Peephole cleanup

manual.md

@@ -1132,6 +1132,16 @@ Console Print and Input Statements
       S = 1234
       ? #6, "SCORE: "; COLOR(32) S
 
+  A function called from within a
+  `PRINT` statement must only compute
+  and return its value. It must not
+  perform its own output or change the
+  I/O channel: the channel and print
+  color are statement-local, so a
+  nested `PRINT` changes the state
+  expected by the rest of the outer
+  statement.
+
   The `TAB` function advances the
   position to a column multiple of the
   argument, so that `TAB(10)` is the

rules.mak

@@ -43,6 +43,8 @@ clean:
 	$(Q)rm -f $(TESTS_ATB)
 	$(Q)rm -f $(TESTS_LBL)
 	$(Q)rm -f $(TESTS_STAMP)
+	$(Q)rm -f $(PEEPHOLE_COVERAGE_FILES)
+	$(Q)rmdir $(PEEPHOLE_COVERAGE_DIR) 2>/dev/null || true
 	$(Q)if [ -d build/tests ]; then \
 		for manifest in build/tests/.fbtest-manifest-*; do \
 			[ -f "$$manifest" ] || continue; \