Qbs Quick Reference

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Introduction

Qbs is the next-generation build system "initially introduced in the Qt Labs Blog. This page is intended as a quick guide to porting project files from qmake .pro syntax to .qbs. It is not intended to supplant the official documentation, rather to be a quick summary of the current status of qbs functionality with a focus on how to port from qmake.

Some things at the time of writing have no equivalent qbs syntax. Bugtracker links are included for missing functionality, where known.

Qbs Manual

The full Qbs Manual is found at http://doc.qt.io/qbs

qbs equivalents

TEMPLATE = app

Use Application or CppApplication as the product:

CppApplication {
 name: "helloworld"
 files: "main.cpp"
 …
}

This is roughly equivalent to:

Product {
 name: "helloworld"
 type: "application"
 files: "main.cpp"
 Depends { name: "cpp" }
 …
}

TEMPLATE = lib

Use DynamicLibrary as the product:

DynamicLibrary {
 name: "mydll"
 files: ["stuff.cpp"]
 Depends { name: "cpp" }
 …
}

TARGET = myappname

Use the "name" property, see the TEMPLATE example above.

HEADERS, SOURCES, FORMS, RESOURCES

Include in files section, eg

files: ['thing.h', 'thing.cpp', 'thing.ui', 'myapp.qrc']

qbs will use file taggers to figure out what kind of file it is dealing with.

CONFIG = console

Application {
 name: "helloworld"
 files: "main.cpp"
 consoleApplication: true
 …
}

CONFIG = designer_defines

DynamicLibrary {
 name: "myplugin"
 files: ["foo.cpp", …]
 Depends { name: "cpp" }
 cpp.defines: ["QDESIGNER_EXPORT_WIDGETS"]
 …
}

QT = modulename

Add an appropriate Depends section to the product. For example:

Product {
 Depends { name: "Qt.core" }
 // …or…
 Depends { name: "Qt"; submodules: ["core", "gui", "network"] }
}

Both forms are equivalent, the first form being quicker to type if you depend on just one module and the second more flexible if you have more complex dependencies.

DEFINES = MACRO

Use the following: Note that in order to reference cpp.defines you must specify a dependency on the cpp module.

Depends { name: 'cpp' }
…
cpp.defines: ['SUPPORT_COOL_STUFF']

The cpp module might define default preprocessor macros. For example on Windows UNICODE is predefined. These are stored in the property cpp.platformDefines. To override these macros do:

Product {
 Depends { name: 'cpp' }
 …
 cpp.platformDefines: ['MY_SPECIAL_DEFINE', 'UNICODE']

To add macros within a group, you need to use outer.concat rather than base.concat(), because you are adding additional macros to what is specified in the outer scope:

Product {
 Depends { name: 'cpp' }
 …
 cpp.defines: ['MACRO_EVERYWHERE'] // This is defined for all files in this product (unless a group overrides it!)
 Group {
 cpp.defines: outer.concat('MACRO_GROUP')
 files: groupFile.cpp
 // MACRO_GROUP is only defined in groupFile.cpp
 // MACRO_EVERYWHERE is also defined in groupFile.cpp because of the outer.concat
 }
}

cpp.defines statements inside a group only apply to the files in that group - therefore you cannot use a group to include a bunch of files and globally-visible macros - the macros must go in a Properties block at the same level as the group if they need to be visible to files outside the group:

Product {
 Depends { name: 'cpp' }
 …
 Group {
 condition: supportFoobar === true
 files: fooFile.cpp
 }

property stringList commonDefines: ["ONE", "TWO"]
 Properties {
 condition: supportFoobar === true
 cpp.defines: commonDefines.concat("FOOBAR_SUPPORTED")
 }
 Properties {
 cpp.defines: commonDefines // else case for the Properties chain
 }
}

INCLUDEPATH = dir

cpp.includePaths: [ '..', 'some/other/dir']

CONFIG -= Qt

Just don't declare Qt as a dependency. Probably you'd want:

Depends { name: "cpp" }

RC_FILE

Just add the file to the "files" list.

QMAKE_INFO_PLIST

Set the cpp.infoPlistFile property.

ICON

Not yet implemented. See QBS-73.

TEMPLATE = subdirs

Inside a "Project" item, use "references":

Project {
 references: [
 "app/app.qbs",
 "lib/lib.qbs"
 ]
}

CONFIG = ordered

QBS uses a different approach of deciding in which order subprojects are compiled than qmake. Instead of referencing them in order in .qbs file user needs to add Depends sections into subprojects.

Depends{name: "subproject"}

QBS then parses all of the included qbs files and computes what should be compiled first based on those Depends.

For example considering the Project in the previous section:

-- in app.qbs --
Product{
name:"app"
Depends{name: "libs"}
}

-- in lib.qbs --
Product{
name:"lib"
}

Lib will automatically be compiled first.

