apache2 build fails in yocto - "/usr/local/include" is unsafe for cross-compilation [-Wpoison-system-directories]

Question

I was trying to build apache2 on yocto. But I was getting below errors.

ERROR: This autoconf log indicates errors, it looked at host include and/or library paths while determining system capabilities. Rerun configure task after fixing this.

Some googling led me to https://lists.yoctoproject.org/pipermail/yocto/2012-March/005125.html

So I looked into conf.log and find out those lines:

cc1: warning: include location "/usr/local/include" is unsafe for
cross-compilation [-Wpoison-system-directories]

arm-poky-linux-gnueabi/4.9.2/ld: warning: library search path "/usr/local/lib" 
is unsafe for cross-compilation

I googled again but, I couldn't understand 3 things yet:

1. Why has the PATH been set to local path ?
2. Why does this error only come when building apache2 [ I can build ngnix, cryptsetup, etc..]
3. How can I fix it?

Answer 1

Usually these types of errors come from configure scripts that have paths (like /usr/local/include, /usr/include and all sorts of other variations) hardcoded into them. So the way to fix it is to patch configure.ac (if there is one in the package, of course, configure otherwise) removing this paths.

For example, take a look at patch for pure-ftpd from current meta-oe, it solves similar problem:

--- a/configure.ac
+++ b/configure.ac
@@ -100,18 +100,6 @@ AC_ARG_VAR(PYTHON,local path to the python interpreter)
 python_possible_path="/usr/bin:/usr/local/bin:/bin:/opt/python/bin:/opt/python/usr/bin:/opt/python/usr/local/bin"
 AC_PATH_PROG(PYTHON,python,/usr/bin/env python,$python_possible_path)

-if test -d /usr/local/include; then
-  CPPFLAGS="$CPPFLAGS -I/usr/local/include"
-fi
-
-if test -d /usr/kerberos/include; then
-  CPPFLAGS="$CPPFLAGS -I/usr/kerberos/include"
-fi
-
-if test -d /usr/local/lib; then
-  LDFLAGS="$LDFLAGS -L/usr/local/lib"
-fi
-
 CPPFLAGS="$CPPFLAGS -D_FORTIFY_SOURCE=2"

 dnl Checks for header files