Add a script to capture preprocessor #define statements

.gitignore

@@ -57,6 +57,7 @@ clean.log
 make.log
 .previous_build
 .current_build
+*.defines
 
 # Visual Studio
 .vs

scripts/dump-preprocessor-defines.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+# Copyright (C) 2020  Kevin Croft <krcroft@gmail.com>
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# This script captures pre-processor #define statements
+# matching the as-compiled state of the source file.
+# The script runs recursively for all source files, and
+# saves the results in corresponding <source>.defines file.
+#
+set -euo pipefail
+
+# Ensure the project has been configured
+if [[ ! -f config.h ]]; then
+	echo "config.h not found. Please ./configure the project first"
+	exit 1
+fi
+
+# Gather include paths
+root_dir="$(pwd)"
+root_include="$root_dir/include"
+gcc_includes="$(gcc -xc++ -E -v - < /dev/null 2>&1 | grep '^ ' | tail -n +2 | sed 's/^ /-I/' | xargs)"
+sdl_includes="$(sdl2-config --cflags)"
+
+# Round up our source files
+sources=( "$(find . -name '*.cpp' -o -name '*.c')" )
+
+# Run it
+parallel \
+	"g++ -std=gnu++11 \
+	    $gcc_includes \
+	    $sdl_includes \
+	    -I$root_dir \
+	    -I$root_include \
+	    -I{//} \
+	    -DHAVE_CONFIG_H \
+	    -E -dM -include '{}' - < /dev/null 2> /dev/null \
+	    | grep '^#define' > '{.}.defines' \
+	    ; echo '{} to {.}.defines'" ::: "${sources[@]}"