mjhjmtu

I've installed a library to ~/.local. The environment variables are set as shown below:

$ echo $LD_LIBRARY_PATH
/home/saga//.local/lib
$ echo $PKG_CONFIG_PATH
/home/saga//.local/lib/pkgconfig

There's an re2.pc file in /home/saga//.local/lib/pkgconfig whose contents are:

prefix=/home/saga//.local
exec_prefix=/home/saga//.local
includedir=/home/saga//.local/include
libdir=/home/saga//.local/lib

Name: re2
Description: RE2 is a fast, safe, thread-friendly regular expression engine.
Version: 0.0.0
Cflags: -std=c++11 -pthread -I$includedir
Libs: -pthread -L$libdir -lre2

There's an re2 directory in /home/saga//.local/include which contains re2.h. But when I try to compile a program which includes re2.h, I get the following error:

$ g++ tst.cpp
tst.cpp:1:9: fatal error: re2/re2.h: No such file or directory
 #include<re2/re2.h>
 ^~~~~~~~~~~
compilation terminated.

and

$ g++ tst2.cpp
tst.cpp:1:9: fatal error: re2.h: No such file or directory
 #include<re2.h>
 ^~~~~~~
compilation terminated.

The output of pkg-config --libs re2 is -L/home/saga//.local/lib -pthread -lre2

How can I fix this?

You're not actually using pkg-config...

$ g++ $(pkg-config --cflags re2) tst.cpp

You can try running pkg-config in debug mode with:

$ pkg-config --cflags-only-I re2 --debug

It should print something like this:

< cut >
Looking for package 're2'
Looking for package 're2-uninstalled'
Reading 're2' from file '/home/saga/.local/lib/pkgconfig/re2.pc'
Parsing package file '/home/saga/.local/lib/pkgconfig/re2.pc'
 line>prefix=/home/saga//.local
 Variable declaration, 'prefix' has value '/home/saga//local'
 line>exec_prefix=/home/saga//.local
 Variable declaration, 'exec_prefix' has value '/home/saga//local'
 line>includedir=/home/saga//.local/include
 Variable declaration, 'includedir' has value '/home/saga//.local/include'
 line>libdir=/home/saga//.local/lib
 Variable declaration, 'libdir' has value '/home/saga//.local/lib'
 line>
 line>Name: re2
 line>Description: RE2 is a fast, safe, thread-friendly regular expression engine.
 line>Version: 0.0.0
 line>Cflags: -std=c++11 -pthread -I$includedir
 line>Libs: -pthread -L$libdir -lre2
Path position of 're2' is 1
Adding 're2' to list of known packages
 pre-remove: re2
 post-remove: re2
 original: re2
 sorted: re2
adding CFLAGS_I string "-I/home/saga//.local/include "
returning flags string "-I/home/saga//.local/include "
-I/home/saga//.local/include

You can see that the last line is what you're currently missing.