How linux and g++ understand what include path it needs to use? - c++

Question

I'm not quite completely understand how linux or g++ (gcc) define what include path it need to use to find some package. Here is what I mean:
I actually have a c++ project in QtCreator and I use qmake build system. I include in my code a header-only framework file, which needs a Boost of one of the last version. I have already in my system boost-1.64.0, but it's too old, so I've installed boost-1.80.0. But when I try to build the program a compilation error raises with the text:
{name_of_my_pro_file}.pro: rpm boost1.64.0-devel is not installed!!!
I thought if I just replace boost folder in /usr/include/ or /usr/local/include/ with folder of the newer boost version linux can use it instead of older one. But the error mentioned above still raises. I've tried to edit boost folder name in Makefile. Directly in my .pro file there is not any mentions about boost. But nothing helped me. I can handle it only when I renamed boost-1.80.0 folder to boost-1.64.0. And now it works.
It seems that name boost-1.64.0 is written somewhere in the system and it doesn't see any other packages.
I guess that I just don't understand how to work with this stuff correctly and doing something wrong. Can somebody explain what should I do?
My distro is Oracle Linux Server 8.4.
EDIT:
My .pro file:
QT += core gui network xml
QMAKE_CXXFLAGS += -std=c++0x
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = TilesDataProvider
TEMPLATE = app
#DESTDIR = ./output
DEFINES += QT_DEPRECATED_WARNINGS
DEFINES += QT_DEPRECATED_WARNINGS
CONFIG += no_abi_dump
INCLUDEPATH += \
$$PWD \
$$PWD\guts \
$$PWD\SRTM \
$$PWD\tileSources \
/usr/include
CONFIG(release, debug|release){
message(release)
TARGET = TilesDataProvider
OBJECTS_DIR = tmp/TilesDataProvider/release
MOC_DIR = tmp/TilesDataProvider/moc
}
CONFIG(debug, debug|release){
message(debug)
TARGET = TilesDataProvider_d
OBJECTS_DIR = tmp/TilesDataProvider/debug
MOC_DIR = tmp/TilesDataProvider/moc
DEFINES += _DEBUG
}
SOURCES += \
main.cpp \
tileSources/MapTileSource.cpp \
tileSources/SrtmTileSource.cpp \
guts/Position.cpp \
guts/t_task.cpp \
guts/MapConversions.cpp \
SRTM/altdatabank.cpp \
SRTM/altdatamap.cpp \
SRTM/geoid.cpp \
SRTM/srtm_coordinate.cpp \
SRTM/t_geodata.cpp \
SRTM/t_pageid.cpp \
t_image.cpp \
tilesdataprovider.cpp
HEADERS += \
tileSources/MapTileSource.h \
tileSources/SrtmTileSource.h \
guts/MapGraphics_global.h \
guts/Position.h \
guts/t_task.h \
guts/MapConversions.h \
SRTM/altdatabank.h \
SRTM/altdatamap.h \
SRTM/geoid.h \
SRTM/srtm_coordinate.h \
SRTM/t_geodata.h \
SRTM/t_pageid.h \
SRTM/tiff_param.h \
t_image.h \
tilesdataprovider.h