scripts: add a helper script to run clang's static analyzer

Using clang's static analyzer is as simple as running "scan-build make",
but in order to obtain clean and reproducible results, the build
environment has to be cleaned beforehand ("make clean distclean").

Moreover the project requires running "make install" before "make test"
in order to install the dependencies needed for the tests, and running
these tests with the newly-built libraries requires a specific
LD_LIBRARY_PATH. This new script takes care of setting up everything
which is needed.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>

scripts/.gitignore

@@ -0,0 +1 @@
+/output-scan-build/

scripts/run-scan-build

@@ -0,0 +1,33 @@
+#!/bin/sh
+# Run clang's static analyzer (scan-build) and record its output in output-scan-build/
+
+# Ensure the current directory is where this script is
+cd "$(dirname -- "$0")" || exit $?
+
+OUTPUTDIR="$(pwd)/output-scan-build"
+
+# Display the commands which are run, and make sure they succeed
+set -x -e
+
+# Use a temporary directory as an installation directory, if $DESTDIR is not set
+if [ -z "$DESTDIR" ] ; then
+    DESTDIR="$(mktemp --tmpdir -d scan-build-destdir-XXXXXXXXXX)"
+fi
+
+# Make sure to use the newly-installed libraries when running tests
+export LD_LIBRARY_PATH="$DESTDIR/usr/lib:$DESTDIR/lib"
+export PATH="$DESTDIR/usr/sbin:$DESTDIR/usr/bin:$DESTDIR/sbin:$DESTDIR/bin:$PATH"
+export PYTHONPATH="$DESTDIR$(${PYTHON:-python} -c "from distutils.sysconfig import *;print(get_python_lib(prefix='/usr'))")"
+export RUBYLIB="$DESTDIR/$(${RUBY:-ruby} -e 'puts RbConfig::CONFIG["vendorlibdir"]'):$DESTDIR/$(${RUBY:-ruby} -e 'puts RbConfig::CONFIG["vendorarchdir"]')"
+
+# Build and analyze
+make -C .. CC=clang clean distclean -j"$(nproc)"
+scan-build -analyze-headers -o "$OUTPUTDIR" make -C .. CC=clang DESTDIR="$DESTDIR" install install-pywrap install-rubywrap all test
+
+# Reduce the verbosity in order to keep the message from scan-build saying
+# "scan-build: Run 'scan-view /.../output-scan-build/2018-...' to examine bug reports.
+set +x
+
+# Remove the destination directory without using "rm -rf"
+chmod u+w "$DESTDIR/usr/bin/newrole"
+rm -r "$DESTDIR"