1 files changed, 27 insertions, 0 deletions
diff --git a/bin/find-unused-defines.sh b/bin/find-unused-defines.sh
new file mode 100755
index 000000000000..6c07de4aeea5
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+++ b/bin/find-unused-defines.sh
@@ -0,0 +1,27 @@
+#
+# This is a pretty brute-force approach. It takes several hours to run on a top-spec MacbookAir.
+# It also produces some false positives, so it requires careful examination and testing of the results.
+#
+# Algorithm Summary:
+#   First we find all #defines,
+#   then we search for each of them in turn,
+#   and if we find only one instance of a #define, we print it out.
+#
+# Algorithm Detail:
+# (1) find #defines, excluding the externals folder
+# (2) extract just the constant name from the search results
+# (3) trim blank lines
+# (4) sort the results, mostly so I have an idea how far along the process is
+# (5) for each result:
+#   (6) grep for the constant
+#   (7) use awk to to check if only one match for a given constant was found
+#   (8) if so, generate a sed command to remove the #define
+#
+git grep -P '^#define\s+\w+\s+\w' -- "[!e][!x][!t]*" \
+  | cut -s -d ' ' -f 2 \
+  | sed '/^$/d' \
+  | sort \
+  | xargs -Ixxx sh -c \
+    "git grep -w 'xxx' | awk -f bin/find-unused-defines.awk -v p1=xxx && echo \"xxx\" 1>&2"
+
+