eclass/multilib-build: add MULTILIB_UNCHECKED_HEADERS variable

This implements the per-header multilib_check_headers()
exclusion feature I discussed on -dev.

MULTILIB_UNCHECKED_HEADERS is in the same format as
MULTILIB_WRAPPED_HEADERS and prevents multilib_check_headers()
from tracking any header listed therein.

Except insofar as both provide a means to prevent
multilib_check_headers fatalities, the two variables
are orthogonal.

Signed-off-by: Gregory M. Tuner <gmt@be-evil.net>

1 files changed, 38 insertions, 2 deletions

diff --git a/eclass/multilib-build.eclass b/eclass/multilib-build.eclass
index 1a5c08f..da34923 100644
--- a/eclass/multilib-build.eclass
+++ b/eclass/multilib-build.eclass
@@ -235,6 +235,28 @@ multilib_for_best_abi() {
 	multibuild_for_best_variant _multilib_multibuild_wrapper "${@}"
 }
 
+# @ECLASS-VARIABLE: MULTILIB_UNCHECKED_HEADERS
+# @DESCRIPTION:
+# A list of header files to ignore when checking for header conflicts.
+# If an ebuild or eclass author has implemented their own solution
+# to a possible header conflict, (if appropriate, that solution may
+# simply be to ignore it, which would typically result in the
+# best-ABI's header being installed (see: multilib_for_best_abi)
+#
+# This variable has to be a bash array. Paths shall be relative to
+# installation root (${ED}), and name regular files.
+#
+# Note that if a header appears in MULTILIB_WRAPPED_HEADERS, adding
+# it to this array, as well, will not prevent the header from being
+# wrapped.
+#
+# Example:
+# @CODE
+# MULTILIB_UNCHECKED_HEADERS=(
+#	/usr/include/foobar/config.h
+# )
+# @CODE
+
 # @FUNCTION: multilib_check_headers
 # @DESCRIPTION:
 # Check whether the header files are consistent between ABIs.
@@ -243,10 +265,24 @@ multilib_for_best_abi() {
 # It obtains the header file checksums and compares them with previous
 # runs (if any). Dies if header files differ.
 multilib_check_headers() {
+	_multilib_check_header_filter()
+	{
+	    local exgrep="" hdr
+	    for hdr in "${MULTILIB_UNCHECKED_HEADERS[@]}" ; do
+	        exgrep="${exgrep}${exgrep:+|}\s${ED}${hdr#/}\$"
+	    done
+	    if [[ ${exgrep} ]]; then
+	        egrep -v "${exgrep}"
+	    else
+	        tee /dev/null
+	    fi
+		return 0
+	}
 	_multilib_header_cksum() {
 		[[ -d ${ED}usr/include ]] && \
-		find "${ED}"usr/include -type f \
-			-exec cksum {} + | sort -k2
+			find "${ED}"usr/include -type f -exec cksum {} + | \
+				_multilib_check_header_filter | \
+					sort -k2
 	}
 
 	local cksum=$(_multilib_header_cksum)