When I run following code:

qDebug() << QProcess::systemEnvironment();

I see in Qt Creator console:

("LOGNAME=shamil", "HOME=/Users/shamil", "XPC_FLAGS=0x0", "QTDIR=/Users/shamil/opt/Qt/5.3/clang_64", "PATH=/Users/shamil/opt/Qt/5.3/clang_64/bin:/usr/bin:/bin:/usr/sbin:/sbin", "__CF_USER_TEXT_ENCODING=0x1F5:0x0:0x0", "USER=shamil", "XPC_SERVICE_NAME=org.qt-project.qtcreator.47744", "DISPLAY=/private/tmp/com.apple.launchd.d6LQTxBQ1t/org.macosforge.xquartz:0", "Apple_PubSub_Socket_Render=/private/tmp/com.apple.launchd.C9YuTSh5eC/Render", "DYLD_LIBRARY_PATH=", "SHELL=/bin/bash", "SSH_AUTH_SOCK=/private/tmp/com.apple.launchd.sXAKBnTj28/Listeners", "TMPDIR=/var/folders/_l/c0pq4q6x4s18_0gwz71k7rxh0000gn/T/")

When I call env command in terminal (bash) I see:

TERM_PROGRAM=Apple_Terminal
SHELL=/bin/bash
TERM=xterm-256color
TMPDIR=/var/folders/_l/c0pq4q6x4s18_0gwz71k7rxh0000gn/T/
Apple_PubSub_Socket_Render=/private/tmp/com.apple.launchd.C9YuTSh5eC/Render
TERM_PROGRAM_VERSION=343
TERM_SESSION_ID=D2E63B32-CA2F-4E55-8AD3-C44AE78F6846
USER=shamil
SSH_AUTH_SOCK=/private/tmp/com.apple.launchd.sXAKBnTj28/Listeners
__CF_USER_TEXT_ENCODING=0x1F5:0x0:0x0
PATH=/opt/local/bin:/opt/local/sbin:/Users/shamil/opt/Qt/5.3/clang_64/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin:/usr/local/go/bin
PWD=/Users/shamil/Downloads/sw
XPC_FLAGS=0x0
XPC_SERVICE_NAME=0
SHLVL=1
HOME=/Users/shamil
LOGNAME=shamil
LC_CTYPE=UTF-8
DISPLAY=/private/tmp/com.apple.launchd.d6LQTxBQ1t/org.macosforge.xquartz:0
_=/usr/bin/env
OLDPWD=/Users/shamil

Therefore Qt's PATH vs bash's PATH (echo $PATH):

Qt: /Users/shamil/opt/Qt/5.3/clang_64/bin:/usr/bin:/bin:/usr/sbin:/sbin

vs

Bash: /opt/local/bin:/opt/local/sbin:/Users/shamil/opt/Qt/5.3/clang_64/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin:/usr/local/go/bin

My ~/.profile is:

export PATH="/opt/local/bin:/opt/local/sbin:/Users/shamil/opt/Qt/5.3/clang_64/bin:$PATH"

My /etc/paths:

/usr/local/bin
/usr/bin
/bin
/usr/sbin
/sbin

My /etc/paths.d folder contains two files:

40-XQuartz

/opt/X11/bin

go

/usr/local/go/bin

This issue affects only on Mac OS X.