1 files changed, 50 insertions, 0 deletions
diff --git a/meson/cleanup-install.bash b/meson/cleanup-install.bash
new file mode 100755
index 000000000..3e229cbc6
--- /dev/null
+++ b/meson/cleanup-install.bash
@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+# Meson will call this with an absolute path to Bash.
+# The shebang is just for convenience.
+
+# The parser and lexer tab are generated via custom Meson targets in src/libexpr/meson.build,
+# but Meson doesn't support marking only part of a target for install. The generation creates
+# both headers (parser-tab.hh, lexer-tab.hh) and source files (parser-tab.cc, lexer-tab.cc),
+# and we definitely want the former installed, but not the latter. This script is added to
+# Meson's install steps to correct this, as the logic for it is just complex enough to
+# warrant separate and careful handling, because both Meson's configured include directory
+# may or may not be an absolute path, and DESTDIR may or may not be set at all, but can't be
+# manipulated in Meson logic.
+
+set -euo pipefail
+
+echo "cleanup-install: removing Meson-placed C++ sources from dest includedir"
+
+if [[ "${1/--help/}" != "$1" ]]; then
+	echo "cleanup-install: this script should only be called from the Meson build system"
+	exit 1
+fi
+
+# Ensure the includedir was passed as the first argument
+# (set -u will make this fail otherwise).
+includedir="$1"
+# And then ensure that first argument is a directory that exists.
+if ! [[ -d "$1" ]]; then
+	echo "cleanup-install: this script should only be called from the Meson build system"
+	echo "argv[1] (${1@Q}) is not a directory"
+	exit 2
+fi
+
+# If DESTDIR environment variable is set, prepend it to the include dir.
+# Unfortunately, we cannot do this on the Meson side. We do have an environment variable
+# `MESON_INSTALL_DESTDIR_PREFIX`, but that will not refer to the include directory if
+# includedir has been set separately, which Lix's split-output derivation does.
+# We also cannot simply do an inline bash conditional like "${DESTDIR:=}" or similar,
+# because we need to specifically *join* DESTDIR and includedir with a slash, and *not*
+# have a slash if DESTDIR isn't set at all, since $includedir could be a relative directory.
+# Finally, DESTDIR is only available to us as an environment variable in these install scripts,
+# not in Meson logic.
+# Therefore, our best option is to have Meson pass this script the configured includedir,
+# and perform this dance with it and $DESTDIR.
+if [[ -n "${DESTDIR:-}" ]]; then
+	includedir="$DESTDIR/$includedir"
+fi
+
+# Intentionally not using -f.
+# If these files don't exist then our assumptions have been violated and we should fail.
+rm -v "$includedir/nix/parser-tab.cc" "$includedir/nix/lexer-tab.cc"