boost include directives use double quotes incorrectly

[John Maddock]

Extracted from issue ​https://svn.boost.org/trac/boost/ticket/11516:

Many Boost headers use double-quoted include directives with paths that are not relative to the current header file. For example, this is an excerpt from boost/aligned_storage.hpp:

#include "boost/config.hpp" #include "boost/detail/workaround.hpp"

This will cause the full search path to be searched for the given files, even the directories supposedly local to the application (set via -iquote option on GCC/Clang), which can make local files interfere with Boost, especially if there's some part in the local project that is also called "boost"...

See a full list of offending directives via:

find /usr/include/boost -type f -exec grep '#.*"boost/' {} +

As can be seen in boost/any.hpp, this might even be intentional for boost/config.hpp, but this is surely not intended for any other file. Handling of boost/config.hpp is not uniform, however; see for example boost/limits.h, which includes config.hpp via angle-quotes.

This bug report does not address double-quoted include directives with header-relative paths, as used copiously by Boost Spirit, for example. These work fine on GCC/Clang and do not interact with local code (but see #3762).

I suggest to change all include directives to a uniform style in order to eliminate interference of local files. The easiest and least-invasive solution would be to change double quotes to angle brackets, something along the lines of

find /usr/include/boost -type f -exec sed -i~ -e 's/\(#.* \)"\(boost\/.*\)"/\1<\2>/' {} +

(warning: search-and-destroy capability; this also updates #defines that are used later in #include directives)

After applying this command, my code still compiles and passes all unit tests, but strace confirms that project-local include directories are no longer searched, except for boost/mpl/aux_/preprocessed/gcc/*.hpp, which is due to some stringification macro magic in boost/mpl/aux_/include_preprocessed.hpp. That's probably obscure enough to not matter in practice.