Add a basic linter for input files

main.mk

@@ -156,6 +156,17 @@ $(TEST_REPORT): $(drafts_html) $(drafts_txt)
 	done; \
 	echo '</testsuite>' >>$@
 
+.PHONY: lint
+lint::
+	@err=0; for f in $(join $(drafts),$(draft_types)); do \
+          if [  ! -z "$$(tail -c 1 "$$f")" ]; then \
+            echo "$$f has no newline on the last line"; err=1; \
+          fi; \
+          if grep -n ' $$' "$$f"; then \
+            echo "$$f contains trailing whitespace"; err=1; \
+          fi; \
+	done; [ "$$err" -eq 0 ]
+
 ## Cleanup
 COMMA := ,
 .PHONY: clean

pre-commit.sh

@@ -2,29 +2,32 @@
 
 exec 1>&2
 
-# No tests to update gh-pages
 BRANCH=$(git symbolic-ref --short HEAD 2>/dev/null)
 if [ "$BRANCH" = "gh-pages" -o "$BRANCH" = "gh-issues" -o -e .git/MERGE_HEAD ]; then
      exit
 fi
 
-files=($(git status --porcelain draft-* | sed '/^[MARCU]/{s/.*draft-/draft-/;p;};d'))
+hash gmake 2> /dev/null && MAKE=gmake || MAKE=make
+
+function abort() {
+    echo "Commit refused: documents don't build successfully."
+    echo "To commit anyway, run \"git commit --no-verify\""
+    exit 1
+}
+trap abort ERR
+
+files=($(git status --porcelain draft-* | sed '/^[MARCU]/{s/.*draft-/draft-/;p;};d' | sort))
 tmpfiles=()
 txtfiles=()
-trap 'rm -f "${tmpfiles[@]}" "${txtfiles[@]}"' ERR EXIT
+trap 'rm -f "${tmpfiles[@]}" "${txtfiles[@]}"' EXIT
 for f in "${files[@]}"; do
     tmp="${f%.*}"-tmp$$."${f##*.}"
     tmpfiles+=("$tmp")
     txtfiles+=("${tmp%.*}.txt")
     # This makes a copy of the staged file.
     git show :"$f" > "$tmp"
 done
-hash gmake 2> /dev/null && MAKE=gmake || MAKE=make
-[ "${#txtfiles[@]}" -eq 0 ] || "$MAKE" "${txtfiles[@]}"
-RESULT=$?
+[ "${#txtfiles[@]}" -eq 0 ] && exit 0
 
-if [ $RESULT -ne 0 ]; then
-  echo "Commit refused -- documents don't build successfully."
-  echo "To commit anyway, run \"git commit --no-verify\""
-  exit 1
-fi
+"$MAKE" "${txtfiles[@]}"
+"$MAKE" lint "drafts=${txtfiles[@]%.*}"