ifthisisn'tthecase,thenyouneedtodosomethingtostopit.

If"mycompiler"isthenameofyourcompilercompoundvariable,thenifyouhaveamember.CONFIGsettono_link,thentheoutputwon'tgetlinked.Example.

mycompiler.output=${QMAKE_FILE_BASE}.outmycompiler.input=MYCOMPILER_INPUT_FILESmycompiler.commands=foo${QMAKE_FILE_NAME}mycompiler.CONFIG=no_linkQMAKE_EXTRA_UNIX_COMPILERS+=my_compiler

Exampleswhenyoumightwanttodothisareforthingslikegeneratingdocumentation.

Usingflexandbison

qmakehasbuiltinsupportforlexandyacc.Unfortunately,itwon'tworkwithflexandbison.

lex

lexisquiteeasy,justset

QMAKE_LEX=flex

bison

bisonisanotherstory.Withabitofeffort,though,itcanbecoerced.Thefirststepiseasy,likelex.

QMAKE_YACC=bison

Afterthat,we'reintrouble.yaccgeneratesfiles"y.tab.h"and"y.tab.c".Qmakeaddstothemakefileruleacommandthatmovesthesefilesto"_yacc.h"and"_yacc.c".

bisongenerates".Y.tab.c"and".Y.tab.h"sothemovestagefails,andalsoevidentlysodoesthecompile.

SoIusedQMAKE_YACCFLAGS_MANGLE,whicharen'tdocumented.Ithinkthatitissupposedtoallowyoutochangethewaythatvariablesarenames(defaultprefixis"yy_",defaultqmakeprefixis"".I'vekeptthisprefix,butforcedbisontogenerate"y.tab.h"and"y.tab.c",whichiswhatqmake



needsforthesubsequentrenameandthencompile.Phew!

MysolutiononSolarisdidn'tworkonLinux.Thistime,Iusedthesamebisonoptiontocontroltheoutputfilename,butIalsoneededdtogeneratetheheaderfile.IalsohadtoclearQMAKE_YACC_HEADER/QMAKE_YACC_SOURCE.

OnSolaris

Usingthesfwversionofbison,1.35

solariscc{QMAKE_YACCFLAGS_MANGLE=oy.tab.cp$base}

OnLinux

linuxg++{QMAKE_YACCFLAGS=doy.tab.cQMAKE_YACC_HEADER=QMAKE_YACC_SOURCE=}

Addingadoxygentarget


Youcanatleastmake"customtargets",suchasfor'makestrip'.Seedocsaboutqmake.Notsurehowtorunthemautomaticallyafterlinkingthough.Example(forrunningdoxygenoverthesourceswith'makedoc'):

#customtarget'doc'in*.profiledox.target=docdox.commands=doxygenDoxyfile\testddoxydoc/html/images||mkdirdoxydoc/html/images\cpdocumentation/images/*doxydoc/html/imagesdox.depends=

...#somewhereelseinthe*.profileQMAKE_EXTRA_UNIX_TARGETS+=dox

Strippingexecutables


Youcanusesomethinglikethisinthe.profile(untested):

unix:QMAKE_POST_LINK=strip$(TARGET)!unix:QMAKE_POST_LINK=xxx$(TARGET)



ReplacexxxwiththesamelinebutwithwhateverthestripcommandiscalledonWindows.

Buildinginsubdirectories

Perhapsthesimplestissomethinglike

system(cdcontrib/sshaskpass&&$${MAKECMD})

WhereyouwouldhavepreviouslysettheappropriateMAKECMD.

Preinstallheaders

Ihadalengthybattleatmyplaceofworkgettingsomethinglike"makeinstall_headers"towork(orevenbetter,tobedoneasaprerequisitebeforeanyothertargets,sojusttypingmakewillpreinstallanyexportedheaders).Why?Well,wehavealotofsourcethatincludesheadersinthecommonunixwayas#include,inparticularwhentheheadersaregoingtobeexported.Thisposesnoproblemforalibrarythathasallsuchheadersinadirectory"basedir/include/library",youcanjustaddINCLUDEPATH+=include,andallwillbewell.

Whenthefilesaren'torganizedinthisway,therearethreepossibilities.

