DEPR: Adding script to detect deprecated features by version (#6581)

scripts/list_future_warnings.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+
+# Check all future warnings in Python files, and report them with the version
+# where the FutureWarning was added.
+#
+# This is useful to detect features that have been deprecated, and should be
+# removed from the code. For example, if a line of code contains:
+#
+#     warning.warn('Method deprecated', FutureWarning, stacklevel=2)
+#
+# Which is released in Pandas 0.20.0, then it is expected that the method
+# is removed before releasing Pandas 0.24.0, including the warning. If it
+# is not, this script will list this line, with the version 0.20.0, which
+# will make it easy to detect that it had to be removed.
+#
+# In some cases this script can return false positives, for example in files
+# where FutureWarning is used to detect deprecations, or similar. The EXCLUDE
+# variable can be used to ignore files that use FutureWarning, but do not
+# deprecate functionality.
+#
+# Usage:
+#
+#     $ ./list_future_warnings.sh
+
+EXCLUDE="^pandas/tests/|"  # tests validate that FutureWarnings are raised
+EXCLUDE+="^pandas/util/_decorators.py$|"  # generic deprecate function that raises warning
+EXCLUDE+="^pandas/util/_depr_module.py$|"  # generic deprecate module that raises warnings
+EXCLUDE+="^pandas/util/testing.py$|" # contains function to evaluate if warning is raised
+EXCLUDE+="^pandas/io/parsers.py$"  # implements generic deprecation system in io reading
+
+BASE_DIR="$(dirname $(dirname $(realpath $0)))"
+cd $BASE_DIR
+FILES=`grep -RIl "FutureWarning" pandas/* | grep -vE "$EXCLUDE"`
+OUTPUT=()
+IFS=$'\n'
+
+for FILE in $FILES; do
+    FILE_LINES=`git blame -sf $FILE | grep FutureWarning | tr -s " " | cut -d " " -f1,3`
+    for FILE_LINE in $FILE_LINES; do
+        TAG=$(git tag --contains $(echo $FILE_LINE | cut -d" " -f1) | head -n1)
+        OUTPUT_ROW=`printf "%-14s %-16s %s" ${TAG:-"(not released)"} $FILE_LINE $FILE`
+        OUTPUT+=($OUTPUT_ROW)
+    done
+done
+
+printf "%s\n" "${OUTPUT[@]}" | sort -V