src/docs/qtcreator.md

Use Qt Creator as an IDE or debugger UI

Qt Creator (Wiki) is a cross-platform C++ IDE.

You can use Qt Creator as a daily IDE or just as a GDB frontend (which does not require project configuration).

[TOC]

IDE

Workflow features

• Built-in code completion.
• Navigate to classes, files, or symbols with ctrl+k.
• Switch between declaration and definition with F2.
• Build with ctrl+shift+b.
• Build and run with ctrl+r, or debug with F5.
• Switch between the header file and cpp file with F4.

Setup

1. Install the latest Qt Creator.
2. Under chromium/src gn gen out/Default --ide=qtcreator.
3. Start it with qtcreator out/Default/qtcreator_project/all.creator.
4. Help - Plugins - check ClangCodeModel to enable std completion.

It takes 3 minutes to parse all of chrome's C++ files on my workstation!!! And it does not block while parsing.

Code Style

1. Help - About Plugins, enable Beautifier.
2. Tools - Options - Beautifier - Clang Format, change the Clang format command to: $depot_tools_dir/clang-format, and set Use predefined style: file. You can also set a keyboard shortcut for it.
3. Tools - Options - Code Style, import this xml file.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE QtCreatorCodeStyle>
<!-- Written by QtCreator 4.2.1, 2017-02-08T19:07:34. -->
<qtcreator>
 <data>
  <variable>CodeStyleData</variable>
  <valuemap type="QVariantMap">
   <value type="bool" key="AlignAssignments">true</value>
   <value type="bool" key="AutoSpacesForTabs">false</value>
   <value type="bool" key="BindStarToIdentifier">false</value>
   <value type="bool" key="BindStarToLeftSpecifier">false</value>
   <value type="bool" key="BindStarToRightSpecifier">false</value>
   <value type="bool" key="BindStarToTypeName">true</value>
   <value type="bool"
     key="ExtraPaddingForConditionsIfConfusingAlign">true</value>
   <value type="bool" key="IndentAccessSpecifiers">true</value>
   <value type="bool" key="IndentBlockBody">true</value>
   <value type="bool" key="IndentBlockBraces">false</value>
   <value type="bool" key="IndentBlocksRelativeToSwitchLabels">false</value>
   <value type="bool" key="IndentClassBraces">false</value>
   <value type="bool" key="IndentControlFlowRelativeToSwitchLabels">true</value>
   <value type="bool"
     key="IndentDeclarationsRelativeToAccessSpecifiers">false</value>
   <value type="bool" key="IndentEnumBraces">false</value>
   <value type="bool" key="IndentFunctionBody">true</value>
   <value type="bool" key="IndentFunctionBraces">false</value>
   <value type="bool" key="IndentNamespaceBody">false</value>
   <value type="bool" key="IndentNamespaceBraces">false</value>
   <value type="int" key="IndentSize">2</value>
   <value type="bool" key="IndentStatementsRelativeToSwitchLabels">true</value>
   <value type="bool" key="IndentSwitchLabels">false</value>
   <value type="int" key="PaddingMode">2</value>
   <value type="bool" key="ShortGetterName">true</value>
   <value type="bool" key="SpacesForTabs">true</value>
   <value type="int" key="TabSize">2</value>
  </valuemap>
 </data>
 <data>
  <variable>DisplayName</variable>
  <value type="QString">chrome</value>
 </data>
</qtcreator>

Build & Run

1. (Optional) Enable the issues pane for easy navigation to the location of compiler errors. qtcreator expects to find compiler errors on stderr, but ninja forwards all subcommand output to stdout. So use the following wrapper script to forward it to stderr instead.

#!/bin/sh
/path/to/depot_tools/ninja "$@" >&2

2. In the left panel - Projects, set up the ninja command in the build and clean steps, and add the path to chrome in the run configuration.

Debugger

You can skip the project settings and use QtCreator as a single file standalone GDB frontend.

1. Tools - Options - Build & Run - Debuggers, make sure GDB is set.
2. Tools - Options - Kits, change the Desktop kit to GDB (LLDB doesn't work on Linux).
3. Open the file you want to debug.
4. Debug - Start Debugging - Attach to running Application, you may need to open chrome's task manager to find the process id.

Tips, tricks, and troubleshooting

The debugger exits immediately

Ensure yama allows you to attach to another process:

$ echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope

The debugger does not stop on breakpoints

Ensure you are using GDB on Linux, not LLDB.

More

See https://chromium.googlesource.com/chromium/src/+/master/docs/linux_debugging.md