1. Editthefiles.Notanoptionforme.2. Changethedirectorystructure(orfakeitwithlinks).Thiswouldworkinmostcases,butIhavea

fewlibrariesthatdon'tconformtothepatternofonesourcedirectoryforone#includedirectory.3. Fightitoutwithqmake.

Asyoumayhavegathered,it'snumberthreethatI'mgoingtopursuehere.I'vehadthreegoesatsolvingthisproblem,allwithvaryingdegreesofsuccess.Sadlynoneofthemseemstobe100%reliableonallplatforms.Iusuallyfindthatsolutions2and3takeafewiterationsofqmakeandmakebeforeeverythingsettlesdown(i.e.,theintermediatemocanduigeneratedfileshavebeengenerated).

1.UsetheINSTALLSqmakevariable

Thissoundslikeitfitsthebill,butunfortunately,thereareacoupleofgotchas,whichI'llcometoshortly.

Here'showitworks.Youdefineacompoundvariable(Iusuallycallit"headers".Ifyouneedmorethanonedestination,you'llneedmorethanonecompoundvariable.Withinyourvariable,youdefinethepath(wherethefileswillgo)andthefiles(whichfilestocopy).

Example.Thisassumesthatyou'vealreadydefinedINSTALLBASE,TARGET,VERSIONandHEADERS.

headers.path=$$INSTALLBASE/include/$${TARGET}_$${VERSION}/$${TARGET}headers.files=$$HEADERSINSTALLS+=headersPRE_TARGETDEPS+=install_headers

Nowforthegotchas.Firstofall,bydefaultqmakewillgenerateamakefilethatusesthebasicOScopyfunctiontoinstallthefiles(e.g.,cponUnixandcopyonWindowsdon'tknowforMac).Thiswillcausethedestinationfiletohaveitstimestampsettothetimethatitwascopied.Obviously,thisisacalamity



foraninterdependentsetoflibrariesbuiltwithmake.Theupdatedtimestampswillcausealotofunnecessarycompiles.Thereisasolution.QMAKE_COPYtotherescue!Simplysetthistosomethinglike"cpfp"andallwillbewell.

OnWindows,Ihadabitofahardertime,andIendedupcreatingalittleshellscripttoovercomethefactthatthoughIwasrunningnmakewithincygwin,withinnmake,pathsallusebackslashes,whichcygwincopydoesn'tunderstand.Thescriptbasicallydoes

cpfp`cygpathu"$@"`

Nowforthesecondgotcha.Thisonehasnorealsolution.Myaimwastohave

HEADERS=...INSTALLS=...asabove...PRE_TARGETDEPS+=install_headers

AlliswelluntilyouwanttoaddanyuicormocgeneratedheaderstoINSTALLS.Theneverythinggoespearshaped.There'snoproblemputtingthegeneratedheadersbeforeinstall_headersinPRE_TARGETDEPS.Thereisaproblemwithacirculardependencythough.qmakeadds'all'tothedependenciesforINSTALLS,buttheuic/mocgeneratedheadersdependonthe.ui/.hfiles.Someversionsofmakewilljustcomplain,otherswillterminatewhentheyseeacirculardependency.

Ithinkthatthebestsolutionwouldbetofixqmaketoallowustoturnoffthedependencyon'all'.Forexample

headers.path=$$INSTALLBASE/include/$${TARGET}_$${VERSION}/$${TARGET}headers.files=$$HEADERSheaders.CONFIG+=no_allINSTALLS+=headersPRE_TARGETDEPS+=install_headers

Note:youmaywanttohavedifferentvariablesforexportedandprivateheaders,e.g.,

PRIVATE_HEADERS=...EXPORTED_HEADERS=...HEADERS=$$PRIVATE_HEADERS$$EXPORTED_HEADERS...headers.files=$$EXPORTED_HEADERS

We'llhavetowaitandseeifTrolltechtakeitup(oranyoneelseforthatmatter).

Becauseofthisproblem,IgaveupwiththissolutionwhereverIneedtoinstallgeneratedheaders.

But,holdthepresses!