DESTDIR

Use the destinationDirectory property:

DynamicLibrary {
 name: "mydll"
 destinationDirectory: "libDir"
 …
}

Using it is not recommended, however; you should rather use the installation mechanism (see below).

message(), warning(), error()

You can use the JavaScript function print for printing messages and throw exceptions on the right hand side of property bindings.

Product {
 name: {
 print("—-> now evaluating the product name");
 return "theName";
 }
 Depends {name: "cpp"}
 cpp.includePath: {
 throw "I don't know. Something bad happened."
 return [];
 }
}

Others not mentioned above

Either I've missed them, or they're not yet implemented.

.pro and .pri

The top-level .qbs file contains the "Project" definition. A project can contain multiple products, so you may find that multiple .pro files can be expressed in a single .qbs. The subdirs pattern will typically convert to a single .qbs containing references to multiple .qbs files. Each .qbs file would then define a single product or sub-project.

.qbs files can also be used like .pri files in that a top-level .qbs can include sections defined in another .qbs. For example:

 —CrazyProduct.qbs—
 import qbs.base 1.0

 Product {
 property string craziness: "low"
 }

 —hellocrazyworld.qbs—
 CrazyProduct {
 craziness: "enormous"
 name: "hellocrazyworld"
 // …
 }

.qbs files in the same directory as the top-level .qbs file are picked up automatically. Others must be explicitly imported and named using an "import … as …" statement:

import qbs.base 1.0
import "../CrazyProduct.qbs" as CrazyProduct
CrazyProduct {
 craziness: "enormous"
 name: "hellocrazyworld"
 // …
}

Conditionals

Instead of the qmake syntax of "windows { … }" or "macx:…", you specify a "condition" property in the relevant block. Conditionally-compiled files should be collected in a "Group" block, while platform-specific properties should go in a "Properties" block rather than being put in the main (outer) block:

Group {
 condition: qbs.targetOS == "windows"
 files: [
 "harddiskdeleter_win.cpp",
 "blowupmonitor_win.cpp",
 "setkeyboardonfire_win.cpp"
 ]
}

Properties {
 condition: qbs.targetOS == "linux"
 cpp.defines: outer.concat([ "USE_BUILTIN_DESTRUCTORS"])
}

See the DEFINES section above for important information about how conditionals and cpp.defines interact.

C++ compiler options

Here is a selection of options that are supported. The full list can be found in share/qbs/modules/cpp/CppModule.qbs in the qbs source tree, these are some of the more useful:

cpp.optimization: "none" // or "fast"
cpp.debugInformation: true
cpp.staticLibraries: "libraryName"
cpp.dynamicLibraries: "libraryName"
cpp.frameworks: "osxFrameworkName"
cpp.precompiledHeader: "myheader.pch"
cpp.warningLevel: "all" // or "none", "default"
cpp.treatWarningsAsErrors: true
cpp.cxxLanguageVersion // E.g. "c++11"

Note that setting things like cflags directly is discouraged (because they are compiler-dependent), and higher-level alternatives like cpp.optimization: "fast" should be used if available.

Installing files

Create a group containing the files, and set qbs.install and qbs.installDir:

Group {
 qbs.install: true
 qbs.installDir: "lib/myproj/"
 files: [
 "Menu.qml",
 "SomeImportantFile.bin"
 ]
}

For files generated by the build (e.g. an executable), you need to match them by their file tag:

Group {
 qbs.install: true
 qbs.installDir: "bin"
 fileTagsFilter: "application"
}

By default, installation happens automatically when building. The default installation root is called "install_root" and is located at the top level of the build directory. It can be overwritten by setting the qbs.installRoot property on the command line.

Command-line examples

64-bit:

qbs -f /path/to/project.qbs --products productname qbs.architecture:x86_64

"Magic" variables

Variables defined in various scopes, which may not be obvious:

qbs

This has lots of useful things in, such as: targetOS ("windows", "linux", "osx", …); buildVariant ("debug", "release"); architecture ("x86", "x86_64", …)

project

Valid anywhere in your project, needed to refer to project properties from within a product:

Project {
 property string version: "1.0"

 Product {
 cpp.defines: ["PROJECT_VERSION=" + project.version]
 }
}

buildDirectory

The top-level build directory. By default will be a subdirectory in the directory where you invoked qbs from, whose name is derived from the current profile. It can also be explicitly specified via the -d option.

Module names

Modules that are declared as dependencies can be referred to by their name and their properties accessed. For example:

Product {
 Depends { name: "Qt.quick" }
 Qt.quick.qmlDebugging: false
}

Inside custom javascript

Generally when writing custom JavaScript logic, things are referenced through the top-level "product" variable. In particular, to get the product's value of the property "baz" of a module "foo", use product.moduleProperty("foo", "baz"). For list values that get automatically combined, like includePaths, use product.moduleProperties("foo", "baz").

Group {
 condition: qbs.targetOS === "windows"
 files: [ "hcf.cpp" ]
}

and

Group {
 files: {
 if (product.moduleProperty("qbs", "targetOS") === "windows") {
 return [ "hcf.cpp" ];
 } else {
 return [];
 }
 }
}