1.aUseINSTALLSandpatchqmake

Itookupmyownchallengeandmadeasmall(andasitturnsout,quitesimple)modtoqmake($QTDIR/qmake/generators/makefile.cp).Hereisthepatch.BeforeImadethispatch,IwasusingINSTALLSforprojectswhereuigeneratedheaderswerenotrequiredtobepublic.Iwasusingthemethodoutlinedinpoint2belowforthoselibrarieswhereIneededtoexportgeneratedheaders.NowI

http://paulf.free.fr/makefile.cpp.diff



useINSTALLSforeverything.

2.UseQMAKE_EXTRA_UNIX_TARGETS

BasicallytheideaistoreinventtheINSTALLSmechanism,butwithoutthecirculardependencies.IwrotealittleTclscriptthattakesthedestinationpath,thenameofa.profiletogenerateandalistofheaders.Inmy.profileIput

HEADERS_PATH=$$INSTALLBASE/include/$${TARGET}_$${VERSION}/$${TARGET}system(preinstallheaders.tcl$$HEADERS_PATHpih.pro$$HEADERS)include(pih.pro)

Andthiswouldgenerate"pih.pro"containing

mkdir.commands=$$QMAKE_MKDIR[pathtoinstallto]mkdir.target=[pathtoinstallto]iheader0.target=[pathtoinstallto]/header.hiheader0.commands=$$QMAKE_COPYsrc/header.h[pathtoinstallto]iheader0.depends=src/header.h...iheaderX...unix:QMAKE_EXTRA_UNIX_TARGETS+=mkdiriheader0...iheaderXPRE_TARGETDEPS+=[pathtoinstallto][pathtoinstallto]/header.h...

Notverypretty,butitgotthejobdone.Iputthe"pih.pro"fileintheworkingdirectorywheretherewouldbesomeriskofoverwritingifIbuiltontwoplatformssimultaneously.Onesolutiontothiswouldbetoputthefileinaplatformspecificdirectory.Ontopofthat,whentheprojectfileincludespih.pro,themakefilewillcontainadependencybetweenpih.proanditself.Thismeansthatifyougoandbuildonadifferentplatform,makewillcauseqmaketoregeneratethemakefile(andpih.pro),whichisunnecessary.

AnotherthingthatIneverbotheredtosolvewasifthefilesneedtobeinstalledtomorethanonedirectory,ifImadetwocallstopreinstallheaders.tcl,theywouldbothcreateextratargetsstartingwithiheader0,sothesecondonewouldhidethethird.Thisshouldbeeasyenoughtosolve,butasitonlyaffectedonelibraryforme,itwasn'tworththeeffort.

Allthesame,Ithoughttomyselfthattheremustbesomethingprettier.So...

3.UseQMAKE_EXTRA_UNIX_COMPILERS

It'sprehapsnotthemostobviousthingtodo,usea'compiler'to'install'aheader.Butthereyougo.Here'sanexample.

install_headers.output=[pathtoinstallto]/${QMAKE_FILE_BASE}.hinstall_headers.input=INSTALL_HEADERSinstall_headers.commands=$$QMAKE_COPY${QMAKE_FILE_NAME}$$make_dir.targetinstall_headers.CONFIG=no_link

QMAKE_EXTRA_UNIX_TARGETS+=make_dir



QMAKE_EXTRA_UNIX_COMPILERS+=install_headers

INSTALL_HEADERS=$$HEADERS$$GENERATED_HEADERS

PRE_TARGETDEPS+=$$make_dir.target$$UIDIR$$GENERATED_HEADERS$$INST_HDRS$$INST_GEN_HDRS

Afewcommentsareinorder.Firstly,'make_dir'isthesamethingasinpoint2above.It'stheretoensurethatthedestinationdirectoryexistsbeforeanyattemptatinstallingfiles.There'snoneedfora.dependsfield.Iuse${QMAKE_FILE_BASE}.hfortheoutputsince${QMAKE_FILE_NAME}mayincludeanundesirablerelativepath.make_dirisatarget,justlikemkdirinthepih.profileinpart2above.$$UIDIRneedstobeinthePRE_TARGETDEPSbefore$$GENERATED_HEADERS,sincethatiswheretheygetput.$$GENERATED_HEADERSneedstobebefore$$INST_GEN_HDRSsincetheheadersneedtobegeneratedbeforetheycanbeinstalled!

CopyrightPaulJohnFloyd20052007,2009

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